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SILICON CHIP If you are seeing a blank page here, it is more than likely that it contained advertising which is now out of date and the advertiser has requested that the page be removed to prevent misunderstandings. Please feel free to visit the advertiser’s website: www.jaycar.com.au Contents Vol.21, No.7; July 2008 SILICON CHIP www.siliconchip.com.au Features 11 House Wiring: Looking At Light Switches How standard and 2-way light switch circuits are wired – by Ross Tester 18 Review: Agilent MSO7034A Mixed Signal Oscilloscope It features four analog inputs, 16 digital inputs, an analog bandwidth of DC350MHz and a 12.1-inch LCD. We liked it so much, we bought it! – by Mauro Grassi Building The DSP Musicolour Light Show – Page 24. 40 Drumroll – Yet Another Picaxe You can never have too many I/O channels and the new Picaxe-20M has lots more – by Stan Swan Pro jects To Build 24 DSP Musicolour Light Show; Pt.2 Second article has the full assembly and test details – by Mauro Grassi 58 A PIC-Based Musical Tuning Aid Compact device can produce any note on the tempered musical scale in any of the eight most commonly used octaves & makes tuning musical instruments easy – by Jim Rowe PIC-Based Musical Tuning Aid – Page 58. 68 Balanced Mic Preamp For PCs & MP3 Players Easy-to-build circuit lets you connect a pro-quality balanced microphone to the line input of a PC soundcard or MP3 player, for high-quality voice recordings – by John Clarke 82 Bridge Adaptor For Stereo Power Amplifiers Want to connect two power amplifier modules in “bridge mode” to get four times the power from a single module into a single loudspeaker system? This simple adaptor is the answer – by Leo Simpson Special Columns 35 Circuit Notebook (1) Capacitance Meter; (2) Mobile Phones Can Power Picaxe Circuits; (3) Simple Door Guard Alarm; (4) Programming Remote Control Codes For The CD-ROM Playback Adaptor; (5) 12V CDI For Motorbikes; (6) Universal DingDong Chime Driver; (7) Picaxe 21 Game; (8) Expanded Scale Voltmeter Balanced Mic Preamp For PC Soundcards & MP3 Players – Page 68. 44 Serviceman’s Log My love-hate relationship – by the TV Serviceman 86 Vintage Radio The Astor KM 4-Valve Reflexed Receiver – by Rodney Champness Departments   2   3 23 57 Publisher’s Letter Mailbag Order Form Products Showcase siliconchip.com.au 93 Book Review 96 Ask Silicon Chip 34, 100 Notes & Errata 101 Market Centre Bridge Adaptor For Stereo Power Amplifiers – Page 82. July 2008  1 SILICON CHIP www.siliconchip.com.au Publisher & Editor-in-Chief Leo Simpson, B.Bus., FAICD Production Manager Greg Swain, B.Sc.(Hons.) Technical Editor John Clarke, B.E.(Elec.) Technical Staff Ross Tester Jim Rowe, B.A., B.Sc, VK2ZLO Mauro Grassi, B.Sc.(Hons.) Photography Ross Tester Reader Services Ann Morris Advertising Enquiries Glyn Smith Phone (02) 9939 3295 Mobile 0431 792 293 glyn<at>siliconchip.com.au Regular Contributors Brendan Akhurst Rodney Champness, VK3UG Mike Sheriff, B.Sc, VK2YFK Stan Swan SILICON CHIP is published 12 times a year by Silicon Chip Publications Pty Ltd. ACN 003 205 490. ABN 49 003 205 490 All material copyright ©. No part of this publication may be reproduced without the written consent of the publisher. Printing: Hannanprint, Noble Park, Victoria. Distribution: Network Distribution Company. Subscription rates: $89.50 per year in Australia. For overseas rates, see the subscription page in this issue. Editorial office: Unit 1, 234 Harbord Rd, Brookvale, NSW 2100. Postal address: PO Box 139, Collaroy Beach, NSW 2097. Phone (02) 9939 3295. Fax (02) 9939 2648. E-mail: silicon<at>siliconchip.com.au Publisher’s Letter Now is the time for Australia to build nuclear power stations In the Publisher’s Letter of the January 2008 issue, I discussed some of the possible implications of Australia’s ratification of the Kyoto Protocol and the Federal Government’s promise to set up a carbontrading scheme by 2010. Now, only six months later, some of those implications are turning out to have real bite. For example, I suggested that “Victoria’s brown coal-fired power stations could well get the chop and quite soon”. That prediction has been confirmed by recent financial analysts’ reports which highlight the resultant cost to Victoria’s electricity consumers. More importantly, the Federal Government’s actions are a real whammy on the potential price that the New South Wales Government will be able to get for the sale of its electricity generation and distribution assets. Since these are coal-fired generators, the prospect of heavy costs for carbon dioxide fees is likely to greatly reduce the eventual sale proceeds. So much so that the State government has mooted the possibility of listing some or all of the assets on the ASX as suitable for “mum and dad investors” (read “mug punters”). No doubt they will be listed as some sort of complicated “stapled security” which will be difficult for most investors to fully assess. If this does come to pass, I would suggest that all investors consult closely with their financial advisers. In fact, if the full effect of carbon trading is taken into account, the NSW State Government really should not be selling those assets. Instead, it should bite the bullet and invest in new generators in its own right. After all, the financial return on their generating assets has been excellent over the years, as they would be well aware. However, both State and Federal governments can act to ensure that their coal fired generating stations are not seriously devalued by the advent of carbon trading. How? Simply by converting them to nuclear power. In essence, all that needs to be done is to disconnect the existing coal fired boilers and hook up nuclear “kettles” instead. This solves the problem of carbon emissions in one fell swoop and we need not worry about complex and costly geosequestration schemes which have yet to be proven viable. Such an approach is entirely practical and could be done progressively over the next decade, with little disruption to supplies. It goes without saying that any new base-load power stations should either be nuclear or gas-fired. I have no doubt that the various state-run electricity authorities have already assessed all their power stations concerning the viability of such nuclear conversions. However, they are likely to have kept such assessments well under wraps until the political climate becomes more favourable to such conversion. Well, now is the time. Australia should not persist with the hypocrisy of being one of the biggest suppliers of uranium ore but not entertaining the idea of using nuclear power generation on its home soil. The sooner we make the change, the better. Leo Simpson ISSN 1030-2662 * Recommended and maximum price only. 2  Silicon Chip siliconchip.com.au MAILBAG Letters and emails should contain complete name, address and daytime phone number. Letters to the Editor are submitted on the condition that Silicon Chip Publications Pty Ltd may edit and has the right to reproduce in electronic form and communicate these letters. This also applies to submissions to “Ask SILICON CHIP” and “Circuit Notebook”. You need one STB for each TV set I really enjoyed your articles on digital TV in the March & April 2008 issues. I do have some problems with my home set-up and how I’m going to manage when digital finally becomes mandatory. We are pensioners and my wife is a semi-invalid and insomniac as well. As a result, we have three analog TV sets of varying ages linked to three VCRs, thus enabling a great deal of time shifting of programs. The sets are in different rooms and are fed from one antenna via a splitter. As we are in a high-strength signal area, we have no problems with that set-up. But after reading your articles, I am rather bemused as to what I can do, come the demise of analog TV. Changing the TV sets is not an option, so does that mean I have to buy three set-top boxes? If so, can they be fed from one antenna via a splitter, as is the case now? There may be other options but 100+ MPG from a Prius is nonsense The modified Prius (SILICON CHIP, February 2008) is using a charger! I can get 100+ MPG from my car too, if I don’t count all the energy (fuel) I put in. And he’s probably substituting coal-fired electricity for cleanly burnt Prius petrol. As the text says, “I wanted to be able to recharge the Li-ion batteries overnight . . .” and the circuit diagram on page 12 shows “connector for battery charger”. This was never an article about fuel economy. No attempt was made to measure the total energy used or to meter the electric power input. It is only about increasing the EV range of the Prius. You can’t compare the fuel economy of a standard Prius with a Prius charged from the mains. Fuel economy is not siliconchip.com.au some seem to be quite expensive. Perhaps a follow-up article with typical cases could be published. Ted Coultas, Mentone, Vic. Comment: the cessation of analog TV will be a problem for people with multiple analog sets since an STB can only deliver one video channel at a time. If you need to have three analog sets with three different off-air programs, you really do need three STBs. They can be fed from one antenna via a splitter, as you suggest. Improving power factor leads to increased power readings I read with interest the article in the May 2008 edition regarding the Enersonic Power Saver. Being in the electrical power industry, I was curious as to why Leo Simpson was surprised that after connecting his fridge via the Enersonic Power Saver the power consumption increased. He stated that the power factor was originally 0.57 and that after connecting via the “improved” by hiding some of the energy supplied. It is a pity that SILICON CHIP could not see this. Allen Reynolds, Glenfield, New Zealand. Comment: we don’t think you are strictly correct. One of the problems with the standard Prius is that its existing battery cannot store a lot of regenerated power and you cannot drive it very far at all on battery power alone. Hence the incorporation of more battery capacity is a big improvement and as you point out, you can use a charger and thereby greatly reduce the amount you are paying for the energy used. And while it is not a big factor, if the battery capacity is increased to enable more regenerated energy to be stored, this will bring about an improvement in petrol economy. device it improved to 0.87. It’s pretty obvious that the real power will increase as the formula states that P = VI (PF) Ross Carter, Peakhurst Heights, NSW. Comment: you are right, of course. So rather than saving money, the Enersonic Power Saver will lead to increased charges for the consumer. Vectrix Motor Scooter and brushless DC motors That was a great article (as always) on the Vectrix Motor Scooter in the May issue. As a two-wheeler myself I’ll be watching how these develop with much interest! But I disagree with you that there is “no such thing as a brushless DC motor” and with the description of the Vectrix motor as a 3-phase synchronous motor. Once upon a time, for an electric motor to run from DC, the current had to be switched mechanically to the commutator via carbon brushes. Now, with modern power transistors and smart electronics, the current is “electronically commutated” in the motor, doing away with the brushes; hence the term “brushless DC motor”. Perhaps we should say, “electronically commutated AC multi-phase motor that works from Direct Current” but that is a real mouthful! “Brushless DC” is much simpler. The implication in saying “DC motor” is what the motor needs in order to work. Just as an AC motor needs Alternating Current, what actually goes on inside the motor for it to work is not the point in question. And “brushless DC” also means there are no cantankerous brushes to wear out. This is gives a great improvement in reliability! And so to the next point: The Vectrix motor. I did a bit of Googling and it seems you are alone. The motor is described as a “brushless DC, radial air-gap motor”. I’m still trying to find it called anything other than “brushless DC”. July 2008  3 JOIN THE TECHNOLOGY AGE NOW with PICAXE Developed as a teaching tool, the PICAXE is a low-cost “brain” for almost any project Easy to use and understand, professionals & hobbyists can be productive within minutes. Free software development system and low-cost in-circuit programming. Variety of hardware, project boards and kits to suit your application. Digital, analog, RS232, 1-Wire™, SPI and I2C. PC connectivity. Applications include: Datalogging Robotics Measurement & instruments Motor & lighting control Farming & agriculture Internet server Wireless links Colour sensing Fun games Distributed in Australia by Microzed Computers Pty Limited Phone 1300 735 420 Fax 1300 735 421 www.microzed.com.au 4  Silicon Chip Vectrix is not the only battery-powered scooter I read the article on the Vectrix motorbike and enjoyed it tremendously. I would like to point out that EVT has been selling ADR’ed scooters for at least two years in Australia. I own the EVT 4000e and it took me nearly four hours to get it registered (June 2006) and I’m still unable to get it insured, as it does not appear on the vehicle register that most insurance companies hold. Information on the EVT 4000e can be found at http://www.evtaustralia. com.au/evt-4000.pdf The only problem I have found with the EVT 4000e is the battery cycling. The “fuel gauge” (I use that term very loosely) on the dash Be that as it may, head over to Microchip.com and do a document search for BLDC and you’ll find a heap of stuff for all things PICs and Brushless. There is a document titled: “Overview – Brushless DC Motor en026720.doc”. It gives a brief but good description of what a brushless DC motor is and how it works. It implies that the motor itself is a 3-phase device but if you take it as a whole with its H-bridge switchers, microcontroller and rotary encoder, then it becomes a motor that does not run directly off a DC voltage source. For more information have a look at document AN885 – “Brushless DC (BLDC) Motor Fundamentals” from Microchip. It’s a good read and really answers the whole question about BLDC motors. I’m glad someone has made a practical electric motorbike! I have long pondered about using a BLDC motor in the front wheel of an engine-powered bike (such as a motocross type) to make it a “two-wheel drive”. These are not new by any means. I think a 2-wheel drive motorbike was first invented back in the 1940s but the problem has always been with unreliability from all the extra mechanical parts. Yamaha tried using hydraulics a few years ago but it was too expensive and added too much weight. Honda recently announced a 2-wheel drive bike, using shaft drives, chain drives and bevel gears. But again, is the extra only has four LEDs to show level. The manual does not state the level of battery charge indicated by each LED. Consequently when the battery meter or “fuel gauge” reads empty, the state of charge of the batteries is only 10%. This in turn damages the batteries and severely reduces the recharging time, range and life span. It has taken me three sets of batteries to learn this and I am now working on constructing a watt-hour meter and four battery meters within a 16 x 2 LCD panel to replace the current battery meter. Alternatively, I may just trade my EVT in on a Vectrix. Craig D. Kaesler, Alice Springs, NT. complexity worth the effort? I think the BLDC motor is one versatile bit of gear. All us “techies” should get well acquainted with them. They may be powering your next mode of transportation! One last thing (and a change of subject): in the Serviceman’s Buzzword Glossary cartoon (page 60, May 2008 issue), it is bleedin’ly obvious that someone had used some whiteout and the name “Roger” (USB: Marry Me Roger) is not the original name. Just what was the original word? I’m curious to know! I love all the Serviceman cartoons and I study them closely as there is a lot of subtle humour in them. Thanks for a great magazine! David Vieritz, Mango Hill, Qld. Comment: it certainly seems as though the Vectrix article stimulated you to do some research. We can probably agree that all DC motors require commutation, whether it is achieved with brushes and a commutator or via electronic switching. On the other hand, a DC motor with brushes has the current commutated to change the direction of the rotors’ poles so that they are continually attracted by adjacent poles of the stator, thereby causing rotation of the rotor. In the Vectrix motor, regardless of whether you call it a synchronous or induction motor, the H-bridge 3-phase siliconchip.com.au Atmel’s AVR, from JED in Australia JED has designed a range of single board computers and modules as a way of using the AVR without SMT board design Pioneer’s halcyon days with NDFL In a letter to “Mailbag” (April 2008) titled “Microcontrollers and Obsessions with Low Distortion”, the writer, in the last paragraph, refers to nested differentiating feedback loops developed by Prof. Cherry (now retired) of Monash University. He also expressed his belief “that one of the major Japanese manufacturers snapped up the patent and shelved it”. Shortly after reading this, a friend showed me his 1981 Pioneer amplifier, purchased on eBay, complete with the original sales brochure. In the brochure Pioneer states (in their own words) that the technology of Nested Feedback Loops (NFL) – (as used in their model A5, A6, A7 and A8 amplifiers – aims for an improvement in distortion. It involves the use of nested differentiating feedback in multiple forms from the output stage. The technology was initiated by (then) Assoc. Prof. Edward M. Cherry of Monash University Australia. drive to the stator coils produces a sinusoidal rotating magnetic field which “pulls” the rotor around. This is the same principle used in AC induction motors (as invented by Nicola Tesla) and is quite different to the siliconchip.com.au This photo was taken on Friday, 18th April, 2008, at Pioneer Elect­ ronics Head Office, Braeside, Vic­ toria, in their main public reception area. I was quite taken aback as I quickly realised it was a stack of 1980s equipment, two pieces of which I have myself. This was a big blast from the past, before they all started producing black plastic audio & TV, some even with hard to read raised black printing on black plastic. Only recently have they been giving a choice of silver again but not usually in metal. The receptionist said many visitors gasp in appreciation and ask if they are available to buy! John Williamson, Cheltenham, Vic. Comment: there is little doubt that the presentation and finish of most hifi equipment from 20-30 years ago was far superior to that sold today. Arguably too, most consumers today have an inferior music listening experience, especially if all they listen to are iPod or MP3 players. commutation of a DC motor, whether it is done by transistors or brushes. In fact, using transistors for such simple commutation is never used, as far as we know. We therefore stand by our statement The AVR570 module (above) is a way of using an ATmega128 CPU on a user base board without having to lay out the intricate, surface-mounted surrounds of the CPU, and then having to manufacture your board on an SMT robot line. Instead you simply layout a square for four 0.1” spaced socket strips and plug in our pre-tested module. The module has the crystal, resetter, AVR-ISP programming header (and an optional JTAG ICE pad), as well as programming signal switching. For a little extra, we load a DS1305 RTC, crystal and Li battery underneath, which uses SPI and port G. See JED’s www site for a datasheet. AVR573 Single Board Computer This board uses the AVR570 module and adds 20 An./Dig. inputs, 12 FET outputs, LCD/ Kbd, 2xRS232, 1xRS485, 1-Wire, power reg. etc. See www.jedmicro.com.au/avr.htm $330 PC-PROM Programmer This programmer plugs into a PC printer port and reads, writes and edits any 28 or 32-pin PROM. Comes with plug-pack, cable and software. Also available is a multi-PROM UV eraser with timer, and a 32/32 PLCC converter. JED Microprocessors Pty Ltd 173 Boronia Rd, Boronia, Victoria, 3155 Ph. 03 9762 3588, Fax 03 9762 5499 www.jedmicro.com.au July 2008  5 Mailbag: continued Helping to put you in Control Motion Control We have a great selection of stepper motors, servo motors & drives High Performance Stepper Motors These bipolar stepper motors are industrial grade and are ideal for CNC applications. They range from the small MOT-110 (1kg-cm) … $22+GST to the large MOT-132 (87kg-cm) …$215+GST Stepper Motor Drives Our microstepping drives from Leadshine allow optimum performance. The M325 is a 2.5A 24VDC drive with 1,2,4 and 8 microstepping. $99+GST DC Servo Motors The permanent magnet DC brush servo motors are fitted with 500 line and 1000 line encoders. They provide low noise, high precision and high velocity. Prices start at $225+GST DC Servo Motor Drive The performance of the DB810A is as good or better than digital AC servo systems in velocity, precision, noise, stability. However, the cost of the DB810A is far lower $229.00+GST Serial Stepper Motor Controller Control up to 4 stepper motors from your serial port with ASCII Commands . $65+GST Parallel Port Interface Control up to 4 stepper motors. 2 relays and 4 limit switches. $45+GST Contact Ocean Controls Ph: 03 9782 5882 www.oceancontrols.com.au 6  Silicon Chip that “there is no such thing as a brushless DC motor”. As far as the cartoon is concerned, the apparent tampering of the script is an artefact of the scanner used by our cartoonist. PICAXE micros are great In response to your request for feedback, I’d like to say that I think your magazine is first rate. My interests lie in the area of computers & industrial applications for microcontrollers. I don’t make projects with pre-programmed PIC controllers, as I like the challenge of programming them myself. For this reason, I stick to the PICAXE microcontrollers, as their ease of use, simplicity of programming and reliability make them outstanding for just about anything. I am the Plant Engineer in a small process plant and I am always finding new uses for PICAXE projects, from simple temperature indicators to complex machinery control applications. The recent article using pressure sensors to measure tank levels is a good example, although I used a PICAXE controller for mine. This is not to say that I dislike other projects that you feature. These use circuits which are adaptable to virtually any application. I think you have a good balance of interests covered. As many of your projects are produced as kits, possibly some kit reviews could be featured. I’m thinking specifically of the Velleman USB experimenters interface kit, as this is outstanding. It is well-made, easy to use, can be easily controlled with Microsoft Excel Visual Basic macros using the supplied DLL procedures and is capable of quite sophisticated process control from a computer interface. I am in the process of adapting one to control a large industrial washing machine. Most projects these days are complex and a simple PICAXE 08M can replace a heap of discrete circuitry, although most circuits will still have additional components. I don’t see the point of using outdated compo- nentry when better is available. As an instance of this, I made a timer circuit to control a chemical pump using 555 and 741 ICs and when the weather was hot, it ran too fast and when cold it was too slow. Now I realise I could have added compensating circuitry to solve this problem but I decided to rebuild it and use a PICAXE 08. It has worked perfectly for four years. I also use the PICAXE data logger at work to carry out performance tests, etc. Features like the Circuit Notebook and Serviceman’s Log are very informative and well worth reading. I was able to copy all my old LPs to CD, thanks to articles from your magazine. Today, the world is run by digital electronics. I don’t see the point of using discrete components just for old time’s sake, and anyone who says there is no challenge in microcontrollers has not tried anything very ambitious. I thought the recent article on I2C & PICAXE VSM was excellent. I have purchased the VSM software and it is very useful, even if you use it to do nothing more than convert all your old circuit sketches into very professional looking circuit schematics. In short, I would say you have got the balance pretty right. Keep it up. Frank Williams, New Plymouth, NZ. Electric vehicles still some way off The ongoing debate regarding electric vehicles is always interesting reading and the prospects are exciting, but then those prospects have been with us for a very long time and we still aren’t there yet. A few things come to mind. Firstly, electric vehicles have been around for over 100 years and nobody should believe they are a new-age, green phenomenon. They have just been waiting all that time for a suitable battery to give the desired range, durability, cost, weight, recharge time, etc. Ultracapacitors are an exciting prospect but if the “electric fuel” problem hasn’t been solved in more than a century of trying, then I won’t be holding my breath. siliconchip.com.au Solar power systems under a cloud I mentioned in one of my letters to Mailbag (February 2008), the economics of grid-connected rooftop photovoltaic (PV) systems. I calculated the payback period after the rebates, at 59 years. However things have changed. Both South Australian and Queensland have now announced Feed-In-Tariffs (FITs) which are a more positive encouragement to going solar on a domestic level. Germany and Italy have for some time been paying customers more for the electricity they feed into the grid than the buying price. For example, in Germany the FIT is 80 Australian cents – two and a half times the buying rate. What’s more, this is calculated on the gross electricity produced, not just the surplus over consumption. South Australia and Queensland have just announced their schemes. A solar bonus of 44c/kWh will be paid for electricity fed into the grid at times when the solar system generates more electricity than the household or business is using. These schemes reward customers whenever they generate more electricity than they are using – not just the balance at the end of the quarter but whenever generation exceeds consumption during the day. It is not easy to calculate the payback period of such a scheme. It will obviously depend heavily on the pattern of usage of the owner of the installation. The advantage of calculating on the gross electricity produced from solar, rather than the excess, is that it is easy to predict with confidence what your payback period will be. On the other hand, it does not encourage efficient use. Using the example quoted in my Mailbag response to David Waplington, let us assume that a household is basically absent during the day and home outside the main sunshine hours, except on the weekends. In this mythical house, let us assume that it is only the fridge using power during the day. That is usually about 100W. Over the five or so hours per day, when the sun is on the panels, they will produce on average about 5.5kWh. Over the same time, the fridge will use 0.5kWh. Assuming over about 250 days, nobody is home and only the fridge is running, the surplus energy will be about 1250kWh per year or at a FIT of 44c/ kwh, $550 of electricity per year. Using David Waplington’s example of a 2.1kW system for $25,000, with an $8000 Federal rebate and $1000 carbon credit, this gives a payback, crudely calculated, of 29 years. Oh dear! Is this Peter Seligman yet again telling us that going green doesn’t work? Not at all. Go and do it! But we need to let our governments know that they are just going to have to try a lot harder if they want us to take this seriously. In Germany, where the FIT is much higher and is based on gross PV electricity production, the payback period is 15 years. Dr Peter Seligman, via email. Comment: unfortunately, this letter was received before the Federal Labour government announced the budget in May this year. This now involves a means test before the solar rebate of $8000 will be paid. PRIME ELECTRONICS Est. 1987 â 115 Compact DMM 3 YEAR WARRANTY CAT III 600V True RMS AC/DC Volts 600V AC/DC Amps 10A Resistance Continuity Frequency Capacitance List Price $245.00 siliconchip.com.au happened to the value of shares in gas companies when Edison introduced electric lighting and gas lighting became redundant overnight. Oil is a globally traded currency as much as a fuel commodity and if its value was greatly diminished by suddenly viable electric transport for the masses then I believe we would see a major upheaval in the world economy. Countries like Saudi Arabia may not Our Price $199.00 179/EDA2 Combo Kit LIMITED LIFETIME WARRANTY CAT III 1000V CAT IV 600V Kit Contains ● ● ● We must also consider that not every vehicle manufacturer is trying very hard to do away with fossil-fuel vehicles. I believe some are doing token research to make it appear that they are doing something when really their heart isn’t in it. And even if the perfect battery was invented tomorrow to make electric cars a long-range and quick-charge reality in the showrooms, what would that do for the value of oil stocks? Probably the same as what Diode Test Analog Bar Graph Backlight Min/Max/Avg Display Hold Auto/Manual Range Holster ● ● ● ● Fluke 179 True RMS DMM TL224 SureGripTM Silcone Test Lead Set TL910 Electronic Test Probe Set AC280 SureGripTM Hook Clip Set TPAK Magnetic Hanger 80BK Intergrated DMM Temp Probe C35 Soft Meter Case List Price $585.00 Our Price $499.00 Prices exclude GST Call for a 2008 Fluke Catalogue www.prime-electronics.com.au Brisbane (07) 3252 7466 Sydney (02) 9704 9000 July 2008  7 Mailbag: continued Modified laminator for toner transfer As a follow-up to my letter on a solder mask for SMDs (Mailbag, June 2008), I should mention that when “pasting”, I tape the solder mask to the PC board. The shimming material curled a bit when I transferred the toner and I have been unable to flatten it out completely. Perhaps it might be of interest to note that I use a modified laminator (with maximum heat ramped up to 140°C) to transfer the toner. I then be too happy to be less than filthy rich and unable to do anything about it. The conspiracy theorists would suggest that viable electric vehicle technology exists but has been suppressed for just those reasons – to save the world from economic meltdown, protect jobs, etc. Who really knows but certainly there is good reason to slow the progress in electric vehicle technology. Secondly, I’ve always wondered why we don’t have vehicles similar to diesel-electric locomotives, where an internal combustion engine drives a generator to power traction motors? Internal combustion engines work most efficiently at sustained medium to high RPM and a small, fuel-efficient diesel or gas-powered engine could 8  Silicon Chip pass it through the toner five or six times to ensure the toner melts properly. I found that the HP toner works far better than the Brother toner. The solder mask referred to in my letter was done “single sided”. If you apply toner to both sides I am sure that sharper edges would be produced. Registration of the two images is not easy and the example pictured is good enough for the job. Frank Winter, Buderim, Qld. do the job adequately. Indeed, I have heard of conversions in the US where the gearbox/transmission is replaced by a generator and the differential replaced with an electric motor. An engine change is optional and all else remains the same. To do the same, the manufacturing level could utilise existing body platforms and layout with little change needed except for wheel-mounted motors. So why the push towards the present hybrid arrangement or fully electric when an engine and generator combination appears to be viable and is proven to work for railway locomotives? And it could be incorporated into present body designs already on the production line, saving a fortune in redesign. Lastly, while a quick-charge fully electric vehicle might be the ideal, we seem to forget that not everyone can or does park his or her car off-street. So will our streets eventually be littered with extension cords when owners of these future vehicles need to recharge them overnight? I don’t jest – that would appear to be a real possibility unless someone has a better idea. Paul Carson, Westmead, NSW. Comment: the method of power transmission used in diesel electric locomotives is also applied to the very large trucks used in mining but it is not viable in smaller vehicles where its weight and complexity are greater than for conventional automatic or manual gearboxes. Nor is the idea of in-wheel motors really practical for cars because it greatly increases the unsprung weight of the suspension. Right of reply to MPG flak What a can of worms was opened as a result of SILICON CHIP’s use of the non-metric fuel consumption units on the cover of the February 2008 issue! How those poor respondees must suffer having to convert to ‘Bessie’s’ units all the time. By the way, were the “gallons” Imperial or US? There can be no such confusion with the use of litres! siliconchip.com.au Litres/100km is most useful. If I plan to drive 900km, at 9l/100km, I will require 100 litres of juice. Currently available at $1.50/l, that will cost $150. Try that with the equivalent mpg or km/l value! Perhaps kilo links per gallon would be better. I am well aware that the old units will never disappear unless civilisation begins again (and I expect that the same “wheels” will be reinvented). As a civil engineering student of the 1970s, I am well aware of the numerous “soft” conversions that have taken place with most building materials. The extreme “accuracy” of roofing sheet dimensions has been obviously deluding many people for a long time. Has Paul Carson noted that when fixing such materials it can (be made to) “shrink” or “grow” (in width) easily by about 6mm (1/4-inch) per sheet; a most useful feature for roofs that are not square! Paul has cited the TopGear program; perhaps this is not a good reference as it is produced in Lizzie Land. What will the producers do in an Australian version? It will be most interesting to note the outcome. At one point, dualscale tape measures and rulers were not produced for sale in Australia. The Imperial police have undermined that! Is Paul Carson referring to the rolling diameter of my vehicle’s wheel or the diameter of the rim (and exactly what part of the rim) on to which the tyre is fitted? A French tyre manufacturer’s (of repute) product fits my “Imperial” sized rim, as well as Australian tyres. Why is this so? Are/were Australian rims “soft converted” from metric in the first place. Most of the other products to which Paul refers are produced overseas; and over which we have no control. Bob Barnes pointed out that altimetry is still a feet-based system. Like his own production problems, there will probably not be a change to this measurement and associated functions. Flights (generally above 10,000 feet altitude, where “flight levels” are utilised) are flown in relation to See article SILICON CHIP May 2008 impAd_A4_outlines.indd 1 2/04/2008 9:47:50 AM the quadrant (heading) planned for the flight. The current (and acceptable) vertical separation of aircraft would be difficult to achieve if altimeters were metric instruments. I recently helped fill an aircraft with Avgas. The fuel Australia’s Lowest Priced DSO! Now you’ve got no excuse ... update your old analogue scopes! Whether you’re a hobbyist, TAFE college or university workshop, the GW GDS-1022 has the price and performance for you. GW GDS-1022 25MHz 25MHz Bandwidth, 2 Ch 250MS/s Real Time Sampling 4k Memory Per Channel TFT Colour Display 19 Auto Measurements Built-in USB & SD Card Slot GW Brand - 28 years in Australia Sydney Melbourne Tel 02 9519 3933 Tel 03 9889 0427 Fax 02 9550 1378 Fax 03 9889 0715 email testinst<at>emona.com.au siliconchip.com.au Brisbane Tel 07 3275 2183 Fax 07 3275 2196 Adelaide Tel 08 8363 5733 Fax 08 83635799 Perth ONLY $ Tel 08 9361 4200 Fax 08 9361 4300 web www.emona.com.au 499 inc GST SAVE $ 50 EMONA July 2008  9 Mailbag: continued was measured in litres) into the aircraft tank (marked with a maximum capacity in imperial gallons). A pilot will generally make flight plans using “gallons of fuel burnt per hour” as specified in the handling notes relating to that aircraft. The Bathurst race does not prove a thing as far as I am concerned. It used to use “real cars” that I could buy from a dealer. Why don’t they use kilograms of fuel any way? Litres or gallons could create a problem due to the density of the fuel. I still maintain that as we currently purchase fuel by the litre and distances are in kilometres, the Prius information should have been metric. Km/l would have been just as acceptable as l/100km. If not, please return to cycles per second (cps) and remove Hertz from frequency descriptions. Ray Smith, Hoppers Crossing, Vic. Clarification on electrolytic capacitor voltage ratings On page 90 of the April 2008 issue of SILICON CHIP, B.H. asks a very good question which I might suggest can be rephrased as “what is the minimum working voltage of an electrolytic capacitor”? I think you were a little rash with your comment “it is just wrong” in the sixth line of the third column. I would suggest the answer somewhat depends on the timeframe of how long you expect the capacitor to 10  Silicon Chip function and the amount of de-rating. An electrolytic capacitor with 0V on it for a long period of time develops undesirable characteristics. Volumes have been written in your magazine alone about how to reform such a capacitor. It seems to me that these undesirable characteristics might also develop if the capacitor is used with a working voltage very much less than its rated working voltage over a long period of time. B.H. might have expressed his concerns with his remark “losing too much efficiency” a little more precisely but I know what he means. I think he might be correct in some instances. I wonder if a 63V electrolytic capacitor, for example, used in a piece of equipment with, say, 1V DC and 0.1V RMS ripple might depolarise over time and in some instances cause the piece of equipment to malfunction. I have read that if an electrolytic capacitor is used at a derated voltage, that voltage will, over time, become the working voltage and if the original specified working voltage were to be suddenly applied that the capacitor may fail. Looking through capacitor manufacturer’s specifications, I can find little help on the topic of de-polarisation. Most of the manufacturers are in China now and have been manufacturing for such a short period of time that 10 years is almost infinity in their timeframe, so I imagine that depolarisation is not an issue. They no doubt imagine that their capacitors will become landfill long before depolarisation is a problem. Some years ago, other manufacturers did show on the capacitor figures like 50V (min.) 150V working. Like B.H., the question has also nagged me for some years and I think your answer is too simplistic. I suggest the correct answer is as “Humphrey” would say “yes and no”, or in this context “it all depends” or, more precisely, it depends on the magnitude of the derating and the expected mean time to failure of the capacitor. Maybe I am wrong and modern electrolytic capacitors do not depolarise and so your answer is correct but I am not holding my breath. Kenneth Moxham, Urrbrae, SA. Comment: it’s true that a 63V capacitor used for a very long time at a much lower voltage will tend to depolarise, to the extent that if you applied 63V to it, the leakage would initially be quite high. However, modern electrolytics are much more stable than in the days of yore and their leakage is much lower anyway, so this is not really a problem. We would also not expect the cap­ acitance or power factor of a 63V capacitor to deteriorate much over time when used at lower voltages, eg, 6V. Ideally though, if you have an application where the operating DC voltage is very low or zero, then a nonpolarised (NP) electrolytic capacitor SC should be used. siliconchip.com.au Continuing our series on D-I-Y house wiring – NZ style Looking at Light Switches A light switch is a light switch, right? You just flick it and the light comes on . . . Of course – but it is very obvious that many people think what goes on behind the architrave or wall is a black art. Magic, even! A siliconchip.com.au P LOO First of all, let’s have a look at a For a start, a light switch is a “double throw” device – this simply means that you can have it switch between two different circuits if you wish (see Fig.2). It has a “common” terminal (labelled C) and two switched terminals, usually labelled 1 and 2, either of which can be connected to the common terminal depending on which way the switch is positioned. You don’t need to connect to both switched terminals – in fact, in the 1 The standard light switch standard mains light switch. “What’s to look at,” you ask? Well, quite a lot when you look into it (pardon the pun!). We have shown both a photo and a drawing of the back of a light switch. As you can see, there are actually four screw terminals on the back – why, when for a standard switch function you need only two terminals. That’s true, but those four terminals give you quite a bit more flexibility than a simple off/on function. 2 C nd then there are those twoway or even three-way light switches which let you turn the light on and off from two or three locations. If single light switches are magic, two-way switches must be the stuff of sorcery to some! There are many areas of a home where two-way light switches make a lot of sense – any room or hallway, for example, where you can enter and leave by different doorways. But there is a right way and a wrong way to do it! More on this shortly. But before we go on, a warning (again!): even though the following is completely legal in New Zealand, it’s not legal in Australia unless you have an electrician’s or electrical contractor’s licence. As we mentioned last month, you might have a PhD in electrical engineering, or a lifetime of experience in electrical repair or assembly but that counts for nought without that ticket! OK, so we’ll assume you’re in NZ and want to replace a light switch. By Ross Tester The back of a standard light switch mechanism (in this case an HPM brand). The four terminals are C (common), switched terminals 1 & 2 and the non-connected “loop” terminal. In a normal light, terminal 2 is seldom used. And here’s a photo of the same thing. Terminal 2 is covered by a thin shield – if needed the shield is easy to remove. July 2008  11 vast majority of lighting installations, only one switched terminal (and the common) is used, effectively making it a “single throw” switch. Incidentally, it is impossible to use the switch to connect together the terminals labelled 1 and 2 – they can only be individually connected to the C (common terminal). You might notice from the photos that terminal 2 is normally covered by a thin PVC shield. To use the switch in its double throw mode you need to remove this (it’s quite easy with a small screwdriver). The standard switch is also a “single pole” device – again, this means that it will only switch one circuit (eg, switching power to a light). There are “double pole” switches available which can switch two circuits at the same time but these are neither required nor used in light switch applications. An example of a double pole switch is (usually) in the main switch in your powerboard. It will switch both Active and Neutral at the same time. Now, what about that fourth screw terminal? Look at the photo/drawing again. There is almost always one screw terminal off by itself (in fact, usually directly opposite the common and two switched terminals). It almost always has the word “loop” moulded into the plastic alongside. This terminal is simply used as an “anchor point” for other wires – for example, it may connect Active wires or Neutral wires together if required. You will almost certainly find the same terminal moulded into the light fitting itself. Only two terminals connect to the base of the bulb, supplying By contrast, the back of a modern Clipsal 530 BC (bayonet cap) light fitting. It’s quite similar in layout to the light switch, the main difference being the earth terminal (here clearly identified with an “E” as well as the green around it) instead of the “C” terminal of the light switch. Note also the looping terminal (identified with an “L” moulded into the plastic), as well as a more coppery colour. Like the light switch, the looping terminal plays no part except as a potential anchor point. The terminals which actually connect with the base of the lamp (here seen as more of a brass colour) are not polarised and can be connected either way around. 