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SILICON CHIP MARCH 2008 PRINT POST APPROVED - PP255003/01272 8 $ 50* NZ $ 9 90 SPEED CONTROLLER WITH GRUNT! Sp ee d, 24V to o! 40A HOW TO SOLDER AND WORK WITH SMDs INC GST FREE with this issue: 2008 DSE CATALOG (Aust only) One for the Amateurs: DDS HD DIGITAL TV VFO ANALOG TV ENDS SOON! INC GST All you need to know about siliconchip.com.au March 2008  1 SILICON CHIP If you are seeing a blank page here, it is more than likely that it contained advertising which is now out of date and the advertiser has requested that the page be removed to prevent misunderstandings.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.3; March 2008 SILICON CHIP www.siliconchip.com.au Features    9 How To Get Into Digital TV Analog TV transmissions are on the way out. Here’s a look at what you’ll need to receive all the new digital transmissions on an analog TV – by Alan Hughes How To Get Into Digital TV – Pages 9 & 14. 14 Review: Tevion TEV8200 HD Set-Top Box Got an analog TV set? You need an HD Set Top Box! – by Leo Simpson 22 How To Solder Surface Mount Devices Here’s how to solder SMD parts using simple tools – by Jim Rowe 46 PICAXE VSM: It’s Time to Play; Pt.3 Using some of the ‘virtual instrumentation’ included with the software, from a simple voltmeter to an advanced I 2C protocol debugger – by Clive Seager 72 The I2C Bus: A Quick Primer Mystified by the I 2C bus communications protocol? Read this – by Jim Rowe 82 Electric Flight Battery-powered aircraft creates aviation history – by Ross Tester Pro jects To Build 30 12V-24V High-Current DC Motor Speed Controller, Pt.1 It’s rated at up to 40A continuous, features automatic soft start & has good speed regulation under load – by Mauro Grassi 12V-24V High-Current DC Motor Speed Controller – Page 30. 58 A Digital VFO with LCD Graphics Display This digital VFO uses a recycled Nokia cellular phone LCD to display analog and digital frequency readouts – by Andrew Woodfield, ZL2PD 78 A Low-Cost PC-to-I2C Interface For Debugging Tracking down bugs in I 2C circuits can be tricky. This PC interface lets you take advantage of the free Philips/NXP “URD” debugging program – by Jim Rowe 91 One-Pulse-Per Second Driver For Quartz Clocks Convert a low-cost quartz clock to GPS accuracy – by Jim Rowe Special Columns 40 Serviceman’s Log Foxing out a Foxtel installation – by the TV Serviceman 67 Circuit Notebook (1) TV Field-Strength Meter; (2) Alternator Controller For Charging Deep Cycle Batteries; (3) Emergency Light Uses 3W White LED; (4) PICAXE Light Box Countdown Timer; (5) Impedance Bridge Measures At Three Frequencies; (6) Simple Mosfet Tester; (7) PC Cooling-Fan Driver Digital VFO With LCD Readout – Page 58. 84 Vintage Radio The batteries used to power vintage radios – by Rodney Champness Departments   2 Publisher’s Letter   4 Mailbag 57 Order Form siliconchip.com.au 96 Ask Silicon Chip 99 Notes & Errata 102 Market Centre PC-to-I 2C Interface For Debugging – Page 78. March 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 Staff John Clarke, B.E.(Elec.) 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 High-definition TV in limbo until the Olympics This month, we highlight the end of analog television broadcasting (planned for December 2009) and outline what you can do to pick up the High-Definition TV broadcasts that are now available. In brief, if you want to keep watching “free-to-air” TV, you have three options. The first and most expensive is to purchase an HD TV, either LCD or plasma display. The second is to buy an HD personal video recorder (PVR) and hook that up to your analog TV set and third, the cheapest option, is to purchase an HD set top box (STB) and hook that up to your analog TV. We would recommend one of the latter two options to most people because they will save a lot of money. Most people have two or more quite useable analog TV sets in their home and they should be capable of giving many more years of service. So there is no hurry to go and buy the latest HDTV. Remember that whatever HDTV set you buy now will be much cheaper in a year or two and that is particularly important to the majority of people who make most of these purchases on credit and then take years to pay them off. Better to save your dollars now and then buy a bigger and better HDTV set for cash in a few years’ time. People may wonder why they should buy a high-definition PVR or STB when they only have an analog set with a picture quality that is well below the state of the art. Why not just wait until the end of analog broadcasting and then get a PVR, STB or whatever? There are several reasons. The first is that the networks are now broadcasting some programs only in HD format and a standard definition STB will not pick them up. Second, an HD STB will provide a composite video output to allow an old analog TV to show the program, even though the picture quality will no better than if you watched a DVD through the same set. In spite of the above, it has to be said that the current selection of HDTV programs is very limited and generally not worth watching. Most of the time, the programs on the HDTV channels are identical to the standard definition (SD) programs on the same networks. The only networks that bother to put out useful programs are the ABC and SBS. (By the way, all those people who reckon that they cannot pick up SBS will have no problems when they go over to digital reception – see next month’s issue). Many documentaries on SBS and ABC are magnificent on the big screen and they are even better in HDTV, with far more visual impact than on a small screen. As far as commercial network programming is concerned, the quality of all digital programs, whether standard definition or high definition is generally woeful, unless you are interested in sport. Even then, while the video might be good, especially on a really big screen or projector, some of the commentary can be utterly banal. In fact, in my own home, the comment which applies to most commercial network programming is that it probably causes brain damage! In truth, while some programs are very good, most digital TV air space is wasted and probably will remain so until the Beijing Olympics in August this year. Leo Simpson ISSN 1030-2662 * Recommended and maximum price only. 2  Silicon Chip siliconchip.com.au USB Mixed Signal Oscilloscope Analog + Digital Inventing the future requires a lot of test gear... ...or a BitScope Digital Storage Oscilloscope 9 Dual Channel Digital Scope with industry standard probes or POD connected analog inputs. Fully opto-isolated. Mixed Signal Oscilloscope 9 Capture and display analog and logic signals together with sophisticated cross-triggers for precise analog/logic timing. Multi-Band Spectrum Analyzer 9 Display analog waveforms and their spectra simultaneously. Base-band or RF displays with variable bandwidth control. Multi-Channel Logic Analyzer 9 Eight logic/trigger channels with event capture to 25nS. 9 Built-in flash programmable DSP based function generator. Operates concurrently with waveform and logic capture. DSP Waveform Generator BS100U Mixed Signal Storage Scope & Analyzer Innovations in modern electronics engineering are leading the new wave of inventions that promise clean and energy efficient technologies that will change the way we live. Mixed Signal Data Recorder It's a sophisticated world mixing digital logic, complex analog signals and high speed events. To make sense of it all you need to see exactly what's going on in real-time. User Programmable Tools and Drivers BS100U combines analog and digital capture and analysis in one cost effective test and measurement package to give you the tools you need to navigate this exciting new frontier. 9 Record to disk anything BitScope can capture. Supports on-screen waveform replay and export. 9 Use supplied drivers and interfaces to build custom test and measurement and data acquisition solutions. Standard 1M/20pF BNC inputs Smart POD Connector Opto-isolated USB 2.0 12VDC with low power modes BitScope DSO Software for Windows and Linux BS100U includes BitScope DSO the fast and intuitive multichannel test and measurement software for your PC or notebook. Capture deep buffer one-shots, display waveforms and spectra real-time or capture mixed signal data to disk. Comprehensive integration means you can view analog and logic signals in many different ways all at the click of a button. The software may also be used stand-alone to share data with colleagues, students or customers. Waveforms may be exported as portable image files or live captures replayed on another PC as if a BS100U was locally connected. BitScope Designs Ph: (02) 9436 2955 Fax: (02) 9436 3764 www.bitscope.com 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”. Bigger battery for Prius not viable That bigger battery in the Prius (SILICON CHIP, February 2008) did not increase its “carbon economy”. It just transferred the emissions from the car’s tailpipe to the power plant’s. And it has increased the mass of batteries that have to be replaced periodically, making the car’s lifetime carbon footprint worse. It has been suggested seriously, with numbers to prove it, that because of the limited life of the batteries, a hybrid like the Prius isn’t any greener over its lifetime than the same car powered by a turbo diesel. Gordon Drennan, Burton, SA. Keep those microcontroller projects coming I have been a reader of SILICON CHIP from day one. You are without a doubt a world-class publication, both by presentation and by quality of projects. Just as a whole generation of technical people enjoy the warm glow of valves, another generation cut Versatile 4-channel mixer fix After building the Versatile 4-Channel Mixer project (SILICON CHIP, June 2007) and not being able to get it working, I noticed in the “Notes and Errata” section of a recent issue that the published PC board design was incorrect in the region of CON1-CON4. The suggested fix was to reverse the metal contacts of these sockets. This was no easy task as these sockets are obviously not meant to be taken apart! The stubborn little beggars bluntly refused to come out of the plastic mounting. However, two days and sore fingers and thumbs later, I managed to complete the task 4  Silicon Chip their teeth on combinational logic. In your wisdom you have moved with the times and have introduced microcontroller projects. I believe you have built a lifeline for your publication by doing this. By virtue of the kind of knowledge you share in your projects I for one have found a very satisfying career as a PIC programmer. I started out by attempting projects in SILICON CHIP and Elektor magazine, undertook some more advanced study, including learning to program in ‘C’, and then went in search of a job that allowed me to apply these skills. My point is that it all started from being able to access the basic knowledge in a structured and non-threatening way through SILICON CHIP. For the sake of the future, please keep pushing microcontroller technology or what ever replaces it in your publication. You have shown the tenacity to survive in a very difficult market by having content and presentation that appeals to many. Long may it continue. Mark Weir, Tauranga, NZ. and install them on the board. My perseverance paid off, as the mixer is now working perfectly. A couple of tips for people who also purchased the early version of the kit: I bought four completely new sockets and swapped the contacts over on them rather than attempting to alter the desoldered ones. Secondly, two of the new ones had the number “3” on the under surface, while the other two had the number “4” on the bottom. Although they were identical, for some unknown reason the ones with number “4” on them were much more co-operative than those with the number “3”. George Green, Wollongong, NSW. Ultrasonic leak tester On page 97 of the November 2007 issue, your correspondent is asking about an ultrasonic device to detect air leaks on vehicles with air brakes. While such a device would probably have advantages, I have found that a very effective method for detecting air leaks on truck air brakes is to “paint on” soapy water, using a small paint brush to suspect areas (pipe joiners and connections etc). Even when you can hear air leaks they can still be difficult to pinpoint but soapy water makes the job easier. Peter Bell, Glenorchy, Tas. What is MPG? Upon seeing the front cover of your latest issue (February 2008), I couldn’t believe what I was seeing! Miles? Gallons? Who in Australia still uses the “old-fashioned” Imperial units? We don’t! And how long has Australia been metric? One thing I do remember is that when I was going to tech some thirty years ago, we students would lose marks if our drawings did not use “metric”. I showed your magazine to my (elderly) mother who still does not fully understand decimal currency! She was as shocked as I was when she saw the references to miles and gallons. If you continue to publish magazines with “old-fashioned” measurements on the front cover, you will lose me, as a reader, forever! T. Robinson, Woodend, Vic. Imperial units no longer used in Australia I have browsed the February 2008 issue and am amazed that SILICON CHIP would use units that are no longer applicable in Australia. Australian vehicles have metric speedometers. Fuel is purchased by the litre (or multiples siliconchip.com.au Serviceman should stop blaming himself I always read the “Serviceman’s Log” with much interest, as I can relate to many of the headaches he has to endure. In particular, the column in the December 2007 issue of SILICON CHIP piqued my interest, since I can comment firsthand on the mystery of diode D10, as follows. The TinySwitch series of ICs are designed for off-line flyback power supplies. The flyback topology, al­ though relatively inexpensive, suffers from very high voltage stresses on the main power switch. The stresses are not only the rectified and reflected voltages but also any additional voltage spikes caused by the transformer’s leakage inductance. If unchecked, these spikes will destroy the 700V Mosfet located inside the IC. To tame the voltage, an RCD (resistor-capacitor-diode) snubber is employed, as described in the IC’s datasheets and application notes. Unfortunately, OEMs are always badgering power supply manufacturers to reduce costs. One of the ways to shave a few pennies off is to thereof) and distance is measured in kilometres (the base unit being the metre). L/100km appears to be the standard unit for fuel economy. I do realise there is something magical about the figure “100”. Ray Smith, Hoppers Crossing, NSW. Comment: you are the second to comment on the 100mpg headline but as you can see from the article, the Prius readout is in mpg and in any case, 100mpg sounds far more impressive than 2.825/100km (the actual equivalent to 100mpg). In fact, in the past we have had readers comment that such figures are meaningless to them. Hydrogen for solar power Why do all the comparisons of “direct” solar energy vs coal/hydroelectric conclude that solar is not suitable for base load power? As a direct to grid power source, this is true enough. However, using solar power to electrolyse water to gain hydrogen which can siliconchip.com.au replace such an RCD snubber with a TranZorb, a surge protector based on a discrete avalanche diode. Although this works and appears to be a reliable solution, the truth is that these diodes were never designed for repetitive avalanche duty and thus create junction hotspots. The diode may start leaking, causing the symptoms described, until it eventually fails com­pletely. I know this first-hand since the company I used to work for (a power supply manufacturer) got hit with a couple of product recalls for the same reason. The problem was that Power Integrations (the IC vendor) had actually suggested this very approach in their older application notes, now revised with the RCD clamp. So please tell the poor Serviceman to stop blaming himself. It was not his fault but rather a poor design solution. If he can make the supply work with the RCD clamp, then leave it that way. Be sure to properly insulate all the exposed leads, as some pretty high voltages will be present. Fernando Garcia, Brownsville, Texas, USA. then be ‘burnt’ directly in a gas turbine is already a proven technology. The efficiency of the solar panels is not really an issue; more panels would make up the difference. With all the land that is salt-affected and becoming useless for anything but sunlight collection, this could be an income stream for those farmers so affected. And if the panels were made to let through the light frequencies they cannot convert to electron release, would the land underneath the panels still be usable for grazing/ crop production? That is assuming that the alternative method of producing hydrogen using ceramic/direct hydrogen conversion proves not to be more efficient. See http://www.unsw.edu.au/news/pad/ articles/2004/aug/Solar_hydrogen. html Hydrogen could also be stored, piped and used for power generation inside the metropolitan areas as easily as natural gas is today. The benefits 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 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 March 2008  5 JOIN THE TECHNOLOGY AGE NOW Mailbag: continued 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, serial RS232, 1-Wire™, and I2C facilities. PC connectivity. Applications include: Datalogging Robotics Measurement & instruments Motor & lighting control Farming & agriculture Internet server Wireless links Colour sensing Fun games of such a scheme are probably lower power transmission losses and less visual pollution, a more disbursed power generation system (greater disaster tolerance plus lower losses in power transmission) plus ‘base load’ generation becomes less of an issue. Schemes such as off-peak hot water would not be required to soak up the spinning reserve power generation as gas turbines are basically best used for full load/turned off systems. And why are trees seen as the only way to recapture carbon from the atmosphere? Surely faster and denser growing plants such as sugar cane would make more sense. Grow the cane, process the cane and remove the sugar and bury the fibre pulp. The sugar can be used to make fuel for use in a co-generation system or be used as a source of hydrogen for fuel cells. As seems to be so common these days, whenever something is proposed by a government department or some group or other, it seems that the proponents have a vested interest in their proposals. Ron Powell, Minchinbury, NSW. Comment: some recent proposals for solar power involve the use of molten salt as the heat storage and transfer medium to run steam-powered generators. This would probably be more efficient and practical than any electrolysis scheme. Comment on Atten oscilloscope review Distributed in Australia by Microzed Computers Pty Limited Phone 1300 735 420 Fax 1300 735 421 www.microzed.com.au 6  Silicon Chip I enjoyed reading the review of the ATTEN ADS7062C low-cost colour digital storage oscilloscope in the February 2008 issue supplied by our company for your evaluation. It was refreshing to see that the reviewer really knew how to drive a DSO. There was one minor point however that could easily be missed. The oscilloscope is supplied with switched x1/ x10 probes. It is possible to manually adjust the setting on the sensitivity to correct the readout on the screen for different probe attenuation settings. The scope actually operates from 2mV/div to 5V/div. This is displayed when set for use with an “x1” probe. It can even be set to work with a x100 probe. In the case of the review, it must have been set for a x10 probe. In case any of your readers got the wrong impression or understood they could put in signals of 400V directly at 50V/ div without a x10 probe, I just thought I had better point out the true scope performance. As mentioned several times in the article, it’s the same as other more expensive scopes. Charles Holtom, Managing Director, Trio Smartcal Pty Ltd. www.triosmartcal.com.au Valve radio of considerable interest I found the article by Keith Walters on building a 3-valve radio (SILICON CHIP, January 2008) from everyday materials of considerable interest. I have made valve shields using the tin-plate from tin cans. Just cut a suitable piece of tin-plate, wrap it around a piece of dowel a little smaller than the diameter of a valve and let it spring out to suit the valve size. Maybe you could solder the edge of the shield or leave it as is, and solder a wire from the shield to the chassis as Keith did. Keith could have even used 6BL8 valves all the way through the set, as the 6BL8 or 6U8 make quite an acceptable audio output valve. Rodney Champness, Mooroopna, Vic. Energy efficiency is just a marketing tool I have been following some of the debate and articles on energy in your magazine. Our electricity usage equates to about $30 a month, up somewhat because of the equipment I use for my research. Our energy efficiency is achieved without double-glazing, we use quite a few incandescent lights and we have no insulation in either roof or walls. Instead, we employ principles of microclimate, ventilation, daylight, etc. I am doubtful that efforts to promote energy efficiency in homes and workplaces will have any overall beneficial effect; just as energy efficiency siliconchip.com.au More on the Peter Seligman articles After reading the Peter Seligman articles and the response by Dave Waplington (SILICON CHIP, February 2008) and Peter’s subsequent comments, I need to add a couple of points. First, it is likely that within the next 10 years we will see geo-sequestration of carbon dioxide commence in Australia and obviously, the CO2 will be sourced from power stations, not moving vehicles. The argument that the electric vehicle just shifts the source of emissions may have to be revised, as it actually shifts the emissions to where they can be more easily contained. Secondly, Peter Seligman says LPG and natural gas are similar and makes comparisons between LPG vehicles and natural gas power stations. Natural gas burnt in the power stations is mostly methane (CH4) whereas LPG is mainly a mixture of propane and butane (C3H8 & C4H10). These are derived from the condensate of the raw natural gas and comprise about 5% of its volume. Petrol is about equivalent to octane (C8H18) or higher, and usually also contains branched and cyclic hydrocarbons. It is clear that the higher the molecular weight of the hydrocarbon fuel, the higher is the proportion of carbon, so that while CO2 emissions from burning methane are about half those from petrol or diesel, those from LPG are only slightly better. A rough calculation I did when working on this subject at Mitsubishi indicated a CO2 reduction of about 10-15%. This is not to be sneezed at but is not in the same league as natural gas. It is possible to convert vehicles to run on natural gas but filling stations are scarce. I understand that there is only one here in Adelaide. About 20 years ago, the gas supply company SAGASCO (now taken over by Origin Energy) was experimenting with a small home compressor which could recharge a CNG vehicle tank from the gas mains. The compressors were made by Sulzer of Switzerland but SAGASCO didn’t push the idea, perhaps because of the road tax problem. They reported that their CNG vehicles such as Falcon utes and vans had reasonably good driveability but somewhat reduced power and range compared to LPG. David Inkster, Meadows, SA. We’re told we make the best speakers in the world… Now you can too “The best speakers I have ever heard” DVD Now “The best bass in the world” Rolling Stone Magazine “We have yet to hear another system that sounds as good” Best Buys Home Theatre in transport will not turn the tide of increased consumption. I was disappointed but not surprised to read of the debacle regarding incandescent lights in Australia. Here in NZ we have an equally stupid new law requiring double-glazing. The reality is, I strongly suggest, that energy conservation will simply end up as a marketing tool. In other words, “more product” is the underlying philosophy, backed up by the iron hand of legislation. Stephen Butcher, Carterton, NZ. Energy saving can be illusory Following on from the topics on energy savings, there was a recent story on ‘Today Tonight’ covering the dangers of leaving devices on stand-by power. In particular, this story targeted TVs which when left on standby have a high risk of starting fires. In the story, a siliconchip.com.au brief mention was made about a device called the “Power Genie” developed by Electronic System Integrators Pty Ltd and used to switch off devices at a single point – see http://www.powergenie.com. I have looked at the site on the Power Genie with some interest and I am left wondering. They are selling this product on the idea that it turns devices off centrally, yet looking at its operation, it is constantly plugged into power and you have a controlling device to turn it on (ie, you have to leave it on standby to then operate by remote). So in effect, it’s a product sold on reducing and saving power and also turning off devices on stand-by, yet this device itself seems to need to be on standby. What is the benefit of such a device over, say, a power-board with a switch to turn off everything?’ Perhaps the true workings of this Seven models from $769pr www.vaf.com.au FreeCall 1800 818 882 vaf<at>vaf.com.au March 2008  7 Mailbag: continued Electric vehicles not yet available Recently I decided to sell my Toyota sedan and to make a serious attempt to import an electric vehicle. In Cape Town, this proved to be practically impossible and after several months, I gave up. Even if it had been possible to import one, I wonder whether any­ one would have been capable of servicing and repairing it. Instead, I imported a Bajaj Pickup from India, a successor of the original 1948 Vespa Ape, which is serviced and repaired locally. So far, fuel efficiency is 3l/100km. Compare this with 5.6-15l/100km for a typical sedan. Not only that but it is very useful and great fun if one isn’t deterred by a top speed of about 60km/h! So here is someone who aspired to an electric vehicle but the times did not yet favour it. Thomas Scarborough, Cape Town, South Africa. device could be covered in an article in SILICON CHIP. This could then flow onto a project on something better which you could position anywhere and centrally turn a number of devices off (and where the device itself does not need to be controlled by another device to turn on). I am beginning to find that this whole issue about saving energy and the environment is becoming a big ‘con’ on society, with everyone getting on the bandwagon and using it as either a political grab or as a means of sucking more hard-earned income from individual consumers. If the world governments really wanted to improve the environment, then the first point of the agenda is to release our reliance on oil and fossil fuels. I was dumbfounded by a report which said that we should be taxed to force new ‘green’ technologies. http://www.news.com.au/business/ story/0,23636,22471121-462,00.html Flavio Spedalieri, Frenchs Forest, NSW. Comment: SILICON CHIP has produced 8  Silicon Chip Comment: it would certainly be economical but we like the protection of a real motor vehicle with lots of airbags and structural crash protection – which means that we might be able to have a major collision and still come through relatively unscathed. two projects which are relevant: (1) the PowerUp in July 2003 and the USB Power Switch in the November 2004 issue. See also the Remote Controlled Mains Switch in this issue. It can be used in conjunction with a powerboard. Efficiency question on Signature Series loudspeakers There appears to be an error in the sensitivity of the Signature Series Kit Loudspeaker article. I have no doubt that these are efficient speakers and I know the tweeter is capable of the efficiency quoted, however the woofer is not. The speakers are reported to have an efficiency of 92.5dB/1m/1W. This is not possible as the drivers only have an efficiency of 88dB/1m/2.83V (or ~87dB/1m/1W with a 6-ohm minimum impedance), so for the 260 series speakers with parallel drivers, the woofers will have a sensitivity of ~90dB/1m/1W or ~93dB/1m/2.83V. Although the 2.83V measurement is more realistic for normal use, as almost all amplifiers are voltage controlled, quoting it as a 1W figure is still misrepresentation. Having said that, the realistic figure of 90dB/1m/1W is still very respectable and I commend you and Russell Storey on a very well-designed speaker. There would be very few commercial speakers that will come close to the level of the Signature Series. Chris Lister, Brisbane, Qld. Russell Storey comments: the 260 Ribbon Speaker was measured using an LMS Speaker Analyser which is calibrated in true SPL dB (speaker pressure level). A B&K laboratory reference microphone pressure calibrator <at> 94 SPL dB is used to calibrate the microphone and LMS Speaker Analyser measurement system before any measurement is made. A constant amplitude sinewave sweep set to 2.83V RMS across the speaker terminals is used as a reference point only. The microphone distance is set to one metre, centred on the tweeter axis. Up to 40 different readings are taken over a period of two hours and then averaged. The 260 sensitivity is quoted at 92.5dB SPL under all of the above conditions and is an average over the 400Hz to 10kHz region. Ambient temperature is the most important factor in measuring any loudspeaker system; this was set at 22°C. SPL dB of any transducer (speaker) can vary by as much as ±3dB to ±6dB in the ambient temperature range from 8-35°C. Other factors that change transducer measurement readings are humidity, barometric pressure and the effect they have on the microphone capsule, transducer motor (magnet) system, voice coil, compliance of the cone and spider materials and heating losses in component in the crossover. Measuring any loudspeaker transducer or speaker system’s response and specifications is like measuring a “sponge with a pair of metal callipers“. Every time you measure the sponge diameter you will get a different set of readings. Russell Storey, Stones Sound Studio. http://www.stonessoundstudio. com.au/ SC siliconchip.com.au Perhaps you are blissfully unaware of it – but the Australian Government plans to progressively switch off all analog TV transmitters, starting in less than two years time. And High Definition digital TV programs are now being shown on “free to air” commercial, ABC and SBS TV. Those programs are not available via Standard Definition digital tuners or settop boxes. So what do you need to do? Y ou might have seen adverts on the Seven & Ten network stating that their new High Definition (HD) TV programs are now available. New Zealand is also converting, with HD Digital on air in all major population centres, ready for the start of the Beijing Olympics on 8th August 2008. Perhaps you have been thinking that you will be able to get the new HD programs with your existing standard definition (SD) set-top box (STB) or SD digital tuner. Well, think again. It doesn’t work that way. If you want to see HD programs, you will need an HD tuner, even if your present display cannot show them in the needle-sharp focus of HD. siliconchip.com.au In Australia there are HD and SD receivers. SD programming will eventually die out with the advent of HD-only programming but an HD STB can produce an SD signal for analog receivers. So even if you decide to stay with your present analog TV set, it will still be possible to watch all the new high-definition free-to-air programs, provided that you have an HD STB. The clock is definitely ticking on analog TV broadcasts. Senator Conroy, the Minister for Broadband, Communications and the Digital Economy, has set the switch-off date for metropolitan analog TV as December 2009, with all analog transmissions to cease by 2013. So there is no escaping it, if you want free-to-air TV programs in the near future, you are going to have to “go digital” and realistically, that means “go HD”. But why wait? Why not enjoy all the advantages that HD TV has to offer, right now? The main advantages are more programs, much better picture and sound quality and no ghosting. If you want to watch HD programs, you must obtain: 1) A wide screen TV which incorporates an HD tuner or 2) An HD Set Top Box (STB) which will receive digital signals and convert them into a form a conventional receiver can display or a standard March 2008  9 You’ll need an HD set-top box if your TV doesn’t have one built in. But don’t despair: they won’t cost an arm and a leg! This Tevion brand HD STB was on sale earlier this year for less than $100 (see the review in this issue). And we’ve seen them for $50 or less on eBay! video recorder can record via its AV inputs or 3) An HD Personal Video Recorder (PVR). This device will receive digital signals and display on a conventional or wide-screen display (and/or record them if you wish). And while it might seem obvious, you need a suitable antenna to receive the digital signals. Your existing antenna may not be good enough. If you live in a home unit, your building’s Master Antenna Television (MATV) system will need upgrading to pass the channels used by digital TV. The cheapest and best way to do this is for all residents to obtain either a STB or PVR first. They may not receive all stations at this stage. Then get the body corporate/building owner to upgrade the MATV system to digital channels. The installation should be made according to Australian Standard AS1367: 2007. The cheapest option is to install STBs near the antenna instead of retuning the channel amplifiers. One STB will be required for each digital channel. The STBs will be used to convert the digital signals back to standard definition analog. However, this approach will prevent you seeing High Definition signals and multi-channel sound on your expensive new TV. And it will probably prevent you seeing the new HD and the supplementary channels already available. See www.dba.org. au/index.asp?sectionID=26 If you live in a free-standing home or dual-occupancy dwelling, you will need to check to see if you get reliable digital reception, particularly in the rain. Check that the picture does not break up into little squares, the sound not go off and on or that the “no signal” sign appears. If any of these things occur, then you require an antenna designed for digital reception (not “digital-ready”) in your viewing area. The antenna cabling may also need replacing. We hope to have more to say on digital antennas next month. HD set-top boxes are getting cheaper all the time. Over the Christmas period, Aldi stores had an HD STB available on special at just $99 (down from $119) while Coles supermarkets have had them even cheaper at $79. You could also pick one up on eBay for less than $50 (but watch those postage charges!). At the same time, we have seen standard definition (SD) STBs on sale for as little as $35. However, in view of the above remarks about HD programming, we see little point in buying an SD STB. In fact, we forecast that once the general public understands their limitations, SD STBs will shortly disappear from the market. PVRs are also becoming cheaper by the day and they are a very good option if you want to record a HD program at a particular time while you watch another HD (or SD) program. This is easy with most PVRs since they usually have two inbuilt tuners. PVRs are similar to a VCR but with some distinct advantages. The first of these is the Electronic Program Guide (EPG). This is where the broadcaster sends out via their transmissions the names of all programs to be shown for the coming week. You can then select the programs you wish to record by name. No more worrying about start and stop times, channel number etc. Another advantage is Time Slip recording, which enables you to pause the program you are watching, while the recording process continues. You can then start playing where you left off while the recording is being completed. Since the recordings are made on a very large hard disk (typically 160GB or 250GB), there is no waiting for a tape to wind to the right place; it is just like playing a DVD. Here’s the rear view of the STB above. At left is the standard coax antenna input and loop output sockets. Alongside is the coaxial (digital audio) and S-video socket, followed by the Y, Pb and Pr component video sockets (labelled HD OUT). The next three sockets are component video (yellow) and L/R audio (white and red). Immediately alongside this is a D-socket for use with a VGA computer monitor. The next four sockets are the interesting ones: DVI out (for projectors, etc), the HDMI output we’ve discussed in the text; a USB socket for USB devices and finally, the optical, or TOSlink audio socket. 10  Silicon Chip siliconchip.com.au PRIME There are many ways to “skin a cat” – some better than others. If you have the option, the best is to use an HDMI cable to connect a personal video recorder to the TV – especially if it is an HD type. 