12  Silicon Chip SINGLE POLE SINGLE THROW (SPST) SINGLE POLE DOUBLE THROW (SPDT) DOUBLE POLE SINGLE THROW (DPST) DOUBLE POLE DOUBLE THROW (DPDT) Fig.1: for those not familiar with switch types, here are the four most common. The simplest, which simply makes or breaks a connection in one wire, is an SPST type – this is the switch you’ll most usually find inside appliances. Light switches are almost always SPDT types, even though the majority of the time they are used in SPST mode. SPDT can switch one wire to two different circuits.Where both active and neutral need to be switched at the same time, a DPST switch is used. Double pole switches are certainly not the largest available – you can easily get four pole (and more) switches. But where large numbers of circuits need to be switched simultaneously, a relay or contactor would normally be used. power to it. The third, again usually labelled “loop”, is used the same way as the loop terminal on the switch; that is, as a connection point for other wiring. Switch wiring colours Unlike flexible mains cables (or so-called “extension leads”), building cables haven’t largely switched over to the IEC colours of brown, blue and green/yellow for Active, Neutral and Earth respectively. Building cable, incidentally, invariably means cable with each of the conductors individually insulated and then sheathed with another layer of (usually white) PVC insulation. The vast majority of homes have their switches wired with standard red and black building cable. The red wire is always Active and the black the switched Active back to the light fitting. However, as you know black normally means “Neutral”. Isn’t that a recipe for disaster? It could easily be, which is why you will find more modern homes with the wiring to their light switches in red and white building cable. Red still means Active while white means switched Active. In either case, it means “bitey – beware!” AS/NZS3000 (and the domestic installation standard AS/NZ3018) in fact specifies the colours of cables: Active can be red, white or blue, Neutral black (only) and Earth a green/yellow combination. Earths on lighting fixtures Many older homes (eg, 30 years +) have only two conductors (switched Active and Neutral) connected to the light fitting. But the rules have changed – now most light fittings (referred to as “luminaires”) must also have an Earth conductor connected to the building Earth. The exceptions are double-insulated luminaires or extra-low-voltage types supplied through a transformer (such as halogen downlights). So if you are adding any new fittings or replacing wiring, it makes sense to run an Earth conductor (in green/gold insulation) from the light fitting back to, and solidly, mechanically connected to, a suitable Earth line. All metal light fittings sold today have provision for connection of an Earth conductor. How to replace a light switch Switch mechanisms do fail – especially in moist or salty environments – and therefore need replacement. Perhaps you have decided to replace a good switch with a modern colourschemed one. Or you might be wanting to install a light in a previously unlit siliconchip.com.au At the risk of getting boring, we’re going to say it again! Check that the circuit is dead before doing anything with a non-contact tester. This circuit is obviously still very much alive and therefore dangerous. Incidentally, you should always check the non-contact tester with a known live circuit before use – just in case the battery is flat or the tester has failed. You want to know that it’s working! NEUTRAL 230/240V (WITH BUILDING CIRCUIT BREAKER EARTH OR FUSE IN ACTIVE LINE) LAMP CONNECTION TERMINAL ACTIVE P C siliconchip.com.au wood screws) or onto a plaster wall (larger screws which fasten it to a mounting plate inside the wall). Some have a faceplate, as we discussed last month, which you’ll need to pry off the subplate underneath, to gain access to the two mounting screws. If the switch is mounted on a painted wall, before undoing the screws score around the very edge of the switch plate with a sharp knife so you don’t pull away paint (as we discussed last month). Now remove the screws and gently pull the switch plate away from the architrave/wall. We said gently because old wiring might be brittle and you don’t want to break it off. If the wiring is brittle and/or you do manage to break it off back in the wall, it really is time to call in an electrician and have the wiring replaced. You’ll LOO place. We’ll look at this a little later but in the meantime we’ll assume you’re simply replacing a switch. You might think this is like teaching people to tie shoelaces –but how often do you see loose or untied laces! To many people, what we are talking about here is like a foreign language. Even if you think you know what you’re doing, read on. You might learn something! Before you start, you have the choice of replacing the whole switch or just the switch mechanism (see the side panel overleaf). There’s not a great deal of price difference in them (in fact, the whole switch is often cheaper than the mech!) so if your switch plate is at all marked, dirty or (shudder!) painted on, we’d always replace the whole thing. First of all, as always, turn off the power at the main switch in the fusebox. If you can positively identify the circuit breaker or fuse which controls the light, this can be tripped or removed but it is nice to know that all power is off when the main switch is off. Second, use your non-contact voltage detector to absolutely confirm that the power is removed. What, you haven’t bought one yet? Shame! Don’t proceed any further until you do . . . Incidentally, before use you should always check the non-contact voltage detector on a known live circuit (eg, a power point) to ensure that it is working. The batteries might be flat or it could have developed a fault. Most light switches have two screws which hold them in place, either directly to an architrave (with small probably find there’s a lot more wiring in your home in a similar state. Remove the wires one at a time by unscrewing the tiny grub screws that hold them in place and simply swap the wire to the new switch, placing it in the same-positioned terminal that it came from (be careful not to mix them up!) and tighten its grub screw. Those grub screws have to be done up as tight as possible to make sure the wires are making the best contact they can. This will help eliminate the possibility of “hot spots” developing caused by high-resistance joins. (You should find the wires which come out of the switch are bent over at the end, forming a double wire and if there are two wires going into the one terminal, they should be twisted tightly together – for exactly the same reason as above). If the switch has wires going into the “loop” terminal, swap these over to the loop terminal on the new switch – and the job is almost done. It’s just a matter of replacing the switch plate in the hole the old one came from – as long as you get it the right way up. The switch mechanism itself usually has some tiny writing or logo moulded into the front – this goes down. If you can’t see the writing or logo, activate the switch. Re-insert the screws and if the switch has a cover plate, simply snap that in place. Finally, turn the power back on and check that the switch works and that the off and on positions are in the conventional places. If the off and on are upside down, turn the power back off before remov- REAR OF LIGHT SWITCH 1 NOTE EARTH TERMINAL -MARKED WITH GREEN AND/OR LABELLED “E” LOOPING TERMINAL L E WHITE GENERALLY MEANS A SWITCHED ACTIVE LAMP CONNECTION TERMINAL REAR OF LIGHT FITTING Fig.2: wiring a single light switch isn’t at all difficult but that doesn’t mean you shouldn’t take proper care. Here’s the way it should look – except that you’d generally have some distance between switch and light socket! Older light sockets may not have the earthing terminal. July 2008  13 A C N Fig.3 SWITCH 1 C LAMP A Fig.4 N A SWITCH 2 N C SWITCH 1 tiny internal arc, which occurs every time any mains switch is turned off, will eventually become a major arc between Active and Neutral. If you’re lucky, this will simply blow a fuse or cut a circuit breaker. If you’re not so lucky . . . You might get away with this in a 110V system (does that give the DIY magazine source away?) because the lower voltage would not create such an arc. But it is still wrong and should never be used. Fig.4 shows the right way to do it. When the position of both switches is “up” or both “down”, the light will be on. When either switch is different to its mate, the light will be off. The difference here is that it is (a) legal because both switches are in the Active conductor and (b) it is safe because Active and Neutral are not applied to the two “switched” terminals, so the arc is minimal; too small to cause any problems. In fact, this method of C SWITCH 2 LAMP Here are two ways to wire a two-way switch. We show the first one (Fig.3) because we have seen it in a D-I-Y magazine available in Australia. Apart from being illegal, it’s definitely NOT the way to do it. The version on the right (Fig.4) is the right way to do it and we’ve shown in more graphical format below for those who have difficulty with circuits. When both switches or up or both down, the light will be on. ing the screws and turning the plate through 180°. Switch mechanism orientation Switch mechanisms almost always operate in the vertical plane (ie, you push down on the switch to turn it on) but the switch plate can be oriented either horizontally (eg on a wall) or vertically (eg, on an architrave). Fortunately (by design!) the switch mechanism can be removed from the plate and turned to the required orientation. If you look at the photo opposite, you’ll see some tiny lugs at the base of the mechanism. These “lock” the mechanism in place in appropriatelyplaced notches moulded into the “well” within the switch plate. As always, turn the power off and/ or flick the circuit breaker/remove the fuse before doing this. Check that the circuit is dead with your non-contact mains voltage tester. The simplest way to remove the mechanism from the plate is to push down on one side at the back, while applying gentle pressure to the switch itself from the front. Turn the switch mechanism to the direction you require and push it back in quite firmly. It will eventually snap into place . . . and that’s that. Wiring a two-way switch LAMP CONNECTION TERMINAL LOOPING TERMINAL E LAMP CONNECTION TERMINAL NEUTRAL 230/240V VIA CIRCUIT BREAKER OR FUSE IN ACTIVE LINE AT FUSEBOX EARTH WHITE GENERALLY MEANS A SWITCHED ACTIVE ACTIVE P C P LOO Fig.5: obviously not to scale but here is the way to wire up a two-way light switch with the circuit of Fig.4. The cables between the REAR OF two light switches REAR OF LIGHT SWITCH 1 LIGHT SWITCH 2 (which we’ve shown CONNECTING CABLES CAN BE in blue for clarity) RED, WHITE OR DARK BLUE would probably be red/white BUT MUST BE DOUBLE INSULATED twin building (lighting) cable in most installations. The last 4-5mm of the bared ends of each cable should be bent back on themselves and the grub screws done up as tight as possible to ensure as good an electrical connection as possible. LOO 14  Silicon Chip REAR OF LIGHT FITTING NOTE EARTH TERMINAL -MARKED WITH GREEN AND/OR LABELLED C We mentioned earlier that there is a wrong way and a right way to wire a two-way switch. Both work, although one will only work for a while before the switch is destroyed (it may even catch fire). Refer to Fig.3 – it shows a popular – but very wrong – way to wire a two-way switch. We’ve actually seen this shown (admittedly some years ago) in a do-it-yourself handyman magazine from overseas that was sold in Australia. Apart from being illegal under AS/ NZ3000 because it can switch the Neutral conductor (rule 2.20.1.2), if you have a switch wired like this, it’s only a matter of time before the mechanism fails. Here if either switch is opposite to its mate, the light is on. If both are the same, either up or down, the light is off. However, switches were never intended (nor designed) to work this way. In this, Active and Neutral are only separated by a very small distance inside the switch mechanism and the siliconchip.com.au NEW! CIRCUIT WIZARD A revolutionary new system that combines circuit design, PCB design, simulation & CAD/ CAM in one complete package for your pc. rom: f o m e d e a fre com Downloeawd-wave-concepts. www.n To see the The switch mechanism removed from the switch plate, so that it can be turned through 90° for horizontal mounting (eg, on a wall). The mechanism simply clicks back into place with those lugs aligning with recesses in the plate. wiring can actually be a little easier because you don’t have to provide Active and Neutral at both switches. You do have to provide a two-wire connection between the two switches. Here it can be a little confusing because the standard says that you can use red, white or blue (but never green, yellow, green/yellow or black). You must NEVER use a green/gold wire for anything but Earth. NEVER. Sure, you might know that it isn’t an Earth wire. But what about the contractor who comes in to do some other work? Or the people who buy your house when you move? It is a perfectly reasonable assumption that green/gold is the Earth wire – and if it happens to be a live wire, disaster is not too far away. Of course, you must not use the red wire for anything but Active and the black for Neutral – but that’s just common sense, isn’t it? Remember: twist and tight! And one final point: at the risk of repeating ourselves, when fitting wires to light switches, lights fittings or even power outlets, it is very important to have as much copper wire in contact with the terminals as possible. We mentioned before so-called “hot spots” which usually develop due to the join between wires, or between wires and terminals, becoming a high resistance. And as everyone knows, pushing current through a resistance causes heat. In fact, this is the most common reason that wires and fittings deteriorate (and become a potential fire risk). So always twist any wires that you are joining tightly together; always bend the end of a wire 180° back on itself to create a larger cross-sectional area . . . and always make sure those grub screws (either in the fittings or in connectors) are done up as tightly as you can get them. SC siliconchip.com.au s between difference essional dard & Prof tures’. ick on ‘fea versions cl Stan IDEAL FOR Schools, TAFEs, Hobbyists & Business Circuit Wizard Standard – $202* & Circuit Wizard Pro – $390*post*incin GST Aust. 555Electronics Australia and New Zealand – for orders or more information, please contact 19 Kensington St, Clovelly Park, SA 5042 Tel (08) 8277 8936 email: bwigley<at>senet.com.au www.555electronics.com.au Radio, Television & Hobbies: ONLY the COMPLETE 00 $ 62 archive on DVD &P +$7 P • Every issue individually archived, by month and year • Complete with index for each year • A must-have for everyone interested in electronics This remarkable collection of PDFs covers every issue of R & H, as it was known from the beginning (April 1939 – price sixpence!) right through to the final edition of R, TV & H in March 1965, before it disappeared forever with the change of name to Electronics Australia. For the first time ever, complete and in one handy DVD, every article and every issue is covered. If you're an old timer (or even young timer!) into vintage radio, it doesn't get much more vintage than this. If you're a student of history, this archive gives an extraordinary insight into the amazing breakthroughs made in radio and electronics technology following the war years. And speaking of the war years, R & H had some of the best propaganda imaginable! Even if you're just an electronics dabbler, there's something here to interest you. NB: Requires a computer with DVD reader to view – will not work on a standard audio/video DVD player Use the the handy handy order order form Use on page 23ofofthis thisissue. issue on page 81 July 2008  15 SILICON CHIP If you are seeing a blank page here, it is more than likely that it contained advertising which is now out of date and the advertiser has requested that the page be removed to prevent misunderstandings. Please feel free to visit the advertiser’s website: dicksmith.com.au SILICON CHIP If you are seeing a blank page here, it is more than likely that it contained advertising which is now out of date and the advertiser has requested that the page be removed to prevent misunderstandings. Please feel free to visit the advertiser’s website: dicksmith.com.au Do we really have to send it back? Agilent MSO7034A Mixed Signal Scope 18  Silicon Chip siliconchip.com.au The MSO7034A from Agilent Technologies is a mixed signal oscilloscope. What does that mean? You get the best of both worlds: four analog channels as well as 16 digital inputs. Review by Mauro Grassi W e have to say that visually, the MSO7034A is very impressive, boasting a 12.1-inch XGA (1024 x 768 pixels) colour screen and a fast overall response, including a waveform update frequency of up to 100kHz and deep memory of 8Mp (Mega points). With a bandwidth of 350MHz and real time sampling rate up to 2GS/s, the MSO7034A is more than adequate for all but the most demanding applications. The MSO7034A is one of Agilent’s new 7000 series of scopes. It has standard connections that make it easily programmable, is network enabled and supports the new LXI standard for instrument control intended to supersede GPIB. This scope easily adapts to more specialised tasks such as FlexRay decoding and spectrum analysis, using optional accessories (both hardware and software). More on all these features shortly. Let us review the many standard features first. Holding down a key displays a help screen explaining its current function. The hierarchical menu system is not too complex and a horizontal row of soft keys allows easy navigation through the menus. Most settings can be changed with the SELECT knob, which illuminates when relevant. The value of the setting can be seen as it is being updated. Important settings controlling the vertical scale of each analog channel and the timebase, for example, have their own dedicated knobs. We should mention that this scope has surprisingly few settings that can be modified. For example, there is limited control of the appearance of the traces on the screen. The traces seem to be rendered too thickly in some cases and although this can be overcome by using the high-resolution mode (or the averaging function), it would be nice to let the user have finer control of the graphical rendering. We would like to see more user options in Specs at a glance Overview future versions of the Analog Input Channels: ................................ firmware to allow for The screen of the ..............................Four Digital Input Channels:........................................ this. Perhaps two differMSO7034A is as big ........................... 16 ent user modes could be as found in some Analog bandwidth: ........................................ ........ ....... DC - 350MHz implemented, one a simnotebook computSampling Rate: .............................................2G S/s for each channel plified version (with the ers. The high resMemory depth: ................ 4Mpts (four channels) most common options olution and size 8Mpts (2 channels) Verti cal Resolution: ................................................ and settings) and the make it pleasant to .................. 8 bits LCD display: ............. 12.1 inch colour TFT (XGA other a full version of the use with variable 1024 x 768 pixels) menu system with more intensity for traces Size (WxHxD):....................454 x 277 x 173m m with legs contracted options for controlling and the grid adding Weight: ................................................................ .................... 5.9 kg the look and behaviour of to its appeal. the scope. The downside The firmware can be to this, of course, programmed easily using any PC, so the firmware features is that the scope must be physically large enough to accan be upgraded as they become available. commodate the display. However, it is light for its size at less than 6kg. Four Analog Channels Another desirable quality of this scope is its very quiet Most of the time, you would use the AUTOSET feaoperation, unlike some other scopes with noisy cooling ture that chooses optimal settings, according to the input fans. signals. This is handy if you wish to view a signal on the It has a very attractive layout with illuminated buttons screen with minimum effort. and digital knobs. Each of the four analog channels has its Each analog channel can be AC or DC-coupled with own vertical scale knob and offset with the vertical resoluselectable input impedances of 50W or 1MW. The input tion of each channel reaching up to 12 bits (depending on impedance and coupling are indicated for each channel with the settings). At worst it is 8 bits. a white and yellow LED, the white LED spelling “AC” if the channel is currently AC coupled, while the yellow LED Accessibility Settings indicates a 50W input impedance. Moreover, each channel On-screen windows, showing the current settings of has its own LED to indicate if it is bandwidth limited, which the knobs, appear when they are activated (a window also increases the accuracy of the trace by reducing spurious informs you when the knob has reached its current limit). high frequency noise. This should be used whenever posThis scope has been designed with accessibility in sible for lower frequency signals. The bandwidth limiting mind, as evident by the context sensitive multi-language is user selectable up to 25MHz. help system. siliconchip.com.au July 2008  19 For the four analog channels, the vernier option allows the channel’s vertical knob to adjust the scale in smaller increments than the usual 1-2-5 scale, enabling better use of the available screen area. The vernier scale was used in the screen grab shown in Fig. 3. The BNC sockets accepting each analog channel also accommodate automatic sensing probes. Both the usual passive probes as well as active probes can be used. For passive probes, the scope can be calibrated to de-skew its capacitance, while active probes have in built amplifiers meaning their capacitance can be kept very low. The latter is desirable to ensure high input impedance even at high frequencies. As well as voltage sensing probes, this scope can accommodate current sensing probes, with the units for the vertical scale of each channel accommodating both Volts and Amperes. The probe attenuation can be set as high as 1000:1 meaning that potentials as high as 30kV can be measured. However, the vertical scale division on a 1:1 probe setting is at most 5V/div, which is on the low side and about the minimum you would want. Maths Functions and Labelling A close-up of the driver’s panel – we found it to be not only very logical and quite easy to use but also found a huge range of integrated help information available simply by pressing and holding any of the buttons. The MSO7034A has the usual mathematics functions including subtract, multiply, integrate, square root and differentiate, as well as the usual Fourier transform. The result is superimposed on the screen as a separate “MATH” trace, as can be seen in Fig. 4. One of the best features is that the result of the maths function can be measured in the same way as any other channel. One can measure, say, the average of an integral (useful for total power measurements), or measure the current through a resistor by using the difference between two voltage measurements (if you don’t have a current sensing probe). We would like to see even more flexibility in the maths functions in future models, including possibly a more Fig.1: the blue trace shows a TTL-level RS-232 data stream. Real time serial decoding is enabled (must be purchased separately) showing the hexadecimal values of the bytes transmitted. The baud rate is set at 115.2kbps with 8 bits per byte and no parity bit. The stream is the output of a microcontroller which is sending commands to an embedded LCD display. The op-code 0x3C corresponds to the command to write a character and the ASCII character follows. Fig.2: the output of a crystal oscillator circuit, an approximately sinusoidal waveform at 20MHz, forming the clock signal for a microcontroller, can be seen as the green trace. The frequency measurement shows 20MHz while the 5 digit frequency counter shows 20,003kHz. The bottom half of the window shows closer detail of the waveform using the zoom feature. The bottom window corresponds to the unshaded area in the top window. The shaded area is user selectable. 20  Silicon Chip siliconchip.com.au general mode where an arbitrary maths expression (within limits) can be defined by the user (however, this would probably add complexity to the hardware). The MSO7034A is a mixed signal oscilloscope, meaning it accepts digital signals as well as the four analog channels. Up to 16 digital traces can be displayed at any one time and Fig. 6 shows an example. Traces on the screen, including all 16 digital traces, can be given alphanumeric labels. This makes the display more intelligible – while the method of entering alphanumeric strings is rather awkward, requiring many presses and turns, it does not need to be done often enough to warrant having a keyboard. The inconvenience is mitigated by having a library of standard labels like IRQ, CLR, INT, etc. Moreover, the library labels can be used as templates by editing them to form new labels. Acquisition and Triggering The peak detect mode on the MSO7034A can detect short peaks down to half a nanosecond. In the averaging acquisition mode, up to 65536 (216) sweeps can be averaged to reduce noise and reveal the general trend of the waveform. The scope has comprehensive triggering modes encompassing the latest video formats for HDTV including 1080i, 1080p, 720p as well as standard video triggering for NTSC, SECAM, PAL and PAL-M video signals. Fig. 5 shows a typical standard definition PAL signal with TV triggering enabled. In addition to these triggering modes, there are serial triggering modes for I2C, SPI, USB and UART/RS232 modes, to list only the most common. For automotive applications, the standard triggering modes include CAN, LIN and FlexRay (FlexRay is the newest automotive serial protocol). An optional licence can be purchased to allow the scope to decode these serial streams. See the protocol analyzer section below for more details. Fig. 3: the trace shows the discharging of a capacitor through a resistor. The rise time is measured to be 1.06ms and the dashed orange lines show the points between which the rise time is measured. The capacitor used was a 1mF electrolytic connected in series with a 680W resistance. Notice that the vernier option has been used in setting the vertical scale. It stands at 800mV per division. The horizontal scale is 1ms/div. siliconchip.com.au In keeping with the four channels, the scope includes four high quality 500MHz probes. The other leads in this shot are 16 the digital input connectors. Quick Measurements 23 automatic measurements can be made with up to four measurements being displayed on the screen at a time. Cursors shown as dashed orange lines automatically track the most recently selected measurement. The is a feature we have not seen on other scopes. While useful for making sense of the displayed measurements and correlating the quantities with points on the waveform, the cursors cannot be disabled (in the current version of the firmware). This would be another desirable option since these indicators can detract from the intelligibility of the waveform, especially when the waveform is rapidly changing and the cursors become distracting. There is also a five-digit frequency counter whose accuracy can be increased to eight digits by using a stable 10MHz external reference signal. The frequency counter is shown in the screen grab in Fig.2. Protocol Analyzer The MSO7034A can be upgraded with a software licence that implements real-time serial decoding. For example, Fig.1 shows a RS232 stream being decoded by the scope. Serial decoding is very useful for debugging purposes, giv- Fig. 4: screen grab showing an approximate square wave at around 155kHz (yellow trace) with its computed FFT (pink trace). The peaks at the odd harmonics can be clearly seen. Four measurements of the square wave are shown towards the bottom of the screen, including RMS, frequency and maximum and minimum values. The minimum measured voltage level of –150mV is indicated by the dashed orange line. July 2008  21 ing a read-out of the hexadecimal or binary representation of the signal. Currently supported protocols include I2C, SPI, UART/RS-232, USB, FlexRay, CAN and LIN. Options A very good feature of this scope is that it is highly customisable, with optional accessories, as well as the serial decode licence mentioned previously. This allows the scope to be upgraded according to need. One significant upgrade is support for segmented memory, useful for high frequency pulsed applications like radar or sonar. It allows the acquisition memory to be effectively used for the relevant detail in the waveform (that is, the pulses) instead of being wasted on the relatively long interim periods when there is no interesting signal to speak of. (Segmented memory is an optional accessory that can be purchased separately). Another useful optional accessory is the power measurement suite. The software, installed on a PC, allows the scope to function as a very fast acquisition engine and allows power analysis using your PC. Many other accessories can be purchased separately to allow for different applications such as spectrum analysis and current sensing. The LAN port is extremely useful. It allows the scope to be addressable on a network and thanks to the LXI compliance, the scope has an in built web server. As such, it can be accessed using any common web browser with the familiar features of any HTML page. A full IO library software suite is included to allow automation and advanced applications may make use of this library. As previously mentioned, the firmware of the scope can be upgraded via a PC. Considering that a scope can have an operational life of many years, this is a must for any serious purchase as it allows features to be upgraded in the future and any bugs to be corrected. Conclusion The MSO7034A scope has standard connections for USB, including two host ports and one device port, LAN, XGA video out (for connection to a monitor) and is LXI class C compliant. LXI is the new LAN-based standard for instrument control, intended to supersede GPIB. One minor criticism of the USB host ports is that they are only version 1.1; they really should be version 2.0 to bring them in line with current standards, as version 1.1 is all but obsolete. Although the speed of version 1.1 is adequate for most purposes, it would be better to have the luxury of the highest speed of the USB. The USB device port is of course version 2.0. The Agilent MSO7034A is an impressive mixed signal scope and has everything you would expect from a higher end scope. It is surprisingly fast and responsive and the display is exceptional. With a recommended retail price of $14,377 (ex. GST) including a 3 year warranty, it is available from Agilent agents, Trio Smartcal. This gets you the scope, a calibration certificate, four analog probes, a digital 16 channel connector with clips, user manual, PC software including IO library and hard plastic front cover. Serial decode licences can be purchased separately for $1550 (ex. GST). A DSO-only equivalent model, the Agilent DSO7034A, is available for $11,229 (ex. GST), also from Trio Smartcal. The DSO version can later be upgraded to the MSO version by purchasing a software licence. See www.triosmartcal.com.au or phone Trio Smartcal on 1300 853 407 for more information. And do you want to know the really good news? He who controls the purse strings (among other things) around here heard how much I liked this scope. So a deal was done – and we’re now the proud owners of a brand new Agilent! SC Fig. 5: the top half of the window shows a PAL video test signal composed of coloured vertical columns (green trace). The unshaded area is magnified and shown in the bottom half of the window. The detail shown corresponds to the colour burst sequence. PAL triggering is used and some measurements are displayed, including the minimum and maximum levels and the frequency of 15.63kHz which is very close to the PAL horizontal frequency. Fig. 6: this screen grab shows 8 digital waveforms captured by the scope on the digital channels D0-D7. The selected triggering mode is shown in icon form at the top right corner of the window. It indicates that the acquisition on all channels is triggered by either a rising or a falling edge on the first digital channel. Two cursors are shown as vertical dashed orange lines, and the logical value at the cursors is shown as a hexadecimal byte. Standard Connections 22  Silicon Chip siliconchip.com.au SILICON CHIP Order Form/Tax Invoice Silicon Chip Publications Pty Ltd ABN 49 003 205 490 www.siliconchip.com.au PRICE GUIDE: SUBSCRIPTIONS YOUR DETAILS (Note: all subscription prices include P&P). 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SUBSCRIBERS QUALIFY FOR 10% DISCOUNT ON ALL SILICON CHIP PRODUCTS* * except subscriptions/renewals Qty Item Price Item Description Subscribe to SILICON CHIP on-line at: www.siliconchip.com.au Both printed and on-line versions available Total TO PLACE YOUR ORDER siliconchip.com.au P&P if extra Total Price BUY MOR 10 OR ISSU E BACK ES A 1 0 & G ET DISC % OUN T $A Phone (02) 9939 3295 9am-5pm Mon-Fri Please have your credit card details ready OR Fax this form to (02) 9939 2648 with your credit card details 24 hours 7 days a week OR Mail this form, with your cheque/money order, to: Silicon Chip Publications Pty Ltd, PO Box 139, Collaroy, NSW, AustraliaJuly 20972008  23 07/08 PT.2: By MAURO GRASSI DSP Musicolour: putting it together In last month’s first part, we described the circuit operation of the DSP Musicolour. In this instalment, we guide you through the construction. The operation of the firmware and troubleshooting tips will be described next month. In this issue there are also notes and errata for the schematic published last month. B efore we start any construction, let’s make a couple of things perfectly clear about the complexity and skill levels needed to build the DSP Musicolour. (1) This project is not suitable for beginners. In fact, you should not attempt to construct this project without considerable experience, particularly with mains devices. (2) This project controls mains (230/240V or 110/120V) voltages. Mains voltage can be lethal. Hence it is especially important to double check and be certain that mains power is not applied whenever working with the PC boards. NEVER apply mains power to the main PC board unless it is fully enclosed in a plastic case with the case screws done up. Construction: Display Board The DSP Musicolour is built on two separate PC boards. The main board consists of the Triac output section at 230/240VAC mains potential and the low voltage section containing the op amps and the dsPIC30F4011 microcontroller. The two sections of the main board are isolated by optocouplers and the mains transformer. The vertical display 24  Silicon Chip board is all low voltage circuitry and its supply rail is +5V. We’ll begin the construction with the display board, which is coded 10107082 and measures 247mm x 76mm. Note: our prototype DSP Musicolour used single-side boards with many links, however kitset suppliers are likely to provide the boards in double-sided form with plated-through holes, in which case only a few links will be necessary. First, you should check the PC board for hairline cracks in the tracks and any visible shorts between tracks. Fix any defects. The component overlay is shown in Fig.1. The first components to go in are the resistors, 31 in total. As you install them, check the colour code of each resistor against the colour code table. Better still, check the values with a digital multimeter before soldering each one onto the PC board. The seven signal diodes can be soldered in next. It is vital that they are oriented correctly and you should refer to the component overlay and check carefully against it. The diode’s cathode (K) is indicated by a line at one end of the body. Next, solder in the four 16-pin IC sockets. Make sure these siliconchip.com.au The main and display boards assembled in the case, before the rear panel (and rear panel wiring) is fitted. This prototype photo has single-sided PC boards – production boards should be double sided to eliminate most links. However, if you etch your own PC board it will probably be as per the prototype and require links as shown above. are oriented correctly as per the component overlay. Although the sockets are optional, we do recommend them. They make replacing the ICs much easier, if needed. The sockets for the three Kingbright dot matrix LED modules can now be installed. Cut three 14-pin IC sockets in half with pliers to get six 7-pin sockets and solder them in as shown on the component overlay. The sockets are used to raise the dot matrix modules to make them sit close to the acrylic front panel. They also make replacing the modules much easier if they should ever fail. Once this is done, you can solder in the 22 BC327 transistors. These are all PNP types and should be pushed down so that they sit quite close the board in order to clear the front panel. However, be careful not to push them too close, as this may damage the leads. About 2mm proud of the board surface is ideal. Next, you can solder in the three 10kW potentiometers and the capacitors. The three 100nF monolithic types are placed near the IC sockets for the 74HC595 shift registers (IC3, IC4 & IC5). The two electrolytics are placed near VR3 and must be installed the right way around. Their negative terminals are indicated on their bodies and you should refer to the component overlay before you solder them to ensure they are correctly in place. The 26-pin IDC (insulation displacement connector) header (CON7) can be soldered in next and you should refer to the component overlay to get the correct orientasiliconchip.com.au tion. Note that there is a key-way on one side of the socket. Pin 1 of the header should be indicated by an arrow in the plastic socket. Finally, solder in the seven vertical tactile switches which have LEDs inside. There are three red and four blue switches. These switches have six leads arranged in two rows of three. The middle leads in each of the two rows are used to connect Warning! All the parts in the red shaded area on the Main Board component layout diagram (Fig .3) operate at mains potential (ie, 240VAC) and contact with any of these parts could be FATAL. These parts include the PC trac ks, the opto-couplers (OPTO1-4), the Triacs, the 100 mH inductors, the 680W resistors, the 100nF 250VAC capa citors, screw terminal blocks CON4-CON6, the transformer primary and the wiring to the mains input and output sock ets. DO NOT TOUCH any of these parts unless the power cord is unplugged from the mains supply. DO NOT CONNECT this device to the mains unless it is fully enclosed in the specified case. This project is not for the inexperi enced. Do not build it unless you know exactly wha t you are doing and are completely familiar with mains wiring practices and construction techniques. July 2008  25 100nF Q4 LED ARRAY 3 Q1 LED ARRAY 2 Q6 470Ω Q9 Q10 470Ω Q12 470Ω Q13 470Ω Q11 Q15 470Ω Q14 470Ω 470Ω 470Ω 470Ω 470Ω 100nF 100nF 470Ω IC1 74HC595 IC2 74HC595 1k S1 S2 S3 VR2 10k LIN YALPSID RUOLOCISUM 28070101 CS Q21 S6 1k 47 ∝F D7 470Ω D6 Q16 D5 S5 Q20 4148 470Ω S7 VR1 10k LIN 470Ω + 1k 1k 4148 D1 4148 4148 VR3 10k LIN 470Ω S4 Q19 1k 470Ω + 1 ∝F D4 1k Q17 D3 4148 470Ω D2 4148 1k 4148 8002/30 GM Q18 Q22 Links LK1, LK2 & LK3 need to be installed, depending on whether you will be powering the DSP Musicolour from 110-120VAC or 230240VAC. If you are in Australia, New Zealand and most parts of Europe, you will be using 230V-240V while 110V-120VAC is used in America and Japan, for example. For 230-240V operation, you should install link LK2 and leave out LK1 and LK3, under the transformer. For 110-120V operation, you should install links LK1 and LK3 and leave out LK2. LED ARRAY 1 Q8 Links for 230/240VAC or 110/120VAC operation TA12-11EWA Q7 470Ω Assembling the main board The main board is coded 10107081 and measures 221mm x 165mm. The component overlay is shown in Fig.3. Again, begin the construction by checking the copper pattern for defects such as track breaks or shorts. Fix any defects that may be apparent. 74HC595 TA12-11EWA 470Ω Attaching the front panel The final task is to attach the acrylic front panel. The four mounting holes are used to attach the front panel to the display board using four M3 Nylon screws (25mm). You will need to cut off 2mm from four 15mm tapped Nylon spacers to make them measure 13mm. This is the correct spacing between the display board and the front panel that fits with the grooves in the plastic case (Altronics H0482). Finally cut the remaining four 15mm tapped Nylon spacers to 4mm and use these as the nuts to attach the front panel. Then simply attach the three knobs to the potentiometers and that should complete the assembly of the display board. IC3 TA12-11EWA 470Ω Q5 This completes the construction of the display board. The last thing to do is to make up the ribbon (IDC) cable used to connect the display board to the main board. To do this, you will need a vise. Cut 15cm of 26-way ribbon cable and slide it into position into each 26-pin IDC line socket. Conductor 1 of the ribbon cable is indicated by a different colour – usually the ribbon cable is grey and conductor 1 is red. This should match pin 1 of the line sockets, indicated by arrows. You should slide the ribbon cable into place and then use a vise to attach the cable. Finally attach the clip to only one line socket leaving the other one without one. The line socket for the display must not have a clip attached, in order to clear the front panel. Once you are satisfied that everything is in order, you can insert the ICs into their sockets, making sure that they are correctly aligned. Then insert the three Kingbright dot matrix LED modules into their sockets. Make sure that pin 1 of the Kingbright modules is facing down as indicated on the component overlay. The modules should show a digit ‘1’ indicating pin 1. 470Ω Q3 Ribbon cable assembly IC4 ULN2003 Q2 the internal LED and you should make sure that they are oriented correctly, otherwise the LED will not light up. For each switch, the cathode is indicated by a dab of coloured paint on the lead with the colour matching the colour of the LED inside the switch. The switch should be soldered with the cathode facing up in the normal orientation. Switches S1-S3 should be red while switches S4-S7 should be blue. Note that this differs from the prototype photos shown here and in last month’s article. 1k 1k 470Ω Fig.1: component overlay for the display PC board with a matching photo opposite. Start assembly with the display PC board as detailed in the text. The top layer of the PC board is shown in green – if you etch your own (single-sided) board, the green tracks will need to be replaced with wire links, with holes drilled in appropriate places. 26  Silicon Chip 25 26 1 2 CON7 (CONNECTS TO CON1 ON MAIN BOARD) siliconchip.com.au You must never install all three links LK1, LK2 and LK3 at the same time. This will short the mains supply and blow the fuse and possibly trip the circuit breakers in your home! Make sure you have installed LK2 (for 230-240V) or LK1 and LK3 (for 110-120V) correctly before proceeding. There is an optional link near the two 270W 1W resistors and CON2. This is shown as LK4 on the main circuit (Fig.2) in last month’s issue and this will normally be omitted. Its operation will be explained in next month’s article. Next, you can move on to installing the resistors. Again, check each value against the component overlay diagram of Fig.3 , the colour code table and with your digital multimeter. There are seven diodes on the board and it is vital that they are oriented correctly. Diodes D11-D14 are 1N4004 while D8-D10 are 1N4148. Notice that diodes D11-D14 (the bridge rectifier) are not all oriented the same way (their orientation alternates). Once the diodes are in, you can solder in the two IC sockets; the 40-pin socket for IC1and the 16-pin socket for the LM324 quad op amp (IC2). Make sure these are oriented correctly as per the component overlay. Next, solder in the four optocouplers (MOC3021). These are 6-pin devices and it is vital that they be oriented correctly, with their pin 1 on the low voltage side of the board. The capacitors go in next. The MKT and monolithic capacitors are not polarised but the electrolytic capacitors are and you should refer to the component overlay to install them correctly. The four 100nF X2-type 250VAC capacitors on the mains side of the board should be soldered in so they are sitting flush, ie, without any of their leads being exposed. Next, to install the LM317T regulator REG1, bend the leads by 90° before threading them through the holes on the board. Then fasten the tabs to the TO-220 mini heatsink and to the main board using one M3 10mm screw and one M3 nut. Do this before soldering the leads, as the stress of tightening the tab could cause cracks in the solder joints if the regulator is soldered in first. The 3mm red LED (LED8) can be installed next. This must be oriented correctly with its flat side as shown on the(HEATSINK) component overlay. LOCK The two 2-pin jumpers labelled M3 LK5 and LK6 on the component SCREW WASHER 10mm terminal strip and soldered overlay can be made from the 28-pin header LONG in. They will accept optional jumper shunts. You should also take two single pins from the 28-pin header terM3 NUT minal strip and solder these in for the two test points TP0 and TP1, near regulator REG1. The test pointsBTA41-600B will be used to measure the input BTA41-600B TRIAC and output of the regulator, as will be TRIAC explained below. After that you can install the electret microphone insert, again making sure that it is oriented correctly. Next, install the 26-way IDC header, as shown on the component PC BOARD (HEATSINK) M3 SCREW 10mm LONG BTA41-600B TRIAC HEATSINK LOCK WASHER M3 NUT BTA41-600B TRIAC BTA41-600B TRIAC M3 SCREW 10mm LONG LOCK WASHER M3 NUT BTA41-600B TRIAC PC BOARD HEATSINK Fig.2: elevation (left) and plan (right) views of the way the Triacs are mounted to the double-sided heatsinks (two Triacs to each heatsink). Use an M3 metal screw (10mm) and an M3 nut. siliconchip.com.au BTA41-600B TRIAC M3 SCREW 10mm LOCK WASHER M3 NUT July 2008  27 OPTIONAL LINK D10 TNORF 1 8 0 7 0 1 0 1 CS LK2 240V JP1 LK1 120V + + CABLE TIES L4 100 µH TRIAC1 TRIAC3 TRIAC2 TRIAC4 100nF 100nF 250VAC 250VAC X2 X2 RE G NAD E GATL OV S NIA M CON4 CABLE TIES 100nF 250VAC X2 L1 100 µH 100nF 250VAC X2 L2 100 µH CON6 N MAINS 110V-240V N A A V 0 5 2-V 0 2 1 S NIA M CON5 K CA B BACK Fig.3: component overlay for the main board, which includes all the mainspotential circuitry (apart from the input/output IEC sockets). The top (component) side of the PC board is shown with green tracks; the bottom side in the usual copper colour. The dotted area above shows the section of the PC board which has components and tracks at mains potential. Never operate the DSP Musicolour unless it is inside its case with the lid screwed on. siliconchip.com.au WARNING: All parts in this section operate at 230/240V. WARNING! DO NOT FIT ALL THREE LINKS AT THE SAME TIME 680Ω 680Ω 680Ω 680Ω JP3 LK3 120V JP2 PRIMARY PRIMARY L3 100 µH 8 0 0 2/ 4 0 G M RU OL O CISU M OPTO1 240V: FIT LK2 ONLY 120V: FIT LK1 & LK3 ONLY OPTO 1–4: MOC3021 TRANSFORMER T1 30VA 7.5V + MIC 220Ω OPTO2 REG1 LM317T 100Ω TPI TP0 100Ω 100Ω 100nF 4.7k 220Ω 220Ω 220Ω OPTO3 FRONT + 470 µF D11 D12 D13 D14 1 µF D9 47 µF SECONDARY SECONDARY L O SI E NIL N OITALINE ISOLATION OPTO4 CON1 470Ω 4700 µF 16V 4148 5.6nF 10k 10k 47 µF 100Ω 1 2 10k 100k 100nF D8 LED8 100nF 270 Ω 1W 1k 4148 dsPIC 30F4011 LK5 LK6 9 10 + 1k CON2 270 Ω 1W 33k 3.3k 68nF 28  Silicon Chip + IC2 LM324 68nF At this stage it is prudent to go back over your work and make sure everything looks in order by comparing your populated board with the component overlay. If you are absolutely satisfied that you have installed or omitted LK1, LK2 and LK3 as per the instructions (depending on the mains voltage in your area), you can solder in the mains transformer. This should only fit one way and its primary and secondary sides should be 10k 33k 68nF Final main board construction IC1 1k 68nF Once that is done you are ready to solder in the four Triacs. It is most important that these be insulated tab types, which is why BTA41-600B are specified. You should use a multimeter and measure the resistance from pin 2 (the middle lead) of each of the four Triacs to their metal tabs. This should indicate a very high resistance or open circuit. On the other hand, if it indicates a low resistance or short circuit you probably do not have the correct Triac and you should not proceed. Once you have verified that the Triacs have insulated tabs, attach two to each double-sided heatsink using an M3 10mm screw and M3 nut as shown in Fig.2. Notice that the tabs of the Triacs are in direct contact with the heatsink. It is then a matter of sliding the heatsink with the two attached Triacs onto the PC board. The heatsink has two mounting pins to locate them on the PC board. You can then solder the two Triacs in place. Repeat this for the other pair of Triacs. The construction of the main board is now complete as regards to soldering in components. The only component missing is the potted transformer. 1k 4148 CON3 Installing the Triacs 270 Ω 1W overlay. This has a keyway on its side which should face the microcontroller. CON2 consists of a 2-way and a 3-way mini terminal block slotted into each other to make a 5-way terminal block. Two 2-way terminal blocks CON4 and CON5 and the 3-way terminal block CON6 should be soldered in next. Their screw terminal inputs should be facing the BACK edge of the main board. You can also solder in the four 100mH chokes (these must be rated at 5A) which sit vertically on the main board. As these are wound with enamelled copper wire, you should ensure that the terminals have been properly stripped and tinned before you attempt to solder them in place. clearly marked. The secondary side should point towards the low voltage side of the circuit while its primary side should point towards the two heatsinks holding the four Triacs. You should attach the transformer to the main board using an M4 screw before soldering the leads. The screw will need to be threaded from the copper side (bottom side) of the board and holds the heavy transformer in place (the screw hole is the one in the middle of the transformer just to the left of LK3 on the component overlay). Now solder the transformer in place. Installation instructions >1mm ENAMELLED COPPER WIRE LINKS (FOR S/S PC BOARD ONLY) This prototype photograph matches the overlay at left, with the exception of most of the wire links which have now been replaced by tracks on a double sided board. Again, if you etch your own single-sided board, the links will be required. In the case of the two heavy enamelled copper wire links in the mains section of the board (arrowed above), make sure you use similar heavy enamelled copper wire – for safety’s sake! siliconchip.com.au If you have followed these instructions, you should now have an assembled display board with its four ICs in their sockets and a 26-way ribbon cable plugged into it with its other end as yet unconnected. You should also have an assembled main board with all components soldered and with IC1 and IC2 out of their sockets for now. Notice that the case is not symmetrical and so the main board has indicators “FRONT” and “BACK” on the component overlay, indicating the back and front panels. Attach the main board to the case using the four mounting holes and M3 10mm screws. The two lower screws attach directly to the case (Altronics H0482) while the top two screws should be attached using two 3mm x 15mm Nylon spacers, cut to 8mm long and with longer M3 Nylon 25mm screws. The spacers are used to provide support to the main board when it is in the case. You will need to drill two 3mm holes in the bottom of the plastic case to thread these through as shown in Fig.7. You can then attach them to the PC board using M3 nuts (also shown in Fig.7). Once the main board has been attached to the case, continue by installing the appropriate fuse inside the male IEC socket – 10A (for 230-240V operation) or 15A (for 110-120V operation). You will now need to make up some connections for the back panel, using the individual cables from the 1m length of three-core mains flex cable, spade lugs and a crimping tool. (The three-core mains cable is used to ensure sufficient voltage rating for these mains-carrying connectors). First remove the outer insulation from the three-core mains flex and use the brown, blue and green/yellow wires, following Fig.4, which details the lengths of the wires you need to make. These are labelled W1 to W9 in Fig.4 and these numbers will be referred to below. July 2008  29 The rear panel of the DSP Musicolour sports the IEC power input socket with integral fuse and mains switch (far right), the four IEC controlled output sockets (centre), 6.5mm audio input socket and stereo audio (speaker level) input sockets (far left). If the speaker level input sockets are used, they’re designed to go in parallel with existing speakers. 50mm All these crimps need to be done carefully to ensure the connections are tight between the spade lugs and the wire. Don’t be tempted to use an automotive-type crimper – they’re not strong enough to produce a quality crimp and your wires could come out of the spade lugs. You need a good quality ratchet-type crimper and good quality spade lugs. W1: 40mm W2: 80mm 80mm 80mm 80mm Back panel installation and wiring 90mm MATES WITH 'N' TERMINAL OF CON6 W3: (IECF4) (IECF3) (IECF2) (IECF1) MATES WITH 'A' TERMINAL OF CON6 (IECM1) 90mm W4: (IECM1) W5: 80mm TO SPADE CONNECTOR UNDER EARTH SCREW ON BACK PANEL 80mm (IECM1) 80mm (IECF1) 80mm (IECF2) 80mm (IECF3) 120mm (IECF4) MATES WITH TERMINAL 5 OF CON2 120mm W6: OC1 (CON5) (IECF1) 120mm W7: OC2 (CON5) (IECF2) 150mm W8: OC3 (CON4) (IECF3) 200mm W9: (IECF4) OC4 (CON4) Fig.4: you will need to make up several crimped connector cables for the DSP Musicolour. This diagram shows the various types, colours and lengths. 