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 Diode Test Analog Bar Graph Backlight Min/Max/Avg Display Hold Auto/Manual Range Holster Our Price $199.00 179/EDA2 Combo Kit LIMITED LIFETIME WARRANTY CAT III 1000V CAT IV 600V Subtitling for the hard of hearing’s data is also recorded along with the program so you can choose whether you display subtitles on playback or not. HDMI or component video? HD STBs and PVRs should be connected to your TV set or projector by HDMI or component video cables. HDMI stands for “high definition multimedia interface”. But which one should you use? HDMI or “component video”? HDMI has the following advantages: • It can carry the three colour signals and up to eight channels of sound siliconchip.com.au on a single cable. • It can tell the display what type of signals is being sent so that the display can automatically adjust. • It can convey control commands for other devices. So for example, a single remote control can be used to control the PVR, etc. • It can carry the High Definition Copy Protection (HDCP) signals. There is talk of only outputting Full Definition (1920 x 1080p) signals to the HDMI output only. This will particularly affect High Definition DVDs such as BlueRay and may actually be a drawback in the future, as far as most users are concerned, since HDCP is a copy prevention method. Kit Contains ● ● ● ● ● ● ● 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 March 2008  11 For the complete “home theatre” experience, you’ll need a 5.1 channel amplifier along with the DVD and PVR. While the subwoofer is shown centre rear in this diagram, it can in fact go just about anywhere as low frequency sound is, for all intents and purposes, nondirectional. Y, Pb and Pr signals. The sharpness of the image will be controlled by the resolution of the display but the accuracy of the colour should be a little better using HDMI compared to component video. In essence, your ultimate picture quality will depend more on the resolution and video conversion processes inside your video monitor or projector than on whether you have selected a component video or HDMI cable connection. HDMI uses only one cable • The signals are not converted into analog. This is an advantage because the display will have to digitise component signals, so that the image can be stored for display. Thus digital to analog and an analog to digital conversions are eliminated. • Finally, it allows the transfer of the xvYCC colour signals to the display. This gives a greater range of strong colours, if they are present on the disc. But in spite of the above, there is presently no clear-cut advantage for HDMI over “component video”. While HDMI is a digital format, it does not have error correction and therefore long cable runs can be more problematical, with possible signal dropouts, than the analog “component video” connection. To explain, both HDMI and analog component video deliver signals as three discrete colour components, together with sync information which allows the TV or projector to produce the video display. HDMI delivers these via three data channels in a format called TMDS (Transition Minimised Differential Signalling). The TMDS format basically involves a blue channel to which horizontal and vertical sync are added and separate green and red channels. TMDS involves two schemes to minimise noise and interference. “Transition Minimised” refers to the conversion of the signal to Grey code, 12  Silicon Chip which only has one bit change at a time in the channel. So if interference is picked up, all channels receive it and it is ignored. At the same time, it employs “Differential Signalling” whereby when a “1” is being sent one wire of the pair goes to +250mV while the other goes -250mV with respect to earth. They reverse when a “0” is being sent. This gives noise immunity. Error correction is also applied to the sound and control signals (but not to the colour signals). The signals are sent as identifiable packets, so the same wires are used for picture and sound. An HD colour signal consists of a luminance (Y) signal. It shows as a black, grey and white signal in sharp detail. The picture is then “coloured in”, by using a Pr signal which colours it either red or aqua, or a Pb signal which colours it blue or yellow. The green and purple colours can be derived from the above three signals. Component video is not much different, with the analog colour information also split three ways: luminance (the “Y” or green channel, representing the total brightness of the image); Red minus Luminance (the “Pr” or red channel); and Blue minus Luminance (the “Pb” or blue channel). The horizontal and vertical sync pulses are delivered on the Y channel. The video display calculates the values of red, green and blue from the HDMI does have the convenience of only using one cable connection instead of three in the case of component video (plus an extra two for the left and right audio channels) but when you consider that component video cables are always moulded together to give one flat “cable”, albeit with three RCA connectors at each end, the advantage is small. Nor is there much advantage if you are using a video projector since you don’t have to worry about connecting audio cables (although you do have to connect separate audio cables to the amplifier). HDMI cables are not normally included when you purchase HD equipment and have to be purchased separately – and they are also more expensive than equivalent high quality component video cables. In fact, they are very expensive for lengths between 10-25m. Cheap HDMI cables can be a problem at lengths above 5m, with the most frequent symptom being “sparkles” in the picture followed by complete dropout. For HDMI cables longer than 1015m, you may need an HDMI repeater such as the one sold by Jaycar Electronics (Cat AC-1698 at $79.95). This is powered by a plugpack. HDMI cables also present problems for installers. This is because you presently cannot buy HDMI cable and then fit it with connectors – you must buy the complete cable with connectors fitted at each end. This can make it very difficult to pull such a cable through wall cavities without damage. Long component video leads can also be a problem, especially if they use cheap cable. The result is picture blurring. For projectors, component connections are an alternative to the high cost of HDMI. However, blurring of siliconchip.com.au A selection of some of the cables you’re likely to come across. At left is an S-Video cable, while to its right is an HDMI cable. A composite video cable is next, with its three RCA plugs (yellow is video, red is right audio and white is left audio). Finally, the cable at far right is a combination component video/audio cable – the green plug is Y, blue is Pb and red is Pr. This cable can also handle composite video (yellow) and stereo audio (red and white). the vertical edges in the picture will occur if they are too long. If you have insufficient HDMI inputs then you can use component inputs, but also feed the sound into the display as well. The other option is to use a home theatre amplifier to do all switching, provided it can delay the sound for the delay in the display. In practice, we think that the decision whether to use a component video or HDMI connection will depend on how many HDMI inputs your TV or projector has. At present, video projectors come with only one HDMI input and many HD TVs are the same. So if you have several HD video sources (eg, HD STB, PVR and DVD), you will probably end up using a mixture of component video and HDMI cables. The most recent “upmarket” HDMI plasma and LCD HD sets may have two or three HDMI inputs so there is less of a problem with these models. If you have one of these, it is best to feed all sources to the display, then take the sound from the display. This also has the advantage of avoiding problems with “lip sync” whereby the video is delayed with respect to the sound. By the way, using S-video or composite video cables for HD connections is really a waste of time and money, unless you are using an analog TV set. What about Surround Sound? If you want to get the complete experience, then you also need a home theatre amplifier and all the necessary loudspeakers. If you purchase an HD STB or PVR, it will have a coax or optical output which can be fed to the Dolby decoder in your home theatre receiver. However, consider that unless you frequently watch “action” movies, there is no real need for surround sound; your TV’s inbuilt speakers will be quite adequate for the purpose. Even if you do watch the occasional “action” movie, a good quality stereo pair of speakers and your existing system amplifier can still give a very satisfactory aural result. In fact, if you have a limited budget, as most people do, then our advice is to buy the biggest HD set (or choose a HD video projector) and leave the decision about a surround system to a later date – if ever! If you do decide to go for the full home theatre experience with multiple speakers, go for the best home theatre receiver you can afford. It will also solve any problems with switching of HD signal sources. Most plasma and LCD TVs have stereo sound systems but many have relatively poor sound due to restricted speaker sizes. HD programs are broadcast with the option of two sound systems. The first of these is MPEG2 which is stereo only. The second is AC-3 or Dolby Digital 5.1 which carries six channels: left, centre and right front, as well as left and right rear. The 0.1 is the low frequency channel which is normally fed to an active subwoofer. Typically, when broadcast AC-3 has a greater dynamic range than SC MPEG2. NEXT MONTH: In part 2 of this feature, we’ll look at some of the traps for young players in HDTV reception – for example, is your old analog TV antenna suitable for digital? The answer is . . . probably not! SUPPLIERS OF Contact PH: 1800 331 301 Email: info<at>alvin.com.au Web: www.alvin.com.au siliconchip.com.au Digital STBs’ MATV Systems Audio Distribution Telephone and Data Accessories Digital and Analogue TV Antennas Digital and Analogue Interconnect Cables DA-5000 Digital Antenna March 2008  13 Got an analog TV set? You’re going to need an HD Set Top Box! If you currently have an analog TV set or a digital projector and don’t want to change it, you will need a high definition set top box to watch HD TV broadcasts – now and more importantly in the future. By LEO SIMPSON W ith that in mind, we purchased a Tevion TEV8200 HD STB from our local Aldi store. This is one of the cheapest HD STBs currently available and has all the features that you are likely to want. With a recommended retail price of $119 (including GST) and occasionally available on special at $99, the Tevion HD STB is hard to go past. It is quite a bit larger than typical SD STBs and is quite heavy to boot. Its front panel has six pushbuttons to control the various on-screen menus, to select channels and control volume. But after the initial setup, there is no need to ever use the front panel controls. The rear panel is of more interest because the number of video output connections is impressive. In fact, the array of connectors on the rear panel is likely to be quite daunting for any non-technical user. It has the standard male and female coax connectors for the antenna input fly lead and an output to VCR, TV or whatever. To connect an analog TV, there are RCA sockets for composite video and L & R stereo audio, S-video and component video. Most analog TV sets will just use the composite video output (yellow socket) and the left/right stereo outputs (red & white). If your set only has a The TV Channel Manager screen shows the channels that are available together with a preview of the channel selected, in this case ABC HDTV. Note the availability of the D44 data signal channels. 14  Silicon Chip mono input, use the left audio (white) output. In the (these days most unlikely) event that your analog set does not have audio/video (A/V) inputs, you will need an RF modulator to connect to the standard antenna input. Both Altronics and Jaycar Electronics have suitable RF modulators. For connection to home theatre receivers, there are two digital outputs, one via a SPDIF coax (RCA) socket and one via a TOSLINK (optical) connector. Having the two options is good since you may find that one of the digital inputs in your home theatre receiver This screen is a program guide showing what is available over most parts of Sydney, including the D44 Datacast channels. The latter include weather, federal parliament, a TV buying channel, a Christian channel and so on. siliconchip.com.au is already in use and so you can use the alternative. In case you were wondering, SPDIF stands for Sony/Philips Digital Interface. TOSLINK is a registered trademark of Toshiba Corporation and hence the origin of the name: TOShiba-LINK. For connection to a PC, there is a DVI socket. For connection to a PC monitor, you can use the VGA RGB/ HV D socket, together with the L & R audio outputs. For connection to an LCD or DLP video projector, you can use the component video or HDMI digital outputs. Of course most good projectors will also take composite video, S-video or RGB/HV inputs but if you want highdefinition pictures, you need to use the component video or HDMI signals. Setting up the Tevion TEV8200 is straightforward. First, you need to select the video output which you have connected to your TV, projector or whatever. To do this, you press the FUNC button on the remote control twice within four seconds and this brings up a fourdash display on the STB’s front panel readout. You then press one of the coloured buttons to select the output: RED for PAL (ie, analog TV); GREEN for VGA; YELLOW for Component Video and BLUE for DVI/HDMI mode. You can also use the Left/Right buttons to select the video resolution you want such as 1080i (interlace), 720p (progressive scan) and so on. siliconchip.com.au For best picture from a video projector, it is desirable to set the STB’s output video resolution to the “native” video resolution of the projector, although most of the better projectors will do a pretty good job of scaling the signal to suit. Most HD projectors will also automatically recognise interlaced or progressive scan signals.    Once you have set the video output, you can ignore the front panel display of the STB, as it will display all the information you want via the video screen. The next step is to get the STB to scan all the available channels. You can do this manually but it is far quicker and easier to just let the STB get on with it. Afterwards you can decide to get rid of channels you don’t want, rename them, change their order or whatever. Inside view of the Tevion TEV8200: note the large and complex PC boards and the large number SMDs and electrolytic capacitors. The electros look as though they might have been hit by a mini-tornado, don’t they? March 2008  15 Initially though, just let the STB do it. It will then come up with a display of all the channels available in your location, together with their signal strength and quality. It is here that an STB can demonstrate surprisingly good results. In my setup I have a 4-bay UHF antenna with direct line of sight to Sydney’s North Head (Mosman/Manly) translator and it gives good reception of the existing analog stations (ABC, SBS, 7, 9 & 10). The Tevion picked up the equivalent digital channels as you would expect, plus a brace of digital datacast channels (D44) which are available only in Sydney at the time of writing. I certainly did not expect to pick up the D44 channels – they must be coming in from the side of the UHF array. (For a signal coverage map, see www.dba. org.au/uploads/images/NSW_Syd_ Datacast_coverage_map.jpg As well, it also picked up the Prime and WIN digital and HD channels from Wollongong, about 85km to the south of my location on Sydney’s northern beaches. These latter channels do come and go at my location and it is possible that the intermittent reception was a case of summer-time tropospheric “ducting”. Suffice to say that there is no equivalent DX (ie, long distance) reception of UHF analog channels from Wollongong and SBS and ABC digital signals didn’t make it either. The really good point about digital TV reception is that, provided the STB can pick up the signal, the picture is rock steady with no sign of ghosting or noise. Even if you have pretty good analog TV reception, the transition to digital is a revelation, with the picture quality the same as obtained from a standard definition DVD, depending on your video signal connection and the quality of your monitor. The Tevion STB has two further benefits when the signal strength momentarily dips, as it may do on the weaker signals. Instead of the annoying random pixellation of the picture, the whole picture freezes and then a panel may be displayed with the message “No signal”. Furthermore, there are no loud zaps or cracks from the speakers as the sound drops out. Instead, the sound is muted, without any clicks. Nor are there any clicks when the sound is restored. Having written that, I noted than when watching weak HD broadcasts the picture does sometimes also suffer from momentary freezing and pixellation. Still, it is not as severe as I have noted on other (SD) STBs. For my checks I connected the Tevion to an older Panasonic 68cm analog TV (TC-68P22A) and a Panasonic AE700 LCD projector. On the analog TV, via the composite video connection, I had the satisfaction of seeing HD TV broadcasts without problems, although the picture quality was no better than noise-free PAL, as you would expect. Via the Panasonic projector and the component video connection, the pictures are first class, even on standard definition. In fact, I must admit, after watching the very large pictures This is what usually happens during loss of signal. The picture freezes and you get a panel with the message, “No signal”. Occasionally the picture becomes pixellated. 