30  Silicon Chip The back panel is made of steel and kits should be supplied with all holes punched and drilled. Snap in the male IEC socket (with the fuse installed as explained previously) and the four female IEC sockets as well as the optional microphone jack and audio speaker terminal block. The audio speaker terminal block is attached using two Nylon M3 12mm screws with two 3mm x 6.3mm nylon spacers used as nuts. Next, install the “earth” spade lug on the back panel using an M3 x 10mm screw, shakeproof washer and two nuts (see Fig.5). These will be used to earth the back panel later on. Check with a DMM that the screw is electrically connected to the back panel (ie, 0W or very close). You may have to scrape some paint away under the nuts to ensure intimate contact. Install the back panel in the case and use the display board with its attached plastic front panel as the front panel (but without yet connecting the display board to the main board using the 26-way ribbon cable). Install W1-W9 as shown in the wiring diagram for the back panel (see Fig.6). The insulated spade lugs are colour coded so that the brown should indicate live (Active) while blue indicates the Neutral mains connection. A green/yellow cable is used for the Earth connection. Follow the wiring diagram carefully to complete the wiring of the back panel. You should be left with seven loose wires from W1-W9. One green and yellow end of W5 connects to pin 5 of CON2 as explained below in the section on Earthing. The other 6 loose ends of W3-W9 connect to CON4, CON5 and CON6 terminal blocks as shown in the wiring diagram Fig.6. Make all these connections, paying particular attention to the earthing instructions below. Also, use the holes on the main board for attaching these wires solidly to the main board using cable ties. Also use cable ties around each of the three wires connecting to each female IEC socket. This is particularly important to hold the wires in place, especially since two of the female IEC sockets sit above the low voltage part of the main board. Should the live connection to one of these come off, the cable ties should ensure that they do not fall onto the siliconchip.com.au DSP Musicolour Parts List Main Board and hardware 1 PC board, coded 10107081, 221mm x 165mm 1 Case (Altronics H0482) with steel panel punched for IEC sockets 1 transparent red acrylic front panel, 254 x 75 x 3mm with silk-screen labelling and drilled to suit 1 30VA 120V-240V 7.5+7.5V Potted Toroidal transformer (Altronics M4615) 1 Chassis Male IEC socket with switch and fuse (Jaycar PP4003) 1 IEC female power lead 240VAC (Jaycar PS4106) 4 IEC male to 3-pin (GPO) socket (Jaycar PS4100) (optional) 4 Chassis Female IEC sockets (Jaycar PS4002, Altronics P8327) 1 3AG 10A fast blow fuse (Jaycar SF2204) 1 26-way IDC header 1 10-way right-angled IDC header (optional) 1 0.15m x IDC ribbon cable 16-way (Jaycar WM4502) (optional) 2 IDC line sockets 10-way (Jaycar PS0984) (optional) 3 2-way Mini PCB Terminal Block –5mm spacing (Jaycar HM3173, Altronics P2032A) 2 3-way Mini PCB Terminal Block – 5mm spacing (Jaycar HM3172, Altronics P2033A) 7 6.4mm blue insulated spade lugs (Jaycar PT4625) 7 6.8mm red insulated spade lugs (Jaycar PT4525) 5 6.8mm yellow spade lugs (Jaycar PT4707) 1 1m 3-core mains flex 10A (Jaycar WB1562) Wire for connecting audio socket 1 6.5mm audio mono chassis socket (Jaycar PS0162) 1 4-way audio speaker terminal block (Jaycar PT3002) 1 40-pin IC socket 1 16-pin IC socket 6 M3 screws 10mm long 1 M4 screw 10mm long 7 M3 nuts 2 Nylon M3 screws 12mm long (Jaycar HP0140) 2 Nylon M3 screws 25mm long (Jaycar HP0142) 4 Tapped Nylon spacers 3mm x 6.3mm (Jaycar HP0920) 2 Heavy Duty TOP-3 (ML97 type) heatsinks (Jaycar HH8526) 1 TO220 Mini (6073B type) heatsink (Jaycar HH8502) 2 Jumper shunts (Jaycar HM3240) 1 28-pin header terminal strips (Jaycar HM3211) 1 1m Tinned copper wire (Jaycar WW4032) 1 0.15m Enamel copper wire (1mm thick) (Jaycar WW4022) 1 electret microphone insert (Jaycar AM4011) 4 100uH 5A toroid suppression chokes (Jaycar LF1270) (L1-L4) 3 push-on 18T spline knobs to suit (Jaycar HK7730/31/32; Altronics H6510) 1 dsPIC30F4011 microcontroller IC (IC1), programmed with 1010708A.HEX 1 LM324 quad op amp (IC2) 4 BTA41-600B insulated tab Triacs 4 MOC3021 optocouplers 3 1N4148 diodes (D8-D10) 4 1N4004 diodes (D11-D14) 1 3mm red LED (LED8) Semiconductors 1 LM317T 3-pin adjustable voltage regulator (REG1) Resistors (0.25W, 1%) 22 470W 9 1kW siliconchip.com.au siliconchip.com.au Capacitors 1 4700mF 16V electrolytic 1 470mF 16V electrolytic 2 47mF 16V electrolytic 1 1mF 16V electrolytic 4 100nF 250VAC X2 style 15mm pitch metallised polypropylene (Jaycar RG5236) 3 100nF monolithic 4 68nF MKT 1 5.6nF MKT Resistors (0.25W, 1%, unless specified) 4 100W 4 220W 3 270W 1W 1 470W 4 680W 4 1kW 1 3.3kW 1 4.7kW 4 10kW 2 33kW 1 100kW Display Board 1 PC board, coded 10107082, 247 mm x 76 mm 3 Kingbright TA12-11EWA red 5x7 dot matrix LED modules (Tenrod TA12-11EWA) 3 9mm 18T Spline Shaft Single Rotary Pots 10kW Linear (Altronics R1946) 3 SPST Vertical PC mount tactile switch with LED (red) (Jaycar SP0612, Altronics SS1174) 4 SPST Vertical PC mount tactile switch with LED (blue) (Jaycar SP0614, Altronics SS1177) 1 26-way IDC header 4 16-pin IC socket 3 14-pin IC socket (cut in half) 4 Nylon screws M3 25mm (Jaycar HP0142) 8 tapped Nylon spacers 3mm x 15mm (Jaycar HP0926) 1 0.15m x IDC ribbon cable 26-way (Jaycar WM4504) 2 IDC line sockets 26-way (Jaycar PS0987) 1 2m tinned copper (Jaycar WW4032) Semiconductors 3 74HC595 shift registers (IC3-IC5) 1 ULN2003 line driver (IC6) 7 1N4148 diodes (D1-D7) 22 BC327 PNP transistors (Q1-Q22) Capacitors 1 47mF 16V electrolytic 1 1mF 16V electrolytic 3 100nF monolithic July 2008  31 K CA B (W1) RE G NAD (W5) (W6) E GATL OV S NIA M IECM1 (W3) CABLE TIES CABLE TIES (W4) IECF1 (W7) (W8) IECF2 + (W9) IECF3 + + 1 2 + IECF4 9 10 CON3 Preliminary power supply check 1 SIG GND (W5) 4 (W3) 3 R IN MIC IN L IN MIC IN CON2 2 5 RIGHT LEFT STEREO SPEAKER INPUT Once you have done that it is time to check the power supply rails before final assembly. To do this solder two wires to the two test-point stakes (TP0 and TP1) near REG1 and use pin 1 of CON2 as the GND reference. The wires should be long enough to leave the case and be accessed from outside the case. You can thread them through the hole used to mount the microphone jack on the back panel. Now close the case – attach the top half and screw in the two screws to seal it. (W2) (W3) CRIMPED QUICK Connect the CONNECTOR TO SPADE LUG green/yellow earth wire (W5) M3 X 10mm TO IEC as shown in the SCREW AND MAINS TWO NUTS wiring diagram INPUT SOCKET in Fig.6 so that the earth of the male IEC socket M3 STAR WASHER connects to the earths of all the Fig.5: the green/yellow female IEC sockets earth wire must be and the crimped securely connected to connector which the back panel via a is fastened to the crimped spade connearthing screw on ector and an M3 screw the back panel, with two nuts and a star washer. as shown at right (Fig.5). The remaining end of W5 should connect to pin 5 of CON2 (the 5-way terminal block) as shown in Fig.6. Do not proceed unless you are satisfied that W5 connects all these points to the male IEC socket’s earth terminal (the middle terminal). Again, you should use a multimeter or continuity tester to make sure that all these points (including chassis earth) are electrically connected (0W or very close). V 0 5 2-V 0 2 1 S NIA M EARTH (MAIN PC BOARD) CON4 OC3 OC4 MUSICOLOUR BACK PANEL CON5 Earthing OC2 OC1 low voltage section of the main board. Once you have attached the cable ties as shown in Fig.6 and the photographs you should proceed to the earthing section below. A mF Code IEC Code EIA Code 0.1mF 100n 104 0.068mF 68n 683 0.0056mF 5n6 562 CON6 Value 100nF 68nF 5.6nF N Capacitor Codes Fig.6: here’s the other side of the back panel, showing the wiring between the IEC mains input socket/fuse/switch (top in this diagram), the four IEC female output sockets (IECF1-4) and the PC board. Note carefully the position of the earth wire. Not shown here are the cable ties around all the cables coming from the IEC sockets (male and female). These are important safety items and should not be overlooked (see photo above right). 32  Silicon Chip siliconchip.com.au Looking from front to rear, the mains wiring can clearly be seen. All wiring here is mains-rated – the easiest way to ensure this is to use lengths of cable stripped from a scrap of mains-rated flexible lead. Don’t forget the cable ties: they’re just in case! You should only proceed if the case is closed, the back and front panels have been installed, the back panel has been wired correctly as shown in Fig.6 and the back panel has been properly earthed as explained above. Notice that the display board is not yet connected to the main board using the 26-way ribbon cable and that IC1 and IC2 on the main board are out of their sockets still. Also the audio terminal block and the microphone jack on the back panel are not yet connected. You can then apply power using an IEC power cable and flicking the switch on the male IEC socket to the ON position. You should measure the voltages at TP0 and TP1 relative to the GND wire using a multimeter. Normal levels should give around +10V DC on TP1 and +5V DC on TP0. If the level on TP1 is not close to +10V you should disconnect power immediately and recheck your work. If the voltage at TP0 is close to +5V it indicates that you are on the right track. If the voltage at TP0 is much different from +5V (note that anything from +4.8 to +5.2V is actually OK) then there is something wrong and you should recheck your work. Check the diodes D11-D14 are oriented correctly. Check that REG1 is correct and the resistors associated with REG1 are indeed 100W. Check that the large 4700mF electrolytic is correctly installed and that all the other electrolytics are correctly oriented according to the component overlay. Final Assembly If (and only if) the voltages at TP0 and TP1 are OK, then proceed. First switch off mains power and disconnect the mains cord. Once you are absolutely certain there is no mains power being supplied, open the case. Unsolder the two wires attached to TP0 and TP1 and also remove the GND connection at pin 1 of CON2. These are no longer needed. Install IC1 and IC2 on the main board IC sockets. Make sure they are oriented correctly. IC1 should be programmed with the latest version of the firmware. If you are building the DSP Musicolour from a kit, IC1 will be pre-programmed. If you are not, CON3, the optional10-way IDC header can be used to program IC1 using an external connection. More on this next month. Now connect the audio speaker terminal block by soldering Resistor Colour Codes o o o o o o o o o o o siliconchip.com.au No. 1 2 4 1 1 13 4 23 3 4 4 Value 100kW 33kW 10kW 4.7kW 3.3kW 1kW 680W 470W 270W (1W) 220W 100W 4-Band Code (1%) brown black yellow brown yellow yellow orange brown brown black orange brown yellow violet red brown yellow yellow red brown brown black red brown blue grey brown brown yellow violet brown brown red violet brown brown red red brown brown brown black brown brown 5-Band Code (1%) brown black black orange brown yellow yellow black red brown brown black black red brown yellow violet black brown brown yellow yellow black brown brown brown black black brown brown blue grey black black brown yellow violet black black brown red violet black black brown red red black black brown brown black black black brown July 2008  33 four wires onto the audio speaker terminals and connecting them to the terminal block CON2. Also solder wires to the microphone jack and connect these to CON2. Fig.6 shows this connection (among others). Connect the 26-way ribbon cable from the display board to the main board (CON1 on the main board). The photo overleaf shows the completed assembly (showing an early but similar prototype) just before closing the case. Close the case of the lid and screw it shut. Your DSP Musicolour is now fully assembled. In next month’s article we will explain the user menus and the operating instructions for the DSP Musicolour as well as calibration instructions. Stay tuned. SC 77.5mm 75mm 94mm (FRONT) (REAR) LOWER HALF OF CASE (VIEWED FROM BELOW) 78.5mm (REAR SMALL SELF-TAPPERS PANEL) SCREWING INTO MOULDED STANDOFFS M3 NYLON SPACERS CUT TO 8mm LONG M3 NUTS (METAL) (FRONT PANEL) MAIN PC BOARD (BOTTOM OF CASE) 25mm M3 NYLON SCREWS Fig.7: this scaled drawing shows how the main board is secured in the case (note the use of Nylon spacers and screws for safety). DSP Musicolour Notes and Errata In the Main Board schematic on pages 34-35 of the May 2008 issue, there are a number of minor errors. The labels P6C and P6D on pins 26 and 25 of IC1 should read PGC and PGD. The labels TRIAC2 and TRIAC3 should be swapped and pin 18 (OC2)‑ of IC1 actually connects to OPTO3 while pin 22 (OC3) connects to pin 1 of OPTO2. In the Display Board schematic published on page 37, there is an extra 470W resistor shown immediately to the right of pin 7 (Q7) of IC4. This resistor is not required – the component overlays and parts list in this issue reflect this. 34  Silicon Chip siliconchip.com.au CIRCUIT NOTEBOOK Interesting circuit ideas which we have checked but not built and tested. Contributions from readers are welcome and will be paid for at standard rates. PIC capacitance meter measures charging time This circuit measures the charging time of a capacitor, using the PIC microcontroller as an accurate timer. As can be seen, the circuit consists simply of a PIC16F628A microcontroller, an LCD panel and not much else. The capacitor is charged via one of three resistors which are manually selected by the second Mobile phone can power PICAXE circuits Many small circuits such as those using PICAXE micros can run on low-voltage supplies such as 3.7V from mobile phone batteries. These make good cheap power supplies if siliconchip.com.au pole of switch S1. The other section of switch S1 is connected to the RA3 & RA4 inputs of IC1, telling it which capacitance range to test for. When charging is started, the PIC starts a 16-bit timer and then stops it when input RB2 detects that the threshold voltage has been reached. This stops the counter. IC1 then computes and displays the capacitance value on the LCD panel. Transistor Q1 is used to discharge the capacitor before its next test. Calibration involves selecting a capacitor of known value and then adjusting the value of the associat­ed charging resistor until the displayed reading is correct. The circuit works for values between 10pF and 470mF. The software for the PIC and more information on the circuit is available by browsing to www. wasdomain.co.nr William Andrew, Lane Cove, NSW. ($40) you have an old phone with a reasonable battery lying around. The problem is that the Li-ion batteries require a special charger. So why not use the old phone? By disassembling the phone, you should be able to access the battery contacts and solder two wires from them to your circuit. You can then use the standard phone charger to recharge the battery or you can connect a small 6V solar panel instead. You then have a fully regulated charger for the battery. Colin Carpenter, Mosman Park, WA. ($30) July 2008  35 Circuit Notebook – Continued Simple door guard alarm This circuit is powered only when the keylock switch, S2, feeds power to the circuit involving the normally-closed reed switch S1 and the associated SCR. If the door is opened, reed switch S1 opens and gate current is fed to the SCR via the associated 100kW resistor. SCR1 then turns on and activates the relay which then connects power to the rest of the circuit involving IC1, a 4060 oscillator/divider. After a short delay, determined by the resistors and capacitor connected to pins 9, 10 & 11, transistor Q1 is turned on to sound the buzzer. To stop the buzzer, the battery supply must be disconnected via switch S2. T. K. Hareendran, Kerala, India. ($35) Programming the remote control codes for the CDROM playback adaptor Some readers who built the CD­ ROM Playback Adaptor (November 2007) from the Jaycar kit have had some problems with the setup of the remote control codes. The remote control is programmed (and must be programmed at least once) by holding down S3 while booting up. However, some readers are having problems programming their remotes. This is most likely because they are using remotes that don’t conform to the RC5 protocol that the adaptor recognises. We have tested the Jaycar kit using the Digitech universal remote (Jaycar Cat. AR1725). Program that remote for the VCR 115 code. Incidentally, most universal remote controls should work with the adaptor. Usually, choosing a Philips appliance will work (as Philips are the original inventors of the RC5 protocol). Note that some keys on some universal remote controls will only work when in the proper mode. For 36  Silicon Chip LCD SETUP PROMPT Press UNUSED: Press CLSOPN: Press Vol Up: Press Vol Dn: Press Chn Up: Press Chn Dn: Press Mute:       Press Play: Press Fast F:             Press Rewind: Press Stop:              Press Pause:            Press Record:          Press MA/SL:           Press Power:    Press 0-9:     BUTTON TO PRESS ON REMOTE press AV press Power press Volume Up press Volume Down press Channel Up press Channel Down press Mute press Play press Fast Forward press Rewind press Stop press Pause press record press the line button (to the right of button 0) press AV (this is not actually used by the firmware) press the corresponding number buttons example, usually the PLAY button on the remote will not work when in TV mode (as this makes no sense for a TV). The Digitech AR1725 remote shows when a signal is being transmitted on its small LCD screen. The Jaycar kit uses version 2.9 of the firmware (shown on boot-up on the LCD screen). Follow the accompanying table to set it up. Note that the UNUSED and Power button definitions are actually not used in the current version of the firmware. Therefore, you can use any key on the remote that will not control the adaptor to define these. Here, we’ve chosen the AV button. We have built the kit and tested it with the above remote and can confirm that it works. SILICON CHIP. siliconchip.com.au G A K K C D3–D10: 1N4007 A E B (AS MANY TRIGGER MODULES AS THERE ARE CYLINDERS) 150 K SCR2 C106D K CHOPPER DISC FOR PHOTOINTERRUPTOR A K E C E * CHOPPER DISC PASSES THROUGH SLOT IN PHOTO-INTERRUPTOR PI1 A (ALTERNATIVE OPTICAL TRIGGER MODULE)   E +HV D2 +12V A A SCR1 C106D A D8 E B K 220 A D1 K Q2 C Q1 E K B C siliconchip.com.au K G 150 K 1 F 600V D8 220nF A K K A 4.7k C D5 A D3 D6 PI1* K A 1k K A CP D1, D2: 1N4148 E +HV +12V A 2.2k 10nF 1kV E +HV K D4 A T1 220 +12V (IGN) 220 F (TRIGGER MODULE #2) A D10 220nF K G A K D9 SCR1 C106D A D7 1 F 600V 120 150 G K A K (TRIGGER MODULE #1) A D8 220nF K 1 F 600V 120 +12V Q1, Q2: 2N3055 CONTACTS TC CP TC CP CONTACTS COIL C106D A EHT TO PLUG EHT TO PLUG COIL 12V CDI for motorbikes This capacitor discharge ignition system was developed to replace the Kettering (points) system on several classic motorcycles. This provides better long-term reliability, longer life from usually hardto-get replacement points and easier starting with better fuel economy. The circuit is adaptable to single or multi-cylinder engines and 2 or 4-stroke designs. The DC-DC inverter is based on two 2N3055 transistors, together with a lowvoltage mains transformer. This has a centre-tapped 12V secondary and is connected back-to-front to step up the 12V battery supply to about 400V DC at the output of the bridge rectifier (D3-D6). This supplies each trigger circuit through isolating diodes D7, D8, D9 etc, with one trigger circuit required for each cylinder. The circuit shows trigger networks for points and an optical trigger module. Each trigger circuit comprises a 1mF 600V capacitor which is charged from the bridge rectifier and then discharged via the ignition via the respective SCR. The points are required only to pass a “wetting” current of 100mA, supplied through a 120W resistor. Consequently, they will not pit or burn. After initial adjustment, the ignition timing will not require resetting for a long time. Ultimately though, it will need adjustment to compensate for the slight wear on the rubbing block and cam. The operating frequency of the inverter depends on the mains transformer and the spark rate. The prototype was found to run at around 130Hz at relatively low engine revs (eg, up to about 2000 RPM) whereupon it jumps frequency, as a function of load, and runs about three times higher than the pulse requirements of the spark plugs and may run at 1kHz or more. At the same time, the DC output from the bridge rectifier drops to around 275V which is still adequate to provide good spark energy at up to 400 sparks/second. CAUTION: do not trigger the unit with an open-circuited ignition coil or with disconnected spark plug. This can damage the coil. The unit can also give a strong electric shock, if the user comes into contact with the spark plug output. Dayle Edwards Taylorville, NZ. ($70) Editor’s Note: readers who want to use this unit on a high-revving motorbike may wish to refer to the Multi-Spark CDI described in the October 1997 issue of SILICON CHIP. July 2008  37 Circuit Notebook – Continued 100nF 220k K 100nF 220k SOLENOID 1 D1 A 3 2 1 14 RCtc Ctc Rtc Vdd –As 13 Osc 8 +T IC1 6 –T 4047B 10 5 Q +As 4 9 S1 MR Retrig 12 Q 11 Vss 7 220k K 100nF SOLENOID 2 D2 A 3 2 1 14 RCtc Ctc Rtc Vdd –As 13 Osc 8 +T 4 10k D G S Q1 BUZ11A 5 6 9 +As –T IC2 4047B Q MR Q Retrig 12 10k 10 D G 12V BATTERY 1000 F 16V Q2 BUZ11A S 11 Vss 7 BUZ11A D1, D2: 1N4007 Universal ding-dong chime driver One frequently finds gongs or chimes for sale in antique shops or eastern markets. But have you considered using these as a ding-dong doorbell? This circuit provides a means of striking two gongs or chimes in sequence – one when the doorbell is pressed, the other when it is released. It does this by briefly activating two solenoids in succession. The circuit is based on two CMOS 4047 monostable timers (IC1 & IC2), one being wired for negative edge triggering and the other for positive edge triggering. The 4047B was selected for its simplicity, wide operating supply range (3-15V) and very low current drain. These two monostables switch two power Mosfets D G A which activate the two solenoids. When pushbutton switch S1 is first pressed, the 100nF capacitor connected to pin 6 of IC1 (and pin 8 of IC2) is immediately charged. This prevents switch bounce. When pin 6 is pulled low, IC1’s output at pin 10 goes high for 100ms, as determined by the capacitor and resistor connected between pins 1, 2 & 3. This causes Mosfet Q1 to conduct for the defined time period, to drive the solenoid and sound one chime. When S1 is released, the associated 100nF capacitor discharges through a 220kW resistor and triggers monostable IC2 for the same period. This causes Mosfet Q2 to briefly conduct and activate the second solenoid. K D S Diodes D1 and D2 protect the Mosfets against the back-EMF spike voltages that are produced when the solenoids turn off. On power-up, there is a possibility that, even before pressing pushbutton S1, either one or both of the solenoids may be activated and “lock”. In this event, press pushbutton switch S1 immediately to release them, to avoid heavy current drain from the battery. The standby current is about 10µA which should ensure a long life from a set of (eight) AA cells. Note: while Q1 & Q2 are shown as BUZ11As, almost any power Mosfet can be used in this application. Thomas Scarborough, Cape Town, South Africa. ($45) Contribute And Choose Your Prize As you can see, we pay good money for each of the “Circuit Notebook” items published in SILICON CHIP. But there are four more reasons to send in your circuit idea. Each month, the best contribution published will entitle the author to choose the prize: an LCR40 LCR meter, a DCA55 Semiconductor Component Analyser, an ESR60 Equivalent Series Resistance Analyser or an SCR100 Thyristor & Triac Analyser, with the compliments of Peak Electronic Design 38  Silicon Chip Ltd – see www.peakelec.co.uk So now you have even more reasons to send that brilliant circuit in. Send it to SILICON CHIP and you could be a winner. You can either email your idea to silchip<at>siliconchip.com.au or post it to PO Box 139, Collaroy, NSW 2097. siliconchip.com.au K S3 S2 S1 D2 1N4004 220nF Vdd P0 P3 22k 10k P4 13 IC1 6 P1 PICAXE -08 2 SER IN 10k P2 A LED1 D G PIEZO – 100 Q1 2N7000 S  LED2 +  K 10k K A A 5 Vss 8 10k 2 3 4 5 6 7 S4 7 D1 1N4148 3 21 1 +5V 100nF 1 PROG SKT 20 19 – A 4 'SOLAR' MOTOR* + K 10k 100 12 11 10 9 8 BELT REDUCTION DRIVE OFF SOLAR MOTOR (NUMBERS 1–21 AROUND DIAL) * SEE TEXT 0V 1N4148 1N4004 A A K PICAXE 21 game This project was inspired by two “Reader Built It” articles featured in the December 1968 and August 1969 issues of “Electronics Australia”. Both games were based on the 21 matchstick game, where two players in turn each removed one, two or three matches from a line of 21. The player left with the last match loses. In this game, played against the PICAXE micro, the player always goes first. Moves are made by press- 2N7000 LEDS K A K D G S ing the 1, 2 or 3 buttons (S1, S2 & S3). LED2 then flashes once, twice or three times and after the PICAXE has made its move, flashes again to indicate the move taken. At the same time, a small motor (Dick Smith Electronics Cat. P-8980) drives a disc with 17° segments marked 1-21. Each move advances the disc across one, two or three segments for both the player and the PICAXE until either the player or the micro is left with the last position. The PICAXE signals a win by sounding the buzzer and turning on LED1 for 8s. Conversely, it signals a win by the player Ross O by turning on LED2 is this m lsen onth’s for 5s and spinning winne the disc. The game Peak At r of a las then resets and the Instrum Test ent disc needs to be reset by hand. Disc movement is determined by timed output pulses at pin 6 of IC1. Each pulse lights LED1 and switches the motor on and off via FET Q1. The “pause 102” delays in the player’s and micro’s moves will need to be adjusted to stop the motor at the numbers on the disc. The software (21Game.bas) can be downloaded from the SILICON CHIP website. Ross Olsen, Wellington, NSW. Expanded scale voltmeter An analog meter used to monitor the voltage of a 12V battery bank is only required to read over the range of 10-15V or so. An ordinary 0-20V scale is of limited use here, as only one quarter of the scale is useful and because of this, resolution is limited. This simple circuit will convert a 1mA FSD (full scale deflection) meter into an expanded scale voltmeter, so that the wanted voltage range is spread over the whole scale. To restrict the voltage range to which the meter responds, an artificial offset is provided by ZD1, a 9.1V zener diode. This is biased by the 1kW resistor from the positive input and it provides the negative reference for the meter. The positive side of the meter is fed via trimpot VR1, resistor R1 and diodes D1 & D2. At the minimum of 10V, the current through D1 & D2 is very small, causing a small non-linearity at the bottom end of the scale but this is normally of little concern. At 10.5V and above, good linearity is achieved. By using a 3.9kW resistor for R1 and adjusting VR1 for full-scale deflection when 15V is applied, the original meter dial markings of 1, 2, 3, 4 & 5 equate to 11V, siliconchip.com.au 12V, 13V, 14V & 15V. This is ideal for lead-acid battery monitoring. The use of diodes in this configuration gives a degree of temperature drift cancellation, increasing the long-term accuracy of the meter. The meter scale can be used as is, or a new scale can be designed with the aid of drawing software. Dayle Edwards, Taylorville, NZ. ($40) July 2008  39 If Swan’s 2nd Law is: “ Microcontrollers can never have too many I/O channels” . . . what’s his first? Drum roll – Yet Another PICAXE! A lthough PICAXE microcontrollers are now well established and popular in numerous electronic projects, due in no small part to SILICON CHIP’s enthusiasm, many users know only of the entry level 08M, versatile 18X or powerful 28X. However, the recent arrival of a 20-pin PICAXE now takes the family to an awesome 14 members, although four earlier offerings are now discontinued and two “X2” fire breathers have yet to be released. This new PICAXE-20M (based upon a MicroChip PIC16F677) is really just a stretched 08M, as it offers similar memory and follows the same commands as the ever popular 08M and more recent 14M. Thankfully, its 10-a-side DIP packaging enables easier identification in the sea of chips lurking in many IC parts drawers, since its 20 pins make it noticeably longer than by Stan Swan common 14,16 or even 18-pin DIP logic ICs. The so-called 20M is mainly intended to meet the demand for further input and output (I/Os) channels than the four offered by the smaller 08M, or 5-6 of the 14M. Its provision of eight I/Os, arranged with inputs (0-7) on one side and outputs (0-7) on the other, looks to have strong appeal for projects where extra chips (such as Shift Registers) and wiring would otherwise be needed. Circuit size will naturally be reduced with just a single IC, yet greater flexibility will result, thanks of course to the PICAXE programmable features. All three “M” chips are especially well-suited for hobbyists and educational users, allowing enhanced design for just a few dollars more, when the need for extra I/O channels arises. The 14 PICAXE microcontrollers Summary – mid 2008 PICAXE type IC pins Memory ~progr. lines Outputs Inputs ADC (8-10bit) EEPROM memory (bytes) Speed (MHz) Best use? Microchip PIC type Approx. Cost (Aust$) 08 8 40 1-4 config. 1-4 config. 1x 4 bit low 128 less prog. 4 - 12F629 $5 08M 8 80 1-4 config. 1-4 config. 3 256 less prog. 4,8 Educ. 12F683 $6 14M 14 80 6 5 3-5 config 256 less prog. 4,8 Educ. 12F684 $7 20M 20 80 8 8 4 256 less prog. 4,8 Educ. 16F677 $8 18A 18 80 8 5 3 256 less prog. 4,8 - 16F819 $11 18X 18 600 8 5 3 256 plus I2C 4,8 Std. 16F88 $16 28X1 28 1000 9-17 0-12 0-4 256 plus I2C 4-20 Std 16F886 $22 28X2 28 2 x 1000 22 configurable I/O 0-12 256 plus I2C 4-40 Adv. 18F2420 $TBA 40X1 40 1000 9-17 3-7 256 plus I2C 4-20 Adv. 16F887 $28 0-12 I2C 4-40 Adv. 18F4420 $TBA 40X2 40 2 x 1000 8-20 33 configurable I/O 256 plus Earlier (2002-05) PICAXEs below are now considered obsolete, with supplies discontinued. 18 18 40 8 5 3x4bit low 128 less prog. 4 X 16F627 ($8) 28A 28 80 8 8 4 64 +256 28X 40X 28 40 40  Silicon Chip 600 600 9-17 8-16 0-12 8-20 4 3-7 4- X 16F872 ($10) 128 plus I2C 4- X 16F873A ($15) 128 plus I2C 4- X 16F874A ($26) siliconchip.com.au 1 2 3 4 PICAXE 08M +V SERIAL IN ADC 4 / OUT 4 / IN 4 INFRAIN 3 / IN 3 8 7 6 5 0V OUT O / SERIAL OUT /INFRAOUT IN 1 / OUT 1 / ADC 1 IN 2 / OUT 2 / PWM 2 / TUNE PICAXE 08M 1 14 2 13 3 4 5 6 PICAXE 14M +V SERIAL IN ADC 4 / IN 4 INFRAIN 3 / IN 3 IN 2 IN 1 ADC 0 / IN 0 12 11 10 9 8 7 2 SERIAL OUT SERIAL IN 3 5 10k 4 0V OUT 0 / SERIAL OUT /INFRAOUT OUT 1 OUT 2 OUT 3 OUT 4 OUT 5 3 PROGRAM EDITOR (TO PC SERIAL PORT) 20 2 19 3 18 4 5 6 7 PICAXE 20M 1 17 16 15 14 8 13 9 12 10 11 8 5 3V BATTERY 1 2 λ 5 λ 7 λ λ 0V SERIAL OUT OUT 0 / INFRAOUT OUT 1 OUT 2 OUT 3 OUT 4 OUT 5 OUT 6 OUT 7 3 8 λ λ 2 9 λ λ 10 λ 12 6 λ λ Pleasingly, the larger 14 and 20 “M” offerings retain the same programming and supply connections as the classic 08M, although only the 08M allows pins to be set either as Inputs or Outputs. I/O background Comparable to kids demanding the attention of a solitary teacher, it’s almost a byword with microcontroller projects that sensors and indicating devices will require more channels than are available. This is especially a problem with outputs and traditionally it has been addressed by multiplexing techniques, so that data signals are “juggled” around the displays at speeds 16-SEGMENT 4 S1 0 1 The three “M” PICAXES are very similar in pinouts and architecture, meaning little change in code as you move up the chain (in fact, the 08M is pin-for-pin for the top eight of the 14M). The main difference is all those beautiful extra inputs and output channels! 14-SEGMENT 7 3 PICAXE 6 08M λ PICAXE 20M 7-SEGMENT 1 11 4 PICAXE 14M +V SERIAL IN ADC 7 / IN 7 IN 6 IN 5 IN 4 ADC 3 / IN 3 ADC 2 / IN 2 ADC 1 / IN 1 INFRAIN / IN 0 2 22k 5x7 MATRIX Here’s an example of a LED chaser using just a PICAXE 08M. In discrete logic this would require at least three or four chips to achieve. Although this looks elegant when compared to 1:1 LED driving, annoying flickering may be an issue and considerable hookup wiring is needed. greater than human persistence of vision (POV). POV makes LEDs appear to be solidly lit, even although they’re being rapidly pulsed (at ~100Hz) and offers a bonus of lowering average LED current demands. The colourfully-named “Charlieplexing” (after Maxim engineer Charlie Allen) also enables relatively few I/O pins to drive a large number of LEDs, utilising the Tri-state nature of micro channels, when a pin can be sink, source or be open circuit. With “n” outputs n x(n-1) LEDs can be controlled. So a 4-output (Pins 0,1,2,4) PICAXE-08M can control 4x(4-1) = 4x3 = 12 LEDs and still have a Pin 3 left for some kind of input. But before you get too excited, realise that multiplexing of any type requires all manner of fancy “digital jigsaw” coding and wiring (as shown above), and for just a dollar or so extra the larger PICAXEs may ease the pain! LED displays Four common types of LED displays. At left is the standard 7-segment (+DP) type we are using in this article. Next in line, extra segments are added to make a much-more versatile 14-segment (+DP) display. Third has the upper and lower segments broken in two to form a 16 segments, capable of displaying most – but not all – letters and numbers (eg, “D” and “O” can’t be displayed because it looks exactly the same as zero). Finally, the LEDs are broken down into a 5x7 matrix which is capable of displaying any letter, numeral and an array of symbols. It’s just a matter of how the LEDs are driven. siliconchip.com.au LEDs have been an enormous success story since their early 1970s introduction and ever-brighter types are now revolutionising lighting and displays. We’re all bombarded daily by single status LEDs on TV sets and phone chargers, to bar arrangements showing volume on audio gear. But aren’t colour LCDs now all the rage? Quite true, but when compared with older 16x2 mono LCDs, LED displays are very bright, much cheaper July 2008  41 COM A B C D E F G C COM A B C D E F G a b f g e c d dp DP 7-SEGMENT DISPLAY1 DATA1 DATA2 DATA3 DATA4 DATA5 DATA6 DATA7 DATA0 E B C a 7-SEGMENT DISPLAY1 b f g e A B C D E F G c d 8 8 E B DISPLAY1 8 DISPLAY2 a b c d e f g dp DP dp 7-SEGMENT DISPLAY2 a b c d e f g dp b g e c d dp COM B DISPLAY1 7-SEGMENT DISPLAY2 a f C E 8 DATA1 DATA2 DATA3 DATA4 DATA5 DATA6 DATA7 DATA0 +V DP A B C D E F G a b f g e c d dp DP COM B C E DISPLAY2 Here’s how the various segments in 7-segment displays are driven. At left is a “common anode” circuit – here the transistor controlling the device must be turned on as well as the data lines controlling the individual segments. For example, if data lines 1, 2, 7, 5 and 4 are activated, the display shows a “2”. At right is the same setup, this time for “common cathode” displays. These are in fact used more frequently than common anode types. ($2-$4), and although rather power hungry (~5mA each segment) are easily driven and understood. In dim lighting, when extra LCD backlighting can draw significant currents, LED displays are supreme, especially for “at a glance” monitoring. If arranged in suitable patterns, traditionally in seven segments with all the LED cathodes joined (hence common cathode or CC), they can spell out numbers and letters that may be quite sufficient for simple status and alerts. Each character is just built up of suitably lit segments, with these traditionally referred to as a,b,c,d,e,f,g and dp(decimal point). The letter or number “0” will use segments a,b,c,d,e,f , while a “3” has a,b,c,d,g illuminated. Aside from displaying the numbers 0-9, with suitable program tweaking even basic characters (E, F, L, J, O, P, H, PROGRAMMING RESISTORS 4.7k 3 5 10k SERIAL IN 22k +V PROGRAM EDITOR (TO PC SERIAL PORT) DS 18B20 OUT ADC7/ INPUT 7 INPUT6 INPUT5 INPUT4 PICAXE 20M 20 10 ADC2/ INPUT2 1 DS18B20 OUT +V 0V SC 2008 ADC3/ INPUT3 ADC1/ INPUT1 INFRAIN/ INPUT0 2 1 19 3 18 4 17 5 16 6 PICAXE 20M 15 7 14 8 13 9 12 10 11 20 OUTPUT1 # OUTPUT2 # OUTPUT3 OUTPUT4 OUTPUT5 OUTPUT6 OUTPUT7 Picaxe 20m LED THERMOMETER # # # 8 2 S, A, I, U and C etc) and sequences such as HI and LO can be shown. The real world is full of crucial information (eg, lift floors etc) shown in such a cryptic manner. 14 and even 16-segment LEDS are available for more specialised displays but LED matrix arrays (such as the 5x7 shown) usually offer more character versatility – we will come back to these on a later project. But why the appeal of LEDs with PICAXEs? Driving a classic 7-segment display, when faced with just a few output lines, normally requires extra ICs like the DIP16 CMOS 4511, specifically designed for the task. Such approaches however involve considerable wiring, extra component costs and loss of display flexibility. Hence it’s VERY satisfying to see the 20Ms “gang of eight” outputs, as these immediately appeal for direct but versatile 7-segment use. It’s akin perhaps to hav+4.5-5V ing your very own personal teacher. (EG 3 x ‘AA’, You can’t beat 1:1 if the luxury is 4 x NiCd or # VALUE DEPENDS NiMH, etc) ON DISPLAY USED available – and each display LED is AND SUPPLY thus fed from a dedicated output, with 0V – 330 Ω TYPICAL an 8th available for the decimal point. SERIAL OUT # Voila – it’s almost as if 20Ms and OUTPUT0/ 7-segment displays were made for INFRAOUT # each other! DP A B C D E F G a b f g e c d dp COM # ACTUAL PINOUTS DEPEND ON 7-SEGMENT DISPLAY USED The new PICAXE-20M, with eight I/Os, is ideal to drive a 7-segment LED display. With a DS18B20 temperature sensor on the input, it makes a great thermometer. 42  Silicon Chip An application – and an answer to Stan’s first law! The 20M inputs can monitor almost any regular sensor using normal READADC, and it would be straightforward to connect a thermistor, LDR or the like in a simple voltage divider, with values being shown on the outputs perhaps via multiple LED bars. However, readers may well recall Swan’s 1st Law –“You can never have too many thermometers” and with this in mind, an enhanced but simple PICAXE 20M + 7 segment LED + DS18B20 digital thermometer circuit has evolved. siliconchip.com.au ‘PICAXE-20M,7 seg LED & DS18B20 demo. Stan.SWAN + PICAXE “Forum” ‘Uses single 7 seg display,sequencing digits so 24°C temp=”2” then “4” etc ‘Ranges very cold subzero (preceeded with flashing -ve) to ~99°C within 1/2°C ‘Suits further tweaking for info.display needs or enhanced battery life etc ‘204/256 bytes.Much tighter programming possible- EEPROM,symbol etc ‘Program download at => www.picaxe.orconhosting.net.nz/20m7segds.bas ‘Breadboard layout => www.picaxe.orconhosting.net.nz/20m7segds.jpg ‘--------------------------------------------------------------------------temp20m:readtemp 7,b0 ‘DS18B20 temp reading at 20M input 7 if b0>128 then gosub negtemps ‘Sub zero temps value correction b1= b0/10 b2= b0//10 if b1=0 then units ‘divide orig temp to get tens value ‘divide orig temp so remainder yields units value ‘suppress “0” if temps between ±9°C,so “4” & not “04” tens: ‘tens numeral test,with first digit suppressed if 0 on b1 gosub zero,one,two,three,four,five,six,seven,eight,nine wait 1:pins=%00000000 ‘blanks all 7 segs to ensure tens & units pause 200 ‘don’t run together if similar- 11,22,33 etc units: ‘units numeral test on b2 gosub zero,one,two,three,four,five,six,seven,eight,nine wait 2 ‘units digit extra hold on,as likely of most interest pins=%00000000:wait 1 ‘blanks for DP heartbeat between each temp.display for b3 = 1 to 3:pins=%00000001:wait 1:pins=%00000000:wait 1:next b3 goto temp20m ‘Bit order follows 20M outputs 7,6,5,4,3,2,1,0 (or 7 seg g,f,e,d,c,b,a,+DP) ‘if wired as on 20M breadboard demo using DSE Z4104 7 seg LED zero: pins=%01111110:return ‘0 shows one: pins=%01100000:return ‘1 shows two: pins=%10110110:return ‘2 shows three:pins=%10011110:return ‘3 shows four: pins=%11001100:return ‘4 shows five: pins=%11011010:return ‘5 shows six: pins=%11111010:return ‘6 shows seven:pins=%00001110:return ‘7 shows eight:pins=%11111110:return ‘8 shows nine: pins=%11001110:return ‘9 shows negtemps:’DS18B20 subzero negative temps routine + flashing -ve alert for b3 = 1 to 2:pins=%10000000:pause 200:pins=%00000000:pause 200:next b3 b0 = b0 - 127:return ‘b0 now correctly able to show subzero temps Stan’s traditional breadboard layout of the PICAXE-20M “thermometer”. The temperature sensor is bottom right. Here’s the commented (‘) code for the Thermometer. It’s not too long to type out – or you can download it if you wish. The ever popular DS18B20, which reads temperatures over a wide range to within ½°C, returns direct °C values for monitoring by the READTEMP command. Rather than use a second 7-segment display, a skinflint approach has been followed, where the display is just sequenced. So a temperature of 24° is shown as “2” then a”4”, with suitable blanking to prevent confusion. The DS18B20 measurement range is from an amazing –55°C to + 125°C, although peaking at 99°C in our case, with sub-zero temperatures preceded by a flashing “-”. Instead of coding with tedious multiple HIGH/LOW commands to build up a 7 segment pattern, outputs are setup in the efficient but cryptic %10101010 style. These are serviced g,f,e,d,c,b,a,dp so the command PINS=%00001110 shows a “7”. Even more efficient coding techniques could be used but the current approach is very readable while leaving scope for ample hacking and display tweaking. may then be required. The LED brightness relates to the values of these resistors, so alter the normal 330W droppers to suit, perhaps even using >1000W if the display is too bright in a darkened room. Such higher values will have the benefit of prolonging battery life (presently perhaps ~100 hours), which will naturally relate to the numbers of segments being lit. The circuit in fact works perfectly well on just 3V (although the display will be dimmer), and when thus compacted the entire design could even be housed in a small sealed waterproof plastic container. The DS18B20 can conveniently be extended off circuit and perhaps sealed in a rugged probe, as naturally the circuitry itself may need protecting if in liquids or at thermal extremes. Circuit layout Using a 7-segment display with side pins, the entire circuit readily fits on a small standard solderless breadboard. Larger or bottom-pinned LED displays will rather cramp the dropping resistor arrays and flying leads or a second board siliconchip.com.au Conclusion At ~$8 the new 20M looks well suited initially just in a cost effective display niche based on its 8 outputs, since these greatly streamline 7-segment LED driving, while offering display versatility. For convenience clickable links for code downloading, resources and references are all hosted at www.picaxe. orconhosting.net.nz/20M.htm SC July 2008  43 SERVICEMAN'S LOG My love-hate relationship I have been messing about with computers for more years than I care to admit. It has been a love-hate relationship and I am here to tell you experience has not improved my Knowledge Base. It has taken away a large chunk of my life and I have now reached the stage of GIGR and EMGO – ie, Garbage In, Garbage Retained and Even More Garbage Out! One thing I have learned is that if your computer works well, don’t mess with it. I need something that works reliably even if it is getting on a bit and until recently, my little hp Pavilion zt3010ap notebook has just chugged along, doing good things at work. It has XP Pro SP2 and the usual anti-virus and anti-spyware programs but because it had been running so well for so long, I got complacent and didn’t keep these up-to-date. I must also confess that I hadn’t been keeping the operating system up to date by installing the latest security fixes. And that’s not a good idea, as the following story illustrates. Basically, everything was OK until recently when I decided to update some applications and download a few other small programs I needed. It was during these downloads that I first noticed things going wrong. Strange messages were popping up and at least half the icons on the desktop disappeared. And then the gremlins really did surface. Suddenly, up popped a message from “System Defender” (a trojan look-alike of Microsoft’s Window Defender) to the effect that my computer was in danger from a malicious software attack and that I should immediately download another program to fix this. While I was contemplating what I should do about this, another web page automatically opened and the machine started downloading the program. I tried to stop it by closing the web page but as fast as I did this, it would open others. In fact, it was somewhat like watching the skeleton soldiers out of 44  Silicon Chip the old film “Hercules”. Eventually, I managed to switch everything off but I felt as though I had just hit an iceberg and my ship was capsizing. Frankly, I didn’t quite know what to do. Several technical friends told me that the best course of action would be to fdisk and reformat the hard drive, then reinstall the operating system but that was advice I found easy to ignore. They really don’t appreciate how much stuff I have on this computer. I mean, I really do have some serious stuff on it, all vitally important, and I wasn’t about to throw the baby out with the bathwater. After all, it took me years to get into this mess and I was going to fight this menace come what may. When I had a quiet moment, I switched it on again and began to notice a number of things I had overlooked before. First, the firewall wasn’t on (or had been turned off), my antivirus definitions were out of date and I was being shut out of the update site, Automatic Updates was switched off and the Taskmanager was not working. Worse still, I could not switch them back on manually. Clearly, something had got past my rather weak (and out-of-date) defences and was now merrily wreaking havoc. Stupidly, I went back onto the Internet and tried to download fixes and software to scan and fix the problems but the gremlins just kept flooding in. It was like pouring more water into my 45° listing, flooded ship and I was getting pretty close to capsizing altogether. I eventually managed to load Spybot Search and Destroy (a freeware anti-spyware program) and run it. It found lots of bugs had infected my computer but as fast as it fixed them, more popped up and this occurred regardless as to whether the machine was connected to the Internet or not. In the end, I had to admit failure and closed the computer down. When I went home that night, I fired Items Covered This Month • • Serviceman’s computer Panasonic TX-68PS12A (MX10A chassis) • Sony KV-HX32M31/Wega AX-1 • Sony KV-KF34M31 (BG-3 chassis) up my dear old clunker, a Gateway PIII, and downloaded as many freeware anti-virus and anti-spyware programs as I could. I also downloaded Norton’s Intelligent Updater for my main antivirus program and while I was at it, the latest Microsoft XP Service Pack 3 (all 316.4Mb of it)! I put all these onto a flashdrive and took them to work the next day. Once in the workshop, I installed SP3, hoping that this would correct some of the problems I was having but it made no difference. I then installed and ran some of the anti-virus and antispyware programs I had downloaded on my home machine and they killed a variety of malicious software but still the bugs kept popping up. I then tried installing Norton’s Intelligent Updater but that didn’t work either. It was time to eat humble pie and ask a real guru for some advice. The kiss principle When I told him of all the problems, his initial (half-joking) advice was that I should reformat the disk and reinstall XP. My response was no way, it would take too long to reinstall everything whereupon he gave me yet another unwanted lecture on the “kiss” principle for computers (as in “keep it simple stupid”). Eventually, he stopped stirring and gave me some useful advice. Booting from a badly infected disk and then trying to use it to repair itself was not the way to go. It would be far better siliconchip.com.au if I could get the disk out and scan it using another good machine. He also told me to initially scan the disk using CWShredder and McAfee Avert Stinger. CWShredder is a freeware program that gets rid of the intensely annoying CoolWebSearch which is a browser hijack trojan. Stinger, also available free, scans for and eliminates some 193 common viruses and trojans (you can download it from http://vil. nai.com/VIL/stinger/)/. Next, he told me to take a look at the hosts file on my notebook computer. Apparently, it’s not uncommon for a virus to make entries in this file, pointing various websites (eg, anti-virus definitions update sites) to incorrect IP addresses. Apparently, when you type a web address into your browser, the system checks this hosts file for the IP address first and if it isn’t there, goes to an Internet DNS server. However, if the web address is in the hosts file but pointing to an incorrect IP, then you are effectively “blocked” from that website. That means you can be prevented from updating anti-virus definitions files, etc. Finally, he pointed me to a program call UBCD4WIN (Ultimate Boot CD For windows). Available as a free download from http://www.ubcd4win.com/ index.htm, this very useful program lets you create a boot CD using your original Windows XP CD. It also allows you to add a range of freeware anti-virus and anti-spyware tools to siliconchip.com.au fight infections of this type and to include the latest definitions updates for these programs. You then boot from this newlycreated disk so that you have a clean system to start with, then use the diagnostic tools to make the repairs. Anyway, I downloaded the program on my home computer, made a UBCD4WIN CD and used this to boot my notebook computer. This gave me a stable platform to work from and I let all the anti-malware programs have a go one after the other. They all found and eliminated problems of one sort or another. Next, I rebooted the computer from its hard drive, ran msconfig and turned off all non-Microsoft services and start-up programs (incidentally, July 2008  45 Serviceman’s Log – continued SP3 has now added a Tools tab to the System Configuration Utility). I also examined C:\windows\system32\ drivers\etc\hosts file which was very long (240Kb), with lots of extra entries. I copied over the hosts file (732b) from my good computer and then rebooted the computer again. At last, everything appeared to be back to normal and I was able to turn on the firewall and automatic updates through the appropriate menus. I immediately updated my Norton AntiVirus and ran a full scan and it gave the all clear, so I re-ran the msconfig utility and reactivated the various services and start-up programs. I also decided to clean-up the registry and again a couple of freeware programs – “CCleaner” and “Wise Registry Cleaner 3 Free” – came to the rescue. Between them, they found lots of unnecessary entries and these were deleted. A commercial registry checker would no doubt do an even better job and I intend to invest in one. Incidentally, CCleaner is a great little freeware program. It’s not only a basic registry checker but can also 46  Silicon Chip delete all the rubbish that accumulates on your hard drive including cookies, temporary internet files, your browsing history, temporary files and lots of other stuff. It even empties the Recycle Bin. Finally, now that my system was up and running again, I decided to strengthen my defences by upgrading my anti-virus software to the latest version. I also installed ZoneAlarm to improve my firewall and for good measure, turned on the firewall in my ADSL modem. And yes, I’ve well and truly learned my lesson. In future, I’ll be keeping all my anti-virus and anti-spyware definitions up to date and installing any security updates as advised. Intermittent Panasonic I was called out to service a 2002 Panasonic TX-68PS12A TV (MX-10A chassis) because its 45kg weight made it too hard for its elderly owner to bring it in. I wasn’t too happy about having to make this service call, especially when they said the vertical scan went down to just a 5cm band after about 30 minutes. As luck would have it, when I called the fault showed up after just six minutes. I asked the client if he had a torch and when he left of the room I gave the set a good hard slap on the side of the cabinet, whereupon the fault got even worse. I turned the set off, removed the back and placed it on its side so that I had access to the PC board. I then examined it carefully with the torch, looking mainly for dry joints, especially around the vertical output IC (IC451, LA7833S). However, I couldn’t see any problems but that is not unusual these days as hairline fractures in the solder can sometimes be hard to detect – especially in a dark corner of the room. I set about resoldering IC451’s pins and any other possible dry joints nearby. When I finished, I ran the set for 15 minutes before replacing the back, collecting my fee and leaving, confident that the set was now OK. But it wasn’t. The client was back on the phone the very next day, complaining of the same problem. I pointed out, with a lot of emphasis, that intermittent faults really cannot be fixed in the home within 30 minutes and told him that it would be better if he brought the set in to my workshop. In the end, reluctantly, I was persuaded to return to the problem set. This time, when I eventually saw the problem, I let the set stay on longer and noticed that there were other symptoms as well. The picture was gradually getting brighter while at the same time its quality was getting poorer, until siliconchip.com.au Repairing Hair Straighteners With High-Temp Epoxy In this age of throwaway items, it is good to know that some items are still worth repairing even though it might be because they are highly priced to begin with. Hair-straighteners essentially consist of two heated flat elements which are used to squeeze and pull hair until it hangs as straight as a die. Most hair-challenged blokes cannot imagine why anyone would want to do it but strangely, a lot of people (with long hair) do use these contraptions. Now there are hair straighteners and hair straighteners and they range in price up to several hundred dollars for a set. These ones are Silver Bullet Titanium Executive (with inbuilt ion generator – wow!) and had been dropped several times, so one of the heated elements was no longer safely retained in the handle. It is a simple job to glue it back into place but you cannot use just any epoxy adhesive because the heated elements can run well in excess of eventually the picture was lost in line tearing. I removed the back and sprayed freezer around inside until I found a heat- sensitive component. It didn’t take long. It was IC884 (PQ05RD1B), a switchable 5V IC regulator. Hitting it with freezer immediately restored the picture completely and then, about six minutes later, it would start to collapse again. Replacing the regulator completely fixed the fault this time. Intermittent Sony With the Panasonic set out of the way, I was almost immediately called out to service another very large, heavy CRT CTV. This time, it was an 80cm Sony KV-KF34M31 (BG-3 chassis) and the problem was that the dark (black) siliconchip.com.au 200°C. By contrast, standard Araldite epoxy adhesive will soften at temperatures above 100°C. The answer is to use JB Weld hightemperature epoxy adhesive. This is rated to withstand temperatures up to 315°C (600°F) and can be used in a wide range of applications where high strength and high temperature resistance is required. The two parts come in separate tubes (pictured) and can be mixed and applied like any 2-part epoxy ad- areas in the picture were intermittently going blue. Fortunately, by the time I arrived, the fault was just about permanent. In this case, it was clear that the greyscale was faulty in the white balance lowlight cut-off circuits. I began by checking for error codes but there were none. I then measured the voltages around the CRT socket but found nothing unusual so I tried bashing, heating and cooling the chassis but nothing would alter the symptoms. Next, I went into the service menu and tried adjusting the greyscale there. This had some effect but not enough. In fact, the only control that had any real effect was the screen G2 control, which I could adjust to give a perfect picture. The only problem was that the hesive. The difference is that JB Weld takes about six hours to set and 24 hours or more to reach full strength, depending on temperature. Hence the repair job needs to be securely clamped and left undisturbed for a day or so. The good news is that the repair was successful and the unused ingredients in the tubes should have a long shelf-life if kept cool. JB Weld is not widely available but we found it in our local Kmart store, priced at $16.95. red LED on the front panel would then flash and sometimes the set would not restart in this condition. Well, I wasn’t really sure what the Ozitronics Tel: (03) 9896 1823 Fax: (03) 9011 6220 Email: sales2008<at>ozitronics.com K146. 