16  Silicon Chip available via an HD LCD projector, I still have problems coming to grips with the excellent picture quality – it still seems too good to be true. For one who has experienced the limitations of black and white and then PAL colour TV reception, the results from digital TV are a revelation, as noted above. In spite of that, it must be said that the picture quality from most of the supposed HD programs is apparently no different from that of SD broadcasts. You only have to see the outstanding quality of the so-called “HD loops” broadcast by some of the commercial networks to see the dramatic difference with true HD. I should also note that the Panasonic AE700 is not a “true HD” projector. True HD requires a picture resolution of 1920 x 1080 pixels or better. Aspect ratio Another point of interest with the Tevion is that you can select the picture aspect ratio to be shown on your TV set or display. You have three choices, 4:3, 16:9 or Panscan. This is perhaps the biggest disadvantage of watching digital TV on an analog set with a 4:3 picture tube; no matter which aspect ratio setting you choose, the results are less than optimum. If you choose 16:9, you will have black strips at top and bottom of the picture, just as you do, for example, with current analog broadcasts of ABC and SBS news programs. If you choose 4:3, you get a 4:3 picture, within a black rectangle – not very satisfying. On changing channels, you get this electronic program guide for a few seconds. Lately, though, we have noticed increasing instances of “no information” . siliconchip.com.au The rear view of the Tevion TEV8200 shows a comprehensive array of video and digital output connectors. Note that DVI and HDMI connectors are included; essential if you are to get the best picture from LCD and DLP projectors. And if you chose panscan, the whole screen area is filled but inevitably, you lose the sides of the broadcast picture. Oh, well...never mind. As an aside, the commercial networks have yet to standardise their program and advertising content and the aspect ratio can vary between 16:9, 4:3, letter-box and so on. It is also very annoying for people with 4:3 sets when watching sports – the 16:9 format means that sport scores often cannot be seen. Also on the negative side, sound quality appears to be only average and there is a fair amount of high frequency “frizzle” and a low level tone which is probably related to the switchmode power supply. You have two choices for sound quality by the way, although the modes are limited: stereo (MPEG1/2) via the audio outputs or Dolby AC-3 via the SPDIF connection. Presumably, the AC-3 mode would be free of highfrequency frizzle but we did not test it. The remote control provides 20-level adjustment and muting. Incidentally, all the screen shots of the Tevion STB shown in this article were taken with a 6-megapixel digital camera (Fuji Finepix S6500fd) from the Panasonic analog TV mentioned above. One of the problems with taking these shots was the strobing effect between the TV scan rate and the camera’s picture update, together with the inevitable Moire patterns evident because of the interference between the camera’s CCD pixel structure and the vertical slot makeup of the TV screen (perhaps this might have been reduced if the shots were taken at siliconchip.com.au maximum file size). A consequence of the strobing is a tendency to get a light band through the centre of the picture, in spite of using a slow shutter speed of 1/15 second. So while some of the various off-screen shots may look fairly poor, the actual picture quality was generally very good, as already noted. Incidentally, all of these picture problems could have been avoided if I had taken the screen shots using the Panasonic projector, particularly if its “freeze frame” feature was used. But this would have defeated the purpose, as I wanted to show what is displayed on a typical analog TV set. Interestingly, I found that the Aspect Ratio selection from the Tevion STB over-ruled the aspect ratio control on the Panasonic projector – not sure why that happens. One aspect of digital TV that is not well-known is that digital radio services are available from ABC and SBS. Also available in rural areas is the Mytalk datacasting service. See www.mytalk.com.au/NewDesign/ Pages/Datacasting.asp Finally, the Tevion offers the ability to view subtitles via teletext and it has a selection of simple video games – perish the thought! Inside the box A look inside the box shows the Tevion HD STB is far more complex than typical standard definition STBs. It has a large main PC board which is packed with surface mount devices and a surprising number of electrolytic capacitors. I have to say that QC in assembly was a bit lacking: the electros are soldered in every-which-way but vertical! The switchmode power supply board is also quite large, again with a number of electrolytic capacitors. Interestingly, while the Tevion is double-insulated, it is fitted with a three-core mains cord and moulded 3-pin plug. Power consumption of the Tevion is listed as 20W. We measured power consumption at 14W, dropping to 12W on standby. Why the small drop? Surely, standby power should only be a watt or two? This means that the Tevion should be switched off at the power socket when not in use. All settings are saved in non-volatile memory when the power is off. A USB socket on the rear panel is included for software upgrades and interestingly, the operating system is Linux. The main chip is an ATI Xilleon X210H. Conclusion If you don’t intend purchasing an HD TV set in the near future, you should consider purchasing an HD STB such as this Tevion TEV8200. For a relatively small outlay, you will get the immediate benefits of much better picture quality and a great range of TV programs. Sure, it’s not perfect and its standby power use is on the high side but the pictures outweigh the drawbacks. And to save power, all you have to do is turn it (and anything else that goes to “standby” with a remote control) off at the power point. Our recent series of articles on power usage showed just how wasteful standby power is – and how much (power AND $$$) you can save with the simple step of turning things off! SC March 2008  17 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 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 How to solder SURFACEMOUNT DEVICES Many electronics enthusiasts hesitate to build projects involving surface-mount devices (SMDs) because they’re daunted by the prospect of soldering such tiny parts to a PC board. But it can be done. Jim Rowe shows us how. . . I T’S TRUE THAT SMDs are not really intended for manual assembly. They’re designed for automated pick-and-place machines and reflow soldering ovens. The problem is that more and more ICs and other components are becoming available only in SMD form. As technology marches on, it’s becoming necessary for everyone to get used to working with SMDs. 222 1.5 3.00 '1206' CHIP RESISTOR 1.5 0.6 3.00 '1206' CHIP CAPACITOR 222 0.6 You may already be familiar with the simpler SMDs like resistors, capacitors, diodes and transistors. Some of these are shown in Fig.1. Note that they’re all shown twice actual size, for clarity. We’ve used these in various projects published in the last few years, and shown how they can be soldered onto a PC board: use a soldering iron with a fine conical or ‘flattened conical’ tip 1.3 2.0 '0805' CHIP RESISTOR 0.5 1.3 2.0 '0805' CHIP CAPACITOR 0.5 1.25 1.7 1.0 SOD-323 DIODE 2.92 4.9 1.3 1.0 SOT-23 TRANSISTOR OR DIODE Fig.1: a selection of common SMD components, shown here twice full size (if we showed them normal size they’d be hard to see in some cases!) 22  Silicon Chip and very fine (0.71mm OD) resin-cored wire solder. Figs.2 & 3 show how this is done. The basic idea is to hold the chip or device in place while you tack-solder one or two of its leads to hold it in position. This then allows you to solder all of the leads to their pads in the usual way. It needs to be done carefully and fairly quickly, so you don’t damage 6.6 3.9 1.5 8-LEAD SOIC 6.1 2.3 D-PAK POWER TRANSISTOR OR REGULATOR siliconchip.com.au either the SMD or the PC pads by overheating. You also need to make sure you don’t apply too much solder, which can cause fine solder “bridges” to short between pads or tracks. If you do get solder bridges, they can be removed by applying the end of some fine de-soldering braid to the top of the “bridge” and briefly applying the tip of your soldering iron to the top of the braid, so the end of the braid heats up to the solder’s melting point and ‘sucks up’ the excess solder by capillary action. OK, so what is the real problem with SMDs? Um, it’s the large SMDs with umpteen dozen closely spaced pins. TIP OF TOOTHPICK 'HOLD DOWN' SOLDERING IRON TIP TINY DROP OF SOLDER UPPER TIP OF CROSSOVER TWEEZER 'HOLD DOWN' SOLDERING IRON TIP SMD CHIP COMPONENT COPPER TRACK AND PAD 1 LOWER TIP OF CROSSOVER TWEEZER PC BOARD Holding SMD chip in place while applying a tiny solder drop with soldering iron tip to “tack” one end SOLDER TACK NOW HOLDING CHIP IN PLACE SOLDER 1 Holding SOT, SOD, SOIC or similar semiconductor device in place while tacking one pin SOLDER TACKED LEAD NOW HOLDING DEVICE IN PLACE SOLDER 2 Other end of SMD chip now soldered to pad in normal way 2 Pin or pons on other side of device now soldered to pads in normal way 3 First end finally re-soldered in normal way 3 Pin on first side re-soldered, others soldered in normal way Fine-pitch ICs More and more VLSI (very largescale integration) devices now come in SMD packages like that shown opposite and those in Fig.4 – quad flat packs (QFPs) with anywhere between about 44 and 208 leads. The lead pitch can be as fine as 0.4mm – less than 16% the pitch of 0.1”/2.54mm used in most familiar ‘dual in line’ IC packages. The width of the leads can also be as fine as 0.18mm (that’s right – only 180mm!), so the actual spaces between the leads can be as small as 0.22mm/220mm. Now it is possible (just!) to solder a 44-lead MQFP device with 0.8mm pitch leads like that shown in Fig.4 using a fine-tipped soldering iron and the technique shown on the right in Fig.3. That’s providing you are extremely careful, have a very steady hand and don’t mind having to use the soldering braid to remove the almost-inevitable solder bridges. If you can do this consistently, you are a champion! The real problem arises when it Fig.2: the basic steps involved in manually soldering smaller SMDs like those shown in Fig.1, using a fine-tipped soldering iron and very fine resincored wire solder. The steps for resistors and capacitors (left) are much the same as those for SOT, SOD and SOIC devices (right). UPPER TIP OF CROSSOVER TWEEZER 'HOLD DOWN' SOLDERING IRON TIP LOWER TIP OF CROSSOVER TWEEZER 1 2 Holding down MQFP or similar “Gull Wing” IC package while tack-soldering one corner lead Opposite diagonal pin of device now tack-soldered in same way, to locate all pins on their pads. FINE (0.71mm OD) RESIN CORE SOLDER 3 Close-up view of a 44-lead MQFP device with 0.8mm pitch (lead spacing), after being reflow soldered using a low cost snack oven. siliconchip.com.au UPPER TIP OF CROSSOVER TWEEZER 'HOLD DOWN' First “tacked” pins now re-soldered, others soldered in normal way. SOLDERING IRON TIP LOWER TIP OF CROSSOVER TWEEZER 1 2 Holding down PLCC or similar “J-lead” IC package while tack-soldering one corner lead Opposite diagonal pin of device now tack-soldered in same way, to locate all pins on their pads. FINE (0.71mm OD) RESIN CORE SOLDER 3 First “tacked” pins now re-soldered, others soldered in normal way. Fig.3: manual soldering of SMD ICs with lead pitches of 0.8mm or more can be done in the same way if you’re VERY careful but be prepared for the accidental creation of solder bridges between leads – and having to remove them using solder wick. As you can see there’s not much difference in approach between ‘gull wing’ and ‘J-lead’ devices. March 2008  23 LEAD PITCH 0.8mm LEAD WIDTH 0.38mm 10.0 LEAD PITCH 0.5mm 14.0 LEAD WIDTH 0.22mm 10.0 14.0 2.45 44-LEAD METRIC QUAD FLAT PACK (MQFP) ALL DIMENSIONS IN MILLIMETRES 1.60 100-LEAD LOW PROFILE QUAD FLAT PACK (LQFP100/SOT407-1) (BOTH DEVICES SHOWN 2x ACTUAL SIZE) Fig.4: the key dimensions of a 44-lead MQFP device compared with those for a 100-lead LQFP device – both shown twice actual size for clarity. You can see why the fine-pitch devices can’t be soldered in manually or even by wave soldering. comes to devices with lead pitches of 0.4mm or 0.5mm, like the 100-lead LQFP device shown in Fig.4. These packages are not even suitable for automated wave soldering, let alone manual soldering. The leads and gaps between them are just too narrow. The only way to solder these devices is by reflow soldering. This process involves applying solder paste to all of the tiny pads on the board (using a laser-cut stencil and squeegee system), then placing the SMDs accurately in position on the board. The boards are then placed on a conveyor belt and passed through an ‘IR reflow oven’ at a controlled rate, using infrared radiant heating. Inside the oven they move through areas with temperatures set for preheating, followed by a ‘ramp up’ to above the melting point of solder and then a ‘ramp down’ to well below the melting point. This is known as a ‘reflow soldering profile’. Using this approach, SMDs with a lead pitch of 0.4mm can be soldered to boards safely and with a high degree of reliability, at the same time as all of the other SMD components. The main drawback is that a commercial IR reflow oven is very expensive (many thousands of dollars) and thus beyond the reach of enthusiasts and even many small manufacturers. Getting laser-cut solder paste stencils made from your PC board CAD file is not cheap either. 24  Silicon Chip So the challenge is to find a much cheaper way of soldering these finepitch SMDs into PC boards. Luckily, there is a way! amount of solder paste to every pad on the PC board where an SMD lead or contact area is to be soldered. This is shown in the upper two diagrams of Fig.5. This technique simply it isn’t practical for small manufacturers or enthusiasts. A much simpler approach involves applying a thin ‘stripe’ of paste along the pads for the SMD leads, as shown in the lowest diagram in Fig.5. The stripe of paste is only a millimetre or so wide and can be applied using a fine brush, a very narrow roller applicator or a fine spatula with a 1mm wide tip. You’d think that applying a continuous stripe of solder paste in this way would be ‘asking for trouble’ for it to SOLDER PASTE SQUEEGEE STENCIL About solder paste Solder paste is available from the better electronics stores. It consists of tiny spheres (<50mm in diameter) of tin-lead solder (63% tin, 37% lead), suspended in a water-soluble paste or gel of flux. It’s typically sold in fairly large plastic syringes, holding about 80 grams of solder paste. This is actually far too much for the average enthusiast, because the ingredients in the flux apparently have a shelf life of only six months after manufacture, even when stored in a refrigerator. Yet 80g of paste is enough to solder many hundreds – even thousands – of SMDs. So while solder paste is available, it’s a pity that it isn’t sold in much smaller quantities – say 5g or 10g. This would mean a lot less wastage. By the way, when you buy solder paste, make sure you store it in a refrigerator so you’ll at least maintain its six-month working life. And if you store it in a fridge that is also used to store food (of course!), place the syringe in an air-tight container because both the solder spheres and the flux apparently give off toxic fumes. Applying the paste As mentioned earlier, largescale manufacturers use lasercut stencils and a squeegee system to apply just the right COPPER PADS PC BOARD APPLYING SOLDER PASTE USING A STENCIL AND SQUEEGEE SOLDER PASTE LEFT ON PADS AFTER STENCIL IS REMOVED THIN SOLDER PASTE STRIPE OVER PADS LOW COST ALTERNATIVE: MANUAL APPLICATION OF SOLDER PASTE 'STRIPE' Fig.5: for reflow soldering, largescale manufacturers apply solder paste to the board pads using a squeegee and a very thin stencil, laser cut from the PC board CAD file (top). This leaves the paste neatly on the pads (centre) but this is not feasible for enthusiasts. Luckily for fine-pitch SMDs, a very thin paste stripe (bottom) is almost as good. siliconchip.com.au Above: a closeup view showing a thin ‘stripe’ of solder paste applied manually to the pads for one side of a 100-lead LQFP device, with the tiny solder spheres just visible. This stripe is a tad uneven in thickness – a little too thick near the left end, and a little too thin towards the centre. Below: closeup of the same board after the device had been reflow soldered using a snack oven. Despite the 0.5mm lead pitch, there were no solder bridges. soldering process - not easy to repair! So the most important thing about this manual approach to applying the solder paste is to take your time and care in making the stripe as even in width as you can. It’s easiest to do this with the board under a magnifier lamp or even a low-power stereo microscope with illumination. I’ve also found that a very thin and narrow-tipped (about 1mm) spatula seems to make it easier to apply and even-up the paste stripe, although a very narrow ‘applicator wheel’ (I made one myself) was almost as good, and easier than a fine brush. Whatever you use, the main ingredient is time and patience – applying solder paste is a bit like trying to spread microscopic caviar evenly on a sheet of glass. In fact, since you have plenty of paste, do a few dry runs on a sheet of PCB copper laminate. Placing the SMDs form bridges between pads, during the reflow soldering process. However the secret of this approach is to make the paste stripe very THIN – only about 100mm wide or two solder spheres thick. If it’s no thicker than this, the result is that surface tension and capillary action causes the solder spheres to ‘pull themselves together’ into the gaps between each SMD lead and its board pad, when they melt during the reflow soldering. Most of the solder spheres in the paste between the pads get sucked into the molten solder directly under each SMD lead, leaving very few to form bridges. Not too thick, not too thin If you make the paste stripe too siliconchip.com.au thick, there WILL be enough spheres left in the gaps between pads to form bridges. On the other hand, if you make the stripe too thin, there will be insufficient spheres to pull together and form a good bond between each SMD lead and its pad underneath. So erring in this direction results in ‘missing joints’ after the reflow Once the solder paste has been applied to the board, you can place your fine-pitch SMD(s) in position, with their leads over the board pads ready for the reflow soldering process. Large-scale manufacturers use a pick and place machine to place all of the components on the board in one pass – not just the fine-pitch SMDs but everything else as well. Then all parts can be soldered to the board in a single pass through the reflow oven. But that’s not really feasible if you’re placing all of the components manually. Our method is to place the fine-pitch ICs on your board first, then do their reflow soldering. After the board cools down you can then inspect the results and if all is well you can proceed to solder in all of the rest of the components one by one, using the fine-tipped soldering iron approach illustrated in Figs.2 & 3. You may be wondering how accu- The business end of a ‘mini spatula’ made by the author for applying a stripe of solder paste on pads for fine pitch SMDs. It’s shown here about 3x