40 Second Message Recorder Multiple message recorder up to 40 seconds. Non-volatile memory using ISD2540 chip. Message looping switch to repeatedly play the first message. Hurry while stocks last! $33.00 More kits & documentation available on website: www.ozitronics.com : July 2008  47 Serviceman’s Log – continued problem was – it could be the flyback transformer, the colour decoder jungle IC (IC301, CXA21305), the CRT socket board (C) or even the CRT itself. And then again, it could be a microprocessor/EEPROM fault. I started by replacing the STV5112 Video Output IC (IC701) on the CRT socket board but it made no difference. It was then that I had a bit of muchneeded luck. Among the bits in my van was a secondhand CRT board from a similar TV. The main difference was that this board used discrete components instead of an IC. Nevertheless, I tried it and not only did it work but it also fixed the fault! Well, this seemed to be the easiest way of fixing the problem – even if I hadn’t actually repaired it to component level. The client, who had been watching me like a hawk, agreed that this was the cheapest fix and agreed to the exchange board and so we parted amicably. But that wasn’t to be the end of things. Two days later, I got an anxious call from the client who now claimed that the replacement board had also gone faulty. I returned and found that the symptoms were quite different than before, with the set now turning itself off intermittently. And once again, there were no error codes. I quickly established that it wasn’t the new board by refitting the original and it wasn’t the screen control G2 setting either. Fortunately, a Sony agent colleague of mine came to the rescue with a Service Bulletin (AUS595 issued 28th May, 2003) which described this symptom, the cause and the fix. The set was intermittently closing down and the relay clicking due to the 5V supply being loaded down by a faulty Teletext board (V1). I removed this board and the symptoms stopped. 48  Silicon Chip However, if I replaced the board, the 5V rail would drop to nearly 3V. I told the client I could either repair the board, replace it or just leave it out. He decided on the latter course as he was actually completely unaware that the set even had Teletext and therefore wouldn’t miss it. The set hasn’t missed a beat since. I hate being beaten Last October, I wrote about two Sony HD CRT TVs that I had to abandon. They were a KV-HX32M31 Wega and a KV-HR32M31, both using the AX-1 chassis. I was able to keep the faulty D Board from the first set and whenever things got quiet in the workshop, I kept going back to it and for further investigation. Call it stubborness if you will but I hate being beaten. As mentioned back in October, the HX model came in with an error code 3, indicating a B+ overvoltage (OVP) and when I replaced R6512 (1W) on the +133V rail, the error code changed to 4, indicating a vertical deflection fault (V-STOP). I then tried replacing IC5101 (STV9379) and despite life-threatening consequences, I even managed to measure the ±15V rails going to it. So what was causing the vertical error? I looked closely and noticed that when I tried switching the set on from cold, a small puff of smoke emanated from the front (RHS) of the board. However, before I could determine which component was the source of this smoke, it promptly stopped. I replaced the IC and the regulators around that area but it made no difference and I then wasted a lot of my time changing flyback transformers, etc. I then tried it again and it let out another puff of smoke. I searched and searched for the source and eventually discovered that diode D6509 was faulty. This supplies +210V to the CRT board (R6509, shown on the circuit as a series fusible resistor, turned out to be just a link). I replaced the diode and the set nearly came on fully. It then eventually went off again with an error 10 code (HV-PROT-DET). I replaced IC8002 (MCZ3001DB) and fitted the new one with an 18-pin IC socket. Apparently, the “DB” version is an improvement on the “D” type but in this set the later type had already been fitted and replacing it with either type made no difference. What eventually fixed the problem was readjusting trimpot RV8001 (HVPROT-ADJ) to a less sensitive position. This control is actually sealed under a large lump of silicone but that hadn’t stopped the salt-air corrosion from getting to it. RV8001 is usually set for to give EHT of 31.5kV (the set cuts off at 36.5kV). The other adjustment required was the Flyback Transformer Screen G2 control. You can follow the complicated set-up procedure in the service manual, involving CROs and other software adjustments, or you can do it by eye and simply adjust it to give the clearest, brightest picture with the best greyscale definition. If you go too far one way or the other, you are back to error code 10. Once the set was finally working, I then went into the self-diagnostic onscreen menu and reset the error codes to zero again. I never did get to the bottom of the faults in the other abandoned set but I suspect its error 10 code was due to much the same problems. IC8002, the horizontal driver (Pulse Width Modulator Control Circuit) for the EHT generator, is now known to give error 10 codes but no-one much knew about it this time last year. Why it fails remains a mystery. Sometimes you can simply desolder it and refit it with a SC socket and it works again. siliconchip.com.au BRIDGE MODE ADAPTOR FOR STEREO AMPLIFIERS Refer Silicon Chip July 2008 This excellent kit will let you run a stereo amplifier in 'Bridged Mode' to effectively double the power available to drive a single speaker. There are no modifications required on the amplifier and the signal processing is done by the kit before the signals are fed to the stereo amp. The kit is perfect for say, using a stereo amplifier as an occasional PA amplifier for social functions or using and old amplifier to drive a sub-woofer in a home theatre system. It sounds like magic, but is just a clever adaptation of basic electronic principles. Kit supplied with silk screened PCB and all specified components. Requires balanced (+/-) power supply. $ 24 95 Cat: KC-5469 LOW COST DMM This full featured digital multimeter is perfect for the home handyman or young experimenter and will give years of reliable service. It features a huge 10A DC current range as well as diode and transistor testing functions. Also measures AC & DC volts and resistance. At this price you should buy two! • 19 range • 3.5 digit • Ideal first meter • Compact size $ 7 95 Cat: QM-1500 NEW STORE NOW OPEN MIDLAND WA IN-DASH MULTIMEDIA PLAYER This excellent unit will play DVDs, VCDs, MP3s, CDs, and AM/FM radio. The built-in 3" TFT screen doubles as a control panel when listening to MP3s etc. It also has an auxiliary audio input for external MP3 or tape player etc. The player fits a standard DIN slot and has a detachable face and can be operated by the included remote. Mounting hardware included. • Resolution 500TV lines • 2 x video inputs • 1 x camera input • 45W RMS per channel • Frequency response: 20Hz - 20kHz $ 349 Cat: QM-3787 WIRELESS NETWORK ACCESS POINT WITH 4 PORT ROUTER ADEL NIBBLING TOOL The original and best. The Adel nibbling tool has been around for years and for good reason. It's still the best hand nibbler going around and is ideal for chassisbashing and all sorts of hobby applications. Cut, notch or trim simple or complex shaped holes in plastics, laminates, leather or metal. • Capacity: • Mild steel: 1.2mm • Aluminium: 1.6mm • Plastics: 2mm • Made in USA • Spare punch: TH-1767 $44.95 $ This router allows communication with up to four wireless network computers. It includes support for WAN, web based and remote management, auto detection and configuration of ISP, built in firewall, and more! • IEEE 802.11g and IEEE 802.11b compatible • Up to 54Mbps data rate • Static and dynamic routing • VPN pass through Was $79.95 $ 69 95 $10 Cat: YN-8086 59 95 Cat: TH-1765 MINI STEREO RESONATOR SPEAKER This uber-cool gadget turns any flat surface into a speaker, creating high quality 360 degree sound. Great for travellers. Mains plugpack included. • Measures: 47(Dia) x 44(H)mm • Requires: 8 x AA batteries for portable $ 95 use 99 Cat: AR-1870 6P/8P MODULAR CRIMP TOOL This tool will crimp 6P2C, 6P4C-RJ11, 6P6CRJ12 &8P-RJ45 plugs. Also cuts and strips the cable. $ 19 95 Cat: TH-1935 ECONOMY FOUR ZONE WIRELESS ALARM An affordable system that provides reliable protection for your home, apartment or small office. The system is simple to install and the alarm panel will detect and 'learn' which sensors have been installed. The control unit also monitors the system status and sensor battery condition to ensure system reliability. The system includes the control panel with keypad, a passive IR motion sensor, and a reed switch sensor for door or window protection. Wireless installation makes the system ideal for tenants. Batteries and power supply included. Specifications: Control Unit • Transmission frequency - 433MHz Siren duration - 3 min • Dimensions - 85(W) x 160(H) x 30(D)mm Cat: LA-5134 PIR Sensor • Coverage - 110° • Detection range - up to 12 metres • Requires 2 x AAA batteries (Use SB-2426) Reed switch sensor • Requires 2 x AAA batteries (Use SB-2426) 208,600 Additional sensors - Available separately Break-ins • LA-5136 wireless PIR sensor - $49.95 • LA-5137 wireless reed switch sensor - $39.95 in Australia • LA-5138 remote control unit - $29.95 in 2006* • LA-5139 repeater/extender sensor - $59.95 $ Unit 1 / 203 Great Eastern Highway Midland WA 6056 Ph: 08 9250 8200 FX 08 9250 8211 99 95 Limited stock on some items. Pricing whilst stocks last - no rainchecks. * Australian Bureau of Statistics reference Free Call: 1800 022 888 for orders! www.jaycar.com.au 1 TOOLS FOR YOUR TRADE TEST & MEASUREMENT 400A AC/DC Clampmeter Quality, intermediate-level clampmeter with more than useful current ranges up to 400 amps AC and DC. • Autoranging • Relative mode • Diode test • Audible continuity • Data hold • Min/max mode • Auto power-off • Jaw opening 30mm • Temperature probe • Carrying case $ DIGITAL THERMOMETERS Digital Thermometer with K-Type Thermocouple Features an excellent measurement range from -50 to 750°C and a hold function to lock the reading on the display. Thermocouple included. Requires 9V battery. • Accepts standard K-type thermocouples. • Specifications: • Display: 3.5 digit LCD • Range: -50 - 750°C $ 95 • Accuracy: ±1°C • Dimensions: 118(L) x 70(W) x Cat: QM-1602 29(H)mm 39 Pro High Temperature Non-Contact Thermometer 99 95 Cat: QM-1563 True RMS Autoranging DMM Autoranging • True RMS • Transistor test • Diode test • Data hold • Audible continuity • Temperature • Capacitance • Frequency • Relative measurement • Auto power-off • Holster • Temperature probe $ $ Cat: QM-7226 LEVEL METERS 69 95 For the DIY car enthusiast. • Standard meter functions • 3.5 digit LCD • Automatic zero adjustment • Low battery warning and auto power off • Dwell angle and RPM (x1, x10) for 4, 5, 6 and 8 cylinder engines • Probes, holster and battery included $ 49 95 Cat: QM-1440 16 Channel Cable Identifier with DMM Easily identifies individual conductors in a multi-core cable with just the remote unit attached to the other end. The remote unit has 16 numbered leads which are clipped to the cable being checked. Supplied with remote terminator, and multimeter leads. • Easy cable ID • Autoranging DMM • Diode test • Continuity test • Two devices in one • Auto power-off • Case included Cat: QM-1329 100 Piece Driver Bit Set Includes just about every driver bit you could want. • Metric and Imperial sizes • Even has a 'Wing Nut' driver • TD-2032 Driver handle to suit $5.55 $ 16 95 Cat: TD-2038 Stainless Steel Side Cutters High quality small side cutters that have thick (2mm) blades and soft comfort plastic spring loaded handles. • 115mm long $ 11 95 With a range of 40 - 100dB, it has a fast response time for transient measurements and is A-weighted for the frequency range of human hearing. Specifications: • Frequency range: 31.5Hz - 8kHz • Measurement range: 40 - 100dB • Accuracy: ± 3.5dB <at> 1kHz • Dimensions: 210(L) x 55(W) x 32(D)mm $ 19 Cat: TD-2022 Low Voltage Circuit Tester 6,12,24V 49 95 Cat: QM-1591 Compact Digital Sound Level Meter Featuring a wide dynamic range from 30 to 130dB, it can measure both A and C weightings and can have fast or slow responses to get an 'ambient' reading or a short noise burst. Includes data hold and min/max functions, as well as tripod mount. Supplied with carry case and wind sock. • Battery included • Dimensions: 210(H) x 55(W) x 32(D)mm $ 99 Looks like a neon test screwdriver but instead of a blade on the end this tester has a probe and a 28" lead which clips to ground. Suitable for 6/12/24 volts for use on cars, trucks, boats etc. Digital Lightmeter Cat: QM-1587 3 50 10PC Spanner Set for Electronics 95 49 95 $ Cat: TD-2049 Cat: QM-1589 $ 1000V- 7 Piece Screwdriver Set High quality, bright red drivers you can find easily. Insulated right to the tip and rated to 1000V. • Drive sizes: Flat: 1.2x6.5x150mm, 1x5.5x125mm, 0.8x4x100mm, 0.6x3.5x75mm. • Phillips: #2 x 100mm, #1 x 80mm, #0 x 60mm. Includes 95 storage box. $ Micro Sound Level Meter Dwell Tacho DMM 89 95 TOOLS Cat: TH-1890 Cat: QM-1536 $ 179 Measure high temperatures with safety. Suitable for lab, furnace, forge and smallscale foundry work. Accurate placement of the measurement point - 30:1 distance-to-target ratio allows for accurate measurement from greater distances. • Temperature range: -50 - 1000°C (-58 - 1832°F) • Built-in laser pointer • Automatic data hold • Max and min logging • High and low alarm • Dimensions: 230(L) x 100(H) x 56(W)mm Here at Jaycar Electronics we are firmly committed to supporting young people and helping them achieve their goal of following a electrical trade or engineering career. The joint Australian Federal Government and the Australian Apprenticeship initiative also supports this and provides an allowance of up to $800 (including GST) for qualified participants to A handy lightmeter for photography, lab work, architectural, engineering and construction. 3 ranges to .01 to 50,000 lux. Battery and sensor cover included. • Features: • 1999 Count LCD • 3.5 Digit Readout $ 14 95 Set of 10 pieces, open end/ring combination. • Includes 4.0, 4.5, 5.0, 5.5, 6.0, 7.0, 8.0, 9.0, 10, 11mm • Plastic carry wallet Cat: TH-1910 Handy Magnet Strip Simplicity itself. Just attach the handy magnets to walls, tables or other surfaces to hold tools, brushes, scissors, key rings, or any other object that contains iron. You'll find dozens of uses for this innovative magnetic storage system. Tools not included $ 14 95 Cat: LM-1624 Limited stock on some items. Pricing whilst stocks last - no rainchecks. 2 Free Call: 1800 022 888 for orders! www.jaycar.com.au TOOLS FOR YOUR TRADE purchase 'Tools for your Trade'. The employer of eligible Australian Apprentices receives a voucher to the value of $800 which can be presented to any Jaycar store. Bring your voucher in and our staff will be happy to help you find the best tools for your trade. For more information visit www.toolsforyourtrade.com.au Great for quick and easy low stress repairs to timber, cardboard, paper, and many household materials. Powered by 240VAC and Australian Standards approved. STORAGE High quality case, supplied with tool pallet, which can be removed if not required. Lid includes a document holder and the padded case includes 5 dividers that can be rearranged or removed. Lockable and includes two keys. • Size: 450(W) x 320(D) x 145(H)mm 49 Cat: HB-6352 $ This tough ABS storage box is ideal for transporting sensitive equipment and has a pluck foam insert with precut squares that can be removed to fit the item you want to protect. It is an excellent case and you will be hard pressed to find a better product, even at twice the price. • Dimensions: • Internal: 239(W) x 94(H) x 159(D)mm Cat: HB-6380 • 260(W) x 100(H) x 200(D)mm Heat the pellets in hot water to around 63°C and they can be formed into any size or shape. The material hardens at room temperature to form a tough plastic material similar to Nylon. It can be machined or heated and reformed again and again. Endless uses in model making, craft, prototyping, engineering, science, lab etc. • Supplied in a 100g bag of 3mm pellets. This 10MHz CRO has an input sensitivity range from 5mV to 5V per division and sweep time from 0.1uSA to 100mS per division. Signal and trigger inputs are BNC connectors and the supplied probe has a 10:1 attenuator as standard. The instrument is housed in a strong steel case and has a Cat: QC-1920 70mm CRT with 5mm square graticule. See our website or catalogue for full specifications. 29 95 $ 9 95 Cat: NP-4260 $ 5 95 Cat: TD-2126 10 Piece Needle File Kit TESTERS & METERS Mains Power Meter The meter can tell you how much an appliance is costing to run and tracks the actual power being used. It can also display the instantaneous voltage or current being drawn as well as peak levels etc. $ 95 10A max rating. Cat: MS-6115 LCD Vernier Type Engineers Calipers 39 95 Cat: TD-2082 $ 13 95 Cat: TD-2128 Ultrasonic Distance Meter with Laser Measures distance, calculates area, sums total readings and stores data for later use in imperial or metric units from 0.6 - 16m (1.6 - 52ft). Backlit LCD, auto power-off, case and belt-clip included. • Accuracy: ±1% of reading • Dimensions: 175(L) x 62(W) x 45(D)mm $ 39 39 95 Test your power points using this versatile tester. It checks power points within 110V to 240V for correct wiring and earth leakage circuit breaker trip levels. The soldering station features a high quality ceramic heating element for accurate temperature control, which is adjustable between 200 and 480°C. The soldering pencil is light weight, making it comfortable for use for extended periods. See in-store or our website for full features. $ 99 Cat: TS-1560 Super Pro Gas Soldering Tool Kit $ 139 Cat: TS-1328 This butane gas soldering iron features adjustable tip temperature and a fold-out stand. Remove the soldering tip and you have a flame torch. • Dimensions: 210(L) x 20(dia)mm $ 19 95 Cat: QP-2000 $ 19 95 Cat: TS-1111 Piezo Ignition Butane Gas Torch 39 Very Versatile! $ 95 Ideal for brazing, silver soldering, jewellery work, Cat: TS-1660 heatshrinking, and a whole lot more. It has an adjustable flame, and is easily filled with Butane gas. Butane Gas 150g Use it for filling up your gas soldering iron, flame torches, cigarette lighters, etc. Includes five different $ 95 adaptors, which cover most different gas valves. Cat: NA-1020 Includes filling instructions. • 150g 4 Solder Stand with Solder Reel Dispenser $ Cat: QP-2295 Power Point and Leakage Tester Temperature Controlled Soldering Station Low Cost Gas Soldering Iron Electronics hobbyists and scale model $8 builders shouldn't be without a good set of hobby files. This set consists of five different files, each with an overall length of 170mm and a file length of 95mm. Files include: round, rectangular, square, triangular, conical. Was $13.95 Contains every profile you could ever need. All have integrated plastic handles and come in a handy storage wallet. Each is162mm long. 14 95 Cat: TH-1996 This kit contains a Portasol Super Pro Gas soldering iron and various tips. • Quality storage case. • Cleaning sponge and tray 5 Piece Needle File Set 155 $ SOLDER Waterproof ABS Instrument Case with Foam Insert $ 2 95 Cat: TH-1995 Polymorph Pellets 10 MHz Single Trace Cathode Ray Oscilloscope (CRO) Simple and easy to use with digital readout • Accurate to 0.01mm $ • Metric or Imperial measurement 17 95 Cat: TH-1992 Aluminium Attaché Case $ Size 11mm dia. X 100mm long • TH-1995 Pk 6 • TH-1996 Pk 45 Large Glue Gun - 240V $ $ Glue Sticks GLUE GUN 14 95 Perfect for the workshop and keeps solder tidy and in its place. Holds reels up to 1kg. • Size 90(L) x 100(W) x110(H)mm • Weight 620g Cat: TS-1504 Duratech Solder - 60% Tin / 40% Lead 1kg reels NS-3002 - 0.71mm $39.95 NS-3015 - 1.00mm $39.95 200g reels 15g pack NS-3005 - 0.71mm $8.95 NS-3010 - 1.00mm $8.95 NS-3008 - 0.71mm $1.65 NS-3013 - 1.00mm $1.65 Limited stock on some items. Pricing whilst stocks last - no rainchecks. Free Call: 1800 022 888 for orders! www.jaycar.com.au 3 CHRISTMAS IN JULY CLEARANCE SALE Buy NOW for Christmas and Save$$$ Over 20 to 75% OFF ALL listed Items Listed below are a number of discontinued (but still good) items that we can no longer afford to hold in stock. We need more space in our stores! You can get most of these items from your local store but we cannot guarantee this. Please ring your local store to check stock. At these prices we won’t be able to ship from store to store. Items will sell fast and stock is LIMITED – ACT now to avoid disappointment – Sorry NO rainchecks! Test Equipment & Tools Cat USB Data Logger 4 Channel with Software Digital Megohmmeter 1000V DMM 3.5 Digit Temperature, Hold, Backlight with Holster DMM CatIII Auto Capacitance, Temperature, Frequency Digital Clamp Meter Amp AC/DC Digital Mini Clamp Meter with NCV Detector Ideal Industries - DMM True RMS Autoranging Ideal Industries - Digital Pro Clamp Meter 4-in-1 Headset Magnifier Magnifier & Desktop Fluoro Lamp Fluoro Tube to suit Lamp QM-3520 Digital Thermometer Non-contact Digital Thermometer Gun Non-contact Voltage Tester with Torch Keychain Voltage Tester Keychain Stud Detector Stud/Voltage Detector with Laser Level Handyman Laser Level Eye Glass Repair Kit Jeweller's Screwdriver Set Ratchet Screwdriver with 165mm Extension and 6 Bits 1000 Volt Insulated Screwdriver - Flat 75mm 1000 Volt Insulated Screwdriver - Flat 100mm 1000 Volt Insulated Screwdriver - Flat 125mm 1000 Volt Insulated Screwdriver - Flat 150mm 1000 Volt Insulated Screwdriver - Flat 175mm 1000 Volt Insulated Screwdriver - Phillips 80mm 1000 Volt Insulated Screwdriver - Phillips 150mm 1000 Volt Insulated Screwdriver - Pozidrive 80mm 1000 Volt Insulated Screwdriver - Pozidrive 100mm 1000 Volt Insulated Screwdriver - Pozidrive 150mm Screwdriver Helper Liquid - 14g Adjustable Hole Saw 63 to 177mm Adjustable Hole Saw 158 to 254mm All-Purpose Sharpener 7 in 1 Screwdriver & Stripper Quick Connector Crimping Tool - 5 Function Fibre Optic Crimp Tool Extended Reach Pick-up Tool - 80cm 16-in-1 Multitool with Pouch Tool Case with Zipper - 380x270mm Cable Identifiers QD-5000 $139.95 $79.95 $60.00 QM-1492 $99.95 $59.95 $40.00 QM-1526 $24.95 $11.95 $13.00 QM-1539 $59.95 $39.95 $20.00 QM-1562 $139.95 $89.95 $50.00 QM-1564 $99.95 $59.95 $40.00 QM-1625 $379.00 $299.00 $80.00 QM-1628 $299.00 $199.00 $100.00 QM-3510 $29.95 $19.95 $10.00 QM-3520 $49.95 $39.95 $10.00 QM-3521 $9.95 $5.95 $4.00 QM-7214 $19.95 $9.95 $10.00 QM-7223 $97.95 $59.95 $38.00 QP-2276 $19.95 $8.95 $11.00 QP-2278 $9.95 $5.95 $4.00 QP-2284 $8.95 $4.95 $4.00 QP-2288 $49.95 $29.95 $20.00 ST-3113 $39.95 $14.95 $25.00 TD-2004 $2.90 $1.00 $1.90 TD-2005 $5.35 $1.95 $3.40 TD-2057 $14.95 $9.95 $5.00 TD-2200 $3.95 $1.95 $2.00 TD-2201 $4.50 $2.25 $2.25 TD-2202 $4.95 $2.45 $2.50 TD-2203 $5.95 $2.95 $3.00 TD-2204 $6.50 $3.25 $3.25 TD-2206 $4.95 $2.45 $2.50 TD-2208 $6.50 $3.25 $3.25 TD-2209 $4.95 $2.45 $2.50 TD-2210 $5.95 $2.95 $3.00 TD-2211 $6.50 $3.25 $3.25 NM-2830 $13.95 $9.95 $4.00 TD-2520 $69.95 $49.95 $20.00 TD-2522 $79.95 $59.95 $20.00 TH-1759 $18.95 $9.95 $9.00 TH-1822 $19.95 $11.95 $8.00 TH-1828 $6.85 $3.95 $2.90 TH-1840 $49.95 $39.95 $10.00 TH-1844 $14.95 $9.95 $5.00 TH-1903 $19.95 $14.95 $5.00 HB-6370 $79.95 $39.95 $40.00 HP-1242 $11.95 $7.95 $4.00 Security & CCD Equipment Cat Access Control RFID Keypad PIR Door Announcer Alarm Security Alarm Telephone System Dummy Camera with Corner Mounting Bracket GSM Alarm Tx & Rx Module GSM Alarm Expansion Board to suit LA-5370 Shed or Garage Alarm wit PIR, Reed Switch & Remote Security Pan, Tilt, Zoom Receiver with PSU Security Pan, Tilt Motor with RS485 Zoom Controller CCD Colour Dome Camera, 520TVL Sony Sensor Varifocal Lens 2.8 - 12mm Manual Iris - CS Security Camera Pan, Tilt with Remote Camera Lead RJ Plug - Socket 20m to suit QC-3250 CCD Colour Pro Varifocal Camera, 380TVL Sony Sensor CCD Colour Covert Smoke Detector Camera, 380TVL CCD Colour Covert PIR Camera, 350TVL Sony Sensor B& W CMOS Video Doorphone with Desktop Console 2.4GHz CMOS Camera to suit QC-3625 14" B&W 4 Channel Switching Monitor with Quad Processor Security DVR & 2 Camera Kit with 250GB HD CCD Colour Camera to suit QV-3085 CCD Colour Dome Camera to suit QV-3085 Security 8 Channel Pro DVR with 250GB HD Security 16 Channel Pro DVR with 250GB HD LA-5123 LA-5166 LA-5200 LA-5312 LA-5370 LA-5372 LA-5400 QC-3212 QC-3218 QC-3290 QC-3347 QC-3395 QC-3456 QC-3518 QC-3555 QC-3557 QC-3620 QC-3626 QM-3418 QV-3085 QC-3086 QC-3087 QV-3088 QV-3089 Was Was $169.00 $49.95 $249.00 $29.95 $599.00 $89.95 $49.95 $149.95 $299.00 $299.00 $99.00 $299.00 $19.95 $299.00 $169.00 $199.00 $99.00 $299.00 $399.00 $999.00 $199.00 $149.00 $1,499.00 $2,399.00 Now Now Save $129.00 $40.00 $29.95 $20.00 $169.00 $80.00 $11.95 $18.00 $399.00 $200.00 $69.95 $20.00 $29.95 $20.00 $79.00 $70.95 $149.00 $150.00 $179.00 $120.00 $59.95 $39.05 $149.00 $150.00 $11.95 $8.00 $199.00 $100.00 $99.00 $70.00 $99.00 $100.00 $59.95 $39.05 $129.00 $170.00 $239.00 $160.00 $499.00 $500.00 $99.00 $100.00 $89.00 $60.00 $600.00 $899.00 $800.00 $1,599.00 *Off Original RRP. Limited stock, no rainchecks, may not be available at all stores – call your local store to check stock details. 4 Save Audio/Video Products Cat Was Now Save DJ Dual Digital CD Player with Backlight AA-0490 Red Laser Light Show with Remote Control SL-2923 Amplifier Module 350W with Remote Control AA-0508 Headset Adaptor USB Mic & Headphones AA-2034 Wireless 2.4GHz Digital Headphone and Transmitter AA-2035 Stereo Earphones with FM Radio and Volume Control AA-2062 Scart Video Converter - YUV RGB with PSU AC-1600 Scart Sync Separator with PSU AC-1602 Source Speaker Selector Switch to suit PS-0480 AC-1677 Speaker Selector Switch to suit PS-0480 AC-1679 Retro Vocal Dynamic Microphone with case - Chrome AM-4091 Two Channel Mixer - 240VAC AM-4210 TFT/Plasma TV Screen Cleaner AR-1419 Digital Camera Case - 80x35x131mm AR-1442 Car MP3/Cassette Adaptor with SD Card Slot AR-1764 Wireless 2.4GHz Audio Receiver with USB Connection AR-1835 Wireless 2.4GHz Portable Digital Audio System AR-1848 Wireless 2.4GHz 2 Channel Amplifier Tx & Rx AR-1894 Wireless 2.4GHz Indoor Speaker AR-1896 Solar Charged Amplified Wireless Speaker AR-1899 Speaker Mid Range 4" 10WRMS 8 ohms CE-2314 Speaker Mid Range 5" 100WRMS 8 ohms CM-2085 In-wall Speaker 100WRMS Subwoofer - 8" 8 ohms CS-2447 Speaker Dome Tweeter Shielded 1" 8 Ohm CT-2006 Speaker Dome Tweeter 40WRMS CT-2010 MP3 Music Centre with Clock Radio & Dual Alarm GE-4064 Retro CD Player & AM/FM Radio - 240VAC GE-4066 Lead TV 75 ohm with Gender Changer & 7m Retractable WV-7368 $399.00 $239.00 $160.00 $89.95 $59.95 $30.00 $299.95 $199.95 $100.00 $29.95 $19.95 $10.00 $99.95 $79.95 $20.00 $19.95 $11.95 $8.00 $119.00 $59.00 $60.00 $129.00 $69.00 $60.00 $19.95 $11.95 $8.00 $19.95 $11.95 $8.00 $79.95 $59.95 $20.00 $149.95 $99.95 $50.00 $24.95 $14.95 $10.00 $8.95 $5.95 $3.00 $69.95 $44.95 $25.00 $249.00 $99.00 $150.00 $139.95 $89.95 $50.00 $199.00 $99.00 $100.00 $199.00 $149.00 $50.00 $199.00 $99.00 $100.00 $14.95 $9.95 $5.00 $29.95 $19.95 $10.00 $49.95 $39.95 $10.00 $19.95 $11.95 $8.00 $22.95 $14.95 $8.00 $99.00 $79.00 $20.00 $89.95 $59.95 $30.00 $14.95 $9.95 $5.00 iPod® & PSP Accessories Cat Was iPod® Nano Earphones & Lanyard iPod® FM Stereo Transmitter Wireless Remote Control for iPod® Colour Changing Cubes MP3/iPod® Speaker iPod® Voice Recorder Adaptor Active Mini-Tripod Speaker iPod® Boom Box with Remote Control Active iPod® Speakers Active Desktop iPod® Speaker iPod® 'Shuffle' Active Speaker MP3 Player Case with Built-In Speaker - Small MP3 Player Case with Built-In Speaker - Large Docking Station for PSP® PSP® UMD Disk Cleaner PSP® High Capacity Clip-On Battery Pack AR-2069 $19.95 AR-3112 $39.95 AR-3119 $24.95 GH-1026 $99.95 XC-0253 $49.95 XC-5159 $49.95 XC-5180 $99.00 XC-5184 $69.95 XC-5188 $59.95 XC-5189 $19.95 XC-5200 $24.95 XC-5201 $34.95 XC-5190 $79.95 XC-5196 $24.95 XC-5198 $119.95 Car Audio & Accessories Digital Full Range Car Amplifier 4x100WRMS Speaker Grille 6.5" with 6 Blue LEDs Speaker Grille 6x9" with 6 Blue LEDs Speaker Grille 10" with 6 Blue LEDs Under Seat 8" Subwoofer with Amp & Crossovers Car Subwoofer 10" 250WRMS - Precision Response Car Subwoofer 12" 300WRMS - Precision Response Car Speaker 5" Kevlar 2-way 50WRMS Car Speaker 6" x 9" Kevlar 2-way 80WRMS Car Subwoofer 10" 250WRMS - Response Car Subwoofer Screened 4" 20WRMS 8 ohm Car Subwoofer Polypropylene 6" 30WRMS 8 ohm Car Subwoofer Paper 8" 30WRMS 8 ohm Car Subwoofer Paper Cone 10" 40WRMS 8 ohm Car Subwoofer Paper Cone 12" 50WRMS 8 ohm Car Subwoofer Polypropylene 6" 80WRMS 8 ohm Car Subwoofer Polypropylene 8" 120WRMS 8 ohm Car Subwoofer Polypropylene 10" 160WRMS 8 ohm FM Transmitter with USB/MP3 Flash Player 7" LCD Monitor with MP3 & MP4 Player In-dash DVD/CD Player w/MPEG4, DIVX/MP3 & Remote - 12V CCFL Tube Light, Red, 100mm CCFL Tube Light, Blue, 100mm CCFL Tube Light, Green, 100mm CCFL Tube Light, UV, 100mm Inverter for CCFL Tubes 100mm -suits SL-286X CCFL Tube Light, Green, 300mm CCFL Tube Light, UV, 300mm Inverter for CCFL Tubes 300mm -suits SL-288X CCFL Light Set 12VDC - Green, 300mm Auto Cable 25A Red - Sold per metre Cat Was AA-0425 AX-3570 AX-3572 AX-3574 CS-2275 CS-2278 CS-2279 CS-2322 CS-2328 CS-2366 CW-2104 CW-2108 CW-2110 CW-2119 CW-2125 CW-2135 CW-2136 CW-2137 GE-4030 QM-3764 QM-3785 SL-2861 SL-2862 SL-2864 SL-2865 SL-2868 SL-2884 SL-2885 SL-2888 SL-2893 WH-3081 $399.00 $9.95 $14.95 $14.95 $199.95 $159.95 $219.00 $109.95 $139.95 $139.00 $24.95 $24.95 $24.95 $29.95 $39.95 $39.95 $49.95 $69.95 $59.95 $299.00 $249.95 $6.95 $6.95 $6.95 $6.95 $5.95 $9.95 $9.95 $7.95 $19.95 $1.50 Now Save $11.95 $24.95 $14.95 $59.95 $29.95 $17.95 $79.00 $59.95 $34.95 $11.95 $14.95 $19.95 $49.95 $14.95 $69.95 $8.00 $15.00 $10.00 $40.00 $20.00 $32.00 $20.00 $10.00 $25.00 $8.00 $10.00 $15.00 $30.00 $10.00 $50.00 Now Save $299.00 $100.00 $5.95 $4.00 $8.95 $6.00 $8.95 $6.00 $129.95 $70.00 $119.95 $40.00 $129.00 $90.00 $79.95 $30.00 $89.95 $50.00 $89.00 $50.00 $14.95 $10.00 $11.95 $13.00 $14.95 $10.00 $19.95 $10.00 $24.95 $15.00 $19.95 $20.00 $29.95 $20.00 $49.95 $20.00 $34.95 $25.00 $199.00 $100.00 $149.95 $100.00 $3.95 $3.00 $3.95 $3.00 $3.95 $3.00 $3.95 $3.00 $3.95 $2.00 $4.95 $5.00 $5.95 $4.00 $4.95 $3.00 $11.95 $8.00 $0.90 $0.60 Free Call: 1800 022 888 for orders! www.jaycar.com.au CHRISTMAS IN JULY CLEARANCE SALE Buy NOW for Christmas and Save$$$ Over 20 to 75% OFF ALL listed Items Torches & Lighting 12V Underwater Halogen Light Five Colour Glass Cap to suit SL-2765 Mini Red Flashing LED Torch on Carabineer Ultrabright Red LED Keyring Torch Desklamp with 20 LEDs and Adjustable Head Flexible LED Cigarette Lighter Socket Light Solar Rechargeable 6 LED Torch Rechargeable 11 Watt CCFL Worklight with Charger Pivot Head 20 LED Desk Lamp Bike Helmet Auxiliary Break Light Stick-on 4 x LED Light - Round 3 LED Waterproof Head Torch 6 LED Waterproof Head Torch 1 Watt LED Head Torch - Rechargeable with PSU USB Rechargeable LED Torch Keyring 16 LED Dynamo Spotlight Pan Tilt Spotlight with Strobe - 12VDC 7 LED Head Torch with 4 Flashing Red LEDs 1 Watt Luxeon Head Torch 1 Watt Aluminium LED Head Torch 3 Watt LED Torch - Black 5 Watt LED Torch - Silver 5 Watt Rechargeable LED Torch 3 LED Dynamo Torch with Screwdriver Set 5 in 1 Dynamo Torch with Radio & Siren Mini Camping Lantern Keyring Car Key Torch Colour Changing LED Lighting Kit Recessed LED Light - White Recessed LED Light - Blue Camping & Outdoors In-ear Driver Dozing Alert Digital Tyre Pressure Gauge Keyring Car Electric Rear Window Sunshade - 12VDC Remote Control to suit Sunshade GH-1027 Camping Portable Table Carabiner with LED Torch Foldable Binoculars and Survival Tool Mini Hedge Trimmer 8L Collapsible Bucket 12V Coffee Maker Rechargeable Long Reach Bug Relocator Travel 12VDC Baby Bottle Warmer Hanging 5kg Hi-res Scale with LCD Rock Climbing Altimeter Spark Plug Tester Digital Pedometer with Clock, Alarm & Stopwatch Pedometer with FM Radio & Calorie Counter Digital Map Measurer with Clock & Compass Solar Pond Fountain Pump for Solar Fountain (YH-5450) Megacatch Mosquito Trap with PSU Radios & Clocks Retro Value-Look AM/FM Radio Desk Alarm Clock powered by Water REV Car Engine Alarm Clock Colour Changing Alarm Clock Sunrise Simulation Alarm Clock Digital & Analogue LED Alarm Clock with PSU Dual Alarm Clock Radio & CD Player Radio FM Colour Changing with Motion Sensor Anti-Fog Shaving Mirror with Splashproof CD Player/Radio Bendable Robot Clock with Clips 40mm dia. Analogue Clock Talking Alarm Clock Mirror Faced Alarm Clock LED Alarm Clock with Projector Under Cabinet Clock Radio with Alarm Digital Colour Changing Alarm Clock Talking Watch with Alarm Digital Wristwatch with Temperature and Pulse Monitor Wrist Watch with RED LED Gadgets for Home UHF 38 Channel Baby Monitor - Rechargeable Portable LCD Picture Viewer Starfish Bath Water Sensor & Thermometer Make-up Mirror Compact with LED Light Make-up Mirror with Interactive Light Personal Ozone Sanitiser Ionic Shoe Odour Eliminator Travel Hair Straightener Now Save SL-2765 $19.95 SL-2766 $6.95 ST-3019 $4.95 ST-3044 $7.95 ST-3053 $24.95 ST-3059 $9.95 ST-3087 $19.95 ST-3127 $69.95 ST-3129 $24.95 ST-3186 $49.95 ST-3188 $6.95 ST-3280 $24.95 ST-3282 $39.95 ST-3285 $79.95 ST-3289 $12.95 ST-3290 $39.95 ST-3294 $79.95 ST-3318 $39.95 ST-3321 $69.95 ST-3333 $59.95 ST-3334 $89.95 ST-3338 $129.95 ST-3339 $149.00 ST-3350 $24.95 ST-3370 $59.95 ST-3387 $9.95 ST-3396 $6.95 ST-3882 $139.95 ST-3885 $19.95 ST-3886 $19.95 Cat Was $11.95 $3.95 $2.95 $3.95 $14.95 $5.95 $11.95 $44.95 $19.95 $39.95 $4.95 $14.95 $14.95 $49.95 $7.95 $24.95 $49.95 $14.95 $44.95 $22.95 $44.95 $69.95 $99.95 $14.95 $34.95 $5.95 $3.95 $99.95 $11.95 $11.95 $8.00 $3.00 $2.00 $4.00 $10.00 $4.00 $8.00 $25.00 $5.00 $10.00 $2.00 $10.00 $25.00 $30.00 $5.00 $15.00 $30.00 $25.00 $25.00 $37.00 $45.00 $60.00 $49.05 $10.00 $25.00 $4.00 $3.00 $40.00 $8.00 $8.00 Cat Now Save Was GG-2306 $6.95 GG-2310 $19.95 GH-1027 $69.95 GH-1028 $19.95 GH-1050 $24.95 GH-1112 $9.95 GH-1114 $9.95 GH-1245 $69.95 GH-1260 $14.95 GH-1381 $29.95 GH-1392 $39.95 GH-1912 $19.95 QM-7230 $39.95 QM-7280 $49.95 QP-2264 $5.95 XC-0262 $12.95 XC-0267 $14.95 XC-0375 $19.95 YH-5450 $49.95 YH-5451 $19.95 YS-5518 $199.00 $3.95 $3.00 $11.95 $8.00 $44.95 $25.00 $11.95 $8.00 $9.95 $15.00 $3.95 $6.00 $3.95 $6.00 $34.95 $35.00 $9.95 $5.00 $19.95 $10.00 $24.95 $15.00 $11.95 $8.00 $14.95 $25.00 $23.95 $26.00 $1.95 $4.00 $5.95 $7.00 $9.95 $5.00 $11.95 $8.00 $29.95 $20.00 $11.95 $8.00 $89.00 $110.00 Cat Now Save $9.95 $11.95 $39.95 $19.95 $59.95 $59.95 $44.95 $49.95 $44.95 $9.95 $5.95 $9.95 $11.95 $11.95 $14.95 $9.95 $14.95 $11.95 $19.95 $5.00 $8.00 $10.00 $10.00 $20.00 $40.00 $25.00 $30.00 $25.00 $5.00 $4.00 $5.00 $8.00 $8.00 $10.00 $15.00 $10.00 $8.00 $10.00 Now Save $49.00 $34.95 $9.95 $5.95 $29.95 $24.95 $19.95 $19.95 $20.00 $35.00 $5.00 $4.00 $40.00 $15.00 $10.00 $10.00 AR-1777 AR-1781 AR-1784 AR-1786 AR-1787 AR-1788 GE-4061 GH-1025 GH-1065 GT-3195 XC-0101 XC-0142 XC-0215 XC-0219 XC-0248 XC-0254 XC-0257 XC-0260 XC-0272 Cat DC-1024 GE-4070 GG-2272 GH-1064 GH-1066 GH-1192 GH-1194 GH-1490 Was $14.95 $19.95 $49.95 $29.95 $79.95 $99.95 $69.95 $79.95 $69.95 $14.95 $9.95 $14.95 $19.95 $19.95 $24.95 $24.95 $24.95 $19.95 $29.95 Was $69.00 $69.95 $14.95 $9.95 $69.95 $39.95 $29.95 $29.95 Cat Gadgets for Home (continued) 10" Blue Plasma Disk with Stand Vibrating Bath Pillow with Relaxing Sounds Spa Bath Massager Changing Colour LED Lava-like Eggs Colour Changing Wave Desk Lamp Colour Changing LED Cube Water Fountain with LEDs, Nature Sounds & PSU Colour Changing World Globe Pre-natal Listening Device Wine Thermometer Digital Thermometer with Flexible Probe Fat Measurement Gauge Alcohol Tester with 5 LED Indicator Alcohol Tester Keychain Talking Photo Frame and Album Self Sealing Luggage Label Self Sealing ID Tags Self Sealing Photo Tags Auto Sensing Pet Feeder Illuminated Pet Leash Dog Collar Night Light GH-1532 GH-1750 GH-1751 GH-1808 GH-1812 GH-1814 GH-1820 GH-1824 GH-1910 GH-1920 QM-7229 QM-7253 QM-7292 QM-7293 XC-0278 XL-2515 XL-2517 XL-2519 GG-2318 GH-1204 ST-3198 Fun & Games Farting Salt & Pepper Shakers Remote Control Burp Machine with Multiple Sounds Farting Electronic Keychain Shot Glass with Flashing Red LED Novelty Swear Box 3-in-1 Shot Glass Board Game- Chess/Checkers/Cards Novelty Sonic Grenade Orgasmic Keyring Bad Breath Tester Keychain GH-1080 GH-1081 GH-1082 GH-1150 GH-1316 GT-3005 GT-3112 GT-3325 QM-7295 Cat Computer Accessories Cat CD Clamshell Cases, Multi-coloured - Pack 10 AR-1482 CD Wallet with Zipper - stores 24 Discs AR-1487 CD Hard Case Blue - holds 24 discs AR-1494 CD Hard Case Black - holds 24 discs AR-1496 Multi-tool with 128MB Memory Stick GG-2302 Security Proximity Alert - Tx & Rx GG-2375 Webcam USB 300k QC-3223 Webcam USB 350k Silver Dog QC-3228 Webcam USB 350k Purple Dog QC-3229 Mini Digital Video camera with 1.5" LCD QC-3230 Battery-less 8 Digit Calculator QM-7275 Water Powered Calculator QM-7276 23 Piece Computer Tool Set with Case TD-2041 55 Piece Computer Tool Set with Case TD-2051 Printer Lead D25 Plug - Plug 1.8m WC-7522 Printer Lead D25 Plug - Plug 3.0m WC-7524 Printer Lead D25 Plug - Plug 5.0m WC-7526 All-in-One USB/Keyboard/Mouse/Gaming Lead 2.0m WC-7760 Digital Voice Recorder 4 - 8 Hr with USB Connection XC-0255 External HDD Case (3.5") with Network & USB2 Connection XC-4679 Media Memory Card Case - Compact Flash/MMC XC-4788 High Definition PCI TV Card** XC-4819 Solar Powered USB HUB Calculator XC-4846 VGA to Composite Video Converter XC-4870 Component Video/S-Video to VGA Converter XC-4872 Wi-Fi Finder XC-4885 Compact Flash Memory Card Cleaning Kit XC-4900 Media Memory Card Cleaning Kit - MMC & SD XC-4902 Media Memory Card Cleaning Kit - Smart Card XC-4904 CD/DVD Labelling Kit XC-4920 CD/DVD Labels for XC-4920 Labelling Kit - Pack 50 XC-4922 USB Data Storage Bridge XC-4962 Wired USB VOIP Telephone Handset XC-4964 Hands Free Wired VoIP Telephone Handset XC-4966 Wireless USB VoIP Telephone Handset XC-4968 Perspex Tri-colour LED Fan Guard 80mm XC-5033 USB GSM Card Reader XC-5102 USB Powered MP3 Speakers XC-5161 Amplified Flat Panelled 5.1 Multimedia Speakers XC-5194 SIM Card Data Protector Keyring XC-5375 PowerPoint Presenter with Remote Control XC-5405 Wireless 802.11g PCMCIA Interface Card YN-8068 Manual CD Shredder YS-2832 Was $49.95 $24.95 $19.95 $49.95 $39.95 $49.95 $59.95 $34.95 $49.95 $29.95 $19.95 $19.95 $49.95 $39.95 $49.95 $3.95 $3.95 $4.95 $34.95 $19.95 $9.95 Was $19.95 $19.95 $9.95 $3.95 $19.95 $19.95 $19.95 $9.95 $39.95 Was Now Save $39.95 $19.95 $11.95 $19.95 $24.95 $24.95 $39.95 $19.95 $39.95 $19.95 $9.95 $11.95 $19.95 $24.95 $29.95 $1.95 $1.95 $2.50 $19.95 $11.95 $5.95 $10.00 $5.00 $8.00 $30.00 $15.00 $25.00 $20.00 $15.00 $10.00 $10.00 $10.00 $8.00 $30.00 $15.00 $20.00 $2.00 $2.00 $2.45 $15.00 $8.00 $4.00 Now Save $9.95 $11.95 $5.95 $0.95 $14.95 $14.95 $11.95 $5.95 $24.95 $10.00 $8.00 $4.00 $3.00 $5.00 $5.00 $8.00 $4.00 $15.00 Now Save $3.95 $2.95 $1.00 $4.95 $2.95 $2.00 $2.95 $1.45 $1.50 $5.95 $3.95 $2.00 $59.95 $34.95 $25.00 $29.95 $19.95 $10.00 $29.00 $19.00 $10.00 $34.95 $20.95 $13.98 $24.95 $14.95 $10.00 $179.00 $75.00 $104.00 $14.95 $5.45 $9.50 $9.95 $5.95 $4.00 $78.95 $59.95 $19.00 $65.00 $39.00 $26.00 $9.95 $5.95 $4.00 $13.95 $9.95 $4.00 $19.95 $14.95 $5.00 $59.95 $34.95 $25.00 $99.95 $59.95 $40.00 $199.95 $119.95 $80.00 $2.95 $1.95 $1.00 $179.00 $79.00 $100.00 $29.95 $17.95 $12.00 $99.95 $59.95 $40.00 $99.95 $59.95 $40.00 $29.95 $19.95 $10.00 $9.95 $5.95 $4.00 $9.95 $5.95 $4.00 $9.95 $5.95 $4.00 $14.95 $6.95 $8.00 $9.95 $4.95 $5.00 $59.95 $34.95 $25.00 $49.95 $29.95 $20.00 $49.95 $29.95 $20.00 $129.95 $99.95 $30.00 $12.95 $6.95 $6.00 $34.95 $24.95 $10.00 $89.95 $44.95 $45.00 $99.95 $69.95 $30.00 $19.95 $8.95 $11.00 $199.00 $129.00 $70.00 $49.95 $29.95 $20.00 $39.95 $19.95 $20.00 *Off Original RRP. Limited stock, no rainchecks, may not be available at all stores – call your local store to check stock details. Valid till 31st July 2008 or while stocks last **Not available in NZ Free Call: 1800 022 888 for orders! www.jaycar.com.au 5 Professional 8CH MPEG4 DVR A complete 8 channel professional surveillance recorder with sophisticated monitoring and recording functions including network connect, DVD burner, PTZ camera control via PELCO D, GPRS support, MPEG4 compression, and 250GB HDD. Crystal clear image clarity with minimal disk consumption. Rack mountable. • Maximum frame rate 200ips (25fps/channel) • Maximum image resolution 720 x 576 pixels • 16 channel model also available • See web site for full specifications and range Price after introduction $1499 $ Ideal for use in retail and commercial environments. It has an effective range of 2 - 8 metres, so it is suitable for most entry points. Includes mains plugpack. Attach the LA5197 counter that counts up to 9999 to easily measure the door entry count in your shop, factory or office. $ 89 95 1349 $150 Cat: QV-3040 QV-3041 Professional 16CH MPEG4 DVR with DVD Backup and GPRS Support Price after introduction $1999 Now $1799 Save $200 Commercial Grade Doorway Beam SECURITY Active Matrix TFT Security Monitors These rugged, high performance TFT monitor is purposebuilt for security applications and includes a toughened front bezel to protect the TFT panel from damage. They can display up to the maximum resolution defined by CCIR standards (720 x 576 / 525 x 625TV Lines) via the incorporated I/P (interlaced to progressive scan) converter. See website for full specifications. • Two models available • QM-3419 17" • QM-3420 19" INTRODUCTORY F OFFER 10% OF 2 Station Wireless FM Intercom Great for communicating around your home. Transmits through the electrical cable already laid in your house. Additional units can be added for multi-point communications. • 2 Channels • Sold as a pair $ 549 $ Cat: LA-5193 649 19in: QM-3420 17in: QM-3419 Stor-A-Key Safe $ 74 95 Cat: AI-5500 USB Digital TV Stick Watch high definition digital telly on your desktop or laptop PC for the same cost as a standard definition set-top box. Simple to set up and use, just connect the USB stick, plug in the antenna, install the software and away you go. • Supports worldwide free-to-air DTV • Software with time shifting and scheduled recording • Compatible with Windows XP, ME and Vista • Windows only - not suitable for Mac $ • Antenna, cable and software included 99 Cat: XC-4859 IPTV Internet Digital TV Tuner Never miss your favourite TV show again! With this unit you can watch your favourite telly shows and schedule recording from anywhere in the world. No need to miss an important family function or your baby's first words or steps. Time shifting and scheduled recording are also supported so $ youcan pause and rewind live TV. Cat: XC-4861 199 Wireless Networking Antenna 5dB Gain $ 99 95 Cat: AR-3272 $ 19 95 Cat: AR-3270 49 COMPUTERS USB DVD Maker Turn your VHS video tapes into exciting video productions or record live video straight to your DVD or CD burner. Editing software lets you add effects as well as sound tracks and titles to your work. • Requires PC with suitable burner. FIREWIRE IEEE1394 4PM-M 2M COMMS LEAD $ 99 Cat: XC-4809 USB to IDE and SATA Hard Drive Adaptor A must have tool for PC technicians! • This clever device will allow you to use an ordinary IDE or SATA disk drive on a USB 2.0 interface. • You can even connect an IDE drive and a SATA simultaneously and transfer data between them. • The adaptor and hard drive can be powered from the USB port for smaller (2.5") hard drives. • An external power supply is included to power larger (3.5" & 5.25") drives. • The adaptor has plug & play support for Windows ME, 2000, and XP. • Interface cables included. $ 79 95 Cat: XC-4833 Need greater distance from your wireless network? Here's a quick and inexpensive way to boost the range at either your base station or terminal. These antennas are specifically designed for 2.4GHz situations and 802.11 wireless networking is the perfect application. • AR-3270 2.4GHz Dipole with 5dB gain • AR-3272 2.4GHz Compact Yagi with 8dB gain Never get locked out again. This unit mounts directly onto a wall or flat surface, holds up to 5 keys and the combination can be easily changed when needed. Great for the caravan or holiday home as well. $ 95 Was $59.95 While Stocks Last Cat: LA-5356 28 Hr Digital Voice Recorder Firewire is a high-speed serial bus standard which bridges the world of consumer electronics and computers. Allows users to attach camcorders, VCRs, DVD and other audio / video components to their computers and printers. Firewire® 4 Pin to 4 Pin WC-7640 - 2.0m WC-7641 - 5.0m $13.95 $23.95 Firewire® 6 Pin to 6 Pin WC-7644 - 2.0m WC-7645 - 5.0m $13.95 $23.95 Firewire® 4 Pin to 6 Pin WC-7647 - 2.0m WC-7648 - 5.0m $ $22.95 $32.95 13 95 From VOICE ACTIVATED This is a stylish digital voice recorder with the features to match. You can record up to 28 hours of voice messages in manual or automatic voice activation mode. • 4 message folders, each folder can hold up to 99 messages • Voice activated recording function • 36(W) x 118(H) x 17(D)mm • XC-0279 128MB digital voice recorder $ 95 with USB available separately - $119.95 79 Cat: XC-0277 Limited stock on some items. Pricing whilst stocks last - no rainchecks. 6 Free Call: 1800 022 888 for orders! www.jaycar.com.au KITS Crystal Radio AUDIO KITS Enjoy AM broadcasting without using battery or other power sources. Ideal for entry-level Measuring only 56(L) students or hobbyist with little x 16(W)mm it electronics experience. Includes incorporates all the circuit explanation. Kit supplied electronics for a 1W Ref: Silicon Chip February 1994 with silk-screened amplifier. 6 to 9VDC This tiny module uses the LM386 audio • PCB (81x53mm), crystal, operating voltage, IC, and will deliver 0.5W into 8 ohms from prewound coil, earphone and all 50mV input sensitivity, 8 ohm output and 20 a 9 volt supply making it ideal for all components. to 25000Hz output frequency. Optional those basic audio projects. $ 95 connection for a 10k ohm - 100K ohm It features variable gain, will happily run logarithmic potentiometer (not included) for from 4-12VDC and is smaller than a 9 Cat: KV-3540 adjustable volume control. volt battery, allowing it to fit into the $ 95 • Kit supplied with PCB tightest of spaces. and all electronic • PCB and all Cat: KG-9032 components electronic $ 95 • Suitable power supply components Cat: KC-5152 required (use MP-3003) included 1 Watt Amplifier "The Champ" Audio Amplifier 11 7 5 POWER KITS Ref: Silicon Chip November 2006 An extremely useful and versatile kit that enables you to use a tiny trigger current - as low as 400µA at 12V to switch up to 30A at 50VDC. It has an isolated input, and is suitable for a variety of triggering options. The kit includes PCB with overlay and all electronic components and instructions. Ref: Electronics Australia August, 1997 A low-powered DC converter suited for many applications such as a computer peripheral power supply, powered speakers, modems, music/MIDI keyboards, etc. Just plug its input into your PC' s internal power supply cable and have selectable regulated voltage out from 3 to 15VDC. Output current capability is around 1.5 amps depending on the size of heatsink used (heat sink sold separately). Cat: KA-1797 $ 6 95 $ Engine Immobiliser MK II Ref: Silicon Chip December 1998 Mixture Display Kit For Fuel Injected Cars Refer: Silicon Chip November 1995 This very simple kit will allow you to monitor the fuel mixtures being run by your car. This type of sensor is also known as an E.G.O. (exhaust, gas, oxygen) monitor. You can use it as a tuning tool, to help in vehicle modification or simply to see the behaviour of the engine control module. Indication is via 10 LEDs to show mixtures rich, lean and normal. The circuit connects to the EGO sensor mounted in the exhaust manifold and the car’s battery. • PCB, LEDs and components supplied. • Thousands sold! $ 14 95 Cat: KC-5195 This Immobiliser repeatedly stalls the engine when a thief tries to start your car. The circuit allows the engine to start, but will stall after about two seconds, giving the thief the impression that there is an intermittent problem. Kit supplied with PCB, plastic enclosure and all specified electronic components. $ Ref: Silicon Chip June 2005 Turns a regular fridge or freezer into a wine cooler by accurately controlling the temperature between 2.5 - 33°. Kit supplied with PCB , panel mount mains socket, mains lead, machined case with screen printed lid and all electronic components. $ 39 95 Cat: KC-5413 29 95 Cat: KC-5255 12V Light Operated Relay Operate as a twilight on/off switch or as a light trigger relay from 12 volts, this versatile project triggers a 6 amp relay when the light intensity falls below an adjustable threshold. Turn lights on around the house when it goes dark or trigger an alarm when a light is switched on. Kit supplied with Kwik Kit PCB, relay and all electronic components. Recommended plugpack - MP3002. 20 $ 6 95 This neat project enables you to dial a time you want to elapse before you want something to happen, say the exposure of a camera shutter or an electrically operated door to stay open. At the end of the timed period (seconds to many minutes) a relay is energized which can switch something on or off. PCB and all parts supplied, including relay. Requires 9V battery. • Instructions NOT included. $ 95 • See KJ-8203 for individual instructions $2.00 or BJ-8504 full Cat: KJ-8202 colour project book $13.95 12 SC2 Project - Hee-Haw Siren with Flashing Light This project will make the noise made by emergency vehicles when they are trying to get through traffic. PCB and all parts supplied including flashing LED. Requires 9V battery. • Instructions NOT included. • See KJ-8205 for individual $ 95 instructions $2.00 or BJ-8504 full Cat: KJ-8204 colour project book $13.95 8 SC3 Project Kit - Light Chase Dazzling display using 10 LEDs that appear to chase each other. Build for a shop, theatre or advertising display. • Kit includes PCB, LEDs and electronic components • 12VDC power required • See KJ-8065 for individual instructions $3.00 or $ BJ-8505 full colour project 95 book $19.95 11 SC2 Project - FM Radio Station While Stocks Last Not available in all stores Liquid Level Sensor Kit $ Here's a simple and easy-tobuild first project. It flashes two LEDs (light emitting diodes) - one red and the other green alternately, a bit like the light on a police car. A great way to learn how a 555 Timer IC works. • PCB and all parts supplied • Requires 9V battery • Instructions NOT included. Cat: KJ-8200 • See KJ-8201 for individual instructions $2.00 or BJ-8504 full colour project book $13.95 Cat: KJ-8064 HOUSEHOLD KITS Tempmaster 14 95 Cat: KC-5434 AUTO KITS SC2 Project - Red/Green flasher SC2 Project - Countdown Timer DC Relay Switch Kit Versatile Regulated Voltage Adaptor SHORT CIRCUIT KITS 95 Cat: KG-9090 When two contacts are shorted by liquid, an LED will illuminate. Use in applications such as an overflow alarm and rain detector. Connect Relay Card KG-9142 for a relay output to operate lights, sirens or other warning devices. • Project requires 9VDC. • PCB size: 28 x 17mm. • Kit supplied with Kwik Kit PCB and all electronic components. $ 95 7 Cat: KG-9138 This is a Three-Stage radio transmitter that is so stable you could use it as your personal radio station and broadcast all over you house. Great for experiments in audio transmission. It $ 95 includes a microphone but you can transmit other material as well. Includes a mic, Cat: KJ-8750 PCB with overlay and all other parts. • Requires 9V battery 19 SC2 Project - No Brainer Amplifier This amp is so easy to build, it’s a no brainer! It will, however, give a powerful output to bring your MP3 player, sound card, etc alive. Speaker, PCB and all electronic component supplied. $ 95 • Two required for stereo • Requires 9V battery Cat: KJ-8216 • Instructions NOT included. • See KJ-8217 for individual instructions $2.00 or BJ-8504 full colour project book $13.95 12 Limited stock on some items. Pricing whilst stocks last - no rainchecks. Free Call: 1800 022 888 for orders! www.jaycar.com.au 7 POWER $ 9 LASER LIGHT SHOW Battery, Charger and Alternator Tester 95 12V: QP-2258 $ 12 Create a dazzling atmosphere at your next party with the green laser show. The unit comes fitted with a microphone that changes the pattern of the lasers to the beat of the music. • 240VAC Adaptor • Inbuilt microphone • Dimensions: 230(L) x 155(W) X 60(D)mm $ 349 95 Cat: SL-2939 Power Voltage Price 300W 400W 400W 600W 12VDC to 230VAC 12VDC to 230VAC 24VDC to 230VAC 12VDC to 230VAC $79.95 $139.95 $149.95 $229.00 A great disco light show that any Saturday Night Fever fan would dream about. The display projects a dazzling light pattern that changes automatically or can set to run fast or slow. Just the thing to liven up any party. • 4 x AAA batteries included Was $69.95 Self Contained Solar Lighting System This excellent kit features a high efficiency Copper Iridium Selenide (CIS) solar panel and comes with everything you need to build a basic solar powered lighting system. Supplied with automatic solar panel, 1 x 5W CFL lamp, E27 base, 2 x 1W LED lamps, 8Ah SLA battery, connecting cable, fuse and switch. Specifications: • 12V 8Ah SLA battery • 10W Copper Iridium Selenide (CIS) Solar panel • Panel dimensions: 458(L) x 458(W) x 34(D)mm YOUR LOCAL JAYCAR STORE $ Australia Freecall Orders: Ph 1800 022 888 NEW SOUTH WALES Albury Ph (02) Alexandria Ph (02) Bankstown Ph (02) Blacktown Ph (02) Bondi Junction Ph (02) Brookvale Ph (02) Campbelltown Ph (02) Erina Ph (02) Gore Hill Ph (02) Hornsby Ph (02) Newcastle Ph (02) Parramatta Ph (02) Penrith Ph (02) Rydalmere Ph (02) 6021 9699 9709 9678 9369 9905 4620 4365 9439 9476 4965 9683 4721 8832 6788 4699 2822 9669 3899 4130 7155 3433 4799 6221 3799 3377 8337 3121 $ 59 95 Cat: SL-2924 $10 Moondot Revolving Disco Light $ 99 95 Cat: SL-2898 199 Cat: MP-4552 Sydney City Taren Point Tweed Heads Wollongong VICTORIA Coburg Frankston Geelong Melbourne Ringwood Springvale Sunshine Thomastown QUEENSLAND Aspley Cairns Ipswich Maroochydore Cat: SL-2935 Red Laser Light Show MI-5107 24VDC IDEAL FOR TRUCKS MI-5104 MI-5106 MI-5107 MI-5108 299 With 500 effect patterns, 10 line modes, and 3 colours, the possibilities are endless. It can be used in auto or music mode and multiple units may be linked together for stage and production use. • Output power: • Red: 30-150mW • Green: 5 - 30mW • Dimensions:245(L) x 297(W) x 127(H)mm Mains Power on the Go Cat. $ Three Colour Laser Light Show 95 24V: QP-2259 Mains Power from your vehicle's battery anytime. Take your creature comforts with you when you go bush or on any road trip as these inverters will produce mains power from your vehicle's battery. A 150W inverter will run some laptops, lights, small TVs and recharge batteries. Inverters 300W and above will also run power tools, fluorescents and larger style TVs. Bluetooth Car Kit with FM Transmitter Green Laser Display System A handy device to quickly indicate the condition of your car or truck battery, charger or alternator. Available in 12 or 24V versions: • QP-2258 12V • QP-2259 24V • Dimensions: 120(L) x 33(W) x 20(D)mm Ph Ph Ph Ph (02) (02) (07) (02) 9267 9531 5524 4226 1614 7033 6566 7089 Ph Ph Ph Ph Ph Ph Ph Ph (03) (03) (03) (03) (03) (03) (03) (03) 9384 9781 5221 9663 9870 9547 9310 9465 1811 4100 5800 2030 9053 1022 8066 3333 Ph Ph Ph Ph (07) (07) (07) (07) 3863 4041 3282 5479 0099 6747 5800 3511 BLUETOOTH Liven up any party with this funky light display. Featuring 18 high brightness red, green and blue LEDs that rotate, change colours and direction in response to music being played. • Auto mode • Sound activated mode • Mains powered • 200(L) x 153(W) x 94(H)mm Mermaid Beach Ph (07) 5526 6722 Townsville Ph (07) 4772 5022 Underwood Ph (07) 3841 4888 Woolloongabba Ph (07) 3393 0777 AUSTRALIAN CAPITAL TERRITORY Belconnen Ph (02) 6253 5700 Fyshwick Ph (02) 6239 1801 TASMANIA Hobart Ph (03) 6272 9955 SOUTH AUSTRALIA Adelaide Ph (08) 8231 7355 Clovelly Park Ph (08) 8276 6901 Gepps Cross Ph (08) 8262 3200 WESTERN AUSTRALIA Maddington Ph (08) 9493 4300 Midland Ph (08) 9250 8200 Northbridge Ph (08) 9328 8252 You can pair it with your Bluetooth enabled mobile phone and it will transmit voice call signals to your car's FM radio allowing you to talk hands-free with friends. Load your USB drive or SD/MMC card with MP3s and plug it in $ 95 for a cheaper alternative to a full-blown car audio player Cat: AR-1860 upgrade. 89 Bluetooth iPod® Transmitter Listen to music wirelessly with this nifty iPod® Bluetooth Adaptor. Pair it with your Bluetooth headset or speaker for an extremely neat and tidy audio $ 95 solution. Recharge it in about 2 hours through your computer's USB port. Works with all iPods ® that Cat: AR-1859 have a docking station. 69 Stereo Bluetooth Adaptor $ Add Bluetooth capability to virtually any audio output device. Just your iPod®, mobile 95 connect phone, CD player, or anything with a 3.5mm audio socket to Cat: AR-1854 the Bluetooth adaptor and you can transmit stereo audio signals wirelessly. • Functional range: 10 metres 69 Bluetooth Boom Box Sit your Bluetoothenabled mobile phone or portable music device near this speaker and play your MP3s wirelessly.You can also set this unit up with your Bluetooth-enabled PC. It features a 3.5mm socket so it $ can still be used for audio output on non-Bluetooth devices. 149 95 Cat: AR-1856 Active Bluetooth Wireless Stereo Speakers This tiny stereo speaker system sounds great and plays music directly from your Bluetooth phone or MP3 player without any messy wires. Also accepts a wired input from almost any music source. • Requires 4 x AAA batteries Cat: AR-1858 • 200(W) x 50(H) x 25(D)mm $ 69 95 NORTHERN TERRITORY Darwin Ph (08) 8948 4043 NEW ZEALAND Christchurch Ph (03) 379 1662 Dunedin Ph (03) 471 7934 Glenfield Ph (09) 444 4628 Hamilton Ph (07) 846 0177 Manukau Ph (09) 263 6241 Newmarket Ph (09) 377 6421 Palmerston Nth Ph (06) 353 8246 Wellington Ph (04) 801 9005 Freecall Orders Ph 0800 452 9227 Limited stock on some items. Pricing whilst stocks last - no rainchecks. 8 Free Call: 1800 022 888 for orders! www.jaycar.com.au PRODUCT SHOWCASE Computronics’ 1kW Battery Charger Means Well! This intelligent 1000W charger for lead-acid batteries, manufactured by Mean Well and distributed in Australia by Computronics Corporation Ltd, is available in 12, 24 and 48V versions. Applications include security systems, UPS systems, electrical wheelchairs, leisure vehicles and any other system that use lead-acid batteries as the power source. The charger features a user-selectable 2 or 8-stage charging program controlled by an internal microprocessor to quickly and efficiently charge flat batteries or using a more complex 8-stage charging curve to store more energy into the battery banks. Two battery banks can be connected to the PB-1000 at the same time. The unit will switch the charging current between two battery banks automatically to ensure both banks are fully charged and maintained at maximum energy capacity level all the time. To effectively extend the lifetime of the batteries and to reduce maintenance the PB-1000 also features a built-in temperature compensation circuit. An NTC sensor supplied with the charger can be attached to the battery and the output voltage will be adjusted according to the temperature. For full details go to www.meanwell.com/search/pb-1000/pb-1000spec.pdf Note: Degen DE1103 receiver not included! Contact: 6 Sarich Way, Technology Pk, Bentley WA 6102 Tel: (08) 9470 1177 Fax: (02) 9470 2844 Website: www.computronics.com.au 25 Winterton Road, Clayton, Vic 3168 Tel: (03) 9562 8222 Fax: (03) 9562-9009 Website: www.hy-q.com.au Computronics Corporation ers and even more so for travellers wanting better MW/SW reception. The “soft loop” itself, about 1m high, is designed to hang from any convenient location (their illustration shows it on a wardrobe). This feeds into the “controlling box”, thence to the receiver’s antenna socket. While intended for the Degen DE1103 it will operate with virtually any receiver, including those without an antenna socket (a clip is provided to make connection with a telescopic whip antenna). A ground clip is also provided for receiver ground. It’s powered by two AAA batteries and covers all of the broadcast band (530-1602kHz) and the 3.9-22MHz section of the shortwave band. Operation is simple: plug it in, turn it on and tune the control box for best reception. Retail price is $88.00 plus s&h. Contact: Av-Comm Pty Ltd 24/9 Powells Road, Brookvale NSW 2100 Tel: (02) 9939 4377 Fax: (02) 9939 4376 Website: www.avcomm.com.au siliconchip.com.au Hy-Q have sent us a bunch of crystals in various types to remind us that they can supply crystals for all SILICON CHIP projects that use these devices. They’re a 100% Australian-owned company, supplying frequency control products to the highest international standards for over 30 years. The product range includes quartz crystal units, filters, DIL’s, voltage controlled, temperature compensated and oven controlled oscillators, monolithic and discrete filters plus ceramic filters and resonators. Contact: Degen Active Loop Antenna from Av-comm Since our review of the Degen DE1103 Synthesised Communications Receiver in January last year, Av-comm’s Garry Cratt tells us they have been running out the door! As a high performance, low cost (~$159) 100kHz-30MHz receiver, it hit a sweet spot in the market. But now that high performance can be significantly improved with the Degen 31MS Active Loop Antenna, especially where it is incovenient (or impossible) to use a long-wire antenna. It’s ideal for flat or home unit dwell- Hy-Q Crystals for SILICON CHIP projects Hy-Q International (Aust) Pty Ltd ANTRIM TRANSFORMERS manufactured in Australia by Harbuch Electronics Pty Ltd harbuch<at>optusnet.com.au Toroidal – Conventional Transformers Power – Audio – Valve – ‘Specials’ Medical – Isolated – Stepup/down Encased Power Supplies Encased Power Supply www.harbuch.com.au Harbuch Electronics Pty Ltd 9/40 Leighton Pl, HORNSBY 2077 Ph (02) 9476 5854 Fax (02) 9476 3231 July 2008  57 A PIC-based Musical Tuning Aid By JIM ROWE This compact device will help you tune almost any musical instrument – acoustic or electronic. It can produce any note on the tempered musical scale (standard pitch) in any of the eight most commonly used octaves, with an accuracy of better than ±0.08% or 1.3 musical cents. The selected note is compared with that from the instrument either by ear or visually by using an eight-LED stroboscopic beat indicator. A FEW GIFTED individuals have “perfect pitch” which allows them to recognise by ear when the note of a musical instrument is accurately tuned (within 1 musical cent, or 1/100th of a semitone). However, the vast majority, including many musicians, simply don’t have this ability or anything like it. For most of us, the only way of tuning an instrument is by 58  Silicon Chip comparing its notes with those from tuning forks or some other source of accurately known sound frequencies. Until about 1970, tuning forks were really the only option. The standard method was to use a single tuning fork at one standard note frequency or “pitch” (usually A = 440.00Hz). The corresponding note of the instrument was first tuned against this frequency, then the other notes of the octave were tuned against this note using the technique of “beats” or heterodynes. This technique involved tuning each note high or low until the audible difference frequency between one of its harmonics and a harmonic of the reference note was correct (for that particular note). Once the notes in the middle octave had been tuned siliconchip.com.au NOTE INDICATOR LEDS1–13 FREQUENCY REFERENCE (16MHz) LINE LEVEL OUTPUT OCTAVE INDICATOR LEDS14–21 VOLUME ADJUST 5-BIT R-2R RESISTOR DIGITAL TO ANALOG CONVERTER PIC16F877A MICROCONTROLLER (IC1) AUDIO AMPLIFIER (IC2) BUILT-IN SPEAKER OCTAL COUNTER (IC4) S2 DOWN S1 UP S4 DOWN NOTE SELECT S3 UP OCTAVE SELECT LED22  RING OF 8 LEDS  LED29 Q1 SWITCH SQUARER (A = 101) AMPLIFIER (IC3a) (IC3b) INPUT FROM MIC OR INSTRUMENT Fig.1: block diagram of the Musical Instrument Tuning Aid. It’s based on a PIC microcontroller (IC1) and a 16MHz crystal frequency reference. The PIC divides down the frequency reference and drives a 5-bit DAC (digital-to-analog converter). This in turn feeds audio amplifier IC2 to deliver the selected tone (set by switches S1-S4). IC3a, IC3b, IC4 and LEDs 22-29 form a simple stroboscope beat indicator, to enable precise “visual” tuning. in this way, the corresponding notes in the other octaves could be tuned against them by adjusting for a zero beat. It was a pretty tedious business and required plenty of patience, as well as a good ear. Instrument tuning became a lot easier in the 1970s when electronic musical tuning aids appeared. In most cases, these aids were based on special ICs known as “top octave synthesiser” or TOS chips, which had been developed mainly for the second generation of electronic organs. Inside a TOS chip were 12 or 13 digital frequency dividers, each of which produced one note of the top octave for the organ by dividing down from a shared crystal oscillator (usually around 2MHz). So by combining a TOS chip with a multi-stage binary divider, it was quite easy to produce a device which could generate virtually any note in any octave, all accurate enough to be used as a tuning reference. As well as becoming available commercially, a number of these TOS-chip-based tuning devices were described for hobbyist construction in the 1980s. These were very popular because they were much cheaper than the commercial units. However, manufacturers stopped making TOS chips when electronic organ makers didn’t need them any more, because they had changed over to designs based on siliconchip.com.au microcontrollers, digital samplers and VLSI devices. PIC micro With TOS chips no longer available, the easiest way to produce a musical tuning aid these days is to use a micro­ controller. And that’s exactly what we’ve done in designing the project described here. Based on a readily available PIC micro, the “Musical Instrument Tuning Aid” can produce any note of the tempered musical scale at standard pitch (A = 440.00Hz) and spans the eight most commonly used octaves. All notes are derived from a single crystal oscillator (nominal frequency 16.000MHz) and the frequency accuracy is better than ±0.08% (in fact, much better in many cases). Since ±0.08% corresponds to about ±1.3 cents, this means that the tuning should be accurate enough even for those with perfect pitch. The reference notes produced by the unit can be easily used for instrument tuning by ear, because they are fed to an inbuilt amplifier and speaker. In addition, there’s a simple “ring of LEDs” stroboscope which allows you to tune for zero beats by eye. To do this, the instrument’s note is fed into the unit – either directly or via a microphone – and the instrument’s tuning adjusted until the rotating pattern on the LEDs slows down and stops. When the LEDs stop, the instrument is correctly tuned to that note. The note frequency produced by the Tuning Aid is set using four pushbuttons on the front panel. Two pushbuttons step the selected octave up or down, while another two pushbuttons select the note. In addition, the front panel carries a power on/off switch, plus a screwdriver-access hole to allow an on-board volume trimpot to be adjusted. Power for the unit comes from either an internal 9V battery or an external 9-12V DC supply such as a car battery or mains plugpack. The circuit is assembled onto a single PC board and is housed together with a 57mm speaker and its battery in a small UB1 jiffy box. How it works Refer now to Fig.1 which shows the block diagram of the Tuning Aid. It’s based on a PIC 16F877A 8-bit microcontroller which does most of the work. The PIC’s clock oscillator uses a 16.000MHz crystal, which also serves the reference frequency. The main job done by the PIC is to generate the desired top octave frequency for whichever note you select, by dividing down from the 16MHz clock. The notes are selected very easily and simply by using pushbutJuly 2008  59 Table 1: The 104 Note Frequencies Produced By The Tuning Aid (Hz) NOTE OCTAVE 1 OCTAVE 2 OCTAVE 3 OCTAVE 4 OCTAVE 5 OCTAVE 6 OCTAVE 7 OCTAVE 8 ERROR* C 32.688 65.376 130.751 261.502 523.004 1046.008 2092.016 4184.032 –0.0473% C# 34.645 69.289 138.579 277.157 554.314 1108.628 2217.256 4434.512 –0.0093% D 36.680 73.360 146.721 293.442 586.884 1173.768 2347.537 4695.074 –0.0758% D# 38.867 77.735 155.470 310.939 621.880 1243.760 2487.519 4975.038 –0.0601% (the third harmonic) will be audible for most adults. This is especially true for the top octave. Visual tuning So that’s how we generate the main reference note 329.809 659.619 1319.238 2638.476 41.226 82.452 164.905 5276.952 E –0.0521% outputs of the new tuning 2793.246 43.644 87.289 174.577 349.156 698.311 1396.623 5586.491 F –0.0207% aid, which are used for tuning instruments by ear. 2958.528 5917.056 46.227 92.454 184.908 369.816 739.632 1479.264 F# –0.0482% Now let’s look at the method G –0.0389% 48.980 195.921 391.843 783.685 1567.371 6269.483 97.960 3134.742 used to allow visual tuning, 51.909 103.819 207.638 415.275 830.550 1661.100 3322.200 6644.400 G# –0.0072% using the “ring of LEDs” 440.133 880.266 55.017 110.033 220.066 1760.533 3521.065 7042.131 A +0.0303% stroboscope. 233.205 1865.639 58.301 116.602 466.409 932.819 3731.278 A# +0.0527% 7462.555 The stroboscope is very simple, consisting mainly of 494.063 988.126 1976.251 3952.502 +0.0363% 61.758 123.516 247.031 7905.005 B eight LEDs connected to the C' 2092.012 8368.048 65.375 261.502 523.003 –0.0474% 1046.006 4184.024 130.751 outputs of an octal (times-8) *Compared with the notes of the tempered musical scale, at standard pitch (A4 = 440.000Hz). All frequencies are with PIC clock oscillator = 15.9992MHz. counter (IC4). The counter’s clock input is driven by an tons S1 (UP) and S2 (DOWN), with the On the other hand, if the PIC reads output from the PIC, which provides selected note shown clearly by one of out every second waveform sample, pulses at a frequency which is a binary LEDs1-13 (red). it will take only 128 top octave note multiple of the main note output for The octave for the desired note is pulses to generate a single period of the octave concerned. As a result the selected in very similar fashion, using the output note waveform. This will counter’s outputs cyclically pulse high pushbuttons S3 (UP) and S4 (DOWN). therefore give the correct division ratio in sequence, in step with the main In this case, the selected octave is in- to produce the second-octave equiva- note output. dicated by LEDs14-21 (green). lent of the selected note. Because the eight LEDs are conInside the PIC, the selected top ocSimilarly, if it reads out every fourth nected to the counter outputs, this tave note frequency is divided down waveform sample, it will take only means they can turn on in sequence to produce the corresponding note 64 top octave pulses to produce one as the outputs pulse high, provided in the selected octave. This division period of the output note waveform that transistor Q1 is also on. This is done in a novel way, as part of the – giving the correct division ratio for transistor is turned on and off using method used to shape the unit’s main the third-octave note equivalent, and the audio signal from the musical note output into a reasonable approxi- so on. instrument, to control which LED is mation of a sinewave (at least for the This is how the frequency division lit at any instant. lower octaves). This involves using needed to produce the notes in each As shown on Fig.1, the signal from the PIC micro to drive a simple DAC octave is combined with the “sample the musical instrument is first fed (digital-to-analog converter) based on playback” method of producing the through amplifier stage IC3b which an R/2R resistor ladder, with five bits output note waveform. This works operates with a gain of about 101 of resolution. quite well, producing a good 5-bit times. It is then fed through a “squarer” The idea here is that the PIC’s approximation of a cosine waveform stage based on IC3a, emerging as a very EPROM memory stores a set of 256 for all notes in the four lowest oc- clean square wave. This is then used to 5-bit samples, corresponding to a sin- taves. The only catch is that the note turn Q1 on and off, with the net result gle period of a cosine waveform. The waveform becomes more “steppy” that Q1 is turned on for the positive PIC reads out these samples from the for the highest octaves, where the half cycles and off for the negative memory and feeds them in sequence resolution inevitably drops because half cycles of the instrument’s note to the DAC, to produce the output note we must step through the samples in waveform. waveform. This is then fed through larger “jumps”. So that’s how the stroboscope works. volume trimpot VR1 to audio ampliAs a result, in the fifth octave, the As Q1 turns on and off, it (and the fier IC2 which then drives the speaker. output waveforms have only 4-bit octal counter) turns the LEDs on and Now if the PIC reads out the wave- resolution, while in the sixth octave off as well. form samples in one-by-one order, it they have only 3-bit resolution. And How does this produce a LED patwill take 256 of the top octave note in the very top octave they have only tern that’s useful for tuning? Well, pulses to produce a single period of the single-bit resolution – ie, they become consider the situation where octal output note waveform. In other words, square waves. counter IC4 is fed with a clock signal there will be an effective frequency This diminishing waveform reso- that’s exactly eight times the frequency division of 256, or 28. lution isn’t really much of a prob- of the note to which we want to tune This happens to be exactly the lem though, because the effective the instrument. When the instrument right division ratio to produce the waveform distortion consists almost is tuned to a frequency close to that bottom-octave equivalent of the se- entirely of odd harmonics – and in note, Q1 will turn on for a period that’s lected note. many cases only the lowest of these long enough to allow four of the LEDs 60  Silicon Chip siliconchip.com.au siliconchip.com.au July 2008  61 K LED1  A   LED7 A A A A  K K K K A A A    A O8 LED21 O7 O6 O5 LED19 A A O3 O4 LED17 A O2 RD0 RB4 RB3 RB2 9 40 39 38 22 21 RE1 RB7 RB6 RB5 RD3 RD2 20 RD1 19 37 36 35 RB1 RB0 RD7 RD6 RD5 RD4 RC7 RC6 RC5 RC4 11,32 4 5 7 17 18 RE0 RE2 RA4 RA0 13 14 8 10 6 2 RA1 3 RA2 RA3 RA5 RC2 RC3 OSC1 12, 31 Vss 1 RC1 16 RC0 15 MCLR OSC2 IC1 PIC16F877A Vdd 33pF X1 16.0MHz 2.0k 2.0k 2.0k 2.0k 2.0k 2.2k DOWN 33pF 2.0k 1.0k 1.0k 1.0k 1.0k 13 14 15 S3 DOWN O5 O6 O7 O8 O9 1 5 6 9 11 +5V 8 O5-9 12 O0 O1 O2 O3 3 2 4 7 IC4 4017B O4 10 16 Vdd A S4 4x 4.7k OCTAVE SELECT UP CP1 Vss CP0 MR S2 100 F NOTE SELECT UP S1 2x 100nF MUSICAL INSTRUMENT TUNING AID     O1 C' B A# 34 A LED15 A 33 30 29 28 27 26 25 24 23 G# G F# F E D# D C# C LED22     K Q1 PN100    E C COM LED29  K A 100nF IN IN 47k B 180 4.7k 100 F 16V 33nF OUT 78L05 GND OUT REG1 78L05 1 10M 10k 2.2k 220 4 IC3a 2 3 7 +8.1–11.1V 2 3 1nF IC3: LM358 2.2M 10k VOLUME TANT VR1 1 F +8.3–11.3V 470 F 16V S5 ON/OFF 4 1M 1 6 5 A 5 220nF C E PN100 B K A LEDS CON3 MIC/INSTR INPUT SPEAKER 8 47nF 220k 1k 9-12V DC INPUT CON2 LINE AUDIO OUT CON1 330 F 10 220k 10 F 7 8 33nF 22 F 16V K 1N4004 TANT 1 F 10k IC3b 8 6 22k 9V BATTERY A IC2 LM386N K D1 1N4004 Fig.2: the complete circuit diagram. PIC micro IC1 monitors switches S1-S4, divides down the 16MHz crystal accordingly and drives LEDs1-21 which indicate the note and octave selected. IC1’s RA0-RA3 & RA5 outputs also drive a resistive ladder network which forms the 5-bit DAC. IC4 is wired as an octal counter and is driven by IC1’s RE0 output. This counter, in company with op amp stages IC3b & IC3a and LEDs22-29, makes up the zero beat indicator circuit. 2008 SC  470 K LED20 K LED18 K A LED14  A LED16 K  LED12  ALED11 LED13 470 K K K LED9 LED8 K  A LED10 A K  K  A   LED6 K K LED5 LED4 K  A K LED3 LED2 K  A K +5V 10 F 470 F 78L05 IC4 4017B LED25 LED26 1 330 F 8  SPKR CON3 LED27 O3 O4 O2 O6 O5 O7 O8 LED14 LED15 LED16 LED17 LED18 LED19 LED20 LED21 Q1 PN100 + S1 UP DOWN NOTE SELECT S4 S3 10M DIA G NI NUT CISU M S2 LED22 + 1 F 1M IC3 LM358 1 1nF 9V BATTERY + – 220nF + CON1 S5 4004 O1 LED8 LED10 LED12 LED13 220k LED6 10k LED5 LED29 180 100 F 220k LED1 LED3 LED23 C’ 10k 2.2k 2.2M F F# G G# A A# B 4.7k C C# D D# E LED28 LED24 LED9 LED11 S 470 100nF LED7 R 470 LED4 220 T LED2 MINI SPEAKER MIC/INSTR INPUT PIC 16F877A REG1 CON2 LINE OUT + D1 9-12V DC IC1 100nF 1 1 VR1 10k 1k + 100nF 1 F 22k 10 2.0k 2.0k 2.0k 2.0k 2.0k 2.2k IC2 18070140 8002 C 100 F 47nF 33nF VOLUME + 47k 1.0k 1.0k 1.0k 1.0k 2.0k LM386N 33pF 33pF X1 16MHz 4.7k 4.7k 4.7k 4.7k 33nF 9V BATTERY (CLIP LEAD) 22 F UP DOWN OCTAVE SELECT POWER Fig.3: follow this parts layout and wiring diagram to build the unit. Make sure that all polarised parts are correctly orientated and note particularly the orientation of switches S1-S4 (their flat sides go to the left). to light in sequence, ie, during the positive half cycles. Conversely, Q1 will be turned off for the rest of each note period (ie, during the negative half cycles). As a result, half the ring of LEDs will light and the other half will remain off. However, unless the instrument note is tuned to the exact note frequency, this “half on/half off” pattern will rotate either clockwise or anticlockwise, depending on whether the instrument note frequency is too high (sharp) or too low (flat). So all you need to do, to tune the instrument correctly, is to adjust its note up or down in frequency until the pattern rotation slows down and stops. By the way, the actual pattern displayed on the LEDs depends on the frequency ratio between the strobe counter’s clock pulses and the instrument note and this again varies over the octaves. However, the tuning procedure is always the same: the instrument note is adjusted until the pattern rotation slows down and stops. A stationary pattern indicates “zero beat” and correct tuning. Circuit details Refer now to Fig.2 for the circuit of the Musical Instrument Tuning Aid. It uses just four ICs and a handful of other parts. 62  Silicon Chip IC1 is a PIC 16F877A device, chosen because its 40-pin configuration allows very easy interfacing to the control buttons, LEDs and resistive ladder DAC. As shown, the 13 note indicator LEDs (LEDs1-13) are connected directly to I/O pins RC4-RC7, RD4-RD7 and RB0-RB4 and share a common 470W current limiting resistor. The eight octave indicator LEDs (LEDs14-21) are connected to outputs RD0-RD3, RB5-RB7 & RE1 in similar fashion. In addition, note select pushbuttons S1 & S2 are directly connected to I/O pins RC0 & RC1, together with 4.7kW pull-up resistors. Octave select buttons S3 & S4 are connected to RC2 & RC3 in the same way, while crystal X1 is connected between pins 13 & 14. The resistive ladder network acts as a 5-bit DAC to produce the tuning aid’s main note output waveform and is driven from pins RA0-RA3 and RA5 of the PIC. A 33nF capacitor is connected across the DAC output to provide a measure of low-pass filtering, after which the note signal is fed via a 47kW resistor and 1mF coupling capacitor to volume control trimpot VR1. From there, the signal is then fed to IC2, a standard LM386 low-power audio amplifier which drives an 8ohm mini speaker. Because the lowfrequency response of 57mm mini speakers is quite poor, the 33nF capacitor and 22kW resistor connected around IC2 are included to provide a small amount of bass boost to improve the audibility of notes in the lowest octave. The audio output signal from IC2 is also fed to line output socket CON2 via a 1kW isolating resistor. This allows the signal to be fed to an external amplifier if desired or alternatively, to a digital counter or scope if you want to check its frequency or use the signal for other kinds of testing. Octal counter IC4 is the counter for the LED stroboscope. This is a 4017B Johnson decade counter with its ninth output connected back to its reset input to configure it as an octal counter. LEDs22-29 are connected to outputs O0-O7, while the counter itself is fed strobe clock pulses from the RE0 pin of the PIC (IC1). The note signal from the instrument being tuned (or from a microphone picking up the sound) is fed into the circuit via CON3, a 3.5mm jack socket. It is then fed to op amp IC3b (LM358), which is wired with a gain of 101, as determined by its 1MW and 10kW feedback divider resistors. From there, the amplified signal at pin 7 is fed to IC3a, which is configsiliconchip.com.au This view shows the fully assembled PC board. Note that the switches are mounted in cut-down IC socket strips – see Fig.4. CUT-DOWN IC SOCKET STRIPS ured as a comparator with positive feedback, so it becomes a Schmitt trigger “squarer”. This stage converts the signal from IC3b into a clean square wave. This is then fed to the base of transistor Q1 via a 4.7kW resistor, to switch it (and the strobe LEDs) on and off. As stated earlier, power for the circuit comes from either an internal 9V battery or an external 9-12V DC supply (fed in via CON1). Diode D1 provides reverse polarity protection, while S5 is the on/off switch. REG1 provides a regulated +5V supply rail for IC1 & IC4, while IC2 runs directly from the unregulated input supply. IC3 runs from this same unregulated supply via a decoupling circuit consisting of a 220W resistor and a 100mF capacitor. Note that the battery is automatically disconnected from the circuit when an external supply is plugged into CON1. Construction Apart from the battery and mini speaker, all of the parts are mounted on a PC board coded 04107081 and measuring 147 x 84mm. This board has rounded cutouts in each corner so that it fits inside a standard UB1 size jiffy box. It is attached to the rear of the case lid via five M3 x 15mm tapped spacers. The three input/output connectors are all mounted at the righthand end of the board, while the LEDs, pushbutton switches S1-S4 and power switch S5 siliconchip.com.au all protrude through matching holes in the lid. Note that connectors CON1-CON3 all mount directly on the top of the PC board, as does switch S5. However, pushbuttons S1-S4 are not tall enough to mount directly on the board, and so must be plugged into spacer sockets made by cutting down a couple of 14pin DIL IC sockets (more on this later). Fig.3 shows the parts layout on the PC board. Here is the suggested order of assembly: (1) Fit the three wire links to the board, followed by the PC board terminal pins for the battery and speaker connections. These terminal pins should be fitted from the underside (copper side) of the board, because the wires to be soldered to them later are under the board. (2) Install connectors CON1, CON2 & CON3, then fit the sockets for IC1, IC3 & IC4, making sure you orientate each of these as shown in Fig.3 (to guide you later when it comes to plugging in the ICs). Note that a socket is not used for IC2; this is soldered directly to the board (later), to ensure stability. (3) Install the resistors, making sure that you fit each one in its correct position. Follow these with the volume trimpot (VR1). (4) Fit the disc ceramic, monolithic and MKT metallised polyester capacitors (these can go in either way around), then fit the tantalum and electrolytic capacitors. Note that the tantalums and electrolytics are all polarised, so be sure to fit them with the correct orientation. (5) Fit diode D1, regulator REG1, transistor Q1 and finally IC2. Be sure to install each of these with the orientation shown on the overlay diagram. (6) Now fit all of the LEDs. These are all fitted vertically, with the lower end of their bodies spaced 13mm above the board (so that they will just protrude through the holes in the box lid when the board is later mounted behind it). The easiest way to do this is to cut a strip of thick cardboard to a width of 13mm and then use this cardboard strip as a spacer between each LED’s leads while it is soldered into position. In practice, the cardboard strip can be left under each horizontal row of LEDs until they are all soldered in place and then withdrawn to be used for the next row of LEDs. It can also be used when you’re fitting the “ring of LEDs” (ie, LEDs22-29). (7) Next on the list are the spacer 14-PIN DIL IC SOCKET (PRESSED CLIPS) CUT CUT CUT CUT REMOVE CENTRE CLIP BY PUSHING UP FROM BELOW Fig.4: the socket strips for pushbutton switches S1-S4 are made by cutting eight 3-pin strips from two low-cost 14-pin IC sockets, then removing the centre pin from each strip. July 2008  63 SILICON CHIP Musical Instrument Tuning Aid C# D# F# G# VOLUME LINE OUTPUT MIC OR INSTRUMENT INPUT STROBE A# C D E F G A B C' 1 2 3 4 5 6 7 8 OCTAVE SELECT POWER 9-12V DC INPUT NOTE SELECT Fig.5: this full-size artwork can be copied and used as a drilling template for the front panel. socket strips for pushbutton switches S1-S4 (necessary to ensure they protrude through the matching holes in the box lid). These spacer strips are cut from low-cost 14-pin IC sockets. Fig.4 shows how these strips are prepared. Each switch is mounted on two 3-pin sections cut from one side of a 14-pin socket but with the centre pin of each section pushed out and discarded. Note that only the spacer strips are soldered to the PC board. The switches then later plug into them (8) Fit crystal X1, toggle switch S5 and the five M3 x 15mm tapped spacers which are used to attach the board assembly to the rear of the case lid. These spacers are attached to the board using M3 x 6mm pan-head screws and washers, while similar screws with countersink heads are used later to attach the spacers to the lid. (9) Complete the board assembly by plugging IC1, IC2, IC3, IC4 and the switches into their sockets. Be sure to orientate the ICs and the flat sides of the switches as shown in Fig.3. Preparing the box Unless you’re building the Music Tuning Aid from a kit, you will now need to prepare the case by drilling the required holes. A photocopy of the front panel artwork (Fig.5) can be used as a drilling Table 2: Resistor Colour Codes o o o o o o o o o o o o o o o o No.   1   1   1   2   1   1   2   5   2   6   5   2   1   1   1 64  Silicon Chip Value 10MW 2.2MW 1MW 220kW 47kW 22kW 10kW 4.7kW 2.2kW 2kW 1kW 470W 220W 180W 10W 4-Band Code (1%) brown black blue brown red red green brown brown black green brown red red yellow brown yellow violet orange brown red red orange brown brown black orange brown yellow violet red brown red red red brown red black red brown brown black red brown yellow violet brown brown red red brown brown brown grey brown brown brown black black brown 5-Band Code (1%) brown black black green brown red red black yellow brown brown black black yellow brown red red black orange brown yellow violet black red brown red red black red brown brown black black red brown yellow violet black brown brown red red black brown brown red black black brown brown brown black black brown brown yellow violet black black brown red red black black brown brown grey black black brown brown black black gold brown siliconchip.com.au 25 ew See revi’08 e n u in J HIP SILICON C 25 9 7 12 A C B ALTITUDE 3500-SS HOLES A & C: 10mm DIAMETER, HOLE B: 7.0mm DIAMETER (ALL DIMENSIONS IN MILLIMETRES) DETAILS OF HOLES IN END OF UB1 BOX, FOR CONNECTORS Fig.6: this diagram shows the drilling details for the righthand side panel. template for the lid. Alternatively, you can download and print out the artwork from the SILICON CHIP website (www.siliconchip.com.au). The holes for switches S1-S4 should be drilled or reamed to 10mm dia­ meter, while the hole for S5 should be 6.5mm in diameter. All of the holes for the LEDs should be 3.5mm, as should the adjustment hole for the volume trimpot. The spacer screw holes are also drilled 3.5mm but countersunk on the top. Another three holes are drilled in the righthand end of the box, to allow access to the three input-output connectors. The locations and diameters of these holes are shown in Fig.6. Finally, you will have to drill two 3mm holes in the bottom of the case for the battery clamp screws and a pattern of holes to allow the sound from the speaker to escape. In the latter case, it’s simply a matter of drilling an array of 5mm holes inside a guide circle 43mm in diameter. Position this guide circle centrally in the left half of the case bottom. Once these holes have been drilled and deburred, clamp the battery into position and glue the speaker in place. The U-shaped battery clamp can be made from a piece of scrap aluminium and is secured using two M3 x 6mm screw, nuts and lock washers. The speaker can be secured using five or six small dobs of epoxy cement around the rim of its frame. The case should then be placed aside for the epoxy cement to cure overnight. The final step in preparing the siliconchip.com.au Table 3: Capacitor Codes Value 220nF 100nF 47nF 33nF   1nF 33pF mF Code 0.22mF 0.1mF .047mF .033mF .001mF      NA IEC Code EIA Code 220n 224 100n 104   47n 473   33n 333    1n 102   33p   33 box lid is to fit the front-panel label. First, print out the artwork on an adhesive-backed label and then apply a rectangle of clear “Contac” or similar adhesive film to the front to protect it from scratches and finger grease, etc. The label is then trimmed to its correct size and the corner holes removed using a leather punch or sharp hobby knife, to provide a guide when you’re positioning it on the lid. Once it’s attached to the lid, the remaining holes can be cut out using either a sharp hobby knife or a hole punch (a hole punch will do a much neater job). Final assembly The PC board assembly can now be attached to the back of the lid and secured using M3 x 6mm countersink head screws. Make sure that all the LEDs and switches go through their mounting holes before doing up the screws. Note that one of switch S5’s nuts is removed before fitting the board and then refitted to the switch when the Valve Stereo HiFi Amplifier 32W/Channel, 4 or 8Ω “This particular valve amplifier performs very well” Leo Simpson SILICON CHIP June 2008 A blend of quality components and modern design Beautifully finished in 7mm brushed aluminium Four stereo analog inputs Gold plated connectors and selectors Extended bandwidth of 10Hz to 90kHz Carefully chosen design layout and wiring location Direct input coupling improves transient response Specialised wide-bandwidth audio output transformers Class A/B pentode output using genuine Russian-made Electro-Harmonix EL34 valves Matched pairs, factory bias adjusted Stainless steel heat shields improve overall efficiency High quality capacitors Beautiful in looks, design and listening The A3500-SS is an exclusive and advanced version developed by Stones Sound Studio. Retail price is just $1899, available now from ELECTRONIC SERVICES AUSTRALIA 138 Liverpool Rd, Ashfield NSW (Locked Bag 30, Ashfield NSW 2131) Ph: (02) 9798 9233 Fax: (02) 9798 0017 Web: www.wagner.net.au July 2008  65 Parts List 1 PC board, code 04107081, 147 x 84mm 1 UB1 plastic utility box, 158 x 96 x 53mm 2 PC-mount momentary pushbutton switches, red (S1,S2) 2 PC-mount momentary pushbutton switches, green (S3,S4) 1 mini toggle switch, SPDT (S5) 1 16.000MHz crystal, HC49U/ US case (X1) 1 PC-mount 2.5mm DC power connector (CON1) 1 PC-mount RCA socket (CON2) 1 PC-mount 3.5mm mini jack socket, (CON3) 5 M3 x 15mm tapped spacers 5 M3 x 6mm machine screws, countersink head 5 M3 x 6mm M3 machine screws, pan head 1 40-pin IC socket 1 8-pin IC socket board is in position. Don’t tighten it down too much, otherwise the panel label may buckle and tear. The switch nut on the underside can be wound up to the bottom of the lid to help prevent this. The next step is to solder two 150mm lengths of light-duty hookup wire to the speaker terminals. The other ends Capacitors 1 470mF 16V RB electrolytic 1 330mF 16V RB electrolytic 2 100mF 16V RB electrolytic 1 22mF 16V RB electrolytic 1 10mF 16V RB electrolytic 2 1mF 25V tantalum 1 220nF MKT metallised polyester 3 100nF multilayer monolithic ceramic 1 47nF MKT metallised polyester 2 33nF MKT metallised polyester 1 1nF disc ceramic 2 33pF disc ceramic 1 16-pin IC socket 2 14-pin IC sockets (see text) 1 57mm 8-ohm mini speaker 4 self-adhesive rubber feet 1 9V battery clip lead 4 PC board terminal pins, 1mm diameter 2 150mm lengths of insulated hookup wire 1 10kW horizontal PC-mount mini trimpot Semiconductors 1 PIC16F877A microcontroller (IC1), programmed with 0410708A.hex 1 LM386N audio amplifier (IC2) 1 LM358 dual op amp (IC3) 1 4017B CMOS counter (IC4) 1 78L05 +5V regulator (REG1) 1 PN100 NPN transistor (Q1) 21 3mm red LEDs (LED1-13, LED22-29) 8 3mm green LEDs (LED14-21) 1 1N4004 diode (D1) Resistors (0.25W 1%) 1 10MW 2 2.2kW 1 2.2MW 6 2kW 1 1MW 5 1kW 2 220kW 2 470W 1 47kW 1 220W 1 22kW 1 180W 2 10kW 1 10W 5 4.7kW of these wires are then soldered to the relevant PC stakes underneath the PC board (near CON2). The 9V battery clip leads are connected to the other two terminal pins, between CON3 and CON1. Note that the black lead must connect to the outermost of these pins (-), while the red lead connects to the innermost pin (+). That completes the assembly of the Musical Instrument Tuning Aid. Now for the check-out procedure. Check-out time Before applying power, adjust volume trimpot VR1 so that it is about 30° clockwise from its fully anticlockwise position. That done, connect the bat- Above: the three holes in the end of the case provide access for the DC input socket (left), the mic/instrument socket and the line output socket. Left: a pattern of holes is drilled in the bottom of the case beneath the loudspeaker mounting position, to allow the sound to escape. 