actual size. March 2008  25 So depending on the location of your fine-pitch SMDs on the board, the reflow operation can easily result in a ring of scorching on the underside of the board. The result is a totally unusable board and the SMDs won’t be able to be salvaged either. TEMPERATURE (°C) 250 225 200 183 Get an old frypan 150 SNACK OVEN TURNED OFF AT 205°C 100 50 0 0 1 2 3 4 5 6 TIME (M) NOTES: SHADED PINK AREA SHOWS RECOMMENDED TEMPERATURE PROFILE LIMITS 183°C = MELTING POINT OF TIN-LEAD SOLDER (60/40) 225°C = RECOMMENDED PEAK REFLOW PACKAGE TEMPERATURE BLACK CURVE = MEASURED TEMP PLOT OF BOARD & ICS ON 220 x 140mm x 4mm THICK ALUMINIUM PLATE, HEATED INSIDE KAMBROOK 650W KOT-150 SNACK OVEN ('BAKE' SETTING, USING BOTH ELEMENTS) Fig.6: The shaded pink area shows the reflow soldering temperature profile limits recommended by SMD manufacturers. The solid black curve shows the measured temperature plot achieved by the author using a low cost snack oven on ‘BAKE’. rately you have to place the fine-pitch IC packages in position, before reflow soldering. The answer is placed FAIRLY accurately but not fanatically so. The main thing is to make sure that every device lead is over its corresponding PC board pad, and closer to that pad than it is to any other pads nearby. If you achieve that, when the solder spheres in the paste melt and coagulate during the reflow process, surface tension and capillary forces in the molten solder will automatically ‘pull’ all of the leads into position centrally over their pads. So the idea is to carefully lower the IC package (orientated correctly, of course) into position using a ‘vacuum pickup tool’ or similar, and then nudge it gently into the correct position using a fine jeweller’s screwdriver or ‘pick tool’. Again, it’s easiest to do this under a magnifier lamp or stereo microscope, preferably one where you can rotate the board and IC until you’re happy that all leads are over their pads on the board. Once all of the fine-pitch SMDs have been placed carefully in this way, your 26  Silicon Chip board will be ready for reflow soldering. Be very careful not to bump or jar it, because the SMDs could easily be jolted out of position. Reflow soldering Now how do we do the actual reflow soldering? If you use an online search engine to track down info on reflow soldering, you’ll find that quite a few have tried doing it with an electric frypan or skillet. The basic idea is to place the PC board in the centre of the frypan, applying power until the solder paste clearly melts and flows under each SMD lead, then turn off the power and allow it all to cool down. This can work – but there is a big risk of scorching the underside of the PC board; inevitably the underside of the board must be raised to a temperature considerably higher than the melting point of solder. This board-overheating problem tends to be made worse because the heating element in the underside of most frypans is circular in shape. This produces uneven heating of the PC board, with a cooler region in the centre surrounded by a ‘ring of heat’. If you decide to try the frypan approach, please don’t use a frypan that is also used for cooking food. The fumes given off by solder paste during the reflow process are quite toxic and are likely to be absorbed by the frypan metalwork and/or Teflon coating. So the toxins may well be transferred into any food cooked in the frypan afterwards. Buy a cheap frypan specifically for the job, and mark it clearly ‘NOT TO BE USED FOR FOOD COOKING’. Because of the toxic fumes given off during reflow soldering, it’s also very desirable to do it in a well-ventilated area – preferably outdoors. This applies regardless of whether you use a frypan or some other heating device. Having read the references on the web about reflow soldering using a frypan, I decided to try it but with a slightly different approach. I bought a cheap frypan, then did a few experiments with it. To try getting around the board scorching problem, I cut a ‘heat spreader’ plate from 4mm thick aluminium sheet, and placed this in the centre of the frypan with my test board sitting on it. This did seem to make the heating fairly even but there was still a major problem. Even with the frypan’s thermostat set for maximum, the temperature on the top of the PC board never reached the melting point of solder (183°C), let alone the 215° level that is necessary to ensure good reflow. Presumably the small air gap between the bottom of the frypan and my spreader plate added too much thermal resistance. So I removed the spreader plate and tried again, with the board placed directly on the bottom of the frypan. This time the temperature on the top of the board did reach about 210°C and reflow took place, but when it all cooled down I discovered that the underside of the board had been scorched in a number of areas that had been directly over the circular heating element. siliconchip.com.au So reflow soldering with a frypan is just not worth the risk. Using a snack oven Another el-cheapo reflow technique that you’ll come across on the web involves the use of a small electric ‘snack’ or toaster oven. Almost all of these use a pair of heating elements, one at the top of the oven compartment and the other at the bottom. Whatever you’re going to heat up in the oven goes on a tray supported by a wire mesh ‘drawer’ in the centre, which is linked to the oven door so it slides in or out when the door is closed or opened. Often there’s a switch which allows you to select either the top element (‘GRILL’) or the bottom element (‘REHEAT’) or both at the same time (‘BAKE’). Each element draws about 325 watts, so the oven uses about 650W when both are used together. Since the reflow operation only involves drawing this power for five or six minutes at most, this isn’t a problem. The main advantage of using this kind of snack oven for reflow soldering is that the heating is done by infrared radiation, on the top of the board as well as from below, just like a ‘proper’ IR reflow oven. The main difference is that your board stays fixed in the oven during the whole process, rather than moving through different temperature regions on a conveyor belt. This means that you have to arrange for the reflow temperature profile to be provided in some other way. This turns out to be easier than you would think. I decided to try the snack oven approach for myself. So I bought a Kambrook KOT-150 snack oven which cost the magnificent sum of $29.95. This has no thermostat, just an electromechanical timer and the element selector switch. But the lack of a thermostat is not a problem and the timer didn’t turn out to be all that necessary either. My first test with the snack oven was to clamp a thermocouple temperature probe onto a test board, which was then placed in the small pressed tinplate tray that came with the oven. The tray was then placed on the oven’s sliding mesh drawer and the oven door closed carefully so the thermocouple lead could exit through a small gap at the top of the door. siliconchip.com.au Here’s the setup we used successfully for reflow soldering of fine-pitch SMDs. The board assembly is clamped on a 220 x 140mm plate of 4mm thick aluminium plate, with a thermocouple probe clamped to the board copper near the 100-lead device. Shortly after this shot was taken the snack oven was turned on, and then turned off again as soon as the digital thermometer reading hit 205°C. The oven was set to BAKE (both elements on) and the timer knob set to apply power for about 10 minutes. I then proceeded to take temperature measurements every 15 seconds. The resulting temperature characteristic turned out to be very close to the solid black curve in Fig.6, which also shows (shaded pink area) the reflow temperature profile limits for fine-pitch SMD IC packages recommended by larger chip manufacturers like NXP/Philips. As you can see, the warm-up characteristic is nicely within the recommended limits. By turning off the power to the snack oven when the temperature on the top of the board just reached 205°C, the board temperature coasted up nicely to a peak at 215° As soon as the temperature coasted down to about 165°C, the door of the snack oven was carefully swung down to allow the entry of more air to speed up the cooling. Both of the SMDs on this board had been reflow soldered very nicely, with no solder bridges between leads or pads. The board had not been damaged in any way, either, so I can recommend the snack oven approach. March 2008  27 and then began to coast down again. It dropped down below the 183°C solder melting point temperature about 6.5 minutes after switch-on, so after waiting about one more minute, I carefully opened the door and drawer to allow cooling to occur more rapidly. When the test board had cooled right down, I took it out of the tray and checked underneath to see if there had been any scorching. There was none at all – even the silk screening on the underside of the board showed no discolouration. Trial run Thus encouraged, I decided to carry out a reflow soldering test on another PC board. This was prepared with solder paste stripes around the pads for a fine-pitch IC and then an SMD device was carefully placed over these pads. Then I made my first mistake. In an effort to make the process a little more controlled, I drilled four 3mm holes in the oven’s tinplate tray, so the board could be fastened into it using four M3 machine screws and nuts. One of the screws was also used to attach the clamp for the thermocouple probe, to hold the probe securely in position with its bead in contact with the board’s top copper close to the SMD chip. The board and tray were carefully It’s not elegant but it works: an SMD chip baking oven, made by the author by converting a discarded blower heater. The reflector part of the heater was flattened and bent into a small rectangular oven shape, then re-attached to the front of the blower heater element (just visible through the opened front door). placed on the oven’s mesh drawer and the oven door gently closed so they slid smoothly inside. Then power was applied to the oven again, measuring the top-of-board temperature every 15 seconds as before. All went well, with exactly the same temperature profile as before. But just as the temperature reached about 200°C (just before I would turn off the power) there was a ‘PING’ sound – apparently the tinplate tray had been under stress as a result of the board being bolted inside and the stress was relieved suddenly when the temperature reached 200°. Having turned off the power as soon as the temperature reached 205°, I waited impatiently while the Ten Tips for successful DIY reflow soldering of SMDs 1. Store your solder paste in a sealed container in the fridge, to prolong its useful life. 2. Take care to apply the solder paste in a 'stripe' along the centre of the SMD lead pads on the PC board, with the stripe no more than about 1.5mm wide and (most important) very thin – no more than about 100 m, or two solder spheres. As even in thickness as you can make it, also – no lumps or voids... 3. Use a small snack oven for reflow soldering. Clamp the PC board on the top of a flat heat diffusion/support plate made from 4mm thick aluminium sheet, say 220 x 140mm in size (to fit comfortably in the snack oven). Also monitor the temperature on the top of the board near one of the SMDs, using a thermocouple probe connected to a digital thermometer. 4. Place the SMD chip(s) in position on the board carefully, with all leads as near as possible to their corresponding board pad. You don't have to be fanatical about this though: the chips will auto-locate during reflow, providing each lead is closer to its own correct pad than to the pads on either side. 5. Place the board and its support plate on the oven's slide-out drawer very carefully, so as not to bump or jolt the SMDs from their positions. Then carefully close the oven door so they slide smoothly into the oven – again without jarring. 6. Use both the upper and lower heating elements of the oven for reflow solder heating. This is usually achieved by selecting the BAKE setting. Using both elements gives more even heating, closer to that in a proper IR reflow oven. 7. Switch on the oven, monitoring the temperature on the top of board using the thermocouple probe and digital thermometer. The temperature should rise fairly smoothly, reaching the melting point of tin/lead solder (183°C) in just under five minutes. Take care not to bump or jar the oven after this. 8. As soon as the temperature reaches about 205°C, turn off the oven power without bumping anything. The temperature will continue rising, to reach a peak at around 215-220°C. It should then begin falling again. 9. Wait until the temperature drops below the melting point of solder – say down to about 165°C. Then it should be safe to open the oven door so the drawer and its contents slides out, to speed up further cooling. 10. When the board has cooled down to around room temperature, remove it from the support plate and check the solder joints on all SMD leads with an illuminated magnifier or stereo microscope. If there are any solder bridges, these can be cut away using the tip of a hobby knife or 'sucked' off using desoldering braid and a fine-tipped soldering iron. 28  Silicon Chip siliconchip.com.au temperature peaked again and crept downwards once more. Once it had dropped to about 165° I carefully opened the door, so the drawer and tray slid outwards. Then I examined the SMD chip with a magnifying glass, only to discover that stress relief ‘ping’ at 200° had caused the SMD chip to be jolted out of position. The reflow soldering had actually occurred quite nicely but with the chip and its leads in the wrong position. Bother! However, the overall result still confirmed that the snack oven was quite suitable for reflow soldering. So I decided to make a much sturdier PC board support plate, to replace the flimsy tinplate tray. The new plate was a 220 x 140mm rectangle of 4mm-thick aluminium plate and had a 3mm hole drilled near each corner, for the board hold-down clamp screws. The holes were countersunk underneath so countersink-head screws could be used to hold down the board, without producing bumps underneath the plate. This was to make sure that the plate and board could be slid smoothly around on the oven’s mesh drawer. Another board was prepared with solder paste and a fine-pitch SMD chip placed carefully in position. Then the board was clamped to the top of the new support plate, the thermocouple probe fitted and the complete assembly placed inside the oven. This time everything went really well. There were no ‘pings’, the solder reflowed nicely and when it all cooled down again a board inspection showed that the SMD chip had settled itself in the correct position and was nicely soldered. And there were no solder bridges! So we are able to report that reflow soldering of fine-pitch SMD chips can be done successfully using a low-cost snack oven like the Kambrook KOT150 shown in the pictures. Listed on the page opposite are the ten important ‘rules of thumb’ when it comes to using a snack oven for successful reflow soldering of finepitch SMD chips. If you follow these rules carefully, success is almost guaranteed. Finally, what about using a “fanforced” snack oven? Not a good idea! That fan could easily blow the SMDs SC out of position. siliconchip.com.au Footnote: About MSL rating If you’re going to be using reflow soldering for SMDs in plastic packages, you should know a bit about the way these devices are rated in terms of MSL or ‘moisture sensitivity level’. Basically, it has been discovered that SMDs in plastic packages have a tendency to absorb moisture when they’re stored in typical ‘shop floor’ or workshop conditions for any significant period of time. The degree of moisture absorption depends on a variety of factors –- including the size of the device package, the number of leads and the relative humidity level in the storage environment. The problem is that when SMDs are heated up during reflow soldering, this absorbed moisture tends to turn into steam, and build up sufficient pressure to cause cracking and other damage inside the package. It can easily damage the chip inside and/or its bonding wires, even if no cracks are visible on the outside of the package. To minimise the risk of this kind of damage during reflow soldering, chip manufacturers nowadays bake most plastic-package SMDs (especially those in fine-pitch packages) for many hours at 125°C in a very dry and inert atmosphere, to drive out any moisture. Then they are sealed in hermetic packaging (‘dry packs’), and the idea is that they should be left in this packaging until just before they’re subjected to reflow soldering. Now because this last-minute unpacking isn’t practical even for big manufacturers and in any case isn’t really necessary for some devices, semiconductor industry standards bodies like JEDEC (formerly the Joint Electron Device Engineering Council) have established a system whereby each device is given a rating to show how long it can be safely left out of its hermetic packaging in a typical 30°C/60%RH workshop or factory environment, before reflow soldering. There are eight of these MSL rating levels, ranging from MSL 1 for packages which are deemed impervious to moisture up to MSL 6 for packages which are very sensitive to moisture and must be reflow soldered within no more than six hours after being removed from their dry packs. You’ll find this MSL rating printed on the dry packs of most SMD devices in plastic packages and certainly for those in fine-pitch packages (which are almost always rated at MSL 2 or higher). Table 2 shows the significance of the various MSL levels. So what do you do if you want to reflow solder an SMD with an MSL level of 2 or higher, if you know has been out of its hermetic packaging for longer than its rated safe time? Or if it hasn’t been out for that long, but subjected to very high relative humidity? The good news is that it can be restored so it can be safely reflow soldered, by baking for about 24 hours at a controlled temperature of between 115-125°C. This can be done in a small fan driven hot-air oven, provided the device is placed in a small metal box to ensure even heating. The box should also have some small vents to allow the escape of any moisture that is released during the baking. I made up a small baking oven by converting a fan-type room heater that had been dumped at council cleanup time. The fan motor, fan and heating element were all in perfect working order, as was its thermostat switch. So all I had to do was remove these components and convert the heater case into a recirculating-air oven. Then the ‘works’ were re-installed and the thermostat tweaked to cycle the oven temperature around 118°C, which produced a rough but quite serviceable DIY baking oven for plastic package SMDs. JEDEC MOISTURE SENSITIVITY LEVEL (MSL) RATINGS MSL rating 1 Safe exposure time at <= 30°C/60%RH before reflow soldering Unlimited (non moisture sensitive) 2 1 year 2a 4 weeks 3 1 week (168 hours) 4 72 hours 5 48 hours 5a 24 hours 6 6 hours (extremely moisture sensitive) March 2008  29 Want to control a really big DC motor? This circuit can handle 12V or 24V DC motors at currents up to 40A. 12V-24V High-Current Motor Speed Controller This 12V or 24V high-current DC Motor Speed Controller is rated at up to 40A (continuous) and is suitable for heavy-duty motor applications. All control tasks are monitored by a microcontroller and as a result, the list of features is extensive. T HIS COMPLETELY NEW speed controller is based on a PIC16F88 microcontroller. This micro provides all the fancy features such as battery monitoring, soft-start and speed regulation. It also monitors the speed setting potentiometer and drives a 4-digit display board which includes two pushbuttons. The 4-digit display board is optional but we strongly recommend that you build it, even if you only use it for the initial set-up. It unlocks the full features of the speed controller and allows all settings to be adjusted. The microcontroller will detect whether 30  Silicon Chip the display board is connected and if not, the speed controller will support only the basic functions. In this simple mode, it will function as a simple speed regulated controller with automatic soft-start and with the speed being directly controlled by a pot (VR1). All the other settings will be the initial defaults or as last set (with the display board connected). When connected, the 4-digit display allows you to monitor the speed and the input voltage (useful when running from a battery). It also enables you to navigate through the various menus to adjust the settings. The circuit can run from 12V or 24V batteries and can drive motors (or resistive loads) up to 40A. Furthermore, this is our first DC speed controller (except for out train controllers) incorporating speed regulation under load. In other words, a given motor speed is maintained, regardless of whether the motor is driving a heavy load or not. Monitoring the back-EMF In speed controllers which do not have good speed regulation (ie, the vast majority of designs), the more a motor is loaded, the more it slows down. In order to provide speed regulation, the siliconchip.com.au Pt.1: By MAURO GRASSI circuit must monitor the back-EMF of the motor, since this parameter is directly proportional to its speed. As a result, our new speed controller monitors the back-EMF of the motor. “Back-EMF” is the voltage generated by any motor to oppose the current through the windings. EMF stands for “electromotive force” and is an obsolete term for voltage. Back-EMF is directly proportional to the motor speed and so by monitoring this parameter, we have a means of controlling and maintaining the motor speed. In practice, the main control loop of the microcontroller tries to match the speed of the motor (back-EMF) to the speed set by the pot or recalled from a preset memory. If the measured speed is lower than the set speed, the duty cycle of the pulse width modulation (PWM) signal used to drive the power Mosfets that control the motor is gradually increased. In other words, siliconchip.com.au if the speed tends to drop, more power is fed to the motor and vice versa. The frequency of the pulse width modulation can be set from 488Hz to 7812Hz. This is a useful feature since different motors will have different frequency responses, as well as different resonant frequencies. This is important to reduce the audible buzzing from the pulse width modulation, as these frequencies are well within the range of hearing. By now you’re probably wondering how the microcontroller monitors the back-EMF of the motor, considering that the motor is continuously driven with pulse-width modulated DC. The answer is that the micro periodically turns off the PWM signal to the motor for just enough time for the back-EMF to stabilise. This “window” needs to be wide enough to ensure that we are measuring backEMF and not the spike generated by the last PWM pulse. On the other hand, we don’t want the window so wide that the maximum power to the motor is significantly reduced or that the motor noticeably slows. The compromise value is that the motor is monitored for 200ms every 7.4ms (ie, about 135 times a second), as shown in the scope diagrams in this article. As a result, the fact that we do monitor the back-EMF around 135 times a second means that the power applied to the motor is slightly less than the theoretical maximum, although this effect is negligible. A low-battery alarm is also incorporated to warn when the battery level drops below a preset value. This is especially useful for applications like electric wheelchairs. There are also eight memory speed settings. All settings are persistent, meaning they are retained in nonvolatile memory. Soft start When the motor is switched off, perhaps by an external switch in series with one of its terminals, the voltage at the drain of the Mosfets will be 0V (this is due to the voltage divider used to scale the back-EMF voltage to within the operating range of the microcontroller). The microcontroller converts this analog value to a digital value using an on-board ADC (analogto-digital converter). The firmware detects this 0V con- Main Features • • • • • • • • • • Good speed regulation under load Automatic soft-start and fast switch-off Eight memory settings 4-digit 7-segment display Variable frequency for pulse width modulation (PWM) Battery level meter Low-battery alarm Persistent settings & defaults Rated up to 40A continuous current 12-24V DC input voltage dition and sets the duty cycle of the PWM to 0%. This ensures that when the motor is switched in, its speed will increase gradually from the stationary state to the desired speed setting. Turn-on currents for motors can be very high and it is desirable to reduce these surge currents as much as possible. That is why the automatic softstart feature has been incorporated into the firmware. It will ensure that the motor is brought up to the set speed gradually. Fast switch-off feature Another feature that has been incorporated into the firmware is the so-called “Fast-off” feature. This means that the duty cycle of the PW modulation is set to 0% (turning off the motor) whenever the selected speed setting of the pot goes to 0%. Rather than decreasing the speed gradually, setting the pot to its lowest setting turns the motor off immediately. This design also incorporates our extensive experience with previous speed controllers featured in SILICON CHIP. As a result, it uses four highcurrent Mosfets to do the switching (pulse width modulation), uses very wide tracks on the PC board and heavyduty (40A) terminal blocks to carry the heavy currents. User interface Two pushbuttons on the display board are used to navigate through the menus, while the pot is used both to vary the speed and to vary certain settings. March 2008  31 Parts List 1 PC board, code 09103081, 124mm x 118mm 2 heavy-duty PC-mount terminal blocks (3-way) (Altronics P2053) 1 8-pin DIP IC socket 1 18-pin DIP IC socket 1 SPDT toggle switch (S1) 1 50A 5AG fuse (Jaycar SF1976) 1 60A 5AG fuseholder (Jaycar SZ2065) 1 12-way pin header (Altronics P-5502) 1 PC-mount mini piezo beeper (Jaycar AB3459 or equivalent) 1 220mH inductor (L1) (Jaycar LF1276 or equivalent) 1 10kW 16mm PC-mount linear single-gang pot (VR1) 1 500W horizontal trimpot (VR2) Semiconductors 1 PIC16F88-I/P microcontroller programmed with 0910308A.hex (IC1) 1 MC34063 switchmode DC-DC converter (IC2) 1 BC327 PNP transistor (Q1) 3 BC337 NPN transistors (Q2-Q4) 4 IRF1405 N-channel Mosfets (Q5-Q8) (Jaycar ZT2468) 1 1N4004 diode (D1) 1 1N5819 Schottky diode (D2) 2 MBR20100CT 20A diodes (Jaycar ZR1039) OR 1 40EPF06PBF 40A ultra-fast diode (Farnell 910-1560) (D3) 5 1N4745 16V 1W zener diodes (ZD1-ZD5) 2 1N5364BG 33V 5W zener diodes (ZD6-ZD7) (Farnell 955-8217) 1 3mm red LED (LED1) Capacitors 1 2200mF 50V low-ESR electrolytic (Altronics R-6207) The two pushbuttons are sensitive to two types of presses, short and long. A short press is of the order of half a second or less while a long press is one around one second. To change a setting, a long press is usually needed. This prevents unwanted changes to the settings, which are stored in EEPROM and thus recalled at the next switch on. Because of the capabilities offer­ed by the PIC microcontroller, we have 32  Silicon Chip 1 470mF 16V electrolytic 1 100mF 63V electrolytic 1 100mF 25V electrolytic 1 10mF 25V electrolytic 3 4.7mF 16V electrolytic 1 220nF 100V MKT polyester 1 100nF 100V MKT polyester 3 100nF monolithic 1 470pF ceramic Resistors (0.25W, 1%) 2 33kW 1 100W 2 4.7kW 1 56W 1 3.6kW 1 22W 1W 6 1kW 4 15W 2 470W 3 1W Display Board 1 PC board, code 09103082, 73mm x 58mm 1 200mm length 16-way rainbow cable 1 12-way pin header (Altronics P-5502) 2 12-way header plugs (Altronics P-5482) (to terminate cable) 1 SPST PC-mount momentarycontact switch, yellow (Jaycar SP0722; Altronics S-1097) (S2) 1 SPST PC-mount momentarycontact switch, red (Jaycar SP0720; Altronics S-1095) (S3) 1 16-pin DIP IC socket (optional) 1 100nF monolithic capacitor Semiconductors 1 74HC595 shift register (IC3) 4 BC337 NPN transistors (Q9-Q12) 4 7-segment common cathode red LED displays (Jaycar ZD1855; Altronics Z-0190 ) Resistors (0.25W, 1%) 4 470W 8 39W been able to incorporate a large number of features into the firmware, as described in the separate panel later in this article. Circuit description The circuit for the speed controller is shown in Fig.1. As noted previously, it can work with 12V or 24V batteries but has been optimised for operation at 24V. Within the circuit itself, there are two separate voltage rails: +5V for the microcontroller and +16V for driving the gates of the Mosfets. Both are derived from the +24V input supply. The main input supply is filtered by a 2200mF low ESR capacitor, to minimise high-voltage transients which can be produced by the inductance of the battery connecting leads. This capacitor is absolutely vital to the proper operation of the speed controller at high currents. S1 is the power switch and diode D1 protects the low-power part of the circuit (IC1 & IC2) from reverse polarity. A 22W 1W resistor, a 33V 5W zener diode (ZD7) and a 100mF capacitor also protect the MC34063 IC from transients on the supply rail. The filtered supply is then fed to the MC34063 (IC2) which operates in a standard step-down converter configuration to provide the +5V rail. Three 1W resistors between pins 6 & 7 are used to set the maximum switching current. The output voltage is set by the voltage divider associated with trimpot VR2. Only about 200mA is ever drawn from this supply and most of this is used to drive the display. IC1 is the heart of the circuit and is the popular PIC16F88 microcontroller which incorporates a number of peripheral functions. Of these, the timers, hardware PWM (pulse width modulation) and three ADC inputs are used. The three ADC inputs used are at pins 1, 2 & 18. As these need to be within the 0-5V range, voltage dividers consisting of 33kW and 4.7kW resistors are used to scale both the input voltage rail (which could be as high as 29V) and the back-EMF from the motor, to be fed to the ADC inputs at pins 1 & 18. The ADCs convert the monitored voltages to 10-bit values. The +16V rail is used as the gate drive supply for the Mosfets and is derived from the 24V supply via a 1kW resistor and a 16V 1W zener diode (ZD1). Bypassing of this rail is particularly important and is accomplished using 100mF and 100nF capacitors near ZD1 and adjacent to the transistors Q1 & Q2. If the battery supply is to be 12V, the 1kW resistor feeding ZD1 should be reduced to 100W. In this case, the supply will actually be between 12V and 14V (depending on the actual battery voltage); still enough to provide adequate gate drive for the Mosfets and siliconchip.com.au siliconchip.com.au March 2008  33 Fig.1: the circuit uses PIC16F88 microcontroller IC1 to provide PWM drive to power-Mosfets Q5-Q8 which in turn control the motor. The microcontroller also monitors the back-EMF from the motor, to provide speed regulation. IC2 is a DC-DC switchmode converter and this provides a +5V rail to power IC1. a f DISP 3 a a b g e f g e c d b f g e c C B E C Q10 b f C Q11 E E g e d B 8x 39 a c d Q9 DISP 4 b c d B C Q12 16 Vdd 15 Qa 1 Qb SRClr 2 Qc 3 Qd IC3 Sck 4 Qe 74HC595 Rck 5 Qf OE 6 Sin Qg 7 Qh Vss 8 100nF 10 +5V 11 12 13 10 9 8 7 6 5 14 4 B 11 12 2 3 470 E 470 Q9–Q12: BC337 470 470 B E SC  2008 CON2 1 (TO MAIN BOARD) DISP 2 DISP 1 C DC MOTOR SPEED CONTROLLER S2 S3 DISPLAY BOARD Fig.2: the display circuit interfaces to the microcontroller & uses a 74HC595 shift register (IC3) & transistors Q9Q12 to drive four 7-segment LED displays. Switches S2 & S3 are used to control the display & for software set-up. ensure minimum heat dissipation (low on-resistance). The PWM output of the PIC16F88 (adjusted by firmware) appears at pin 6 and drives transistor Q3 which then drives complementary transistors Q1 & Q2. Q1, Q2 & Q3 thus provide buffering and voltage level translation for IC1’s PWM output to drive the gates of Mosfets Q5-Q8 via 15W resistors. Note that these resistors need to be relatively low in value (ie, 15W) in order to ensure quick charging and discharging of the gate capacitances. That’s because the gate capacitance of these Mosfets can be quite high, of the order of 5000-10,000pF each. If the gate charging time is too long, the Mosfets will spend too much time between the on and off states and this will lead to much higher heat dissipation. In fact, the gate voltage transitions need to be very fast, of the order of 1ms or less. This has been accomplished, as shown by the oscilloscope screen grab of Fig.4. The specified Mosfets are from International Rectifier, type IRF1405. This is a 55V 169A N-channel Hexfet with an exceptionally low on-resistance (Rds) of 5.3 milliohms (5.3mW) typical. Their pulse current rating is a stupendous 680A. The IRF1405 is specifically intended for automotive use, in applications such as electric power steering, anti34  Silicon Chip lock braking systems (ABS), power windows and so on and is therefore ideal for this speed control application. Why four Mosfets? In fact, since the ratings of this Mosfet are so high, you might think that just one device on its own would be enough to handle the 40A rating of this speed controller project. So why are we using four Mosfets in parallel? As always, real world use brings us down to earth. For a start, we are using these Mosfets without heatsinks, apart from the vestigial heatsink effect of their being bolted to and connected to the copper side of the PC board – not much heatsink benefit there. Their thermal characteristic is 62°C per watt (junction to ambient), assuming that are mounted in free air (which they are not). Assuming an ambient temperature of 25°C and an on-resistance of 10mW (conservative), we can approximate the temperature of the Mosfets at their highest operating current (10A per Mosfet for a total of 40A). At 10A and 10mW on-resistance, the power dissipated is: 102 x .01 = 1W This means that the temperature of the case will be approximately: 25 + 62 x 1 = 87°C This means that at full current, the Mosfets will be very hot to the touch. Careful: they will burn you. Our measurements produced a top temperature of around 77°C after a test period of half an hour. In practice, even with much higher ambient temperatures, the Mosfets should not get quite this hot because in “real world” operation, the speed control is not likely to be providing full power to the motor on a continuous basis. At 24V and 40A, the motor would have 960W applied (ie, more than 1HP) and this equates to relatively high power operation. Protection Zener diodes ZD2-ZD5 are included to protect the Mosfets from excessive gate voltages. In normal circuit operation, these zener diodes do nothing. Additional protection for the drains of the paralleled Mosfets is provided by 33V 5W zener diode ZD6, in parallel with a 100nF capacitor. The zener is there to clip any residual voltage transients which get past the 2200mF low-ESR input filter capacitor. The Mosfets are further protected by fast-recovery diode D3 and its parallel 220nF capacitor. These parts are wired across the motor terminals and are used to suppress the high back-EMF spikes caused by the armature inductance when the motor is switched off by the Mosfets. These components are crucial to siliconchip.com.au Fig.3: the yellow trace is the voltage waveform at the drain of the Mosfets, when a motor is connected. There are narrow spikes up to 31.7V when the Mosfets switch off due to the inductance of the armature. The small windows where the Mosfets are switched off to sense the back-EMF of the motor can also be seen. The two vertical cursors show that the period between such intervals is of the order of 7.6ms. In other words, the speed of the motor is monitored at 131Hz. Fig.4: the yellow trace is the voltage waveform at the drain of the Mosfets, while the purple trace is the gate drive. The gate drive goes as high as 15.3V. The rise time of the gates is 526ns while the fall time is 92ns. When switching the Mosfets on and off, it is necessary that the transition be fast, ideally under 1ms, otherwise the Mosfets will dissipate more heat than is necessary. To ensure fast switching of the Mosfets their gate capacitance needs to be charged and discharged very quickly. Fig.5: the yellow trace shows the voltage waveform at the drain of the Mosfets when a motor is connected. The irregular waveform corresponds to the back-EMF monitoring. The Mosfets are then off and the voltage is then directly proportional to the speed of the motor. The window is narrow enough so that the motor’s deceleration is negligible. Turning off the Mosfets to monitor the backEMF is asynchronous to the PWM driving the Mosfets. Fig.6: the yellow trace is the voltage waveform at the drain of the Mosfets and the purple trace is the waveform at the gate of the Mosfets when a motor is connected. Again, the irregular yellow waveform (arrowed) corresponds to the period when the Mosfets are switched off to sense the back-EMF and hence the speed of the motor. You can see from the purple trace that the gate drive during this time is 0V. the operation of the speed controller. Without them, the high voltages generated can and probably would