66  Silicon Chip siliconchip.com.au The PC board is fitted with five tapped spacers and secured to the lid using machine screws. A clamp fashioned from scrap aluminium secures the battery, while the speaker is secured using a few dobs of epoxy resin. tery snap lead and switch on. Because the PIC’s program is set to deliver a default output note of A = 440Hz, you should immediately be greeted by a tone of this frequency from the speaker. At the same time, the red “A” note LED (LED10) should light, along with the “octave 4” green LED (LED17). If nothing happens, the odds are that you have reversed the battery clip lead connections at the PC board or diode D1 is in the wrong way around. Assuming it works so far, try changing the note by pressing either S1 or S2 (red). Each time you press one of these buttons, the note produced by the Musical Instrument Tuning Aid will step up or down by a semitone – until you get to the upper or lower limit. Similarly, pressing switches S3 or S4 (green) should step the tone frequency up or down through the octaves. To check the operation of the beat siliconchip.com.au stroboscope, first reset the unit’s output to A = 440Hz. This can be done either by using the pushbutton switches to return to this note and octave or by simply switching the unit off and then waiting a second or two before turning it on again (to get the note by default). Now feed an audio signal of around 440Hz into the unit via CON3. This should preferably come from an audio oscillator, so you can easily vary its frequency. As soon as this external signal is applied, four or more of the stroboscope’s ring of LEDs (LEDs22-29) should light. If the signal frequency is not very close to 440Hz, they will probably all appear to be continuously lit. However, if you carefully adjust the input signal frequency to approach 440Hz, only four of the strobe LEDs should light at any time. In addition, this semicircle of light should rotate – either clockwise or anticlockwise. As you adjust the frequency closer to 440Hz, the speed of rotation will slow down. In fact, it will stop rotating altogether when the two frequencies are equal. If you then keep adjusting the signal’s frequency “out the other side”, the stroboscope LEDs will begin rotating in the opposite direction, slowly at first and then faster as the frequencies move further apart. If all of this happens as described, your Musical Instrument Tuning Aid is working as it should and the assembly can be fastened into its box. At the same time, you will have seen just how easy it is to use the ring of LEDs stroboscope to achieve exact “zero beat” tuning of the notes from virtually any musical instrument. It’s simply a matter of setting the unit to the note concerned and then adjusting the instrument until the SC strobe LEDs stop rotating. July 2008  67 By JOHN CLARKE Microphone preamp for PCs & MP3 players Want to connect a professional microphone with balanced outputs to the line input of your PC’s soundcard or an MP3 player, for high-quality voice recordings? This microphone preamp circuit lets you do just that. It features a balanced input, has a clipping indicator LED and can be powered from a USB port or from an external DC source. Main Features • • • • • • Balanced input Stereo output USB or plugpack powered Level control Peak indicator Line level output 68  Silicon Chip A LTHOUGH MOST PCs have a microphone input for recording, these inputs are for basic electret microphone types only. Electret microphones are typically used in headsets and are generally of low quality. Similarly, some MP3 players include an internal electret microphone for recording but again the quality is limited. These players often also in- clude a line input, to accept external audio signals. Using an electret microphone will generally be satisfactory for recording brief announcements and reminders. However, if you want really good sound quality, a professional microphone will be required. This type of microphone will also be necessary when the microphone needs to be siliconchip.com.au ALTERNATIVE DC INPUT OUTPUT TO COMPUTER VIA 3.3mm STEREO PLUG MICROPHONE INPUT VIA XLR PLUG AUDIO OUT TO COMPUTER POWER IN VIA USB 'A' PLUG XLR MIC INPUT DC IN USB LEVEL SWITCH 1 PEAK POWER POWER SWITCH SWITCH 2 NEON 3 Fig.1: this diagram shows how the Balanced Microphone Preamplifier is connected to a computer. Power can come either from a USB port or from an external DC plugpack supply (see text). more than just a metre or two away from the computer or MP3 player. Why are they better So why do the professional microphones give better sound than lowcost electret microphones? There are several reasons. First, professional microphones use a high-quality microphone element that has a smooth frequency response plus low noise and low distortion. Typical low-cost electrets do not have a smooth frequency response but a response that peaks around the mid audio frequencies. And while low-cost electret microphones readily detect handling and breathing noises, professional microphones are designed to minimise this problem. Professional microphones also have a tailored pickup response that is more sensitive towards the front of the microphone than to the rear. This lack of sensitivity towards the rear helps prevents unwanted noise pickup. Another advantage of professional microphones, particularly for voice recordings, is that they give more depth to the sound. That’s because the bass siliconchip.com.au response is more pronounced when the microphone is brought close to the mouth. A headset electret microphone, on the other hand, usually has a poor bass response. Taken together, these refinements mean that a professional microphone will produce a recording that sounds far crisper and cleaner than one from an electret microphone – all without extraneous noises masking the wanted sound. Of course, electret microphones are ideal for many applications. In fact, high-quality electret microphone inserts are often used in professional microphones and can produce excellent sound quality when placed inside a professional microphone housing. It’s just that if you want high-quality recordings, a professional-quality microphone is the way to go. Balanced outputs While professional microphones can come in many forms (eg, dynamic and electret types), they all have one thing in common and that is a balanced output. A balanced output provides two signals that are 180° out of phase with each other. These signals are fed out via a 3-pin XLR plug that connects Specifications Signal-to-noise ratio: 80dB with respect to 1V output and 50mV input & with 600W input loading impedance (this measurement includes a 20Hz - 22kHz bandpass filter). Frequency response: within 0.25dB from 20Hz to 20kHz. Total harmonic distortion: less than 0.01% at 1V output and 50mV input for all frequencies from 20Hz - 20kHz. Signal handling: 2.8V RMS output Sensitivity for 1V out: 9mV July 2008  69 Parts List 1 PC board, code 01107081, 102 x 83mm 1 diecast aluminium box, 119 x 94 x 34mm 1 3-pin small size female XLR panel socket 1 Type-A PC-mount USB socket 1 2.5mm PC-mount DC socket 1 3.5mm PC-mount stereo jack socket 1 Ultra Mini SPST rocker switch (S1) 1 1kW 16mm linear pot (VR1) 1 50kW multi-turn top-adjust trimpot (code 503) (VR2) 1 knob to suit potentiometer 4 M3 tapped x 6.3mm standoffs 8 M3 x 5mm screws 2 M3 x 10mm screws 2 M3 nuts 4 M3 flat washers 1 solder lug 17 PC stakes 1 150mm length of red mediumduty hookup wire 1 75mm length of green mediumduty hookup wire 1 75mm length of 2-core shielded cable 1 25mm length of 6mm diameter heat­shrink tubing 4 rubber feet Semiconductors 2 TL072CP dual op amps (IC1,IC2) 1 LM393N dual comparator (IC3) 1 MAX232CPE RS232 line driver (IC4) 1 LM336-2.5 2.490V reference (REF1) 1 BC327 PNP transistor (Q1) 1 5.6V 1W zener diode (ZD1) to a matching 3-pin XLR socket on the microphone lead. As a result, the two balanced microphone signals are fed down the microphone cable via separate leads. These leads are shielded to help prevent them from picking up noise and mains hum. In addition, this arrangement effectively removes any noise that is picked up when connected to a balanced input on an amplifier. In operation, the balanced leads each pick up the same noise signals along the length of the microphone 2 MICROPHONE INPUT (XLR CONNECTOR) lead. That’s because these leads are run very close to each other, often as a twisted pair. When fed into a balanced amplifier, the signal from each lead is subtracted and this removes the common noise signal in each lead (ie, the noise signals are cancelled out by the amplifier because they are in phase). The wanted audio signal from each microphone lead is also subtracted but because these are in anti-phase, the signal level is actually doubled as a result of the subtraction. This means that balanced microphone leads can be BALANCED INPUT AMPLIFIER OUTPUT (3.5mm STEREO SOCKET) 1 3 IC1a,IC1b, IC2a VR1 LEVEL POWER INPUT PEAK DETECTOR POWER SUPPLY (IC4) – +  POWER LED IC2b, IC3  PEAK LED Fig.2: the block diagram of the Balanced Microphone Preamplifier. The balanced signals from the XLR socket are amplified by IC1a & IC1b and summed in IC2a to give an unbalanced output which is fed to the output socket. IC2b, IC3 and the associated LED provide peak level indication, 70  Silicon Chip 1 1N5819 1A Schottky diode (D1) 1 3mm green LED (LED1) 1 3mm red LED (LED2) Capacitors 1 100mF 25V PC electrolytic 2 22mF NP electrolytic 1 10mF 16V PC electrolytic 6 1mF monolithic ceramic 2 100nF MKT polyester 4 220pF ceramic 2 100pF ceramic Resistors (0.25W 1%) 1 220kW 1 180W 3 100kW 2 150W 2 22kW 1 68W 1W (R1) 1 20kW 1 39W 1W (R1) 12 10kW 2 33W 1 2.2kW 1 10W 2 680W 1 10W (R1) many metres long without any noticeable increase in noise pickup. In addition, the output impedance of professional microphones is usually very low and this also minimises noise pickup. Impedances are often well below the standard 600W, with some high-quality microphones having an output impedance as low as 150W. Of course, a balanced amplifier is also required in order to use a balanced microphone and this is always found on professional audio gear. We also published a Balanced/Unbalanced Converter in the June 2008 issue of SILICON CHIP (it can convert signals both ways). In operation, the balanced amplifier correctly subtracts the balanced signals and provides the gain required to bring the signal level up to line levels. This means that the recording can be made using the line input rather than the microphone input at the computer. Alternatively, for an MP3 player, you can again use the line input and forget about the internal microphone. Recording at line levels also helps to minimise noise. That’s because the signal does not have to pass through an internal preamplifier in the computer or MP3 player. How it’s connected Fig.1 shows how the SILICON CHIP Microphone Preamplifier is connected siliconchip.com.au POWER BC327 B E C A POWER LED1 C1 1 F  2 6 1 4 IC4 MAX232 3 K ADJ + K 16 C3 1 F 680 +5V LM336-2.5 – TYPE 'A' USB SKT +5V 33 A 13 11 14 S1 100 F 25V D1 1N5819 C4 1 F 10 USE ONE ONLY R1 C2 1 F 5 12 ZD1 5.6V 1W 1 F K +7V OPTIONAL MUTE SWITCH XLR INPUT SOCKET 2 100pF 22k 8 2 NP 3 180 3.5mm STEREO JACK SOCKET 150 150 10k 10k 10k 7 IC1b 5 22k 68  1W 20k 6 +7V 1 4 10k OPTIONAL THROUGH XLR PLUG +5V IC2a 3 220pF 220pF LEVEL 1k LIN VR1 2 10 39  0.5W 10k 10k 100k R1 VALUE 10k 1 IC1a 2 22 F 1 9V 12V 220pF 3 220pF 100k DC INPUT VOLTS 6V IC1, IC2: TL072 100nF +7V 22 F NP 3 DC IN 33 15 1 A 4 10 F –6V 100pF LEDS K A +5V 1N5819 A 100k 2.2k +2.5V K TP1 6 + REF1 LM336-2.5 A SC 2008 IC2b 10k – 10k ZD1 8 5 100nF 2 TP2 10k 7 +5V ref 3 IC3a 220k 1 5 6 TP3 1 F 10k E B Q1 BC327 C IC3: LM393 VR2 50k TPG 8 IC3b 7 4 10k PEAK LED2 A  K 680 K MICROPHONE PREAMP FOR COMPUTERS & MP3 PLAYERS Fig.3: the full circuit. IC4 functions as a charge-pump converter to provide +7V & -6V supply rails for op amps IC1 & IC2. IC1a & IC1b are wired as non-inverting amplifier stages, while IC2a sums their outputs. IC3a & IC3b function as a window comparator. They compare a sample of the output signal with reference voltages set by REF1, IC2b & VR2. to a computer. It includes the 3-pin XLR connection for the microphone lead and a stereo 3.5mm jack socket output. The connection is made to the computer using a 3.5mm stereo jack-to-jack lead or a 3.5mm stereo siliconchip.com.au jack to RCA plug lead if the computer has RCA inputs. Power for the unit can come from either a DC plugpack supply or from the computer’s USB port. In the latter case, the USB port provides a +5V rail to the preamp via a standard ‘A’ Male to ‘A’ Male USB connector lead. In operation, the preamp is switched on and off via a power switch on the side of the case and a “Power” LED lights when the unit is on. The output July 2008  71 XLR INPUT SOCKET DC INPUT D1 10k TPG 100k REF1 LM336-2.5 1 2 22 F NP 2-CORE SHIELDED CABLE signal level is adjusted using a pot and a peak indicator LED lights when the signal exceeds line level. If the peak indicator LED lights, then the signal level is too high. This will cause clipping and distortion in the recording. In practice, it’s simply a matter of adjusting the level to avoid any peak indication during microphone use. Fig.2 shows the block diagram of the Microphone Preamplifier. The balanced microphone signal is fed in via the XLR input socket and the two anti-phase signals are then amplified by op amps IC1a & IC1b. The signals are then subtracted in IC2a and fed to the output jack socket. The peak detector circuit monitors the output signal level and flashes the Peak Indicator LED when the signal exceeds the threshold level. This circuit comprises IC2b & IC3, plus the LED itself. Circuit details Refer now to Fig.3 for the complete circuit details. As shown, the balanced input signals from the microphone are coupled in via 22mF non-polarised capacitors and fed to the non-inverting inputs 72  Silicon Chip VR1 LEVEL 680 LED2 100pF 100pF 2.2k IC4 MAX232 TP2 TP1 Q1 220pF 3 1 F 1 F TP3 1 F 1 F 1 F 10k 1 F VR2 50k 10 F IC3 LM393 10k 33 680 22k 22k NP 100 F ZD1 5819 10k 100k 180 220k 33 10k 10k 10k 220pF 100nF 20k IC2 TL072 IC1 TL072 10k 100nF 10k E 1 4 10 150 220pF 10k 10k 220pF 2 R1 10k 100k 1 3 150 22 F USB TYPE A SOCKET 3 2 3.5mm STEREO JACK SOCKET Fig.4: install the parts on the PC board & complete the wiring as shown in this assembly diagram. The pot is secured by soldering its body to four PC stakes, then soldering its terminals to another three PC stakes (see photo). LED1 K A PEAK A DE C NALA B CI M P MAERP K 18070110 S1 POWER of op amps IC1a & IC1b (pins 3 & 5). These input signal lines (ie, pins 2 & 3 on the XLR socket) are each tied to ground using a 100kW resistor, to prevent them from floating with no input connected. The 220pF capacitor across the two inputs shunts radio frequencies while the 100pF capacitors at pins 3 & 5 also shunt RF signals to ground. Pins 3 & 5 of the op amps are each tied to ground via a 22kW resistor, again to prevent spurious operation in the absence of an input signal. Note that the signal ground and the supply ground are isolated in this part of the circuit to reduce earth loops and this is the reason for the different earth symbols shown. Op amp IC1a amplifies the pin 3 microphone signal, while IC1b amplifies the pin 2 signal. Both are configued as non-inverting amplifiers with 10kW feedback resistors, while a 180W resistor and 1kW pot (VR1) are connected in series between their inverting inputs. The 220pF capacitors across the 10kW resistors roll off the high-frequency response above 70kHz. VR1 is the level control and this varies the gain of IC1a & IC1b between about 9 and 56. The outputs from these op amps appear at pins 1 & 7 and are summed in unity gain differential amplifier IC2a. For signals coming from IC1a, IC2a functions as an inverting amplifier with a gain of -1, as set by its 10kW feedback resistors. However, for signals on its pin 3 input, IC2a operates as a non-inverting amplifier with a gain of 2. Because of this, the signal from IC1b is divided by two using a 10kW resistive divider before being applied to IC2a. This means that each signal path from IC1a & IC1b has overall unity gain through IC2a. However, IC2a inverts the signals from IC1a, so that they are now in phase with the signals from IC1b. As a result, both signals add to provide an overall gain of 2 for the stage (ie, IC2a sums its two input signals). The resulting unbalanced signal appears at pin 1 of IC2a and is fed to the left & right terminals of a 3.5mm stereo jack socket via 150W isolation resistors. The 220pF feedback capacitor across IC2a rolls off the high-frequency response of this stage. Peak detector IC2a’s output also drives the peak siliconchip.com.au INSTALL EITHER THE DC SOCKET OR THE USB SOCKET BUT NOT BOTH detector circuit. This consists of op amps IC3a & IC3b which are wired as a window comparator, plus IC2b and REF1 which provide an accurate reference voltage for the comparator. As shown, the signal level is first attenuated using a 20kW and 10kW resistive divider and then coupled to pins 2 & 5 of IC3a & IC3b respectively via a 10mF capacitor. REF1, an LM336-2.5, is used to provide a 2.5V reference and this is applied to the pin 5 input of op amp IC2b. This stage operates as a noninverting amplifier with a gain of 2 and provides a 5V reference at its pin 7 output. This reference voltage is fed to a voltage divider network consisting of a 10kW resistor, trimpot VR2 and a second 10kW resistor to ground. As a result, two different reference voltages are applied to pins 3 & 6 of IC3a & IC3b, with VR2 used to set the voltage between these inputs. These two reference voltages are labelled as TP2 and TP3 on Fig.3 and are equally spaced either side of 2.5V. Pin 3 of IC3a is set to the TP2 voltage, while pin 6 of IC3b is biased to the TP3 voltage. The pin 2 & pin 5 inputs of IC3a & IC3b are biased to the 2.5V reference set by REF1 via a 100kW resistor. As a result, the signal from IC2a swings above and below this 2.5V reference. Note that IC3’s outputs are open collector and so the outputs can be tied together. They are connected to the +5V rail via a 220kW resistor and so are normally held high. Provided that the signal level at pins 2 & 5 does not exceed the reference thresholds (ie, doesn’t go above or below these levels), the outputs of IC3a & IC3b will remain high due to the pull-up resistor. Conversely, if the signal exceeds one of these reference threshold voltages, the corresponding op amp will switch its output low. Thus, if the voltage on pin 2 of IC3a goes above the reference voltage on pin 3, IC3a’s output will switch low. Table 2: Capacitor Codes Value 1mF 100nF 220pF 100pF mF Code 1mF 0.1mF NA NA IEC Code 1u0 100n 220p 100p EIA Code 105 104 221 101 Similarly, if the voltage on pin 5 of IC3b goes below the voltage on pin 6, pin 7 of IC3b will switch low. This output low from either comparator then turns on PNP transistor Q1 and lights the peak indicator LED (LED2). The associated 1mF capacitor between the op amp outputs and the +5V rail ensures that the outputs remain low for 200ms after the comparator switches off, so that very fast overload transients aren’t missed. In practice, trimpot VR2 is set so that the TP2 & TP3 reference voltages are 442mV above and below the 2.5V reference respectively. This corresponds to a 1V RMS sinewave signal at IC2a output. Note that for a 1V RMS sinewave, the peak voltage is 1.414V. This is divided by 3.2 using the resistive divider on IC2a’s output and the 100kW resistor at pins 2 & 5 of IC3a & IC3b. As a result, the 1.414V peak is reduced to 441.8mV which is why VR2 is adjusted for 442mV above and below 2.5V at TP2 & TP3 to give peak indication when IC2a’s output signal goes above the 1V RMS level. Power supply As mentioned previously, the unit can either be powered from a USB Table 1: Resistor Colour Codes o o o o o o o o o o o o o o siliconchip.com.au No. 1 3 2 1 11 1 2 1 2 1 1 2 1 Value 220kW 100kW 22kW 20kW 10kW 2.2kW 680W 180W 150W 68W 39W 33W 10W 4-Band Code (1%) red red yellow brown brown black yellow brown red red orange brown red black orange brown brown black orange brown red red red brown blue grey brown brown brown grey brown brown brown green brown brown blue grey black brown orange white black brown orange orange black brown brown black black brown 5-Band Code (1%) red red black orange brown brown black black orange brown red red black red brown red black black red brown brown black black red brown red red black brown brown blue grey black black brown brown grey black black brown brown green black black brown blue grey black gold brown orange white black gold brown orange orange black gold brown brown black black gold brown July 2008  73 Above: the prototype was fitted with both a DC power socket and a USB socket but you should fit one or the other – see text. The rear panel carries the XLR socket and has access holes for the USB connector (left), the adjacent DC power socket and the line output jack. port or via a DC plugpack. Diode D1 provides reverse polarity protection if a DC plugpack is used, while series resistor R1 depends on the plugpack voltage (see table on circuit). In practice, any 300mA DC plugpack with an output voltage of 6V, 9V or 12V can be used. A 100mF capacitor filters the incoming supply rail, while S1 is the power on/off switch. Zener diode ZD1 en74  Silicon Chip sures that the resulting supply rail is limited to 5.6V to prevent damage to IC4, while R1 is necessary to prevent excessive current through ZD1. Note that no reverse supply protection is provided for the USB supply since this uses a polarised connector that cannot be reversed. Note also that only one type of supply should be used with this preamplifier. DO NOT install both a USB socket and a DC socket on the PC board, as damage to the USB port could occur if both supplies were used at the same time. IC4 is a MAX232 RS232 line driver IC but the line driver section is not used in this circuit. Instead, we are simply using it to generate the necessary plus and minus supply rails for the rest of the circuit. Basically, the MAX232 includes two internal charge pumps that convert the +5V supply to nominal unloaded ±10V rails. The first converter switches capacitor C1 and dumps its charge into C3 to double the supply to derive the +10V rail. Similarly, the second converter inverts this +10V rail by switching C2 at a rapid rate and dumping the charge into C4, to provide the -10V rail. This switching of C1 and C2 takes place at a nominal 400kHz rate. In practice, the resulting supply rails are loaded down to about +7V and -6V by op amps IC1 & IC2. Note, however, that the LM393 op amps (IC3a & IC3b) are powered directly from the +5V supply rail, to prevent excessive loading on IC4. The positive and negative supply rails generated by IC4 appear at pins 2 & 6 respectively and are decoupled using 33W resistors. In addition, these rails are bypassed using a 100nF capacitor to minimise supply noise. The power LED (LED1) is driven from the +5V rail via a 680W resistor. Finally, note that the signal earth for the preamplifier and the earth for the power supply are isolated via a 10W resistor. This reduces any current flow in the ground when the preamplifier is connected to a computer using both USB power and the stereo 3.5mm jack to feed in the signal. This is necessary because in this case there would be two earth paths between the unit and the computer – one via the USB connector and the other via the audio connection. Construction Construction is straightforward with most of the parts mounted on a PC board coded 01107081 and measuring 102 x 83mm. This is housed in a diecast aluminium box measuring 119 x 94 x 34mm. Begin by checking the PC board for any defects such as shorted tracks and breaks in the tracks. Check also that the hole sizes are correct by test fitting siliconchip.com.au 19 13 30 8 3MM 11.5 13 16 22.5 MM 6 HOLE DIA. 6MM HOLE DIA. 7MM 3MM REAR PANEL DRILLING DETAILS 15 19 5 This close-up view shows how the Level Control potentiometer (VR1) is mounted on the PC board. siliconchip.com.au SWITCH CUTOUT -- RIGHTHAND SIDE 10.5 94 10.5 7 3MM DIA. HOLE 3MM DIA. HOLE 76.5 the major parts, ie, the 3.5mm stereo jack socket and either the DC socket or the USB socket. The holes for the four-corner mounting screws should be 3mm in diameter. Finally check that the PC board fits into the box and that the cutout has been made for the XLR socket. Fig.4 shows the parts layout on the board. The resistors can be installed first. Table 1 shows the resistor colour codes but a digital multimeter should also be used to check each resistor before soldering it in place. Follow these with the ICs, taking care to ensure that they are correctly oriented. Make sure also that the LM393 goes in the IC3 position. We used sockets for IC1 & IC2 but this really is unnecessary and you can solder the ICs straight in. Next on the list are PC stakes for all the following: test points TP1-TP3, TP GND, the GND terminal, the switch terminals, the potentiometer mounts and its terminal connections, and the three input terminals (to terminate the stereo shielded cable from the XLR socket). Note that four PC stakes are used to support the metal body of VR1, which sits about 1mm above the PC board (see photo). Transistor Q1 (BC327) and the LM336-2.5 voltage reference (REF1) can now be installed, followed by diode D1 and zener diode ZD1. Take care to ensure that they are all oriented correctly and don’t get Q1 and REF1 mixed up (they look alike). Note that D1 and ZD1 face in opposite directions. The capacitors can go in next. Be 6.5 3MM DIA. HOLE 3MM DIA. HOLE BASE DRILLING DETAILS Fig.5: follow this diagram to mark out and drill the holes in the metal case. Alternatively, the diagram can be downloaded from the SILICON CHIP website, printed out and used as a drilling template. sure to orient the electrolytic types as shown in Fig.4. That done, install 10-turn trimpot VR2, then solder potentiometer VR1’s metal body to its four PC stakes. To do this, first bend the pot’s three terminals down at right angles, then position the potentiometer vertically on the board and push it’s metal body down between the four PC stakes until July 2008  75 LINE OUT MIC INPUT 9-12V DC INPUT USB IN SILICON CHIP BALANCED MICROPHONE PREAMPLIFIER + PEAK POWER + + POWER ON/OFF LEVEL Fig.6: this full-size front panel artwork shows the hole locations for the Level control and the two LEDs. Drill the Level control hole to 7mm & the holes for the LEDs to 3mm it sits about 1mm proud of the board. Mark the solder points on the body, then remove the pot and scrape away the anodised coating at those points. Next, cut the pot shaft off about 17mm from its threaded boss, then reposition the pot on the board and solder it’s body to the four PC support stakes. The pot mounting can then be completed by soldering its three terminals to the adjacent PC stakes. The two LEDs are mounted with the tops of their lenses exactly 25mm above the PC board. A 20mm-wide cardboard strip slipped between the leads of each LED makes a handy “standoff” tool when soldering them in position. Note that, in each case, the anode lead (the longer of the two) goes to the left. Finally, you can complete the PC board assembly by installing the 3.5mm stereo jack socket and either the DC power socket or the USB socket (but NOT both). This depends, of course, on how you intend to power the unit. As previously stated, you don’t fit both because the computer could be damaged if both supplies were connected at the same time. Internal wiring If you buy a complete kit for this design, it will probably be supplied with all the holes pre-drilled and with a screen printed front-panel label. If not, you will have to drill the holes yourself. Fig.6 shows the front panel layout and this can be used as a drilling template. You will need to drill 3mm holes for the Power & Peak indicator LEDs, plus a 7mm hole for the Level pot shaft. The latter is best made by drilling a pilot hole and then carefully enlarging it using a tapered reamer. Next, you will have to drill holes in the rear panel for the 3.5mm jack socket, the XLR socket and either the DC input socket or the USB socket. Fig.5 shows the drilling details. You will need to drill a 6mm hole for the DC input socket, while the stereo jack socket requires a 7mm hole. The square cutout for the USB socket can be made by first drilling a row of holes and then carefully filing to the final shape. The large hole for the XLR socket is a bit trickier to make. This hole is too big for most tapered reamers, so you will have to drill a series of holes around the inside circumference, then knock out the centre piece and carefully file it to shape. Its two mounting screw holes are each drilled to 3mm. Next, a square cutout for the power switch must be made in the righthand side of the case – see Fig.5. Again, this is made by drilling a series of holes, then knocking out the centre piece and filing the hole to shape, until the switch clips into position. Finally, four 3mm mounting holes for the PC board must be drilled in the base of the case. This is best done using Fig.5 as a template. Once the box has been drilled, the next step is to insulate the threaded ferrule of the 3.5mm jack socket with a short piece of heatshrink tubing, to prevent it making contact with the case. This heatshrink tubing should be shrunk on using a hot-air gun but be careful not to apply too much heat, otherwise you could damage the socket’s plastic casing. The PC board can now be installed in the case. To do that, secure four 6.3mm tapped standoffs to the base using M3 x 5mm screws, then place the board in position and secure it using another four M3 x 5mm screws and four M3 washers. With the board in place, you can now fit the XLR socket and complete the wiring as shown in Fig.4. Note that 2-core shielded cable is used for the connections between the PC board and the XLR socket and that the pin 1 terminal on the XLR socket is the ground or shield pin. Note also that a solder lug is fitted under one Issues Getting Dog-Eared? Keep your copies safe with these handy binders. REAL VALUE AT $13.95 PLUS P & P Available Aust, only. Price: $A13.95 plus $7 p&p per order (includes GST). Just fill in and mail the handy order form in this issue; or fax (02) 9939 2648; or call (02) 9939 3295 and quote your credit card number. 76  Silicon Chip siliconchip.com.au INSULATE SCREW FERRULE OF JACK SOCKET WITH HEATSHRINK TUBING ANTRIM TRANSFORMERS manufactured in Australia by Harbuch Electronics Pty Ltd harbuch<at>optusnet.com.au Toroidal – Conventional Transformers Power – Audio – Valve – ‘Specials’ Medical – Isolated – Stepup/down Encased Power Supplies Be sure to insulate the threaded ferrule of the line output jack socket with heatshrink tubing. This ensures that it cannot make contact with the case and cause an earth loop which would lead to hum. of the XLR socket’s mounting screws, to terminate the earth wire from the PC board. Testing To test the unit, first apply power and check that the power LED lights. Now measure the voltage between TPGND and pin 16 of IC4 – you should get a reading of 5V for a USB supply, or 5.6V if a plugpack supply is used. Check also that pin 4 of IC1 is about -6V, pin 8 of IC1 is at about +7V and that TP1 is at about 2.5V (with respect to ground). If any of these voltages is incorrect, switch off immediately and check the supply wiring. Check also that IC4 has been installed correctly. Assuming everything checks out so far, adjust trimpot VR2 so that the voltages at TP2 and TP3 are 442mV above and below 2.5V respectively (ie, TP2 should be +442mV with respect to TP1, while TP3 should be -442mV with respect to TP1). This sets the peak level indication. Note that because of resistor tolerances, you will not be able to adjust VR2 so that TP2 and TP3 are exactly the same value above and below TP1. Note also that if you intend using this Balanced Preamplifier with a computer, then it’s a good idea to set the peak indicator so that it agrees with siliconchip.com.au the level indicator in your recording software. Alternatively, if using this preamplifier with an MP3 player (ie, via the line input), adjust VR2 for the ±442mV levels at TP2 & TP3, then check that the sound is undistorted for all levels unless the peak level is exceeded. The assembly can now be completed by fitting four stick-on rubber feet to the underside of the box, then attaching the front-panel label, the lid and the control knob. Make sure that the two LEDs just protrude through their holes in the lid. The front panel label can be made by downloading the artwork from the SILICON CHIP website and printing it out on a colour printer. It can be attached to the panel using either double-sided tape or a thin smear of silicone sealant. Options If you wish to have a through XLR plug (so that you can feed through the signal to another preamplifier or mixer), then you will have to use a diecast box measuring 119 x 94 x 57mm. Extra positions for PC stakes have been included on the PC board (at the front, left) for this wiring. Finally, a switch can be added to close the connection between pins 2 & 3 of the XLR socket for microphone SC muting. Encased Power Supply www.harbuch.com.au Harbuch Electronics Pty Ltd 9/40 Leighton Pl, HORNSBY 2077 Ph (02) 9476 5854 Fax (02) 9476 3231 Want a real speed controller kit? If you need to control 12 or 24 volt DC motors and want a speed controller that will easily handle 30 amps, then this is the kit for you. This controller allows you to vary the speed of DC motors from 0 to 100%. It is also ideal for controlling loads such as incandescent/halogen lamps and heating elements. This kit makes a great controller for use on small electric vehicle projects, such as electrically assisted bikes and go-carts. We have tested it to over 30 amps without problems—it barely gets warm! Item code: SPEEDCON. We also have solar maximiser kits, Luxeon LEDs, and lots of interesting products and publications. Go to shop.ata.org.au or call us on (03)9639 1500. July 2008  77 SILICON CHIP If you are seeing a blank page here, it is more than likely that it contained advertising which is now out of date and the advertiser has requested that the page be removed to prevent misunderstandings. Please feel free to visit the advertiser’s website: www.altronics.com.au/ SILICON CHIP If you are seeing a blank page here, it is more than likely that it contained advertising which is now out of date and the advertiser has requested that the page be removed to prevent misunderstandings. Please feel free to visit the advertiser’s website: www.altronics.com.au/ SILICON CHIP If you are seeing a blank page here, it is more than likely that it contained advertising which is now out of date and the advertiser has requested that the page be removed to prevent misunderstandings. Please feel free to visit the advertiser’s website: www.altronics.com.au/ SILICON CHIP If you are seeing a blank page here, it is more than likely that it contained advertising which is now out of date and the advertiser has requested that the page be removed to prevent misunderstandings. Please feel free to visit the advertiser’s website: www.altronics.com.au/ Bridge adaptor for stereo power amplifiers 4x The Power Of A Single Module Would you like to connect a stereo amplifier in “bridge mode” in order to deliver double the power to a single loudspeaker system? This simple adaptor allows you to do it, without any modifications being necessary to the power amplifiers themselves. W By LEO SIMPSON E REGULARLY GET requests from readers asking how to connect a stereo power amplifier in “bridge mode” but up until now we have not had a specific project article to suit the application. Then recently we received an email from a reader asking how to run the SC480 ampli- fier modules (SILICON CHIP, January & February 2003) in bridge mode, just as we were proof-reading last month’s article on the “Balanced/Unbalanced Converter for Audio Work”. We immediately realised that half of that project would provide the needed adaptor. Before going into the details, let’s BRIDGE ADAPTOR Out-of-phase signals The two power amplifiers are driven with signals that are out-of-phase by 180°. If we consider a sinewave signal (or any other audio signal for that matter), when one power amplifier is delivering the positive half cycle of the waveform, the other amplifier will be delivering the negative half-cycle. The amplifiers drive a single loudspeaker and the result is that the two amplifier voltage waveforms are added, ie, we SPEAKER CONNECTED BETWEEN +VE L & R SPEAKER TERMINALS STEREO AMPLIFIER LEFT INPUT OUTPUT 1 AUDIO INPUT SIGNAL briefly describe how a pair of power amplifiers can be run in bridge mode to extract more power. Fig.1 shows the set-up. For a start, you must have two identical power amplifiers and this is why this arrangement is often convenient with a stereo amplifier. LEFT AMP INPUT OUTPUT 2 (STANDARD RCA-RCA STEREO CABLES) RIGHT INPUT RIGHT AMP + – + + – – Fig.1: this diagram shows how the Bridge Adaptor is connected to two power amplifiers to drive a single loud­speaker. Note that only the active output terminals of the power amplifiers are connected to the loudspeaker while the ground terminals are not connected. 82  Silicon Chip siliconchip.com.au V+ 10 F NP INPUT 2 100k 10k 100nF 8 3 22 F NP 1 IC3a 150 OUT1 4 100pF 100k V– 100pF 10k IC3: LM833 TO AMPLIFIER GND INPUTS 10k 6 4.7k 5 IC3b 7 22 F NP 150 OUT2 100k + R2 R1 V+ K – SC  2008 ZD1 15V A 1W 470 F 25V DC INPUT RAILS 0V FROM AMPLIFIER K 470 F 25V R4 R3 A Resistors R1-R4: Values for Various Supply Voltages ZD2 15V 1W V– BRIDGE adaptor for power amplifiers INPUT VOLTAGES (FROM AMPLIFIER) R1– R3 VALUES, POWER RATING R2– R4 VALUES, POWER RATING ±15V DC ±30V DC ±40V DC ±50V DC ±60V DC 33 , 0.5W 1k, 1W 1.8k, 1W 1.2k, 1W 1.5k, 1W (WIRE LINK) (WIRE LINK) (WIRE LINK) 1.2k, 1W 1.5k, 1W ZD1, ZD2 A K Fig.2: the Bridge Adaptor uses a dual op amp to provide “in-phase” and “out-of-phase” signals to drive two power amplifiers and a single loudspeaker. get double the output voltage of one amplifier across the loudspeaker. Since power is “voltage squared” times current, the resultant power in the loudspeaker is four times the power that could be obtained with one power amplifier driving that same loudspeaker. Well, that’s the theory anyway. In practice, the results may not be quite as good but it is still a worthwhile exercise if you have two amplifier modules and a single loudspeaker that you want to drive with a lot of power. What if you use the SC480s? Let’s now consider a real case, as suggested for the SC480 modules in the email mentioned above. As originally published and using the specified power supply circuit, the SC480 module is rated to deliver 50W into an 8-ohm load and 70W into a 4-ohm load. Furthermore, its music power was 77W into an 8-ohm load and 105W into a 4-ohm load. Hence, under music power conditions and depending on the regulation siliconchip.com.au of the power supply, two SC480 modules in bridge mode could be expected to deliver over 200W into an 8-ohm load. In fact, that is four times the rated power from a single module into an 8-ohm load, so our general rule of “four times the power” is not far off. Note that the continuous power would only be about 150W or twice the rated power into a 4-ohm load. Do not use a 4-ohm speaker So could we go even further and use a 4-ohm loudspeaker instead of an 8-ohm model. Well sorry, but that is not possible because it would overload the amplifier modules. The reason for this is that each amplifier in a bridge set-up actually “sees” half the real load impedance. So, for the 8-ohm example we have just talked about, each SC480 amplifier module sees or behaves as if was driving a 4-ohm load and it can only deliver the power it would deliver if it was driving a 4-ohm load. Why is that? Consider two modules driving a single 8-ohm loudspeaker, with each amplifier delivering a sinewave of 8V. Since the voltages across the speaker are added, the resultant current flowing in it is 16/8 or 2A. So as far as each amplifier module is concerned, it is delivering 8V and 2A is flowing, therefore as far as the amplifier is concerned, it is driving a 4-ohm loudspeaker. Now you know as well as we do that amplifiers are not “animate” and they cannot think or see but you get the picture. To repeat the concept: each amplifier in a bridge set-up “sees” half the real load impedance. Therefore, if you are going to use a 4-ohm load in a bridge set-up, each amplifier must be able to drive a 2-ohm load. The SC480 is not rated to drive 2-ohm loads and that is the end of the story as far as that module is concerned. Now let us describe the circuit of the Bridge Adaptor. Before doing so, we should note that if you want to drive a subwoofer in bridge mode, then the Subwoofer Controller featured in the August 2007 issue is your answer, July 2008  83 CUT PC BOARD HERE (OPTIONAL) Parts List OUTPUTS TO AMPLIFIER INPUTS 150 + 0V – R4 ZD2 ZD1 10k R3 R1 10k IC3 LM833 NP 100nF NP R2 22 F 100k 22 F 100pF 100k 150 DC POWER FROM AMPLIFIER OUT2 GND OUT1 GND 4.7k 100pF NP SIG 100k 10 F 10k ADD THESE WIRE LINKS UNDER PC BOARD 470 F 470 F /DE C NALA B DE C NALA B NU RETREV N O C 18060110 GND AUDIO INPUT Fig.3: use this diagram to populate the PC board. Only one half of the board is used and the unused section can be cut off if you wish. Fig.4: repeated from our August 2007 issue, this scope shot shows the principle of bridged power amplifier operation. The two upper traces show the in-phase (yellow) and out-of-phase (purple) signals. The red trace shows the expected signal across the loudspeaker and this is the “sum” of the two amplifier drive signals which will result in four times the power being delivered into the loudspeaker. In practice, depending on the amplifier output configuration and the power supply regulation, the results may not be quite as good. 1 PC board, code 01106081, 103 x 85mm 1 3-way screw terminal blocks (5.08mm or 5mm spacing) 3 2-way screw terminal blocks (5.08mm or 5mm spacing) 3 M3 x 6.3mm tapped standoffs 3 M3 x 6mm screws 1 60mm length of 0.8mm tinned copper wire (for links) Semiconductors 1 LM833 dual op amp (IC3) 2 15V 1W zener diodes (ZD1, ZD2) Capacitors 2 470mF 25V PC electrolytic 2 22mF NP electrolytic 1 10mF NP electrolytic 1 100nF MKT polyester 2 100pF ceramic Resistors (0.25W, 1%) 3 100kW 1 4.7kW 3 10kW 2 150W R1-R4: see table in Fig.2 adaptor and in fact, it is identical to the Unbalanced to Balanced Output Converter shown on page 70 of the June 2008 issue. We show it as using one LM833 low-noise dual op amp which is labelled as IC3. IC1 & IC2 on the same circuit are deleted. The input signal is fed to op amp IC3a which is connected as a unitygain buffer by virtue of the fact that its output (pin 1) is connected directly to its inverting input (pin 2). The output of IC3a is fed via a 22mF non-polarised (NP) capacitor and a 150W resistor to become the “in-phase” output signal to one of the power amplifier modules. IC3a also drives op amp IC3b which is connected as an inverting amplifier with a gain of -1, due to the 10kW resistors connected to pins 6 & 7. IC3b’s output is fed via a 22mF non-polarised (NP) capacitor and a 150W resistor to become the “out-of-phase” output signal to the second power amplifier module. Power supply since it already has the bridge drive facility. The same comment can be made on the Sub Bass Processor featured in the September 1999 issue of Electronics Australia, as it also has 84  Silicon Chip out-of-phase signals to drive a subwoofer loudspeaker. Bridge adaptor circuit Fig.2 shows the circuit of the bridge The power supply for the Bridge Adaptor assumes that the power amplifier modules will be run from balanced positive and negative supply rails. These supply rails are fed in via siliconchip.com.au Still Confused As To How It Works? Separate Boards Some readers may still be confused about how feeding out-of-phase signals to a single loudspeaker can result in double the drive voltage (and four times the power). After all, out-of-phase signals cancel, don’t they? They may be further confused if they look closely at the scope screen grab (Fig.4) and see that the MATHematical operation used to produce the large amplitude red trace is minus (-). So let us explain. Normally, if you add two out-of-phase signals using an oscilloscope, they do cancel. The sum would be written as: V1 + (-V1) = 0 However, when you have out-of-phase signals delivered to a loudspeaker (or any other load, for that matter), the loudspeaker always responds to the voltage difference between the two signals. So if one side of the loudspeaker is at +6V (say) and the other side is at -6V, the total voltage across the speaker will be 12V. Once you have built the Bridge Adaptor and hooked it up to a pair of amplifiers, you can confirm this with a digital multimeter set to a low-voltage AC range. That is why we set the scope to subtract the signals to portray the correct result. The sum would be written as: V1 - (-V1) = 2V1 Bob Barnes at RCS Radio (Phone (02) 9738 0330) has produced separate boards for the two sections of the “Balanced/Unbalanced Converter” project published in June 2008. The “Unbalanced To Balanced Converter” board is coded 01106082.PCB, while the “Balanced To Unbalanced Converter” board is coded 01106083.PCB. For this Bridge Adapator project, you can use the 01106082.PCB board. Note, however, that you will still have to install a wire link under the board between the junction of ZD1 & ZD2 and the junction of the two 470mF capacitors. This is necessary because of the different power supply arrangement for the Bridge Adaptor. The two wire links to the left of the input terminal block in Fig.3 are taken care of by the new board design. series resistors (R1-R4) and regulated using two 15V 1W zener diodes (ZD1 & ZD2) which are each shunted by 470mF 25V capacitors to ensure low hum and noise. A table on the circuit shows the values for various supply combinations. In particular, if you are using the power supply board for the SC480 amplifier modules, they already have provision to provide ±15V supply rails. In that case, you can simply install wire links in place of R2 & R4 and 33W resistors for R1 & R3 and omit zener diodes ZD1 & ZD2. The 33W resistors are included to improve the supply filtering (bypassing) in conjunction with the 470mF capacitors. To illustrate another case, if your amplifier modules use ±50V supply rails, you should install four 1.2kW 1W resistors in the R1-R4 positions. Construction As already noted, the Bridge Adaptor uses the same PC board as the Balanced/Unbalanced Converter except that one half of the board is unused. The parts layout is shown in Fig.3 and includes three links which must be installed underneath the board. If you want, you can cut off the unused section of the board to make it smaller but then you should also provide a third plastic pillar and mounting screw. Installation is simply a matter of deciding how you want to mount the board in conjunction with your power amplifiers which may or may not be in a common chassis. We’ll leave the SC details to you. Looking for real performance? PERFORMANCE ELECTRONICS FOR CARS • Learn how engine management systems work • Build projects to control nitrous, fuel injection and turbo Fro m the pu bli sh ers 160 PAGES 23 CHAPTE RS boost systems • Switch devices on and off on the basis of signal frequency, temperature and voltage • Build test instruments to check fuel injector duty cycle, fuel mixture and brake and coolant temperatures • Speedo Corrector, Turbo Timer, Nitrous Fuel Controller & Digital Thermometer Projects of Intelligen t turbo timer I SBN 095 852 9 7809 5 294 - 4 8 5229 4 $19.80 (inc GST) TURBO B OOST & nitr ous fuel co ntrollers 6 NZ $22.00 (inc GST) How eng in managemene t works Mail order prices: Aust. $A22.50 (incl. GST & P&P); Overseas: $A26.00 via airmail. Order by phoning (02) 9939 3295 & quoting your credit card number; or fax the details to (02) 9939 2648; or mail your order with cheque or credit card details to Silicon Chip Publications, PO Box 139, Collaroy, NSW 2097. siliconchip.com.au July 2008  85 Vintage Radio By RODNEY CHAMPNESS, VK3UG The Astor KM 4-Valve Reflexed Receiver Developed during the very early days of radio, reflex circuits were used in receivers right up until the 1950s. One such set was the Astor KM. R EFLEX RECEIVERS were sets that used one of their valves to perform several functions. In fact, some early receivers had more than one stage reflexed. In the case of the Astor KM, it’s the intermediate frequency (IF) stage (6B8G) that performs several functions – ie, IF amplifier, detector, AGC and first audio stage. Despite using quite conventional components, radios with reflexed stages were not particularly popular with servicemen. To understand why, read the early “Serviceman Who Tells” articles in “Radio and Hobbies” which came out from 1939 onwards (now available on DVD from SILICON CHIP). 86  Silicon Chip My own experiences with this set back up those early Serviceman stories. The servicemen of the era were usually self-taught. Some of them had a good understanding of the radios they serviced but others were purely “valve jockeys”. A “valve jockey” had no understanding of the workings of the receiver and just replaced valves until (hopefully) the receiver worked. Valves weren’t as reliable back then as they were in later years and valve jockeys often got sets going reasonably well, even if the real cause of the fault had not been found. Another problem for early servicemen was the lack of test instruments. During the 1930s, even a basic multimeter was an expensive item and this situation persisted right up until the 1960s. Today, we can buy a digital multi­ meter (or DMM) that is vastly superior to the meters of the 1930s for as little as $8. After taking inflation into account, the comparative cost of a simple multimeter in the 1930s would have been many hundreds of dollars. However, even that doesn’t reflect the true cost, since wages in the 1930s were considerably less than they are now in real terms. As for other test instruments, oscilloscopes were only laboratory instruments before WW2, while capacitor testers, modulated oscillators and even simple valve testers were very expensive and relatively rare. To get around this problem, many servicemen built their own test instruments, often from the designs that appeared regularly in “Radio and Hobbies”. At the same time, servicemen were becoming better trained thanks to organisations such as the Australian Radio College and the Marconi School of Wireless, the latter an adjunct of AWA. In addition, many radio servicemen learnt their trade through the PMG, DCA (Department of Civil Aviation) and military training schools. Servicing reflex receivers So why didn’t servicemen like servicing reflex receivers? Well, the IF circuit in a reflex receiver is more complicated than a normal IF stage, as it amplifies audio signals as well as the IF signals. To do this, the operating conditions for the stage must be suitable for both audio and IF signals. This by its very nature involves a compromise and so when the valve or any of its associated components deteriorate, the stage quickly malfunctions. The problem for servicemen was that, with the elementary servicing tools they had at their disposal, it wasn’t siliconchip.com.au easy to determine which component or components were at fault. Most servicemen, for example, were unable to test paper capacitors (eg, for leakage and capacitance) and so many faulty capacitors would have remained in the receivers they serviced. Replacing multiple components in an attempt to eliminate a stage fault wasn’t the answer either. Components at that time were much more expensive than they are today and replacing multiple components to eliminate a single faulty part wasn’t an economic proposition. So if reflex circuits were such a problem for servicemen, why were they used? Quite simply, valves were very expensive up until the 1950s and reducing the number of valves used in a receiver saved a considerable amount of money. In fact, a valve in the 1920s could cost as much as a man earned in a week. As a result, receiver manufacturers and experimenters used reflex circuits to keep costs down, without compromising performance to any extent. The logic was simple: a 4-valve set that could perform like a 5-valve set would be cheaper to manufacture than a set that actually used five valves. The Astor KM The little Astor KM receiver featured in this article sat on a shelf in my garage for years before its eventual restoration. I don’t remember where it came from but it had obviously lived in a dusty kitchen before being relegated to someone’s shed as a background source of “noise”. The dust had been well and truly stuck to the chassis and cabinet by vaporised cooking oil and the chassis was in a sorry state. A brief inspection revealed quite a few obvious problems. First, the loudspeaker was just hanging in the general area where it is normally mounted and the speaker transformer leads had been cut off (I have no idea why this had been done). In addition, the dial pointer was missing, the dial cord was broken, the speaker cloth had disappeared and there was a crack in the dial scale. The twin-lead power cord had also been lengthened using another length of mains cable and was in quite an unsafe condition. It was also crudely “anchored” using just a knot tied in the cable, which is illegal these days. It was later replaced with a securelysiliconchip.com.au These two views show the top of the chassis before restoration. Note the bodgie (and unsafe) extension job on the dilapidated power cord. anchored 3-core mains lead, so that the metal chassis could be earthed. Circuit details Fig.1 shows the circuit details of the 4-valve Astor KM. In this set, the antenna circuit has a primary winding that resonates just below the broadcast band and there is a small coupling capacitor from the top of the primary to the top of the tuned winding. This type of antenna circuit is designed July 2008  87 Fig.1: the Astor KM uses 4-valves – a 6A8G converter stage, a 5B8G reflex stage, a 6V6GT audio output stage and a 5Y3GT rectifier. The 6B8G reflex stage functions as an IF amplifier, detector and first audio stage and also supplies AGC to the converter. to give good performance across the broadcast band with relatively small antennas. The following 6A8G valve acts as the converter. It has cathode bias as well as AGC applied to the signal grid. Its signal is coupled to the 6B8G IF stage via IF transformer 46. The output from this stage is then fed to IF transformer 47 and the resulting signal detected by the two diodes wired in parallel in the 6B8G. These diodes also supply simple AGC (automatic gain control) back to the converter stage. Note, however, that AGC is not applied to the 6B8G as this would alter the operating conditions of this valve and cause the audio output to drop with increased signal level. The audio output from the detector is fed to the volume control (44) and then fed back to the grid of the 6B8G via the tuned secondary output of the first IF transformer. This IF transformer has no effect on the audio signal but RF bypassing is achieved using capacitor 15 at the bottom of the transformer’s 88  Silicon Chip secondary (its value is small so that it doesn’t shunt the audio signal to ground). The audio output from the 6B8G is fed through IF transformer 47 and is developed across resistor 31. Capacitor 41 bypasses any IF signal to ground, after which the audio signal is coupled to the grid of the 6V6GT audio output valve via a .02mF capacitor (8). The 6V6GT stage includes both RF bypassing and audio top-cut filtering, achieved using capacitors 10 and 16. As with most Astor circuits, a quite complex tone correction circuit is run from the voice coil winding on the speaker transformer back to a tapped volume control. With only slight modifications, this network acted as a very comprehensive and effective tone control circuit in many Astor receivers. Note that the 6V6GT is the only one in the circuit that has back bias applied from the power supply. The power supply is conventional and uses a 5Y3GT as the rectifier. All valve filaments, except the 5Y3GT, are supplied from a 6.3V filament winding on the power transformer, while the dial lamps are supplied from a lower voltage tapping on this winding. This is intended to prolong the life of the lamps. Mechanical restoration The chassis can normally be slid out of the cabinet after removing the knobs and two screws on the back edge of the chassis. However, due to the build up of gunk, this chassis had to be prised out of its cabinet. Originally, there would have been a cardboard back on the set but that had long since disappeared. Once the set had been dismantled, the cabinet and knobs were scrubbed clean with warm soapy water and a large nailbrush. They came up looking pristine, apart from some sticky residue left over from some packaging tape which a previous owner had used to hold the back on (before it was lost). This sticky residue was easily cleaned siliconchip.com.au This under-chassis view shows the unit before restoration. Note the crude (and now illegal) method of “anchoring” the power cord (ie, using a knot). The loudspeaker had several tears in its cone (top) and these were repaired using several layers of nail polish. Despite its age, the repaired speaker still worked quite well. off using a rag soaked in methylated spirits. The cabinet now look quite good, so much so that I didn’t bother resorting to my customary treatment with car cut and polish. The chassis was also rather grotty so I began by removing all the valves and the loudspeaker. As mentioned above, the speaker was just sitting in its mounting position but was not actually attached to the mounts. Removing these parts gave reasonable access to the chassis and the loose dust and fluff was brushed away from under and on top of the chassis using a small paintbrush. I then got busy with a kitchen scourer soaked in kerosene and some cleaning rags and thoroughly cleaned the chassis and any large components mounted on it. This is a straightforward task and the kerosene does a great job when it comes to loosening the muck. Perished insulation One thing that was obvious during the chassis clean-up was that the insulation on the power transformer leads siliconchip.com.au The unit after restoration. All but one of the original paper capacitors has been replaced, some resistors changed, the dial restrung and a new 3-way mains cord fitted and anchored using a cable clamp. In addition, the chassis is now earthed, in the interests of safety. had hardened and become brittle. In fact, the previous owner had noticed this and had put electrical tape around a number of these leads. This tape looked rather ordinary so I decided to remove it to see just how bad the insulation was. It was, in fact, very bad and I ended up cracking the remaining brittle insulation off eight of the leads using a pair of pliers. I then cut off the wires one by one where they terminated in the circuit and slid plastic sleeving over each one before reconnecting them. Once all the leads had been reconnected, I used neutral-cure silicone on the transformer ends of the leads to hold them in place. No shorts were found when I tested the transformer with my multimeter. July 2008  89 This top-of-the-chassis view shows the Astor KM receiver after restoration. The chassis was cleaned using a kerosene-soaked kitchen scourer, while the valves were cleaned by washing them in warm soapy water. Most of the wiring under the chassis had also perished and so had to be replaced. This was done one lead at a time (as with component replacement) to prevent any wiring mistakes and took almost a day to complete. In addition, the speaker had a few tears in its cone and this was repaired using several coats of nail polish. The cone moved in and out of the annular gap quite freely and did not appear to be poling, so the speaker was still OK. Component replacement The next step was to replace any paper capacitors that showed excessive leakage. I also found a few resistors that were out of tolerance and these too were replaced. I then tested the electrolytic capacitors and replaced two out of the three (my electrolytic capacitor reformer did a good job of sorting out the good from the bad). The speaker transformer was next on my checklist. Unfortunately, this had an open-circuit primary winding and this type of fault can quickly destroy a 6V6GT. What happens is that when the transformer primary is open-circuit, the valve’s plate has no voltage on it. As a result, the screen acts as the plate and the valve draws too much current. Subsequently, I found that the 6V6GT had indeed been ruined by this fault. Getting back to the transformer, this was replaced by first drilling out the rivets that secured it to the speaker and then bolting another transformer into place. I then refitted the speaker into the set and wired it into circuit. Firing up It was now time to start bringing the set back to life but first I used my A new dial pointer was made by gluing a length of thick copper wire to an aluminium bracket. The pointer was then painted white. 