destroy the Mosfets. Other protection measures As already mentioned, diode D1 provides reverse polarity protection for microcontroller IC1 and the switchmode supply (IC2). Zener diode ZD1 is self-protecting in the case of siliconchip.com.au reverse supply connection. However, if the supply is reversed, there will be a heavy conduction path via fast recovery diode D3 and the internal substrate diodes in the four power Mosfets. If you are lucky, the 50A fuse will blow before the Mosfets are damaged but there is no guarantee of this. SO DON’T REVERSE THE BATTERY CONNECTIONS! In a similar vein, if the outputs are shorted while power is applied, high current will flow through the Mosfets. Again, if you are lucky, the 50A fuse will blow before the Mosfets go up in smoke. In reality, the 50A fuse is there to stop a fire! SO DON’T SHORT THE OUTPUTS TO THE MOTOR. If the motor is under heavy load and becomes stalled, high currents will flow in its armature. Depending on the motor’s rating, this may or may not March 2008  35 This view shows the fully assembled main board. The assembly details are in next month’s issue. Fig.7: the yellow trace shows the voltage waveform at the drain of the Mosfets, the purple trace shows the voltage waveform at the gates and the cyan trace shows the voltage waveform at the PWM output of the microcontroller. Note that transistors Q1-Q3 provide voltage translation by stepping up the 5V output from the microcontroller to 12-16V. This higher voltage is needed to ensure that the Mosfets are fully turned on. blow the fuse. If the fuse does not blow during stall conditions of the motor, the Mosfets should survive although they may get very hot. Warning buzzer If the circuit is overloaded, the battery voltage should drop to the point where the warning buzzer will sound. LED1 and its 470W current limiting resistor are switched by a high level on the output of pin 3 of the microcontroller. This is configured as a simple digital output. It also turns on Q4 and the piezo beeper. This output is controlled by the firmware and can be disabled. A 1kW pull-up resistor is used on pin 4 (reset) of the PIC16F88-I/P. This ties the reset pin high which means that the microcontroller is reset only at power-on. Finally, the rest of the outputs of the microcontroller, namely pins 7-17, are used to drive the optional display board. Display board Fig.2 shows the optional display board circuit. It connects to the main board via 12-pin header CON1 and a ribbon cable. The display board consists of two pushbuttons, four 7-segment displays which are multiplexed by the firmware, four transistors and some resistors, as well as a 74HC595 shift register (IC3). Pins 1 & 2 of 12-way connector CON2 supply +5V to the display board. Pin 3 is connected to a digital input The optional display board is connected to the main board via a 12-way ribbon cable. It displays the motor speed as a percentage of full speed and is used for the software set-up. 36  Silicon Chip of the microcontroller and is pulled high by a 1kW resistor on the main board. Conversely, it is pulled low by the display board. This is used by the microcontroller to detect whether the display board is connected or not. Pins 4-7 of CON1 are used to drive the transistors Q9-Q12 on the display board. These transistors switch the 7-segment display cathodes. Pins 8-10 of CON1 are respectively the CLK, DATA and OUTPUT ENABLE lines and these go to the 74HC595 shift register (IC3). The microcontroller drives these lines to load a new 8-bit value into the shift register. The outputs of the shift register are connected across the four 7-segment displays and drive the anodes. Finally, pins 11 & 12 are connected to pushbuttons switches S2 & S3 on the display board. They are also connected to digital inputs on the microcontroller (which have internal pull-ups enabled) and these inputs are used to monitor the pushbuttons. Next month, we will cover the construction and troubleshooting of the speed controller. In the meantime, take a look at the “Software Features & Set-up” panel on the facing page. siliconchip.com.au DC Motor Speed Controller: Software Features & Set-up T HE STRUCTURE of the firmware for the DC Motor Speed Controller is shown overleaf in Fig.8. The transitions between the various menus are made using the switches on the display board and are indicated with labelled arrows. There are four possible switch presses, either Short or Long and either the Left (L) or Right (R). Thus, for example, “Short R” refers to a short press of the right pushbutton. Main menu The Main menu is as shown in Menu 1. It consists of the letter ‘P’ (for “percentage”) and three digits with a decimal point indicating the range 00.0% to 99.9%. The percentage value indicates the fraction of full speed the motor is currently running at. In this mode, the motor’s speed can be adjusted by varying the pot. The letter ‘P’ will flash while the motor’s speed increases or decreases to the new setting. When the current speed reaches the speed set by the pot, the letter ‘P’ will stop flashing and there will be a short beep (if enabled). Since there is a small periodic window when the pulse width modulation is turned off by the firmware in order to read the backEMF, at full speed the reading will not indicate 99.9% but will achieve its maximum at around 98% or so. Monitoring the input voltage From the Main menu, press “Short R” once and you will be taken to the display shown in Menu 2. It consists of a ‘b’ (for “battery”) followed by three digits with a decimal point indicating a level from 00.0V to 99.9V, to monitor the battery. For good voltage accuracy, it is important that the +5V supply rail be precisely set using trimpot VR2. In practice, with the supply rail to the microcontroller set at 5V, the level will not register any higher than around 40.1V. This is because the voltage divider used to derive the voltage reading consists of 33kW and 4.7W resistors. The relatively high series resistance of 37.7kW was chosen to avoid damaging the input of IC1 if the input voltage goes any higher than around 40V. To go back to the Main menu, either press “Short L” or press “Long R”. If you press “Long L”, you will set the low-battery alarm level to 91.6% of the current voltage input level (and then return to the Main menu). This is a shorthand way to set the low-battery alarm level when you know that the batteries are fully charged. For a typical 12V battery, they are fully charged at around 13.8V (with charger connected) and should not be discharged beyond 11V. Press “Short R” to go to the lowbattery alarm level menu. Setting the low-battery alarm From the Main menu, press “Short R” twice. You will be taken to the low-battery alarm level menu as shown in Menu 3. It consists of an ‘A’ (for “alarm”) followed by three digits which indicate a level between 00.0V and 41.6V. This will show the current setting of the low-battery alarm or rather, the voltage level below which the alarm will sound (if enabled). Whenever the input voltage is below this level, the display will flash (with increasing frequency as the voltage drops) while if the alarm sound is enabled, there will be a flash from LED1 and a beep. To set the low-battery alarm level . . . continued next page Looking for real performance? NOT A REPRINT – Completely NEW projects – the result of two years research & development • • • • 160 PAGES 23 CHAPTE RS Fr om th e pu bli sh Learn how engine management systems work Build projects to control nitrous, fuel injection and turbo 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 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 er s of Intellig I SBN 9 780 95 $19.80 (inc GST) turbo tient mer 095 852 294 - 4 8 52 29 46 NZ $22.00 (inc GST) TURBO & nitrou BOOST s fuel cont rollers How en g managemine ent work s March 2008  37 DC Motor Speed Controller: Software Features & Set-up . . . continued press “Long L”. The ‘A’ will start flashing and then the low-battery alarm level can be modified by adjusting the pot setting. To turn the alarm off completely, simply set the level to 00.0V. When you have reached the required level, simply press any button and the level will be recorded (and stored in EEPROM). Then there will be a beep (if enabled) and you will be taken to the Main menu. Note that the motor will be turned off automatically when setting the low-battery alarm level. Setting the PWM frequency From the Main menu, press “Short R” three times. You will be taken to the frequency menu as shown in Menu 4. This consists of an ‘F’ (for “frequency”) followed by three digits with a decimal point indicating a level between 0.48kHz and 7.81kHz. This is the current PWM frequency. As the frequency increases, the resolution of the PWM setting decreases. At 0.48kHz (actually 488Hz) the resolution is 10 bits. This decreases to six bits at 7812Hz. Thus, the resolution is at worst six bits or 64 levels and at best 10 bits or 1024 levels. While in this menu, press “Long L” and you will be able to set the frequency. The ‘F’ will start flashing and then the frequency will be modified according to the pot setting. When you have reached the required frequency, simply press any button and the level will be recorded and stored in EEPROM. Then there will be a beep (if enabled) and you will be taken to the Main menu. Note that the motor will be automatically turned off when setting the frequency. Enabling & disabling audible cues From the Main menu, press “Long L”. You will be taken to the settings menu as shown in Menu 8. It consists of ‘A’ (for alarm) followed by either ‘0’ or ‘1’ (0 = disable, 1 = 38  Silicon Chip enable) and a ‘b’ (for beep) followed again by either ‘0’ or ‘1’ (0 = disable, 1 = enable). In this menu, pressing “Short L” will toggle the alarm setting (enable/disable) and pressing “Short R” will toggle the beep setting (enable/disable). When the alarm setting is disabled, there will be no beeping when the input voltage falls below the alarm level. There will still be a warning flashing on the display, however. To disable the latter, simply set the alarm level to 00.0V. When the beep setting is disabled, audible beeps emitted by the firmware at certain points (as when setting certain values or when the desired speed is reached) will be blocked. If you do not want any beeping from the piezo buzzer, simply set ‘A’ to 0 and ‘b’ to 0. In this menu, pressing “Long L” will take you to the Reset Menu, as explained below. Pressing “Long R” will take you back to the Main menu. Reset menu From the Main menu, press “Long L” twice. You will be taken to the Reset Menu as shown in Menu 9. It consists of the letters ‘CL’ (for “clear”) followed by two digits and a decimal point of the form X.X. The X.X represents the current version of the firmware, which for this release stands at 3.0. It is possible that future releases of the firmware will add new features or refinements to critical sections of the code. While in this menu, press “Short L”, “Short R” or “Long R” to go back to the Main menu. Note, however, that pressing “Long L” will reset all settings to the default values and the speed controller will lock until power is turned off. When a power-on reset next occurs, the default values for the frequency, low-battery level alarm and audible beeps will be restored. This feature is useful for initialising the firmware variables and for making sure that you begin from a known state. Most of the time, it will not be used. Memory speed mode From the Main menu, press “Short L” to enter memory mode. The display will be as shown in Menu 6. It consists of the letter ‘C’ (for “constant”) followed by a digit from 1-8 (indicating one of the eight available memories), in turn followed by two dashes. Now adjusting the pot will select one of the eight memories. When the pot becomes stable for a short period, the speed of the motor will be set according to the current value of that memory. The display will change as shown in Menu 7. This display still consists of the letter ‘C’ followed by the number of the memory but it will then have a decimal point followed by two digits representing the speed percentage from 00% to 99% (the first two letters will flash until the set speed is reached). Adjusting the pot will now change the selected memory and the speed setting will be recalled from one of the eight stored memory speed settings (after a short beep, if enabled). To go back to normal mode, where the motor speed is controlled directly by the pot, simply press any key, long or short. Setting the memory To set one of the eight memory speed values you press “Long R” from the Main menu. The display will change as shown in Menu 5. It consists of the letter ‘C’ (for “constant”) followed by a digit from 1-8 (indicating one of eight memory settings) and two dashes. Now adjusting the pot will select one of the eight memory settings to store the current value of the speed of the motor. When the pot becomes stable for a short period, the speed of the motor will be stored at that particular memory. This can be recalled later by entering memory mode, as explained in the previous section. There will be a short beep (if enabled), indicating that the value has been stored and you will be taken SC back to the Main menu. siliconchip.com.au siliconchip.com.au HALT STATE. TURN POWER OFF AND BACK ON TO RECALL DEFAULT SETTINGS. LONG L) MENU 9: LAST TWO DIGITS SHOW THE FIRMWARE VERSION. PRESS LONG L TO RESET ALL SETTINGS TO DEFAULT VALUES. (PRESS (PRESS SHORT L) (INACTIVE OR ACTIVE POT) (PRESS ANY KEY OR INACTIVE POT) (SET FREQUENCY WITH POT AND PRESS ANY KEY TO (PRESS RETURN LONG L) TO MAIN MENU) (SET ALARM LEVEL WITH POT AND PRESS ANY KEY TO RETURN (PRESS TO MAIN LONG L) MENU) MENU 5: SET MEMORY MENU. CHANGE MEMORY NUMBER BY VARYING POT. ONE OF EIGHT MEMORY PLACES CAN BE CHOSEN. CURRENT SPEED IS STORED IN THE CHOSEN MEMORY. (PRESS LONG R) SCREEN SHOWING THE LOW BATTERY WARNING. IT SPELLS “Lo” FOR LOW BATTERY. MENU 7: SHOWS THE MEMORY NUMBER CURRENTLY RECALLED AND THE CURRENT SPEED AS A 2-DIGIT PERCENTAGE. MENU 6: RECALL MEMORY MENU. CHANGE MEMORY NUMBER BY VARYING POT. THE STORED SPEED WILL BE RECALLED. (PRESS ANY KEY) (PRESS SHORT R) (PRESS SHORT R) (PRESS SHORT R) MENU 4: CURRENT FREQUENCY IS SHOWN IN KILOHERTZ. MENU 3: CURRENT ALARM LEVEL IS SHOWN IN VOLTS. (PRESS ANY KEY EXCEPT LONG L TO RETURN TO MAIN MENU) (PRESS LONG R OR SHORT L) MENU 2: INPUT VOLTAGE IS SHOWN. USEFUL FOR MONITORING BATTERY (PRESS LONG L TO LEVEL. SET ALARM LEVEL* ) (PRESS LONG R OR SHORT L) Fig.8: this diagram shows the structure of the firmware for the DC Motor Speed Controller. The transitions between the various menus are made using the switches on the display board and are indicated with labelled arrows. (PRESS ANY KEY EXCEPT LONG L TO RETURN TO MAIN MENU) (PRESS LONG L) MENU 8: DISABLE OR ENABLE AUDIBLE CUES. 0=DISABLED, (PRESS 1=ENABLED. A=ALARM, LONG L) B=GENERAL BEEP. PRESS SHORT L OR R TO TOGGLE SETTINGS. (PRESS LONG R) MENU 1: MAIN MENU. SPEED SHOWN AS THREE DIGIT PERCENTAGE. VARY SPEED WITH POT. * ALARM LEVEL IS SET TO 91.6% OF CURRENT INPUT VOLTAGE. March 2008  39 SERVICEMAN'S LOG Foxing out a Foxtel installation Fixing TV reception problems in units can be a real problem, especially if other technicians have been involved and you don’t know what they’ve done. It also doesn’t help if you’re told that the fault is in equipment that doesn’t even exist. I recently received a handwritten work order from the managing agents of a block of 12 units, stating that the antenna amplifier in the basement needed urgent replacement. According to the order, it was ruining all the Foxtel reception. Now I had never been to this address before and knew nothing about it. I tried phoning the agents but the man in charge wasn’t available. In the end, 40  Silicon Chip I decided that as I had been contracted to do the job, I might as well see what I could do. When I arrived, I discovered that the block was a security building to which I had no access except to the basement. Inside, I could find no sign at all of a distribution amplifier, nor any trace of one ever having being there. There was, however, a Foxtel amplifier. The distribution amplifier was probably up in the roof (which would make more sense), so I drove to the manag- Items Covered This Month • • • • • • Foxtel satellite system TCL TFW76BO3 76cm widescreen CRT TV Toshiba 42WP48A plasma TV TCL L32M61A7 LCD TV set Dell Latitude D600 notebook computer Ford Falcon XE electrical problems ing agent and obtained the key. Back at the units, I finally got into the roof area but there was no amplifier there either. There was, however, ample evidence to show that there used to be one because there was an empty box for one and there were cable fittings for one to be installed. Fortunately, I managed to talk to a long-time resident of the block who was pretty cluey and he told me that there used to be an amplifier there but it had been removed many years ago. He also told me that what was now in place at the units was a Foxtel Satellite System that had been installed privately except for the dish and LNB which had been fitted by Foxtel. It had been running successfully for a few years but had failed about two months earlier and several previous technicians had called but had failed to fix the problem. Now the story I had previously been given had a certain ring of truth about it, as it is not uncommon for a distribution amplifier to interfere with Foxtel transmissions. That’s because most technicians invariably run free-to-air transmissions and Foxtel on the same line through this amplifier. A faulty DC power supply can thus introduce hum bars into the distribution amplifier and severely affect the Foxtel signal, sometimes to the extent that it prevents the decoder from working at all. siliconchip.com.au However, in this instance, there was no distribution amplifier and unfortunately, I am not all that familiar with the Foxtel satellite system. For starters, I don’t know the satellite channel plan or what sort of levels to expect, nor do I have the correct signal level measuring equipment. Fortunately, I managed to borrow the correct meter from a colleague although I wasn’t initially all that confident as to how to drive it. However, having familiarised myself with the gear, I checked the signal level output from the Foxtel amplifier to be 75dB, which is not enough for a 12-outlet building. As a result, I picked up a new Foxtel satellite amplifier (identical to the original unit) from my wholesaler, along with a generic spare and an 18V power supply. I connected the brand new Foxtel amplifier, only to find it was DOA (dead on arrival) – faulty straight out of the box! I then fitted the new generic amplifier and set its