90  Silicon Chip high-voltage tester to check for leakage between the power transformer’s primary winding and its frame and between the primary and secondary windings. This is an important safety step and in this case the transformer proved to be in good condition. Having cleared the transformer, I wired in the new mains cord and applied power with no valves installed. All the voltages were as expected, being a little higher than the published figures because there was no load on the transformer. Previously, I mentioned that the dial lamps are supplied from a tapping on the 6.3V filament winding. However, in this set the dial lamps had been connected across the entire 6.3V winding and not to the 5V tapping on this winding. This was corrected by wiring the dial lamps to the tapping, to agree with the circuit diagram. Next, I plugged in the 5Y3GT and carefully checked the resulting HT voltages and the operation of the power supply. All was normal, with the HT voltages slightly higher than specified because there was still no real load on the power supply. The set was then left running like this for some time, then disconnected from the mains and checked for signs of overheating in the transformer and other components. Only the 5Y3GT was getting hot, so all was well so far. At this stage, the original 6V6GT was plugged in but it didn’t draw any current (ie, there was no voltage across resistor 42). It had indeed been overloaded and had failed when the speaker transformer primary had gone open circuit. A replacement 6V6GT solved that problem. Chaos reigns! Everything was looking good so far, so I fitted the other two valves – a 6B8GT and a 6J8G for the converter. These are not the specified types but will work perfectly well in this set. I then turned the set on and it immediately started working and drew 36W of power, which is normal for a set of this size. Unfortunately though, it wasn’t working properly as the set motorboated and also appeared to be squegging. Motorboating refers to a “pop-pop” type of noise a little like that made by old single-cylinder inboard motorboat engines and is a form of instability. By contrast, squegging usually ocsiliconchip.com.au Silicon Chip Binders REAL VALUE AT $13.95 PLUS P & P The replacement speaker cloth was held in position using clamps until the glue (contact adhesive) dried. These binders will protect your copies of S ILICON CHIP. They feature heavy-board covers & are made from a dis­ tinctive 2-tone green vinyl. They hold 12 issues & will look great on your bookshelf. H 80mm internal width curs with oscillators. What happens is that the oscillator operates briefly and then stops due to cut-off bias being applied to the grid of the valve (due to incorrect operating conditions). After a short time, the charge dissipates and the valve starts operating again. In this case, the set would operate at low volume reasonably well but turned nasty at high volume. Inadequate filtering in the power supply usually causes motor boating but I had already replaced the faulty filter capacitors. I tried adding extra capacitors but to no avail. Next, I took a closer look at the 6B8GT in the IF stage. I’m not sure if this valve is supposed to be shielded or not in this set, so I substituted the specified G version, fitted a shield around it and earthed this shield to the chassis. This slightly improved the performance of the set but was clearly not the answer. My next step was to try replacing the 6J8G with the specified 6A8G. This made no difference to the set’s stability but it did alter the tuning range. Instead of tuning to around 1650kHz at the top end of the dial, it now tuned to around 1750kHz. It would appear that either the capacitance of the valves was different or that the Miller effect was causing the apparent capacitance across the tuned circuit to change. siliconchip.com.au I retuned the front-end stages and also the IF stage but again there was no improvement in the stability. In fact, the set’s alignment was fairly accurate except for the highest frequency that the oscillator tuned to. This was easily corrected by adjusting the oscillator’s trimmer capacitor. At this stage, I considered that there might be too much IF energy from the detector circuit getting back into the input of the 6B8G. As a result, I fitted an additional RF filter consisting of a 270pF capacitor from the “hot” end of the volume control to chassis and a 56kW resistor from the “hot” end of the control to the top of capacitor 13. This removed most of the RF from the line to the grid of the 6B8G but there was still no noticeable improvement in the stability. Next, I considered the possibility that there might be too much IF energy getting into the 6V6GT audio output valve. To test this theory, I initially placed a 50pF capacitor between the 6V6GT’s grid and chassis to reduce the amount of IF energy getting to the valve. This gave a slight improvement so I did some calculations which showed that substituting a 270pF capacitor would cut most of the IF energy but still not affect the higher audio frequencies. Again there was only a slight improvement (note: these H SILICON CHIP logo printed in gold-coloured lettering on spine & cover H Buy five and get them postage free! Price: $A13.95 plus $A7 p&p per order. Available only in Aust. Silicon Chip Publications PO Box 139 Collaroy Beach 2097 Or call (02) 9939 3295; or fax (02) 9939 2648 & quote your credit card number. Use this handy form Enclosed is my cheque/money order for $________ or please debit my  Visa    Mastercard Card No: _________________________________ Card Expiry Date ____/____ Signature ________________________ Name ____________________________ Address__________________________ __________________ P/code_______ July 2008  91 Photo Gallery: Eddystone 77U VHF/UHF Receiver Having discovered the cause of the problem, I removed the extra 270pF capacitor and 56kW resistor I had fitted and the receiver has remained stable ever since. The plate resistor on the 6B8G was left at 15kW, as no discernible difference in volume was observed. Dial scale & speaker cloth ONE OF THE BEST RECEIVERS ever made, the Eddystone 770U VHF/UHF set was often found in radio manufacturers’ test departments. It employs a total of 17 miniature 9-pin and 7-pin valves and two octal valves in the power supply. It tunes from 150MHz to 500MHz over six bands and its sensitivity is quoted at better than 10mV for 15dB over all bands. The unit shown here outperformed its specifications. Apart from performance, a feature is the flywheel-weighted tuning which allows the operator to spin the dial knob and travel rapidly to each end of the dial, even though it is highly geared. Photo supplied by the Historical Radio Society of Australia Inc (HRSA), PO Box 2283, Mt Waverley, Vic 3149. www.hrsa.net.au observations were made with a signal tracer and an oscilloscope). Back to the bible By now, I was running out of ideas so I decided to consult the “Radiotron Designers Handbook” and see what it said about reflex circuits. And there was a clue, with the text stating that care was needed in setting the audio level being fed back into the IF valve. If this level exceeded the valve’s bias, the valve would cut off and the result would be the type of instability present in my Astor KM. In fact, I had already discovered that the grid and cathode voltages of the 6B8G varied wildly when the instability showed up. Furthermore, the text stated that the plate resistor used for most reflex stages was around 15kW instead of the 70kW that Astor commonly used in such circuits. As a result, I reduced the value of this resistor in steps and eventually came down to the recommended 15kW. The set was still unstable but the good news was that the instability was 92  Silicon Chip not occurring until the volume was wound higher than before. I also observed that the instability occurred more readily on programs with a lot of low-frequency content. Next, I disconnected the audio signal from the 6V6GT and used my signal tracer to listen to the IF/audio stage for any sign of the instability. There was none, so I reconnected the audio to the 6V6GT and the instability immediately reappeared. Frankly, I was at a loss to understand what was going on until I put my finger on the cone of the loudspeaker and the instability largely disappeared. I then wedged a piece of paper between the frame of the speaker and the cone in such a position that cone was distorted and the instability disappeared altogether! A new speaker will be fitted at a later date when I get one to suit. It would seem that the speaker “fault” was being fed back to the 6V6GT, which in turn fed it back to the 6B8G and caused the instability problems. It could only happen in a reflexed receiver! Having fixed the circuit, it was time to fit some fresh speaker cloth. I have some dark brown cloth and this was cut to size, glued and clamped in place until the glue (contact adhesive) dried. The next job was to restring the dial cord but this proved to be relatively straightforward. It employs the usual unique Astor method, which doesn’t slip like many other dial-drives often do. However, I did have a real problem with the dial pointer – it was missing, which meant that I would have to make a new one. Eventually, I decided to make one using a small scrap of aluminium roof flashing and a short length of thick copper wire. I cut two slots in one side of the flashing and de-burred them to make sure the edges would not cut the dial cord when it was routed through these slots. I then laid the wire across the flashing and secured it in place using superglue along the join (see photo). Finally, the pointer was painted white to show up against the speaker cloth. It looks just like the original. Summary Reflex sets can be difficult to troubleshoot because it’s often almost impossible to determine whether the RF (radio frequency) sections or the audio sections are at fault. However, most reflex sets eventually respond to normal fault-finding techniques so don’t be intimidated by them – they are an interesting part of our radio history. Once its faults were overcome, the Astor KM set performed well and is quite sensitive. However, Astor’s choice of rubber-insulated hook-up wire has been a problem in many of their sets. In summary, it’s quite a pleasant little set to use and look at and is certainly worthy of a place in my vintage SC radio collection. siliconchip.com.au BOOK REVIEW by Leo Simpson Switching Power Supplies, A to Z by Sanjaya Maniktala. 1st Edition, published 2006 by Elsevier, Inc. 504 pages, 241 x 195, Hardcover with Mathcad calculations on companion CD-ROM. ISBN0 7506 7970 0 $106.00 M ost electronics enthusiasts and technicians regard the design of switching power supplies as very much a black art and considering the special techniques and components required, that is probably not far off the mark. However, it is not black magic, as is very ably demonstrated by the author. In fact, a great deal of the technique of switchmode power design depends on a very good understanding of analog electronics and in particular, the behaviour of inductors. This last factor is driven home right at the start of this text book and the author is never far away from the topic all the way through. Chapter 1 is titled “The Principles of Switching Power Conversion” and begins with a review of basic power supply types and then has a large section devoted to “Understanding the Inductor”. This is crucial to anyone who wants to get a good background in switchmode techniques. If you carefully read this chapter, you will realise the full implications of the formula V = Ldi/dt, as never before. Chapter 1 also has a good discussion of the various switchmode power supply topologies such as boost, buck and buck-boost. Chapter 2 is titled “DC-DC Converter Design and Magnetics” and deals in considerable detail with inductor current waveforms, defining peak currents and so on. It continues the discussion in inductors and inductance, their size relative to frequency and current ratings and how to specify current ratings for a given application. Chapter 3 is titled “Off-line Converter Design and Magnetics” and is devoted to mains powered designs using an isolating transformer, typically flyback or forward converter. This gets down to the nitty-gritty of flyback transformer design, discussing core material, windings, interleaving and so on. Chapter 4 is “The Topology FAQ” and is whole section of specific questions and answers on switchmode topology, ie, the range of possible circuit configurations. Chapter 5 is devoted to “Conduction and Switching Losses” and treats the switching process in detail, explaining how most of the dissipation in the switching element (Mosfet, transistor etc) takes place in transition from on to off and vice versa. In particular, it discusses the effects of gate capacitance on switching times and how drivers can be optimised. Chapter 6 is on “Printed Circuit Board Layout”. This is perhaps the most important chapter of the lot since even siliconchip.com.au if it is a brilliant circuit it can be brought undone by poor PC board layout. Chapter 7 is on “Feedback Loop Analysis and Stability” and you will need a good background of AC circuit theory and feedback to get the full value from this. Chapters 8 to 13 are devoted to the topic of EMI and EMI filters. This is essential to the performance and type approval of any commercial switchmode design. Finally, Chapter 14 is titled “The Math behind the Electromagnetic Puzzle” and is devoted to analysis of switchmode filters. Fourier analysis comes in here so you will need to revise this topic to get the benefit of this chapter. The book concludes with a comprehensive appendix which is a collection of topics relating to power supply design published by the author – all good practical stuff. Also included in the book is a CD-ROM which is a collection of Excel spreadsheets, PowerPoint presentations, Word files, some useful PDFs and a large number of Mathcad files for which you will need “Mathcad 2000” (or higher) on your PC. In conclusion, this is the best textbook we have ever come across on the subject of switchmode technology. Any designer of switchmode power supplies or controllers should have it on the bookshelf. It is available from SILICON CHIP. SC July 2008  93 Silicon Chip Back Issues January 1994: 3A 40V Variable Power Supply; Solar Panel Switching Regulator; Printer Status Indicator; Mini Drill Speed Controller; Stepper Motor Controller; Active Filter Design; Engine Management, Pt.4. February 1994:90-Second Message Recorder; 12-240VAC 200W Inverter; 0.5W Audio Amplifier; 3A 40V Adjustable Power Supply; Engine Management, Pt.5; Airbags In Cars – How They Work. March 1994: Intelligent IR Remote Controller; 50W (LM3876) Audio Amplifier Module; Level Crossing Detector For Model Railways; Voice Activated Switch For FM Microphones; Engine Management, Pt.6. April 1994: Sound & Lights For Model Railway Level Crossings; Dual Supply Voltage Regulator; Universal Stereo Preamplifier; Digital Water Tank Gauge; Engine Management, Pt.7. May 1994: Fast Charger For Nicad Batteries; Induction Balance Metal Locator; Multi-Channel Infrared Remote Control; Dual Electronic Dice; Simple Servo Driver Circuits; Engine Management, Pt.8. June 1994: A Coolant Level Alarm For Your Car; 80-Metre AM/CW Transmitter For Amateurs; Converting Phono Inputs To Line Inputs; PC-Based Nicad Battery Monitor; Engine Management, Pt.9. July 1994: Build A 4-Bay Bow-Tie UHF TV Antenna; PreChamp 2-Transistor Preamplifier; Steam Train Whistle & Diesel Horn Simulator; 6V SLA Battery Charger; Electronic Engine Management, Pt.10. August 1994: High-Power Dimmer For Incandescent Lights; Dual Diversity Tuner For FM Microphones, Pt.1; Nicad Zapper (For Resurrecting Nicad Batteries); Electronic Engine Management, Pt.11. July 1996: VGA Digital Oscilloscope, Pt.1; Remote Control Extender For VCRs; 2A SLA Battery Charger; 3-Band Parametric Equaliser;. August 1996: Introduction to IGBTs; Electronic Starter For Fluores­cent Lamps; VGA Oscilloscope, Pt.2; 350W Amplifier Module; Masthead Amplifier For TV & FM; Cathode Ray Oscilloscopes, Pt.4. September 1996: VGA Oscilloscope, Pt.3; IR Stereo Headphone Link, Pt.1; HF Amateur Radio Receiver; Cathode Ray Oscilloscopes, Pt.5. October 1996: Send Video Signals Over Twisted Pair Cable; 600W DC-DC Converter For Car Hifi Systems, Pt.1; IR Stereo Headphone Link, Pt.2; Multi-Channel Radio Control Transmitter, Pt.8. November 1996: 8-Channel Stereo Mixer, Pt.1; Low-Cost Fluorescent Light Inverter; Repairing Domestic Light Dimmers.. December 1996: Active Filter For CW Reception; Fast Clock For Railway Modellers; Laser Pistol & Electronic Target; Build A Sound Level Meter; 8-Channel Stereo Mixer, Pt.2; Index To Vol.9. January 1997: Control Panel For Multiple Smoke Alarms, Pt.1; Build A Pink Noise Source; Computer Controlled Dual Power Supply, Pt.1; Digi-Temp Thermometer (Monitors Eight Temperatures). February 1997: PC-Con­trolled Moving Message Display; Computer Controlled Dual Power Supply, Pt.2; Alert-A-Phone Loud Sounding Telephone Alarm; Control Panel For Multiple Smoke Alarms, Pt.2. March 1997: 175W PA Amplifier; Signalling & Lighting For Model Railways; Jumbo LED Clock; Cathode Ray Oscilloscopes, Pt.7. September 1994: Automatic Discharger For Nicad Batteries; MiniVox Voice Operated Relay; AM Radio For Weather Beacons; Dual Diversity Tuner For FM Mics, Pt.2; Electronic Engine Management, Pt.12. April 1997: Simple Timer With No ICs; Digital Voltmeter For Cars; Loudspeaker Protector For Stereo Amplifiers; Model Train Controller; A Look At Signal Tracing; Pt.1; Cathode Ray Oscilloscopes, Pt.8. October 1994: How Dolby Surround Sound Works; Dual Rail Variable Power Supply; Talking Headlight Reminder; Electronic Ballast For Fluorescent Lights; Electronic Engine Management, Pt.13. May 1997: Neon Tube Modulator For Light Systems; Traffic Lights For A Model Intersection; The Spacewriter – It Writes Messages In Thin Air; A Look At Signal Tracing; Pt.2; Cathode Ray Oscilloscopes, Pt.9. November 1994: Dry Cell Battery Rejuvenator; Novel Alphanumeric Clock; 80-M DSB Amateur Transmitter; 2-Cell Nicad Discharger. June 1997: PC-Controlled Thermometer/Thermostat; TV Pattern Generator, Pt.1; Audio/RF Signal Tracer; High-Current Speed Controller For 12V/24V Motors; Manual Control Circuit For Stepper Motors. December 1994: Car Burglar Alarm; Three-Spot Low Distortion Sinewave Oscillator; Clifford – A Pesky Electronic Cricket; Remote Control System for Models, Pt.1; Index to Vol.7. January 1995: Sun Tracker For Solar Panels; Battery Saver For Torches; Dual Channel UHF Remote Control; Stereo Microphone Pre­amp­lifier. February 1995: 2 x 50W Stereo Amplifier Module; Digital Effects Unit For Musicians; 6-Channel LCD Thermometer; Wide Range Electrostatic Loudspeakers, Pt.1; Remote Control System For Models, Pt.2. March 1995: 2 x 50W Stereo Amplifier, Pt.1; Subcarrier Decoder For FM Receivers; Wide Range Electrostatic Loudspeakers, Pt.2; IR Illuminator For CCD Cameras; Remote Control System For Models, Pt.3. April 1995: FM Radio Trainer, Pt.1; Balanced Mic Preamp & Line Filter; 50W/Channel Stereo Amplifier, Pt.2; Wide Range Electrostatic Loudspeakers, Pt.3; 8-Channel Decoder For Radio Remote Control. May 1995: Guitar Headphone Amplifier; FM Radio Trainer, Pt.2; Transistor/Mosfet Tester For DMMs; A 16-Channel Decoder For Radio Remote Control; Introduction To Satellite TV. June 1995: Build A Satellite TV Receiver; Train Detector For Model Railways; 1W Audio Amplifier Trainer; Low-Cost Video Security System; Multi-Channel Radio Control Transmitter For Models, Pt.1. July 1995: Electric Fence Controller; How To Run Two Trains On A Single Track (Incl. Lights & Sound); Setting Up A Satellite TV Ground Station; Build A Reliable Door Minder. August 1995: Fuel Injector Monitor For Cars; A Gain Controlled Microphone Preamp; Identifying IDE Hard Disk Drive Parameters. September 1995: Railpower Mk.2 Walkaround Throttle For Model Railways, Pt.1; Keypad Combination Lock; Build A Jacob’s Ladder Display. October 1995: 3-Way Loudspeaker System; Railpower Mk.2 Walkaround Throttle For Model Railways, Pt.2; Nicad Fast Charger. July 1997: Infrared Remote Volume Control; A Flexible Interface Card For PCs; Points Controller For Model Railways; Colour TV Pattern Generator, Pt.2; An In-Line Mixer For Radio Control Receivers. October 1997: 5-Digit Tachometer; Central Locking For Your Car; PCControlled 6-Channel Voltmeter; 500W Audio Power Amplifier, Pt.3. November 1997: Heavy Duty 10A 240VAC Motor Speed Controller; Easy-To-Use Cable & Wiring Tester; Build A Musical Doorbell; Replacing Foam Speaker Surrounds; Understanding Electric Lighting Pt.1. December 1997: Speed Alarm For Cars; 2-Axis Robot With Gripper; Stepper Motor Driver With Onboard Buffer; Power Supply For Stepper Motor Cards; Understanding Electric Lighting Pt.2; Index To Vol.10. January 1998: 4-Channel 12VDC or 12VAC Lightshow, Pt.1; Command Control For Model Railways, Pt.1; Pan Controller For CCD Cameras. February 1998: Telephone Exchange Simulator For Testing; Command Control For Model Railways, Pt.2; 4-Channel Lightshow, Pt.2. April 1998: Automatic Garage Door Opener, Pt.1; 40V 8A Adjustable Power Supply, Pt.1; PC-Controlled 0-30kHz Sinewave Generator; Understanding Electric Lighting; Pt.6. March 1999: Build A Digital Anemometer; DIY PIC Programmer; Build An Audio Compressor; Low-Distortion Audio Signal Generator, Pt.2. April 1999: Getting Started With Linux; Pt.2; High-Power Electric Fence Controller; Bass Cube Subwoofer; Programmable Thermostat/ Thermometer; Build An Infrared Sentry; Rev Limiter For Cars. May 1999: The Line Dancer Robot; An X-Y Table With Stepper Motor Control, Pt.1; Three Electric Fence Testers; Carbon Monoxide Alarm. June 1999: FM Radio Tuner Card For PCs; X-Y Table With Stepper Motor Control, Pt.2; Programmable Ignition Timing Module For Cars, Pt.1. July 1999: Build A Dog Silencer; 10µH to 19.99mH Inductance Meter; Audio-Video Transmitter; Programmable Ignition Timing Module For Cars, Pt.2; XYZ Table With Stepper Motor Control, Pt.3. August 1999: Remote Modem Controller; Daytime Running Lights For Cars; Build A PC Monitor Checker; Switching Temperature Controller; XYZ Table With Stepper Motor Control, Pt.4; Electric Lighting, Pt.14. September 1999: Autonomouse The Robot, Pt.1; Voice Direct Speech Recognition Module; Digital Electrolytic Capacitance Meter; XYZ Table With Stepper Motor Control, Pt.5; Peltier-Powered Can Cooler. October 1999: Build The Railpower Model Train Controller, Pt.1; Semiconductor Curve Tracer; Autonomouse The Robot, Pt.2; XYZ Table With Stepper Motor Control, Pt.6; Introducing Home Theatre. November 1999: Setting Up An Email Server; Speed Alarm For Cars, Pt.1; LED Christmas Tree; Intercom Station Expander; Foldback Loudspeaker System; Railpower Model Train Controller, Pt.2. December 1999: Solar Panel Regulator; PC Powerhouse (gives +12V, +9V, +6V & +5V rails); Fortune Finder Metal Locator; Speed Alarm For Cars, Pt.2; Railpower Model Train Controller, Pt.3; Index To Vol.12. January 2000: Spring Reverberation Module; An Audio-Video Test Generator; Parallel Port Interface Card; Telephone Off-Hook Indicator. February 2000: Multi-Sector Sprinkler Controller; A Digital Voltmeter For Your Car; Safety Switch Checker; Sine/Square Wave Oscillator. March 2000: Resurrecting An Old Computer; 100W Amplifier Module, Pt.1; Electronic Wind Vane With 16-LED Display; Build A Glowplug Driver. May 2000: Ultra-LD Stereo Amplifier, Pt.2; LED Dice (With PIC Microcontroller); 50A Motor Speed Controller For Models. June 2000: Automatic Rain Gauge; Parallel Port VHF FM Receiver; Switchmode Power Supply (1.23V to 40V) Pt.1; CD Compressor. July 2000: Moving Message Display; Compact Fluorescent Lamp Driver; Musicians’ Lead Tester; Switchmode Power Supply, Pt.2. August 2000: Theremin; Spinner (writes messages in “thin-air”); Proximity Switch; Structured Cabling For Computer Networks. September 2000: Swimming Pool Alarm; 8-Channel PC Relay Board; Fuel Mixture Display For Cars, Pt.1; Protoboards – The Easy Way Into Electronics, Pt.1; Cybug The Solar Fly. October 2000: Guitar Jammer; Breath Tester; Wand-Mounted Inspection Camera; Subwoofer For Cars; Fuel Mixture Display, Pt.2. June 1998: Troubleshooting Your PC, Pt.2; Universal High Energy Ignition System; The Roadies’ Friend Cable Tester; Universal Stepper Motor Controller; Command Control For Model Railways, Pt.5. December 2000: Home Networking For Shared Internet Access; White LED Torch; 2-Channel Guitar Preamplifier, Pt.2 (Digital Reverb); Driving An LCD From The Parallel Port; Index To Vol.13. July 1998: Troubleshooting Your PC, Pt.3; 15W/Ch Class-A Audio Amplifier, Pt.1; Simple Charger For 6V & 12V SLA Batteries; Auto­ matic Semiconductor Analyser; Understanding Electric Lighting, Pt.8. January 2001: How To Transfer LPs & Tapes To CD; The LP Doctor – Clean Up Clicks & Pops, Pt.1; Arbitrary Waveform Generator; 2-Channel Guitar Preamplifier, Pt.3; PIC Programmer & TestBed. August 1998: Troubleshooting Your PC, Pt.4; I/O Card With Data Logging; Beat Triggered Strobe; 15W/Ch Class-A Stereo Amplifier, Pt.2. February 2001: An Easy Way To Make PC Boards; L’il Pulser Train Controller; A MIDI Interface For PCs; Build The Bass Blazer; 2-Metre Groundplane Antenna; LP Doctor – Clean Up Clicks & Pops, Pt.2. May 1996: High Voltage Insulation Tester; Knightrider LED Chaser; Simple Intercom Uses Optical Cable; Cathode Ray Oscilloscopes, Pt.3. October 1998: AC Millivoltmeter, Pt.1; PC-Controlled Stress-O-Meter; Versatile Electronic Guitar Limiter; 12V Trickle Charger For Float Conditions; Adding An External Battery Pack To Your Flashgun. November 1998: The Christmas Star; A Turbo Timer For Cars; Build 10% OF SUBSCR F TO IB OR IF Y ERS OU 10 OR M BUY ORE Just fill in and mail the handy order form in this issue; or fax (02) 9939 2648; or call (02) 9939 3295 and quote your credit card number. Price: $A9.50 each (icl. GST) in Australia or $A13 each overseas. Prices include postage and packing. Email: silicon<at>siliconchip.com.au 94  Silicon Chip January 1999: High-Voltage Megohm Tester; A Look At The BASIC Stamp; Bargraph Ammeter For Cars; Keypad Engine Immobiliser. November 2000: Santa & Rudolf Chrissie Display; 2-Channel Guitar Preamplifier, Pt.1; Message Bank & Missed Call Alert; Protoboards – The Easy Way Into Electronics, Pt.3. September 1998: Troubleshooting Your PC, Pt.5; A Blocked Air-Filter Alarm; Waa-Waa Pedal For Guitars; Jacob’s Ladder; Gear Change Indicator For Cars; Capacity Indicator For Rechargeable Batteries. How To Order: December 1998: Engine Immobiliser Mk.2; Thermocouple Adaptor For DMMs; Regulated 12V DC Plugpack; Build A Poker Machine, Pt.2; Improving AM Radio Reception, Pt.2; Mixer Module For F3B Gliders. May 1998: 3-LED Logic Probe; Garage Door Opener, Pt.2; Command Control System, Pt.4; 40V 8A Adjustable Power Supply, Pt.2. November 1995: Mixture Display For Fuel Injected Cars; CB Trans­verter For The 80M Amateur Band, Pt.1; PIR Movement Detector. June 1996: Stereo Simulator (uses delay chip); Rope Light Chaser; Low Ohms Tester For Your DMM; Automatic 10A Battery Charger. A Poker Machine, Pt.1; FM Transmitter For Musicians; Lab Quality AC Millivoltmeter, Pt.2; Improving AM Radio Reception, Pt.1. March 2001: Making Photo Resist PC Boards; Big-Digit 12/24 Hour Clock; Parallel Port PIC Programmer & Checkerboard; Protoboards – The Easy Way Into Electronics, Pt.5; A Simple MIDI Expansion Box. April 2001: A GPS Module For Your PC; Dr Video – An Easy-To-Build Video Stabiliser; Tremolo Unit For Musicians; Minimitter FM Stereo Transmitter; Intelligent Nicad Battery Charger. May 2001: 12V Mini Stereo Amplifier; Two White-LED Torches To Build; PowerPak – A Multi-Voltage Power Supply; Using Linux To Share An Internet Connection, Pt.1; Tweaking Windows With TweakUI. June 2001: Universal Battery Charger, Pt.1; Phonome – Call, Listen In & Switch Devices On & Off; Low-Cost Automatic Camera Switcher; Using Linux To Share An Internet Connection, Pt.2. July 2001: The HeartMate Heart Rate Monitor; Do Not Disturb Tele­ phone Timer; Pic-Toc – A Simple Alarm Clock; Fast Universal Battery Charger, Pt.2; Backing Up Your Email. August 2001: DI Box For Musicians; 200W Mosfet Amplifier Module; Headlight Reminder; 40MHz 6-Digit Frequency Counter Module; Using siliconchip.com.au Linux To Share An Internet Connection, Pt.3. September 2001: Making MP3s; Build An MP3 Jukebox, Pt.1; PCControlled Mains Switch; Personal Noise Source For Tinnitus; Directional Microphone; Using Linux To Share An Internet Connection, Pt.4. November 2001: Ultra-LD 100W/Channel Stereo Amplifier, Pt.1; Neon Tube Modulator For Cars; Audio/Video Distribution Amplifier; Build A Short Message Recorder Player; Useful Tips For Your PC. December 2001: IR Transceiver For PCs; 100W/Ch Stereo Amplifier, Pt.2; Pardy Lights Colour Display; PIC Fun – Learning About Micros. January 2002: Touch And/Or Remote-Controlled Light Dimmer, Pt.1; A Cheap ’n’Easy Motorbike Alarm; 100W /Channel Stereo Amplifier, Pt.3; Build A Raucous Alarm; FAQs On The MP3 Jukebox. February 2002: 10-Channel IR Remote Control Receiver; 2.4GHz High-Power Audio-Video Link; Touch And/Or Remote-Controlled Light Dimmer, Pt.2; Booting A PC Without A Keyboard; 4-Way Event Timer. March 2002: Mighty Midget Audio Amplifier Module; 6-Channel IR Remote Volume Control, Pt.1; RIAA Pre­-­Amplifier For Magnetic Cartridges; 12/24V Intelligent Solar Power Battery Charger. April 2002:Automatic Single-Channel Light Dimmer; Pt.1; Water Level Indicator; Multiple-Output Bench Power Supply; Versatile Multi-Mode Timer; 6-Channel IR Remote Volume Control, Pt.2. May 2002: 32-LED Knightrider; The Battery Guardian (Cuts Power When the Battery Voltage Drops); Stereo Headphone Amplifier; Automatic Single-Channel Light Dimmer; Pt.2; Stepper Motor Controller. August 2002: Digital Instrumentation Software For PCs; Digital Storage Logic Probe; Digital Therm./Thermostat; Sound Card Interface For PC Test Instruments; Direct Conversion Receiver For Radio Amateurs. Theatre Systems; Dog Silencer; Mixture Display For Cars; ESR Meter Mk.2, Pt.2; PC/PICAXE Interface For UHF Remote Control. Controller; Studio Series Stereo Preamplifier; Stop Those Zaps From Double-Insulated Equipment. May 2004: Amplifier Testing Without High-Tech Gear; Component Video To RGB Converter; Starpower Switching Supply For Luxeon Star LEDs; Wireless Parallel Port; Poor Man’s Metal Locator. August 2006: Picaxe-Based LED Chaser Clock; Magnetic Cartridge Preamplifier; An Ultrasonic Eavesdropper; Mini Theremin Mk.2, Pt.2. June 2004: Dr Video Mk.2 Video Stabiliser; Build An RFID Security Module; Simple Fridge-Door Alarm; Courtesy Light Delay For Cars; Automating PC Power-Up; Upgraded Software For The EPROM Programmer. July 2004: Silencing A Noisy PC; Versatile Battery Protector; Appliance Energy Meter, Pt.1; A Poor Man’s Q Meter; Regulated High-Voltage Supply For Valve Amplifiers; Remote Control For A Model Train Layout. October 2006: Thomas Alva Edison – Genius, Pt.2; LED Tachometer With Dual Displays, Pt.1; UHF Prescaler For Frequency Counters; Infrared Remote Control Extender; Picaxe Net Server, Pt.2; Easy-ToBuild 12V Digital Timer Module; Build A Super Bicycle Light Alternator. August 2004: Video Formats: Why Bother?; VAF’s New DC-X Generation IV Loudspeakers; Video Enhancer & Y/C Separator; Balanced Microphone Preamp; Appliance Energy Meter, Pt.2; 3-State Logic Probe. November 2006: Radar Speed Gun, Pt.1; Build Your Own Compact Bass Reflex Loudspeakers; Programmable Christmas Star; DC Relay Switch; LED Tachometer With Dual Displays, Pt.2; Picaxe Net Server, Pt.3. September 2004: Voice Over IP (VoIP) For Beginners; WiFry – Cooking Up 2.4GHz Antennas; Bed Wetting Alert; Build a Programmable Robot; Another CFL Inverter. December 2006: Bringing A Dead Cordless Drill Back To Life; Cordless Power Tool Charger Controller; Build A Radar Speed Gun, Pt.2; Heartbeat CPR Training Beeper; Super Speedo Corrector; 12/24V Auxiliary Battery Controller; Picaxe Net Server, Pt.3. October 2004: The Humble “Trannie” Turns 50; SMS Controller, Pt.1; RGB To Component Video Converter; USB Power Injector; Remote Controller For Garage Doors & Gates. November 2004: 42V Car Electrical Systems; USB-Controlled Power Switch (Errata Dec. 2004); Charger For Deep-Cycle 12V Batteries, Pt.1; Driveway Sentry; SMS Controller, Pt.2; PICAXE IR Remote Control. December 2004: Build A Windmill Generator, Pt.1; 20W Amplifier Module; Charger For Deep-Cycle 12V Batteries, Pt.2; Solar-Powered Wireless Weather Station; Bidirectional Motor Speed Controller. September 2002: 12V Fluorescent Lamp Inverter; 8-Channel Infrared Remote Control; 50-Watt DC Electronic Load; Spyware – An Update. January 2005: Windmill Generator, Pt.2; Build A V8 Doorbell; IR Remote Control Checker; 4-Minute Shower Timer; The Prawnlite; Sinom Says Game; VAF DC-7 Generation 4 Kit Speakers. October 2002: Speed Controller For Universal Motors; PC Parallel Port Wizard; Cable Tracer; AVR ISP Serial Programmer; 3D TV. February 2005: Windmill Generator, Pt.3; USB-Controlled Electrocardiograph; TwinTen Stereo Amplifier; Inductance & Q-Factor Meter, Pt.1; A Yagi Antenna For UHF CB; $2 Battery Charger. November 2002: SuperCharger For NiCd/NiMH Batteries, Pt.1; Windows-Based EPROM Programmer, Pt.1; 4-Digit Crystal-Controlled Timing Module. December 2002: Receiving TV From Satellites; Pt.1; The Micromitter Stereo FM Transmitter; Windows-Based EPROM Programmer, Pt.2; SuperCharger For NiCd/NiMH Batteries; Pt.2; Simple VHF FM/AM Radio. January 2003: Receiving TV From Satellites, Pt 2; SC480 50W RMS Amplifier Module, Pt.1; Gear Indicator For Cars; Active 3-Way Crossover For Speakers. February 2003: PortaPal PA System, Pt.1; SC480 50W RMS Amplifier Module, Pt.2; Windows-Based EPROM Programmer, Pt.3; Fun With The PICAXE, Pt.1. March 2003: LED Lighting For Your Car; Peltier-Effect Tinnie Cooler; PortaPal PA System, Pt.2; 12V SLA Battery Float Charger; Little Dynamite Subwoofer; Fun With The PICAXE, Pt.2 (Shop Door Minder). April 2003: Video-Audio Booster For Home Theatre Systems; Telephone Dialler For Burglar Alarms; Three PIC Programmer Kits; PICAXE, Pt.3 (Heartbeat Simulator); Electric Shutter Release For Cameras. May 2003: Widgybox Guitar Distortion Effects Unit; 10MHz Big Blaster Subwoofer; Printer Port Simulator; PICAXE, Pt.4 (Motor Controller). June 2003: PICAXE, Pt.5; PICAXE-Controlled Telephone Intercom; PICAXE-08 Port Expansion; Sunset Switch For Security & Garden Lighting; Digital Reaction Timer; Adjustable DC-DC Converter For Cars; Long-Range 4-Channel UHF Remote Control. July 2003: Smart Card Reader & Programmer; Power-Up Auto Mains Switch; A “Smart” Slave Flash Trigger; Programmable Continuity Tester; PICAXE Pt.6 – Data Communications; Updating The PIC Programmer & Checkerboard; RFID Tags – How They Work. August 2003: PC Infrared Remote Receiver (Play DVDs & MP3s On Your PC Via Remote Control); Digital Instrument Display For Cars, Pt.1; Home-Brew Weatherproof 2.4GHz WiFi Antennas; PICAXE Pt.7. September 2003: Robot Wars; Krypton Bike Light; PIC Programmer; Current Clamp Meter Adapter For DMMs; PICAXE Pt.8 – A Data Logger; Digital Instrument Display For Cars, Pt.2. October 2003: PC Board Design, Pt.1; JV80 Loudspeaker System; A Dirt Cheap, High-Current Power Supply; Low-Cost 50MHz Frequency Meter; Long-Range 16-Channel Remote Control System. November 2003: PC Board Design, Pt.2; 12AX7 Valve Audio Preamplifier; Our Best Ever LED Torch; Smart Radio Modem For Microcontrollers; PICAXE Pt.9; Programmable PIC-Powered Timer. December 2003: PC Board Design, Pt.3; VHF Receiver For Weather Satellites; Linear Supply For Luxeon 1W Star LEDs; 5V Meter Calibration Standard; PIC-Based Car Battery Monitor; PICAXE Pt.10. January 2004: Studio 350W Power Amplifier Module, Pt.1; HighEfficiency Power Supply For 1W Star LEDs; Antenna & RF Preamp For Weather Satellites; Lapel Microphone Adaptor For PA Systems; PICAXE-18X 4-Channel Datalogger, Pt.1; 2.4GHZ Audio/Video Link. March 2005: Windmill Generator, Pt.4; Sports Scoreboard, Pt.1; Swimming Pool Lap Counter; Inductance & Q-Factor Meter, Pt.2; Shielded Loop Antenna For AM; Cheap UV EPROM Eraser; Sending Picaxe Data Over 477MHz UHF CB; $10 Lathe & Drill Press Tachometer. April 2005: Install Your Own In-Car Video (Reversing Monitor); Build A MIDI Theremin, Pt.1; Bass Extender For Hifi Systems; Sports Scoreboard, Pt.2; SMS Controller Add-Ons; A $5 Variable Power Supply. May 2005: Getting Into Wi-Fi, Pt.1; Build A 45-Second Voice Recorder; Wireless Microphone/Audio Link; MIDI Theremin, Pt.2; Sports Scoreboard, Pt.3; Automatic Stopwatch Timer. June 2005: Wi-Fi, Pt.2; The Mesmeriser LED Clock; Coolmaster Fridge/ Freezer Temperature Controller; Alternative Power Regular; PICAXE Colour Recognition System; AVR200 Single Board Computer, Pt.1. July 2005: Wi-Fi, Pt.3; Remote-Controlled Automatic Lamp Dimmer; Serial Stepper Motor Controller; Salvaging & Using Thermostats; Unwired Modems & External Antennas. January 2007: Versatile Temperature Switch; Intelligent Car AirConditioning Controller; Remote Telltale For Garage Doors; Intelligent 12V Charger For SLA & Lead-Acid Batteries. February 2007: Remote Volume Control & Preamplifier Module, Pt.1; Simple Variable Boost Control For Turbo Cars; Fuel Cut Defeater For The Boost Control; Low-Cost 50MHz Frequency Meter, Mk.2; Bike Computer To Digital Ammeter Conversion. March 2007: Programmable Ignition System For Cars, Pt.1; Remote Volume Control & Preamplifier Module, Pt.2; GPS-Based Frequency Reference, Pt.1; Simple Ammeter & Voltmeter. April 2007: The Proposed Ban On Incandescent Lamps; High-Power Reversible DC Motor Speed Controller; Build A Jacob’s Ladder; GPSBased Frequency Reference, Pt.2; Programmable Ignition System For Cars, Pt.2; Dual PICAXE Infrared Data Communication. May 2007: 20W Class-A Amplifier Module, Pt.1; Adjustable 1.3-22V Regulated Power Supply; VU/Peak Meter With LCD Bargraphs; Programmable Ignition System For Cars, Pt.3; GPS-Based Frequency Reference Modifications; Throttle Interface For The DC Motor Speed Controller. June 2007: 20W Class-A Amplifier Module, Pt.2; Knock Detector For The Programmable Ignition; 4-Input Mixer With Tone Controls; Frequency-Activated Switch For Cars; Simple Panel Meters Revisited. July 2007: How To Cut Your Greenhouse Emissions, Pt.1; 6-Digit Nixie Clock, Pt.1; Tank Water Level Indicator; A PID Temperature Controller; 20W Class-A Stereo Amplifier; Pt.3; Making Panels For Projects. August 2007: How To Cut Your Greenhouse Emissions, Pt.2; 20W Class-A Stereo Amplifier; Pt.4; Adaptive Turbo Timer; Subwoofer Controller; 6-Digit Nixie Clock, Pt.2. September 2007: The Art Of Long-Distance WiFi; Fast Charger For NiMH & Nicad Batteries; Simple Data-Logging Weather Station, Pt.1; 20W Class-A Stereo Amplifier; Pt.5. August 2005: Mudlark A205 Valve Stereo Amplifier, Pt.1; Programmable Flexitimer; Carbon Monoxide Alert; Serial LCD Driver; Enhanced Sports Scoreboard; Salvaging Washing Maching Pressure Switches. October 2007: DVD Players – How Good Are They For HiFi Audio?; Electronic Noughts & Crosses Game; PICProbe Logic Probe; Rolling Code Security System, Pt.1; Simple Data-Logging Weather Station, Pt.2; AM Loop Antenna & Amplifier. September 2005: Build Your Own Seismograph; Bilge Sniffer For Boats; VoIP Analog Phone Adaptor; Mudlark A205 Valve Stereo Amplifier, Pt.2; PICAXE in Schools, Pt.4. November 2007: Your Own Home Recording Studio; PIC-Based Water Tank Level Meter, Pt.1: Playback Adaptor For CD-ROM Drives, Pt.1; Rolling Code Security System, Pt.2; Build A UV Light Box For Making PC Boards. October 2005: A Look At Google Earth; Dead Simple USB Breakout Box; Studio Series Stereo Preamplifier, Pt.1; Video Reading Aid For Vision Impaired People; Simple Alcohol Level Meter; Ceiling Fan Timer. November 2005: Good Quality Car Sound On The Cheap; Pt.1; PICAXE In Schools, Pt.5; Studio Series Stereo Headphone Amplifier; Build A MIDI Drum Kit, Pt.1; Serial I/O Controller & Analog Sampler. December 2005: Good Quality Car Sound On The Cheap; Pt.2; Building The Ultimate Jukebox, Pt.1; Universal High-Energy Ignition System, Pt.1; Remote LED Annunciator For Queue Control; Build A MIDI Drum Kit, Pt.2; 433MHz Wireless Data Communication. January 2006: Pocket TENS Unit For Pain Relief; “Little Jim” AM Radio Transmitter; Universal High-Energy Ignition System, Pt.2; Building The Ultimate Jukebox, Pt.2; MIDI Drum Kit, Pt.3; Picaxe-Based 433MHz Wireless Thermometer; A Human-Powered LED Torch. February 2006: PC-Controlled Burglar Alarm, Pt.1; A Charger For iPods & MP3 Players; Picaxe-Powered Thermostat & Temperature Display; Build A MIDI Drum Kit, Pt.4; Building The Ultimate Jukebox, Pt.3. March 2006: The Electronic Camera, Pt.1; PC-Controlled Burglar Alarm System, Pt.2; Low-Cost Intercooler Water Spray Controller; AVR ISP SocketBoard; Build A Low-Cost Large Display Anemometer. April 2006: The Electronic Camera, Pt.2; Studio Series Remote Control Module (For A Stereo Preamplifier); 4-Channel Audio/Video Selector; Universal High-Energy LED Lighting System, Pt.1; Picaxe Goes Wireless, Pt.1 (Using the 2.4GHz XBee Modules). February 2004: PC Board Design, Pt.1; Supply Rail Monitor For PCs; Studio 350W Power Amplifier Module, Pt.2; Shorted Turns Tester For Line Output Transformers; PICAXE-18X 4-Channel Datalogger, Pt.2. May 2006: Lead-Acid Battery Zapper ; Universal High-Energy LED Lighting System, Pt.2; Passive Direct Injection (DI) Box For Musicians; Picaxe Goes Wireless, Pt.2; Boost Your XBee’s Range Using Simple Antennas; Improving The Sound Of Salvaged Loudspeaker Systems. March 2004: PC Board Design, Pt.2; Build The QuickBrake For Increased Driving Safety; 3V-9V (or more) DC-DC Converter; ESR Meter Mk.2, Pt.1; PICAXE-18X 4-Channel Datalogger, Pt.3. June 2006: Pocket A/V Test Pattern Generator; Two-Way SPDIF-toToslink Digital Audio Converter; Build A 2.4GHz Wireless A/V Link; A High-Current Battery Charger For Almost Nothing. April 2004: PC Board Design, Pt.3; Loudspeaker Level Meter For Home July 2006: Mini Theremin Mk.2, Pt.1; Programmable Analog On-Off siliconchip.com.au September 2006: Thomas Alva Edison – Genius, Pt.1; Transferring Your LPs To CDs & MP3s; Turn an Old Xbox Into A $200 Multimedia Player; Picaxe Net Server, Pt.1; Build The Galactic Voice; Aquarium Temperature Alarm; S-Video To Composite Video Converter. December 2007: Signature Series Kit Loudspeakers; IR Audio Headphone Link; Enhanced 45s Voice Recorder Module; PIC-Based WaterTank Level Meter; Pt.2; Playback Adaptor For CD-ROM Drives; Pt.2. January 2008: PIC-Controlled Swimming Pool Alarm; Emergency 12V Lighting Controller; Build The “Aussie-3” Valve AM Radio; The Minispot 455kHz Modulated Oscillator; Water Tank Level Meter, Pt.3 – The Base Station; Improving The Water Tank Level Meter Pressure Sensor. February 2008: UHF Remote-Controlled Mains Switch; UHF Remote Mains Switch Transmitter; A PIR-Triggered Mains Switch; Shift Indicator & Rev Limiter For Cars; Mini Solar Battery Charger. March 2008: How To Get Into Digital TV, Pt.1; The I2C Bus – A Quick Primer; 12V-24V High-Current DC Motor Speed Controller, Pt.1; A Digital VFO with LCD Graphics Display; A Low-Cost PC-to-I2C Interface For Debugging; One-Pulse-Per Second Driver For Quartz Clocks. April 2008: How To Get Into Digital TV, Pt.2; Charge Controller For 12V Lead-Acid Or SLA Batteries; Safe Flash Trigger For Digital Cameras; 12V-24V High-Current DC Motor Speed Controller, Pt.2; Two-Way Stereo Headphone Adaptor. May 2008: Replacement CDI Module For Small Petrol Motors; High-Accuracy Digital LC Meter; Low-Cost dsPIC/PIC Programmer; High-Current Adjustable Voltage Regulator. June 2008: DSP Musicolour Light Show, Pt.1; PIC-Based Flexitimer Mk.4; USB Power Injector For External Hard Drives; Balanced/Unbalanced Converter For Audio Signals; A Quick’n’Easy Digital Slide Scanner; Altitude 3500-SS Stereo Valve Amplifier Reviewed. PLEASE NOTE: issues not listed have sold out. All listed issues are in stock. We can supply photostat copies of articles from sold-out issues for $A9.50 each within Australia or $A13.00 each overseas (prices include p&p). When supplying photostat articles or back copies, we automatically supply any relevant notes & errata at no extra charge. A complete index to all articles published to date can be downloaded free from our web site: www.siliconchip.com.au July 2008  95 ASK SILICON CHIP Got a technical problem? Can’t understand a piece of jargon or some technical principle? Drop us a line and we’ll answer your question. Write to: Ask Silicon Chip, PO Box 139, Collaroy Beach, NSW 2097 or send an email to silchip<at>siliconchip.com.au Battery charging at low temperatures Why doesn’t the design of the LeadAcid Battery Charge Controller (April 2008) allow charging below 0°C? Even in the fully discharged state, the electrolyte contains about 20% sulphuric acid by weight, and its freezing point is -14°C. (In a fully charged battery, the freezing point is -29°C). My reference for the freezing point data is “CRC Handbook of Chemistry and Physics”, 55th Ed. 1974-5, CRC Press. From my experience in Armidale, cars will start at -10°C and if the battery can deliver a hundred or more amps at this temperature, it will certainly suffer no harm from charging at 10A. (R. S., Armidale, NSW). • Most lead-acid battery manufacturers recommend not charging below 0°C. Car batteries have a hard life and are generally not charged correctly due to temperature extremes (both high and low) and insufficient full charging. Power supply for Neon Modulator I was wondering if it is possible to run the Neon Modulator (SILICON CHIP, November 2001) from a 24V supply. Looking at the schematic, I can see no reason why not but I might be overlooking something. (B. C., via email). • The circuit cannot be directly run from 24V. First, the gates of Q2 and Q3 should not exceed 20V and the 100mF 25V electrolytic is not rated for operation from a 24V battery (may be up to ~29V when being charged). Also the neon tube driver itself may not be rated for 24V. Ideally it would be better to run the circuit from 12V using a 7812 3-terminal regulator. you could offer to overcome this problem? (P. G., via email). • That is a problem with any addon circuit for a car. The car has the door switches wired in parallel so the headlight alarm will sound with any door opening. You could add your own separate door switch for the driver’s side door only and connect this to the Headlight Reminder instead of the existing switches. Alternatively, it might be possible to isolate the driver’s door switch with a suitably rated diode, say a 1N5404. Headlight reminder trips on all doors Playback adaptor for CD-ROM drives I’m in the process of installing the wiring in a car for the Headlight Reminder kit (SILICON CHIP, August 2001). One of the sensor inputs is the door switch. However, as these are wired in parallel inside the wiring loom in a 4-door car, it appears the headlight reminder will operate if any door is opened. This is a problem when the passengers alight but the driver remains in the car. I checked another car with an original equipment headlight alarm and it only operates off the driver’s door. Are there any errata or other advice I built the Playback Adaptor For CDROM Drives (Nov-Dec. 2008) and had a problem after having programmed the ATMega8515. I used the procedure as described for programming but after that, the ATMega seemed to work very slowly; it recognised the drive but it took about one minute and 10 seconds to be ready. It was impossible to enter the remote codes. As I am not familiar with the ATMega family, I read the ATMega8515 manuals and after having a look at the XTAL 1 and XTAL 2 signals with my scope, I assumed that the clock has not been programmed for the Query on Air-Conditioner Efficiency I notice in the January 2008 issue you refer in the Publisher’s Letter to the superiority of reverse-cycle air-conditioning (r.c.a.) over radiant heaters as efficient users of electricity and hence better for the environment. This is a commonly held belief but it seems to me that radiant heaters are close to 100% efficient at converting electricity to heat. Hence a conundrum, usually explained in terms of “an r.c.a. does not make heat, it just gets the heat from outside and brings it inside”. Run that past 96  Silicon Chip me again – I didn’t quite get it. After it has been explained, please tell me why we don’t use r.c.a. for heating water? (F. M., via email). • Electric radiators are very close to 100% efficient. However, reverse cycle air-conditioners are “heat pumps” working on thermodynamic principles. Typically, a domestic air-conditioner will be able to pump three times as much heat into or out of a room as it consumes in electricity. Therefore a 1kW air-conditioner can pump as much as 3.5kW of heat. There are significant limitations though and reverse-cycle heating cannot be used if the external temperature is less than about -5°C. Heat pumps are used for heating water and they are available in Australia under brands such as Quantum, Dux and Rheem. For example, see http://www.enviro-friendly.com/ quantum-heat-pump-water-heater. shtml In general though, heat pump hot water systems are very expensive and for most regions of Australia a gas-assisted solar hot water system would be the best choice. siliconchip.com.au 7.3728MHz crystal. So I had a look at PonyProg2000 and it seems that standard options for programming the fuses are not suitable for the playback adaptor: the checked options were SPIEN BOOTSZ1 & 0 SUT0 CKSEL3, 2 & 1. I had to check CKOPT SUT1 & CKSEL0 and to uncheck SUT0 CKSEL3, 2 & 1. After reprogramming the chip with those fuse parameters, the Playback Adaptor worked fine, as well as entering the remote codes. But I’m not sure that my fuse parameters are the best I should use. Can you clarify these? (P. S., Grenoble, France). • The fuses for the CDROM playback adaptor should be programmed as described below: Programmed (0)= S8515C, EESAVE, BODLEVEL, BODEN Unprogrammed (1)= WDTON, CKOPT, BOOTSZ1, BOOTSZ0, BOOTRST, SUT1, SUT0, CKSEL3, CKSEL2, CKSEL1, CKSEL0. Are LCD sets prone to burn-in? I purchased the latest Sony XBR40 LCD Full HD Television and a black stripe appears on each side of the screen when I watch the analog pay TV channel. Some technicians say that the black stripes will burn in on the LCD screen and leave the marks while others say LCD TVs do not have burnin problems like plasma sets. Would you be so kind as to give me your answer to the burn-in problems? Also, the pictures of the analog TV channels appear much worse compared with the old CRT TV. Is there any way to improve it? (V. J., via email). • It is only bright spots on a screen that can suffer burn-in and burn-in is usually not a problem with LCD sets. Your LCD set may not be as sensitive as your old CRT set. If you feed the set via your VCR’s antenna loop connection, you may find that it has some amplification and may fix the reception problem. Component substitutes for speed control I downloaded a copy of the October 2002 version of the Universal Speed Controller from SILICON CHIP to control an 1100W heater. Unfortunately, some of the semiconductor components are currently unavailable: BTA41-600B siliconchip.com.au Feedback Modifications Not Recommended After building the 20W Class-A Stereo Amplifier and connecting it to a CD player and comparing it with a turntable with a built-in preamp, I found that I needed a loudness circuit to boost the bass and treble to improve the sound quality of LP records. As a result, I modified the feedback circuit to provide switchable +6dB bass boost below 300Hz and +6dB treble boost above 3kHz. The resultant amplifier sounds precise and very accurate and I felt that separate tone controls would affect the sound quality. (G. H., Southport, Qld). • We do not recommend this modification to the feedback circuit of the amplifier. It may well cause loud pops from the speakers if this feedback circuit is switched while the Triac (TRIAC1), C103B sensitive gate SCR (SCR1) and R250H 6A 400V diode (D3). Could you advise if there are currently available substitutes? (A. B., via email). • We have specified the BTA41-600B Triac in the DSP Musicolour featured in this month’s issue so it should be available in the near future from kitset suppliers. In the meantime, it is available from Farnell, Cat. 105-7288. The C103B can be replaced by an MCR100-8G which is also available from Farnell (Cat. 955-7288), while the R250H diode substitute can be a PX6007 (Jaycar Cat. ZR-1024). However, if you are going to control a heater you would be better off using our zero-voltage switching Heat Controller from the July 1998 issue. This has two advantages over the speed control circuit. First, because it switches at the zerocrossing points of the 240VAC 50Hz mains waveform, it does not generate any electromagnetic interference (EMI). Second, because it switches both half-cycles of the waveform, it controls the power over the full range. By contrast, the speed control only switches the positive half-cycles and therefore can only control over the range from zero to half power. The Heat Controller also uses the BTA41-600B Triac but its other com- amplifier is on and it may also lead to increased noise and prejudice the amplifier stability. If the sound from the turntable is deficient in bass and treble when compared to CDs, it suggests that the built-in preamplifier is not giving the correct RIAA equalisation. Unfortunately, cheap turntables with builtin preamps are often not correct in this regard and their signal-to-noise ratio is often not good either. That being the case, we would recommend that you either modify your existing preamplifier to provide correct equalisation or better still, build one of the SILICON CHIP phono preamplifiers such as that published in March 2002 or the high-quality design described in the August 2006 issue. ponents are readily available. Farnell are at www.farnellinone. com.au, while Jaycar is at www.jaycar. com.au Fan cooling for speed controller I built three of your Heavy Duty 10A 240VAC Motor Speed Controllers (SILICON CHIP, November 1997) and am quite happy with their performance. However, I want to modify one of them as I wish to leave it operating for long periods and as the diecast box that houses this circuit gets relatively hot, I wish to install twin 40mm 12V fans to exhaust heat out of the box. I have tried to use a 7812 12V regulator tapped into the 15V and common rails to run the two 12V 120mA fans, however as soon as the connection is made, the circuit stops operating. I am assuming the 15V rail on the circuit cannot supply enough current to support this extra load or is there a more technical problem? (G. H., Sale, Vic). • Unfortunately, the circuit cannot supply the current for the two 12V 40mm fans. You could use a larger box to provide for more heatsinking or attach a finned heatsink to the box for better dissipation. To use the fans would first require a transformer to step down from 240VAC to 9VAC. This would then July 2008  97 Does HD Digital TV Mean Poorer Quality Sound? I’ve had a wide-screen TV and a VCR with an SD digital tuner for a while. Recently I set up a spare computer as a media PC with a dual tuner TV card that can do analog and all digital channels. The first thing I noticed was that where there are corresponding matching pairs of SD and HD channels (digital channel 10 broadcasting SD and 12 broadcasting HD and the same with 21 and 20) transmitting the same content, the HD channel has subjectively poorer sound. The sound is as clear on both but the SD channels sound richer. I asked on a forum whether that was normal or a problem with the particular TV tuner hardware and software I’m using. The answer I got was that you notice the same whether it’s through a set-top box or a computer TV tuner card. Is that right? Does HD means a better quality picture but poorer quality sound? (G. D., via email). • We put your questions to Alan be rectified and filtered for the fans. There is no room in the box for this. Lead-acid battery capacities I am involved in a project where 12V 5Ah and 12Ah sealed lead-acid batteries are used for battery backup of some rather important equipment. Every battery is tested for capacity before it is installed using a Voltcraft Charge Terminal that actually charges and then discharges the battery to accurately measure the capacity. I am alarmed at the high proportion of batteries that fall short of the advertised capacity and in quite a few cases, measure less than 80% of the rated capacity (80% being the industry benchmark for end of life). This seems to affect more than one brand of battery so I was wondering if you have seen this also and whether it is an industry-wide problem? Incidentally, further charge/discharge cycles do not significantly alter the capacity of the sick batteries which are also delivered in a fully charged state (typically showing around 12.6V 98  Silicon Chip Hughes and the following is his answer. The picture and sound quality are affected by every link in the chain. As far as picture quality is concerned, there are not many programs produced by HD cameras. There is a lot of “up-scaling” happening. This is where a box of electronics makes educated guesses as to what the missing detail should be and inserts it into the picture. This signal may also have been analog as well. This generally causes wriggly grey lines around sharp edges in the picture. On sound quality, two sound signals are transmitted. One is MPEG2 which is stereo and is compulsory for all Australian transmissions. On HD there is also AC3 sound which can consist of left, centre, right, left rear, right rear and a subwoofer. Typically only left and right signals are transmitted, as the networks do not transmit much surround sound. The sound standard for the movie industry is that all dialog with a voltmeter), so it seems unlikely their capacity has reduced due to sitting on a shelf for years before being sold to the customer. (M. N., Christchurch, NZ). • We do not have experience of this problem. Maybe your method of measuring capacity is not the same as that of the manufacturers. Typical battery capacities are taken at the 20-hour rate. In other words, a 5Ah battery should be discharged at 250mA to get the stated capacity. If discharged at a higher rate, the effective capacity will always be less. Is your Voltcraft discharging at the correct rate? Faulty DI Box has supply problem I have a problem with the Active DI Box (SILICON CHIP, August 2001). I built three kits for a church sound desk. We use them as phantom-powered units and they all initially worked fine. However, recently one failed and I cannot work out what is wrong. When powered from a 12V 1A regulated supply, the test LED lights must be on the centre channel. News broadcasts are produced in mono. AC3 sound locates the sound much more accurately but it is also transmitted with more dynamic range. It can also contain data to compress the volume range, if the decoder is equipped to use it and it is selected. On SD, some stations transmit MPEG2 & AC3 sound. I suggest you check which sound signal is being used and select the one you want. If you tune to ABC1 on Logical Channel Number 2, an SD video signal is sent and you can chose either MPEG2 or AC3. LCN21 and 22 both have MPEG2 sound only. In summary, computers generally have poor sound quality and you can select which sound you wish. So there is no truth in the statement that HD has poorer sound than SD. Commercial TV stations have started putting movies on as a separate program at night, leaving the SD channel with another program. brightly. There is 9.63V at ZD1, pin 8 of IC1 and pin 7 of IC2; not the 12V I expected from the construction notes. Powered from phantom power, it is totally different picture. The LED does not light. The 48V on the balanced lead (two different 48V phantom supplies were tried) is only 8V on the “rear” side of the socket when the lead is plugged in. There is only 2.37V at the zener and IC pins. There is no continuity between pins 2 or 3 and ground on the XLR socket. I cannot figure out what the likely cause of the massive voltage drop on the phantom power supply circuit is or why there is only 9.6V and not 12V with a plugpack supply. I presume there is a component failure somewhere. (G. C., via email). • The first thing to note is that the 7812 needs an input of about 15V in order to give its stated output of 12V. In other words, it should be used with a conventional unregulated plugpack, not a regulated one. Not that this really makes any difference to the overall performance since the unit can be powered a 9V battery. We suspect that there is a fault siliconchip.com.au across the supply. Try removing IC1 and IC2 as one of these may be faulty. Also there could be a capacitor that has failed, so you could remove the 100mF and 10mF capacitors across the 12V supply. More than likely it is one of these parts. Modified sensor probe for water tank I recently purchased a Tank Water Level Indicator, as described in the July 2007 issue. My question is can I adapt this to a caravan water tank? The tank is moulded plastic about 200mm deep and placing the sensor rod inside is impossible. Could I simply screw brass screws through the tank wall and attach sensor wires to them and then continue with resistors, as per the instructions? (B. B., Toodyay, WA). • You could tap stainless steel screws into the side of the plastic water tank, provided the tank wall is thick enough. Using neutral-cure silicone sealant under the screw heads should prevent water leakage. Stainless screws are recommended over brass screws because the latter would tend to quickly corrode inside the tank. Wires could attach to the screws using eyelets captured under the screw heads. The resistors can then be wired externally. New TV emits a pungent odour I recently purchased a new 68cm CRT television and I was concerned when it gave out a “burning resistor” smell whenever it was on. Over a period of three weeks the smell slowly disappeared and it is now odour-free. I wondered if resistors have a “running-in” period when they emit an odour, similar to the “new car” smell. I also noticed that the handbook specs state that the maximum temperature for operating the set should be 30°C, as the temperature when I first purchased the set was reaching some 29°C. The set has a 12-month warranty but I worry about next summer. Any suggestions? (A. F., Chinderah, NSW). • Most areas of Australia could easily have indoor temperatures of 40°C or more in hot summers when airconditioning is not available, so the spec for operating at 30°C (max.) is a siliconchip.com.au Optimum Tin Diameter For Radar Speed Gun I have purchased the Radar Speed Gun kit and have a question regarding the diameter of the “coffee tin” used as a wave-guide. I am curious to know why the diameter of 127mm was chosen. I have done some research (in my old ARRL Handbook & various web sources for 802.11b “cantennas” <at> 2.4GHz) and it seems that the best “tuned” diameter for 2.45GHz would be 82mm, with a distance from the driven element to tin base of 44mm. I have a set of 100mm tins (each 130mm long) I was intending to use and while I’m sure they would work OK (I would probably need to joke. Clearly, if the TV is not rated for operation above 30°C, it is not suitable for sale in this country. It is not unusual for electronic equip­ment to have a pungent smell when it is brand new. Increasing the resolution of rain gauge I have question with respect to the Automatic Rain Gauge described in the June 2000 issue. This unit has a resolution of ±1mm. That is, it can’t give a reading to one or more decimal places whereas the “Data Logging Weather Station” described in the September & October 2007 issues will give a reading to 0.2mm. As such, can the detector in the earlier project either be “tweaked” to give decimal point results or can it be adapted to use the same sensor as that used in the later project? Would the modifications required to make the earlier project capable of displaying the rainfall data to the same accuracy as the later project be significant? Is it possible to make the earlier detector more sensitive, such that the “bucket” tips with less water in it to give a 0.5mm or even 0.2mm resolution? (P. M., Karabar, NSW. • The rain gauge was designed with 1mm resolution and a 255mm maximum reading. To increase resolution to 0.1mm you would have to compromise with a maximum reading of 25.5mm and this is too low for general use. reposition the driven element location a little), I am interested in the difference in performance of these different sizes and the selection of the wider diameter for the kit. (B. H., via email). • The choice of 127mm coffee tins for the radar speed gun project was done fairly empirically, on the basis of selecting cans that were readily available, yet gave good results. We tried cans of smaller diameter but these didn’t seem to work nearly as well. That’s not to say that you couldn’t get acceptable results if you experimented with the spacing between the antenna wire and the “rear reflector”. The resolution can only be increased by changing the bucket to tip at 0.1mm instead of 1mm rainfall. This would be best done by increasing the collection area by a factor of 10 and keeping the bucket mechanism as described. To change the resolution to 0.5mm, the collection area could be increased by a factor of 2. In this case the software would need to be changed so the reading is correct. Brushless DC motor is a misnomer Congratulations on your article about the Vectrix electric motorbike. What a wonderful thing. The Harley boys will turn their noses up but they do that anyway. I’ve been riding an electric pushbike (150W, 36V, no registration required) for about five years but it’s not in the same class as the Vectrix. I’d love to own one but I have red-green colour blindness and I doubt I’d pass the licence test. Just one thing: you say there is no such thing as a brushless DC motor but I recently pulled apart my computer fan. It’s clearly labelled “brushless DC motor” and I couldn’t see any brushes. Did I not look hard enough? (G. H., Mt. Martha, Vic). • When we say there is no such thing as a brushless DC motor, we mean that the term is a misnomer. Your fan motor will be using a similar drive scheme to that described for the Vectrix – the electronics will no doubt be inside the July 2008  99 Notes & Errata Minispot 455kHz Modulated Oscillator, January 2008: the PC board overlay on page 74 shows R8 with a value of 330kW. It should be 10MW, as shown on the circuit on page 72. 12-24V DC High-Current Motor Speed Controller, March 2008: the circuit on page 33 has two errors. The 1kW resistor connected to pin 6 of IC1 should be connected to the base of Q3 instead. Also, the wiper of trimpot VR2 is shown connected to ground whereas it should be connected to the 1kW resistor on its high side. The PC board overlay on page 65 of the April 2008 issue is correct. USB Power Injector For External Hard Drives, June 2008: the 100nF capacitor on the output of the LM2940CT-5 regulator (REG1) should be increased to a 22mF 16V (or larger) electrolytic to ensure stability. In addition, the front panel label should indicate the power supply input as 6V DC, not 9VAC/DC. The corrected panel artwork appears below. USB OUT SILICON CHIP USB +Vbus PC USB PORT 6V DC INPUT USB POWER INJECTOR motor housing or it has three leads connecting to electronics elsewhere in the computer. Big inverter required I need to take the 12-14V DC from an ordinary vehicle battery/alternator and step it up to 48-60V at between 5A and 10A. Where can I obtain a step-up device that will do this? What current draw at the supply voltage of 12-14V will be present when the output voltage is 48V <at> 5A, 48V <at> 10A, 60V <at> 5A and 60V <at> 10A? (D. H., Central Tilba, NSW). • What you require is a 600W stepup converter. Its input current will depend on the required output power, so at, say, 60V and 10A the output power is 600W. Assuming an 80% efficiency, 750W would be required at the input. At 12V the current would be 750W/12V or about 63A. Other current input requirements at lower output voltages and currents can be calculated in a similar manner. The closest project we have developed that suits your application is the 600W DC-DC converter published in the October and November 1996 issues of SILICON CHIP. RF switch will not drive a relay I have built the 4-channel RF switch featured in the Circuit Notebook pages of the September 2006 issue of SILICON CHIP. I have built many of these types of circuit using the 4013 chip but I cannot get this circuit to work with a relay. It will turn a LED on and off but not a relay. Can you give any reason for this malfunction? (K. L., Kallangur, Qld). • Without seeing your circuit construction it is hard to guess where the problem would be. The circuit should work as shown so: (1) Make sure the relay is supplied with 12V when switched on; (2) Ensure that the diode across the relay is correctly oriented; (3) Make sure the transistor is a BC337 (ie, NPN type); (4) Try using a 10kW resistor for the base of the BC337 to prevent undue loading of the pin 9 input to IC1c when in pulse mode; (5) Check that pins 4 & 10 of IC2 are pulled to ground via the 1MW resistor. You should also check that your relay works when the 12V supply is SC directly applied to it. WARNING! SILICON CHIP magazine regularly describes projects which employ a mains power supply or produce high voltage. All such projects should be considered dangerous or even lethal if not used safely. Readers are warned that high voltage wiring should be carried out according to the instructions in the articles. When working on these projects use extreme care to ensure that you do not accidentally come into contact with mains AC voltages or high voltage DC. If you are not confident about working with projects employing mains voltages or other high voltages, you are advised not to attempt work on them. Silicon Chip Publications Pty Ltd disclaims any liability for damages should anyone be killed or injured while working on a project or circuit described in any issue of SILICON CHIP magazine. Devices or circuits described in SILICON CHIP may be covered by patents. SILICON CHIP disclaims any liability for the infringement of such patents by the manufacturing or selling of any such equipment. SILICON CHIP also disclaims any liability for projects which are used in such a way as to infringe relevant government regulations and by-laws. Advertisers are warned that they are responsible for the content of all advertisements and that they must conform to the Trade Practices Act 1974 or as subsequently amended and to any governmental regulations which are applicable. 100  Silicon Chip siliconchip.com.au MARKET CENTRE Cash in your surplus gear. Advertise it here in SILICON CHIP Advertising rates for these pages: Classified ads: $29.50 (incl. GST) for up to 20 words plus 85 cents for each additional word. Display ads: $54.50 (incl. GST) per column centimetre (max. 10cm). Closing date: 5 weeks prior to month of sale. To book your classified ad, email the text to silicon<at>siliconchip.com.au and include your name, address & credit card details, or fax (02) 9939 2648, or post to Silicon Chip Classifieds, PO Box 139, Collaroy, NSW, Australia 2097. DOWNLOAD OUR CATALOG at www.iinet.net.au/~worcom WORLDWIDE ELECTRONIC COMPONENTS PO Box 631, Hillarys, WA 6923 Ph: (08) 9307 7305 Fax: (08) 9307 7309 Email: worcom<at>iinet.net.au RCS Radio Pty Ltd is FOR SALE The long-time supplier of PC boards to enthusiasts is finally calling it a day and needs to make arrangements to keep this valued service to readers in operation. The prospective buyer will need to be an enthusiast and also happen to have a large shed, 3-phase electricity supply and broadband internet. For more info on plant, SAV etc, contact Bob Barnes at sales<at> rcsradio.com.au FOR SALE AMATEUR RADIO FOUNDATION COURSES by Liverpool & Districts Radio Club. Tel: 02 9896 5763(h) after 6.00pm or VK2TSR<at>bigpond.com RCS RADIO/DESIGN is at 41 Arlewis St, Chester Hill 2162, NSW Australia and has all the published PC boards from SC, EA, ETI, HE, AEM & others. Ph (02) 9738 0330. sales<at>rcsradio.com. au; www.rcsradio.com.au LEDs! Nichia superbright oval LEDs and 5mm Agilent (HP) LEDs - brandname quality LEDs at Chinese LED siliconchip.com.au prices! Osram surface mount range and other NOS standard and superbright brand name LEDs from just a few cents each. Cree XR-E LEDs, LED drivers, kits and other interesting stuff. www. ledsales.com.au FACTORY OUTLET: flexible neon wire. Sheet (Backlight cuttable) flower. LGP Backlight. EL products. Phone 041 771 8607 Fax (07) 3397 5787. Email: cjappliance<at>gmail.com MicroByte Electronics: PIC Micros – Development Board – Development tools & Components. Phone: (03) 9378 4288. info<at>microbyte.com.au; www. microbyte.com.au Must-have books for the hobbyist “Will fascinate, captivate” FROM A.R. Winstanley, Electronics Editor $2.95 http://stores.lulu.com/thomasscarborough Hobbyist will pay cash. (07) 5471 1062. johnmurt<at>highprofile.com.au PCBs MADE, ONE OR MANY. Any format, hobbyists welcome. Sesame Electronics Phone (02) 9593 1025. sesame<at>sesame.com.au www.sesame.com.au CUSTOMERS: Truscotts Electronic World – large range of semiconductors and passive components for industry, hobbyist and amateur projects including Drew Diamond. 27 The Mall, South Croydon, Melbourne. (03) 9723 3860. electronicworld<at>optusnet.com.au WANTED KIT ASSEMBLY WANTED: EARLY HIFIs, AMPLIFIERS, Speakers, Turntables, Valves, Books, Quad, Leak, Pye, Lowther, Ortofon, SME, Western Electric, Altec, Marantz, McIntosh, Tannoy, Goodmans, Wharfedale, radio and wireless. Collector/ KEITH RIPPON KIT ASSEMBLY & REPAIR: * Australia & New Zealand; * Small production runs. Phone Keith 0409 662 794. keith.rippon<at>gmail.com July 2008  101 VIDEO - AUDIO - PC Satellite TV Reception distribution amps - splitters digital standards converters - tbc's switchers - cables - adaptors genlockers - scan converters bulk vga cable - wallplates International satellite TV reception in your home is now affordable. Send for your free info pack containing equipment catalog, satellite lists, etc or call for appointment to view. We can display all satellites from 76.5° to 180°. DVS5c & DVS5s High Performance Video / S-Video and Audio Splitters AV-COMM P/L, 24/9 Powells Rd, Brookvale, NSW 2100. Tel: 02 9939 4377 or 9939 4378. Fax: 9939 4376; www.avcomm.com.au MD12 Media Distribution Amplifier QUEST ® Quest AV® VGA Splitter VGS2 C O N T R O L S HQ VGA Cables faster with the world’s easiest controllers! best v alue! AWP1 A-V Wallplate Come to the specialists... You get results Do you have wireless problems? Telelink has wireless solutions! 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At Telelink we sell solutions, not problems! 01010101 Telelink Communications www.telelink.com.au e-mail Jack Chomley – jack<at>telelink.com.au or call (07) 4934 0413 or 0428 199 551 ® Quest Electronics® Pty Limited abn 83 003 501 282 t/a Questronix ELNEC IC PROGRAMMERS Products, Specials & Pricelist at www.questronix.com.au fax (02) 4341 2795 phone (02) 4343 1970 email: questav<at>questronix.com.au MS120OEM216 $149 1-off Developer’s Kit $193 includes programming cable & software Made in Australia - enthusiastic users world-wide www.dontronics.com has 300 selected hardware and software products available from over 40 world wide manufacturers, and authors. Olimex Development Boards & Tools: ARM, AVR, MAXQ, MSP430 and PIC. Atmel Programmers And Compilers: STK500, Codevision C, Bascom AVR, FED AVIDICY Pro, MikroElektronika Basic and Pascal, Flash File support, and boot loaders. 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Money back guarantee. www.dontronics-shop.com 102  Silicon Chip splat-sc.com ISM ISM Tx/Rx + 8051 Modules eRF-PoB. 433, 868 or 915MHz Programmable On Board Via RF Use any 8051 Assembler/Compiler Nordic Semiconductors nRF9E5 8051 Processor: 32K Eeprom: 8 I/O:SPI:RS232:16MHz XTL etc. Mini RF Programmer Development Platform 1 off Module Price $59.00 Plus GST High quality Realistic prices Free software updates Large range of adaptors Windows 95/98/Me/NT/2k/XP CLEVERSCOPE USB OSCILLOSCOPES 2 x 100MSa/s 10bit inputs + trigger 100MHz bandwidth 8 x digital inputs 4M samples/input Sig-gen + spectrum analyser Windows 98/Me/NT/2k/XP IMAGECRAFT C COMPILERS ANSI C compilers, Windows IDE AVR, TMS430, ARM7/ARM9 68HC08, 68HC11, 68HC12 GRANTRONICS PTY LTD www.grantronics.com.au ellert-technologies.com.au Battery Packs & Chargers Siomar Battery Engineering www.batterybook.com Phone (08) 9302 5444 siliconchip.com.au Do You Eat, Breathe and Sleep TECHNOLOGY? Opportunities for full-time and part-time positions all over Australia & New Zealand Jaycar Electronics is a rapidly growing, Australian owned, international retailer with more than 39 stores in Australia and New Zealand. Our aggressive expansion programme has resulted in the need for dedicated individuals to join our team to assist us in achieving our goals. We pride ourselves on the technical knowledge of our staff. Do you think that the following statements describe you? Please put a tick in the boxes that do: Knowledge of electronics, particularly at component level. Assemble projects or kits yourself for car, computer, audio, etc. Have empathy with others who have the same interest as you. May have worked in some retail already (not obligatory). Have energy, enthusiasm and a personality that enjoys helping people. Appreciates an opportunity for future advancement. Have an eye for detail. Why not do something you love and get paid for it? Please write or email us with your details, along with your C.V. and any qualifications you may have. We pay a competitive salary, sales commissions and have great benefits like a liberal staff purchase policy. Send to: Retail Operations Manager - Jaycar Electronics Pty Ltd P.O. Box 6424 Silverwater NSW 1811 Email: jobs<at>jaycar.com.au Jaycar Electronics is an equal opportunity employer and actively promotes staff from within the organisation. RFMA RF Modules Australia Low Power Wireless Connectivity Specialists Applications: TX2H-433-64 Rural UHF FM Transmitter UHF Narrowband Transceiver Utilities In Stock NOW! In Stock NOW! Industrial Range: 500m Range: 500m Commercial Power: 25mW Power: 10mW Data rate: 64kbps Government Data rate: 10kbps 33mm x 23mm x 12mm Meter Reading Receiver: RX2A-433-64 RADIOMETRIX: Low Power, Licence Exempt Radio Modules NiM2-434.650-10 RF Modules Australia. P.O. Box 1957 Launceston, TAS., 7250. Ph: 03-6331-6789. Email: sales<at>rfmodules.com.au. Web: rfmodules.com.au FISCHERTECHNIK ROBOTIC KITS An extensive range of construction kits are now available. Controlled by the ROBOPro interface and flowchart style software. Communicates with the PC via COM, USB or RF data link. We specialise in: The fischertechnik range includes kits for the junior engineer through to training models for schools and universities. Interface drivers and C language compiler examples included. Extensive range of spare parts stocked. Mini lathes, milling m/c. Data logging, test and measurement equipment. Rezap battery chargers. Ultra-Violet torches. Weather stations. Power supplies. *Free Varta alkaline batteries with all orders. www.procontechnology.com.au P.O. Box 655 Mt.Waverley VIC 3149. Phone: 1300304125 Fax: (03) 98306481 email: procon<at>tpgi.com.au BUSINESS FOR SALE Sydney’s premier electronic musical equipment repair and service facility Music industry “Household name” Established 28 years Retail, Trade and Authorised Warranty Clinentelle Long standing Government and School client base Guitar amps Recording equipment Huge customer base Synthesisers Keyboards Mixers PA Digital Drums Effects Digital Audio Massive technical database Opportunity to take over new enterprise or add to your existing repair business Phase Engineering Pty Ltd. 2/32 Campbell Ave. Dee Why NSW 2099 Phone: Warren on 02 99820000 siliconchip.com.au email: warren<at>phaseng.com.au Advertising Index 555 Electronics............................. 15 Alternative Tech. Association........ 77 Altronics.................................. 78-81 Aztronics........................................ 8 Av-Comm................................... 102 Computronics............................. 102 Dick Smith Electronics............ 16-17 Dontronics.................................. 102 Ecowatch.................................... 101 Ellert Technologoes.................... 102 Emona Instruments........................ 9 Force Electronics........................... 8 Furzy Electronics.......................... 48 Futurlec........................................ 15 Grantronics................................. 102 Harbuch Electronics..................... 77 Hare & Forbes.......................... OBC High Profile Communications..... 101 IMP Printed Circuits....................... 7 Instant PCBs.............................. 101 Jaycar........................ IFC,49-56,103 JED Microprocessors..................... 5 Keith Rippon............................... 101 LED Sales.................................. 101 Microbyte Electronics................. 101 MicroZed Computers...................... 4 Ocean Controls.............................. 6 Ozitronics..................................... 47 Prime Electronics........................... 7 Procon Technology..................... 103 Quest Electronics....................... 102 RCS Radio................................. 101 RF Modules................................ 103 RF Power..................................... 10 Sesame Electronics................... 101 Silicon Chip Back Issues......... 94-95 Silicon Chip Binders................ 76,91 Silicon Chip Bookshop........ 104,IBC SC Perf. Electronics For Cars....... 85 Silicon Chip Subscriptions........... 23 Siomar Battery Industries........... 102 Soundlabs Group......................... 47 Splat Controls............................. 102 Telelink....................................... 102 Tenrod Pty Ltd.............................. 33 Thomas Scarborough................. 101 Truscotts Electronic World.......... 101 Trusys......................................... 101 Wagner Electronics................. 45,65 Worldwide Elect. Components... 101 PC Boards Printed circuit boards for SILICON CHIP designs can be obtained from RCS Radio Pty Ltd. Phone (02) 9738 0330. Fax (02) 9738 0334. July 2008  103 ALL S ILICON C HIP SUBSCRIBERS – PRINT, OR BOTH – AUTOMATICALLY QUALIFY FOR A REFERENCE $ave 10%ONLINE DISCOUNT ON ALL BOOK OR PARTSHOP PURCHASES. CHIP BOOKSHOP 10% (Does not apply to subscriptions) SILICON For the latest titles and information, please refer to our website books page: www.siliconchip.com.au/Shop/Books PIC MICROCONTROLLERS: know it all SELF ON AUDIO Multiple authors $85.00 The best of subjects Newnes authors have written over the past few years, combined in a one-stop maxi reference. Covers introduction to PICs and their programming in Assembly, PICBASIC, MBASIC & C. 900+ pages. PROGRAMMING and CUSTOMIZING THE PICAXE By David Lincoln (2nd Ed, 2011) $65.00* A great aid when wrestling with applications for the PICAXE See series of microcontrollers, at beginner, intermediate and Review April advanced levels. Every electronics class, school and library should have a copy, along with anyone who works with PICAXEs. 300 pages in paperback. 2011 PIC IN PRACTICE by D W Smith. 2nd Edition - published 2006 $60.00* by Douglas Self 2nd Edition 2006 $69.00* A collection of 35 classic magazine articles offering a dependable methodology for designing audio power amplifiers to improve performance at every point without significantly increasing cost. Includes compressors/limiters, hybrid bipolar/FET amps, electronic switching and more. 467 pages in paperback. SMALL SIGNAL AUDIO DESIGN By Douglas Self – First Edition 2010 $95.00* The latest from the Guru of audio. Explains audio concepts in easy-to-understand language with plenty of examples and reasoning. Inspiration for audio designers, superb background for audio enthusiasts and especially where it comes to component peculiarities and limitations. Expensive? Yes. Value for money? YES! Highly recommended. 558 pages in paperback. Based on popular short courses on the PIC, for professionals, students and teachers. Can be used at a variety of levels. An ideal introduction to the world of microcontrollers. 255 pages in paperback. PIC MICROCONTROLLER – your personal introductory course By John Morton 3rd edition 2005. $60.00* A unique and practical guide to getting up and running with the PIC. It assumes no knowledge of microcontrollers – ideal introduction for students, teachers, technicians and electronics enthusiasts. Revised 3rd edition focuses entirely on re-programmable flash PICs such as 16F54, 16F84 12F508 and 12F675. 226 pages in paperback. AUDIO POWER AMPLIFIER DESIGN HANDBOOK by Douglas Self – 5th Edition 2009 $85.00* "The Bible" on audio power amplifiers. Many revisions and updates to the previous edition and now has an extra three chapters covering Class XD, Power Amp Input Systems and Input Processing and Auxiliarly Subsystems. Not cheap and not a book for the beginner but if you want the best reference on Audio Power Amps, you want this one! 463 pages in paperback. DVD PLAYERS AND DRIVES by K.F. Ibrahim. Published 2003. $71.00* OP AMPS FOR EVERYONE By Bruce Carter – 4th Edition 2013 $83.00* This is the bible for anyone designing op amp circuits and you don't have to be an engineer to get the most out of it. It is written in simple language but gives lots of in-depth info, bridging the gap between the theoretical and the practical. 281 pages, A guide to DVD technology and applications, with particular focus on design issues and pitfalls, maintenance and repair. Ideal for engineers, technicians, students of consumer electronics and sales and installation staff. 319 pages in paperback. by Sanjaya Maniktala, Published April 2012. $83.00 Thoroughly revised! The most comprehensive study available of theoretical and practical aspects of controlling and measuring EMI in switching power supplies. Subtitled Exploring the PIC32, a Microchip insider tells all on this powerful PIC! Focuses on examples and exercises that show how to solve common, real-world design problems quickly. Includes handy checklists. FREE CD-ROM includes source code in C, the Microchip C30 compiler, and MPLAB SIM. 400 pages paperback. By Garry Cratt – Latest (7th) Edition 2008 $49.00 Written in Australia, for Australian conditions by one of Australia's foremost satellite TV experts. If there is anything you wanted to know about setting up a satellite TV system, (including what you can't do!) it's sure to be covered in this 176-page paperback book. See Review Feb 2004 SWITCHING POWER SUPPLIES A-Z PROGRAMMING 32-bit MICROCONTROLLERS IN C By Luci di Jasio (2008) $79.00* PRACTICAL GUIDE TO SATELLITE TV See Review March 2010 ELECTRIC MOTORS AND DRIVES By Austin Hughes & Bill Drury - 4th edition 2013 $59.00* This is a very easy to read book with very little mathematics or formulas. It covers the basics of all the main motor types, DC permanent magnet and wound field, AC induction and steppers and gives a very good description of how speed control circuits work with these motors. Soft covers, 444 pages. NEWNES GUIDE TO TV & VIDEO TECHNOLOGY By KF Ibrahim 4th Edition (Published 2007) $49.00 It's back! Provides a full and comprehensive coverage of video and television technology including HDTV and DVD. Starts with fundamentals so is ideal for students but covers in-depth technologies such as Blu-ray, DLP, Digital TV, etc so is also perfect for engineers. 600+ pages in paperback. RF CIRCUIT DESIGN by Chris Bowick, Second Edition, 2008. $63.00* The classic RF circuit design book. RF circuit design is now more important that ever in the wireless world. In most of the wireless devices that we use there is an RF component – this book tells how to design and integrate in a very practical fashion. 244 pages in paperback. AC MACHINES By Jim Lowe Published 2006 $66.00* Applicable to Australian trades-level courses including NE10 AC Machines, NE12 Synchronous Machines and the AC part of NE30 Electric Motor Control and Protection. Covering polyphase induction motors, singlephase motors, synchronous machines and polyphase motor starting. 160 pages in paperback. PRACTICAL VARIABLE SPEED DRIVES & POWER ELECTRONICS Se e by Malcolm Barnes. 1st Ed, Feb 2003. $73.00* Review An essential reference for engineers and anyone who wishes to design or use variable speed drives for induction motors. 286 pages in soft cover. Feb 2003 BUILD YOUR OWN ELECTRIC MOTORCYCLE PRACTICAL RF HANDBOOK by Carl Vogel. Published 2009. $40.00* by Ian Hickman. 4th edition 2007 $61.00* A guide to RF design for engineers, technicians, students and enthusiasts. Covers key topics in RF: analog design principles, transmission lines, couplers, transformers, amplifiers, oscillators, modulation, transmitters and receivers, propagation and antennas. 279 pages in paperback. Alternative fuel expert Carl Vogel gives you a hands-on guide with the latest technical information and easy-to-follow instructions for building a two-wheeled electric vehicle – from a streamlined scooter to a full-sized motorcycle. 384 pages in soft cover. *NOTE: ALL PRICES ARE PLUS P&P – AUSTRALIA ONLY: $10.00 per order; NZ – $AU12.00 PER BOOK; REST OF WORLD $AU18.00 PER BOOK To Place Your Order: INTERNET (24/7) PAYPAL (24/7) eMAIL (24/7) www.siliconchip. com.au/Shop/Books Use your PayPal account silicon<at>siliconchip.com.au silicon<at>siliconchip.com.au with order & credit card details FAX (24/7) MAIL (24/7) Your order and card details to Your order to PO Box 139 Collaroy NSW 2097 (02) 9939 2648 with all details PHONE – (9-5, Mon-Fri) Call (02) 9939 3295 with with order & credit card details You can also order and pay for books by cheque/money order (Mail Only). Make cheques payable to Silicon Chip Publications. ALL TITLES SUBJECT TO AVAILABILITY. PRICES VALID FOR MONTH OF MAGAZINE ISSUE ONLY. ALL PRICES INCLUDE GST ALL S ILICON C HIP SUBSCRIBERS – PRINT, OR BOTH – AUTOMATICALLY QUALIFY FOR A REFERENCE $ave 10%ONLINE DISCOUNT ON ALL BOOK OR PARTSHOP PURCHASES. CHIP BOOKSHOP 10% (Does not apply to subscriptions) SILICON For the latest titles and information, please refer to our website books page: www.siliconchip.com.au/Shop/Books PIC MICROCONTROLLERS: know it all SELF ON AUDIO Multiple authors $85.00 The best of subjects Newnes authors have written over the past few years, combined in a one-stop maxi reference. Covers introduction to PICs and their programming in Assembly, PICBASIC, MBASIC & C. 900+ pages. PROGRAMMING and CUSTOMIZING THE PICAXE By David Lincoln (2nd Ed, 2011) $65.00* A great aid when wrestling with applications for the PICAXE See series of microcontrollers, at beginner, intermediate and Review April advanced levels. Every electronics class, school and library should have a copy, along with anyone who works with PICAXEs. 300 pages in paperback. 2011 PIC IN PRACTICE by D W Smith. 2nd Edition - published 2006 $60.00* by Douglas Self 2nd Edition 2006 $69.00* A collection of 35 classic magazine articles offering a dependable methodology for designing audio power amplifiers to improve performance at every point without significantly increasing cost. Includes compressors/limiters, hybrid bipolar/FET amps, electronic switching and more. 467 pages in paperback. SMALL SIGNAL AUDIO DESIGN By Douglas Self – First Edition 2010 $95.00* The latest from the Guru of audio. Explains audio concepts in easy-to-understand language with plenty of examples and reasoning. Inspiration for audio designers, superb background for audio enthusiasts and especially where it comes to component peculiarities and limitations. Expensive? Yes. Value for money? YES! Highly recommended. 558 pages in paperback. Based on popular short courses on the PIC, for professionals, students and teachers. Can be used at a variety of levels. An ideal introduction to the world of microcontrollers. 255 pages in paperback. PIC MICROCONTROLLER – your personal introductory course By John Morton 3rd edition 2005. $60.00* A unique and practical guide to getting up and running with the PIC. It assumes no knowledge of microcontrollers – ideal introduction for students, teachers, technicians and electronics enthusiasts. Revised 3rd edition focuses entirely on re-programmable flash PICs such as 16F54, 16F84 12F508 and 12F675. 226 pages in paperback. AUDIO POWER AMPLIFIER DESIGN HANDBOOK by Douglas Self – 5th Edition 2009 $85.00* "The Bible" on audio power amplifiers. Many revisions and updates to the previous edition and now has an extra three chapters covering Class XD, Power Amp Input Systems and Input Processing and Auxiliarly Subsystems. Not cheap and not a book for the beginner but if you want the best reference on Audio Power Amps, you want this one! 463 pages in paperback. DVD PLAYERS AND DRIVES by K.F. Ibrahim. Published 2003. $71.00* OP AMPS FOR EVERYONE By Bruce Carter – 4th Edition 2013 $83.00* This is the bible for anyone designing op amp circuits and you don't have to be an engineer to get the most out of it. It is written in simple language but gives lots of in-depth info, bridging the gap between the theoretical and the practical. 281 pages, A guide to DVD technology and applications, with particular focus on design issues and pitfalls, maintenance and repair. Ideal for engineers, technicians, students of consumer electronics and sales and installation staff. 319 pages in paperback. by Sanjaya Maniktala, Published April 2012. $83.00 Thoroughly revised! The most comprehensive study available of theoretical and practical aspects of controlling and measuring EMI in switching power supplies. Subtitled Exploring the PIC32, a Microchip insider tells all on this powerful PIC! Focuses on examples and exercises that show how to solve common, real-world design problems quickly. Includes handy checklists. FREE CD-ROM includes source code in C, the Microchip C30 compiler, and MPLAB SIM. 400 pages paperback. By Garry Cratt – Latest (7th) Edition 2008 $49.00 Written in Australia, for Australian conditions by one of Australia's foremost satellite TV experts. If there is anything you wanted to know about setting up a satellite TV system, (including what you can't do!) it's sure to be covered in this 176-page paperback book. See Review Feb 2004 SWITCHING POWER SUPPLIES A-Z PROGRAMMING 32-bit MICROCONTROLLERS IN C By Luci di Jasio (2008) $79.00* PRACTICAL GUIDE TO SATELLITE TV See Review March 2010 ELECTRIC MOTORS AND DRIVES By Austin Hughes & Bill Drury - 4th edition 2013 $59.00* This is a very easy to read book with very little mathematics or formulas. It covers the basics of all the main motor types, DC permanent magnet and wound field, AC induction and steppers and gives a very good description of how speed control circuits work with these motors. Soft covers, 444 pages. NEWNES GUIDE TO TV & VIDEO TECHNOLOGY By KF Ibrahim 4th Edition (Published 2007) $49.00 It's back! Provides a full and comprehensive coverage of video and television technology including HDTV and DVD. Starts with fundamentals so is ideal for students but covers in-depth technologies such as Blu-ray, DLP, Digital TV, etc so is also perfect for engineers. 600+ pages in paperback. RF CIRCUIT DESIGN by Chris Bowick, Second Edition, 2008. $63.00* The classic RF circuit design book. RF circuit design is now more important that ever in the wireless world. In most of the wireless devices that we use there is an RF component – this book tells how to design and integrate in a very practical fashion. 244 pages in paperback. AC MACHINES By Jim Lowe Published 2006 $66.00* Applicable to Australian trades-level courses including NE10 AC Machines, NE12 Synchronous Machines and the AC part of NE30 Electric Motor Control and Protection. Covering polyphase induction motors, singlephase motors, synchronous machines and polyphase motor starting. 160 pages in paperback. PRACTICAL VARIABLE SPEED DRIVES & POWER ELECTRONICS Se e by Malcolm Barnes. 1st Ed, Feb 2003. $73.00* Review An essential reference for engineers and anyone who wishes to design or use variable speed drives for induction motors. 286 pages in soft cover. Feb 2003 BUILD YOUR OWN ELECTRIC MOTORCYCLE PRACTICAL RF HANDBOOK by Carl Vogel. Published 2009. $40.00* by Ian Hickman. 4th edition 2007 $61.00* A guide to RF design for engineers, technicians, students and enthusiasts. Covers key topics in RF: analog design principles, transmission lines, couplers, transformers, amplifiers, oscillators, modulation, transmitters and receivers, propagation and antennas. 279 pages in paperback. Alternative fuel expert Carl Vogel gives you a hands-on guide with the latest technical information and easy-to-follow instructions for building a two-wheeled electric vehicle – from a streamlined scooter to a full-sized motorcycle. 384 pages in soft cover. *NOTE: ALL PRICES ARE PLUS P&P – AUSTRALIA ONLY: $10.00 per order; NZ – $AU12.00 PER BOOK; REST OF WORLD $AU18.00 PER BOOK To Place Your Order: INTERNET (24/7) PAYPAL (24/7) eMAIL (24/7) www.siliconchip. com.au/Shop/Books Use your PayPal account silicon<at>siliconchip.com.au silicon<at>siliconchip.com.au with order & credit card details FAX (24/7) MAIL (24/7) Your order and card details to Your order to PO Box 139 Collaroy NSW 2097 (02) 9939 2648 with all details PHONE – (9-5, Mon-Fri) Call (02) 9939 3295 with with order & credit card details You can also order and pay for books by cheque/money order (Mail Only). Make cheques payable to Silicon Chip Publications. ALL TITLES SUBJECT TO AVAILABILITY. PRICES VALID FOR MONTH OF MAGAZINE ISSUE ONLY. ALL PRICES INCLUDE GST