output for 100dB. That done, I went to one customer’s unit and measured 70dB at his outlet which is perfect for Foxtel. But there was still no Foxtel. Foxtel use horizontal and vertical polarisation in their systems, controlled by the power supply, ie, 12V = vertical and 18V = horizontal. The question was, which one was being used? I tried the 18V power supply I had with me but no go, so I went back to my friendly wholesaler and picked up a 12V power supply. It made no difference so I left the original 18V power supply in place. Foxtel also uses two local oscillator siliconchip.com.au frequencies – 11.3GHz and 10.7GHz – to match the appropriate LNB, so that was the next thing to look at. I managed to get the locked Foxtel security code (set-up menu 0611) to get into the service menu and changed the local oscillator from 11.3GHz to 10.7GHz. At last – perfect pictures! It was then just a matter of going around to all the other Foxtel owners and readjusting their menus in the same way. When the job was completed (all in the same day), I had time to reflect on what had probably happened. When the original fault occurred, there was a lot of miscommunication as to what the problem was and too many different technicians got involved. The cause was actually the Foxtel amplifier but a previous technician had changed the LNB on the dish for one with a different local oscillator frequency and didn’t replace the original when he found it made it worse – probably because he was told to just change it and didn’t have time to check the result. TCL widescreen TV Tim O’Brian (not his real name) has a TCL TFW76BO3 76cm widescreen CRT TV which is about 18 months old. Unfortunately, it was now cutting off after just a few minutes of operation. TCL (Thomson China Ltd) is the largest manufacturer of TV sets in the world and also makes sets for many other brands such as NEC, etc. TCL is their own brand name and the sets are sold with a 3-year warranty. And so, as the local service agent, off I went Ozitronics Tel: (03) 9896 1823 Fax: (03) 9011 6220 Email: sales2008<at>ozitronics.com Introducing the MT System A series of C programmable chips based on the latest generation of 8051, Atmel AVR or ARM core flash microcontrollers. Onboard 16-bit run-time interpreter for fast program development Multiple, selectable program storage Lots of sample programs Free IDE includes text editor, compiler, simulator, test terminal & serial downloader (no programmer required) Demoboards available for quick and easy project development Prices & documentation available on website: www.ozitronics.com : to Tim’s address at unit 23/123 Mary St to do an in-home warranty repair. I was not familiar with Mary St, which turned out to be a very long street with a lot of home units. Anyway, I soon found number 123 but I couldn’t find unit 23 (the units were very poorly labelled). I phoned Tim on the mobile and spoke to his mother, whose English was not too good, and explained my predicament. Unfortunately, our communications weren’t the best so I asked her to come outside and look out for me or at least describe some kind of landmark. Even so, I still couldn’t find her or the unit, so I queried the street address and nearest cross street. She kept telling me “unit 23/123 Mary St” but the nearest cross street she nominated was nowhere to be seen. In the end, I got back into the car and cruised up and down until I reached the cross street but I still couldn’t find 123. It took a long time, interspersed with March 2008  41 Serviceman’s Log – continued some fairly terse phone calls, to work out what was happening. It turned out that the street address was actually 1-3 (1 to 3) and its entrance was in the cross street. Once that had been sorted out, I had to negotiate the full-security lift which required a card to operate it before I was finally let into Tim’s place on the third floor. When I saw the set, I knew that this was just going to be “one of those days”. It was, of course, situated in an entertainment centre in the corner with pitiful access. What’s more, the set weighed more than I do – which is a lot these days! On the plus side, the fault just might have been due to another symptom I hadn’t been told about, namely retrace lines on the screen. My first step was to remove the back and swing it around while dodging both the baby and the dog who were trying to eat my tools. I then carefully readjusted the flyback transformer screen control until there were no more lines and waited 15 minutes to see if the set switched off. It didn’t and I then managed to put the back on the TV and replace it in the entertainment cabinet without leaving either the baby or the dog inside. After completing the necessary 42  Silicon Chip paperwork, I left, confident that the repair had been completed satisfactorily. But of course, that wasn’t to be the end of it. A few days later, Tim phoned back and said that while it was now taking longer, the set was still cutting out. Drat! There was nothing for it but to go back to “123”. This time, I went armed with a new flyback transformer and a video output IC (TDA6107AJF/N1) which isn’t even shown on the circuit diagram (it just shows discrete transistors). Fortunately, I didn’t get lost this time and even better, the baby and dog were in other rooms. Anyway, I removed the chassis, replaced both items and checked and resoldered a few possible dry joints. That done, I adjusted both the horizontal and vertical focus pots and the screen controls very slowly and deliberately. After an hour or so, I was finally finished and was demonstrating the set when it went off all by itself. I was ropeable and completely bamboozled by the whole turn of events. Now I couldn’t even switch the set back on and prior to it going off, I couldn’t change the stations with the remote control. Fortunately, yours truly had caused the problem and there was a simple solution. I had brought along a spare service remote control to help with the adjustments and it was in an open carrier bag into which I had just put my University multimeter. The heavy multimeter was pressing against the remote control’s pushbuttons, causing the random results I was experiencing! Aaaarghh!! After a job like that, you need a stiff drink and a lie down! Toshiba plasma TV I was recently called to a Toshiba 42WP48A plasma set that had been in heavy-duty use at a club. The barman had phoned to say it was dead and asked if I could fix it straight away because of the sport. I asked him if there was any clue beforehand that the set was about to fail and he replied that there was absolutely nothing. Apparently it had been working one minute and was “dead” the next. When I called, I could see that there was no power and so the set had to go to the workshop. Back at the ranch, I took the back off and a few quick measurements showed that the power supply – a Sanken PKG-4000 PDC20360 – was dead. I have seen a few of these power supplies before and have sometimes found the white wirewound resistors to be faulty for no apparent reason. There is no circuit for the power supply as it is considered unrepairable. The PC board is mounted on a sheet of aluminium using over 30 screws and 12 plastic mounting clips to hold it in place. In this case, R26 (10W 5W) was open circuit so I replaced it. However, when I switched the set on, it was still dead. It was then that I noticed that IC1 and R32 (1.5W) had blown so badly that I couldn’t read what the device type numbers were. The IC was obviously part of the standby power supply, judging by the size of the chopper transformer – probably one of those 8-pin Mosfet and control ICs. That was as far as I was allowed to go. The club then told me the set had actually been killed during a thunderstorm (great – now they tell me!) Anyway, a new power supply was ordered and the $900 repair charged to the insurance company. If the service manual had shown more detail on the power supply, the repair would have cost much less than that. TCL warranty job I had a brand new TCL L32M61A7 LCD TV come in under warranty with intermittent no sound when hot. I thought that this would be a straightforward repair. However, after fooling around for some time with vibration tests, I finally nailed the problem by applying freezer to the main microprocessor. This large-scale surface-mount IC is not designed to be replaced and so a new main board had to be ordered to fix the problem. Dell notebook I was recently asked to repair a friend’s Dell Latitude D600 notebook. His problem was that the computer would not run from the battery, nor would it even charge the battery. A quick check of the BIOS indicated that there was provision for two batsiliconchip.com.au teries but only one was installed. After checking to see that the machine’s existing 11.1V Li-Ion battery wasn’t on the factory recall list, I decided to get a new one on eBay. I also ordered a new 7.2V CMOS backup battery for good measure. When these new batteries were installed, not a lot had changed. The computer continued to run correctly from the PA-12 +19.5V AC adaptor but not from either the new battery or the old battery. The BIOS (which I upgraded to ver. A16 from A8) still reported two batteries and that one was charging but the old battery always measured 0V while substituting the new one gave an indication of 74% charged. Neither value changed at any time. Obviously there was something fishy about the battery charging system within the computer but was it a hardware problem or a software problem? The main battery has a 9-pin connector. Pins 1 & 2 are the +11.1V rail, while pins 6, 8 & 9 are the negative rail. Pins 3, 4 & 5 measured +5V and pin 7 measured +3.26V. I downloaded the service manual from the web and stripped the notebook right down to just the motherboard to see if I could find anything wrong. I then examined and measured the voltages around the power supply very carefully but I couldn’t find any clues. There were no blown fuses, burnt resistors or even hot components – all looked perfect. Most of the charging is controlled via surfacemounted switching ICs. I didn’t have the user’s guide but I did discover the 5-green LED charge gauge which confirmed that there was no charge in either battery, despite what the BIOS displayed. I then trawled the web but could find nothing, so I went to the Dell website and asked for help via email, quoting my service tag number. I really wasn’t expecting very much but I was subsequently very pleasantly surprised when a gorgeous chick phoned me up and told me they would send a technician round the very next day to change the motherboard. I was still very cynical, expecting some monstrous catch, but lo and behold, a technician did rock up the next day and replaced the motherboard under warranty – all done in a tenth of the time it took me to dismantle the notebook in the first place. Not only that, it was all free and under warranty. The new battery still would not work even though the BIOS said it was 74% charged. However, the original completely discharged battery now did work and really started to charge, continuing to do so until it was at 100%. Furthermore, it ran the notebook quite satisfactorily. My friend was delighted and both of us were mightily impressed with Dell’s customer service. They have really put the meaning back into those oft-misused words. So why does the BIOS indicate two batteries? Well, there’s provision to install a second main battery in the space that’s normally reserved for a floppy disk drive. As for the new battery, I sent it back for a refund. Falcon electrical problems Finally, here is an interesting story concerning some strange electrical faults in an old XE Ford Falcon. It was sent in by R. S. of Hoppers Crossing, Victoria and I’ll let him tell it in his own words: An acquaintance’s youngest son, Brett, requested my assistance to solve some electrical problems that he was siliconchip.com.au CIRCUIT ! W E N 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 oncepts.com d a o l n w o D ave-c w w e n . w ww ions click on s between difference To see the ional vers d & Profess ‘features’. Standar 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 experiencing with his aging XE Falcon sedan (late 1984 model). This vehicle had originally been purchased new by his late grandfather, so its service history was well known. The were several symptoms that concerned Brett. First of all, the speedometer tended to react to the flashing of the turn indicator, which was very strange indeed. In addition, the righthand indicator lamp was permanently illuminated, unless the indicator switch was set to activate the righthand blinkers. And when the righthand blinkers were activated, the indicator lamp turned off when the front and rear globes illuminated. Another strange fault was that the temperature gauge swung from the low end of the scale to the high end in a most alarming manner. This was so bad that Brett had disconnected the sender wire in the engine bay to prevent possible damage to the gauge. Another problem was that the air-conditioning (a/c) fan was intermittent, as was the a/c compressor clutch which only worked if the fan worked. This problem had been apparent for some time but had not previously been investigated. It was open to conjecture as to whether it was related to the other problems. Due to rain, it was great day to work indoors and so I suggested that we meet at his parent’s house, where the garage/workshop has a pit – useful should it be necessary to work underneath the vehicle. In my opinion, a pit is more of a requirement than an ensuite when designing and building a house! Anyway, we examined the circuit diagram in the workshop manual and soon determined that the vehicle was March 2008  43 Serviceman’s Log – continued a base Falcon which had been fitted with air-conditioning on the production line. At this stage, I was favouring an earthing problem as the common cause of all the symptoms. As a result, I tracked down a common earth point on the diagram for all the dashboard wiring. According to the manual, it was located on the lefthand side of the vehicle. This was eventually found after removing the glovebox and a kick panel and appeared to be in good order. Furthermore, a quick check with a DMM found just a millivolt or so across the connection when everything was powered up. Brett then advised me that turning on the headlights (either low or high beam but not the parking lights) would cause the fan to operate. This really was strange. He had also noticed that there was a single clicking sound just before the fan began to rotate. Brett also advised me that “hitting” the car reasonably firmly in the vicinity of the click would also activate the fan. And that in turn led us to a plug-in 44  Silicon Chip 30A relay. This relay is used to control the fan and I suspected that it might have an intermittent fault. The relay was pull­ed from its socket and its coil resistance checked. This turned out to be about 87W which is normal. The relay was then checked by connecting it to a 12V DC supply and this showed that the relay was operating correctly. In addition, its normally open (NO) contacts had almost no resistance when closed. My next step was to bridge the matching NO connections in the socket and this showed that the fan was in perfect working order on the full speed setting. However, it did not function on the low or medium-speed settings and I suspected a faulty high-wattage series resistor as one was indicated on the diagram. I wasn’t too concerned about this at this stage, though – finding and testing the resistor could wait until the intermittent electrical problem had been solved. I went back to the circuit diagram and traced the wiring to the relay coil. This led me to a separate diagram relating to the a/c control which showed that the feed was directly from the switched side of the ignition switch. More precisely, it came from a connection on the high side of the fuse safeguarding the supply lead to the fan. Checking the coil control voltage gave me my first real clue to the problem. It ranged from 3V to a maximum of 10V. No wonder the relay wasn’t operating correctly! Next, I reinserted the relay as it had passed all the necessary tests. It was then that I happened to lightly touch the thermal overload breaker that serves the headlight circuit and, for a fraction of a second, the fan roared into life. The headlight’s thermal interrupter unit is located towards the bottom of the fuse block. However, the fuse block shown in the diagram was different to that fitted to the vehicle. I took another look at the diagrams we had discarded and found that the more upmarket models (Fairmont, etc) were fitted with the fuse block I was looking at in this vehicle. This also showed that the control signal for the relay came from the low side of a 20A fuse labelled ‘acc’, just to the left of the thermal overload breaker. Touching this fuse very lightly immediately brought the fan to life. I felt around the back of the fuse block and moved the connecting wire, to see if it was loose. It wasn’t loose but the slightest movement caused the fan to run so I removed the fuse and found that it was intermittently going open circuit. Carefully dismantling this 3AG fuse showed that the soldered connection between the fuse element and the end cap was the problem. I replaced the fuse with a new one and no amount of wiggling, tapping, banging or activation of the headlight switch would cause the fan relay to switch off. What’s more, with the engine running, the a/c compressor clutch now worked reliably as well. I was also surprised to find that the low and medium-speed fan settings also now worked. So by replacing just one fuse, I had fixed the intermittent siliconchip.com.au fan and a/c operation problems and the lower fan speed problems as well. Indicator problems That left the righthand indicator lamp problem. It was still lighting when the control was in the middle of its travel (ie, neither the right nor left indicator selected). So was there a problem with the control switch unit? There are three connector blocks associated with the electrical controls on the steering column, so I disconnected them all. Re-connecting the ignition/power circuit then caused the fault to reappear. That meant that the indicator selector, the high/low beam circuit, the horn circuit and their switches were OK. There was nothing for it now but to remove the instrument module. That done, I probed the flying socket for voltage on the connection serving the repeater light. This showed that the connection was at 0V with the indicators in the off position, which is correct. Moving the indicator to the righthand position then showed a pulsing 0-12V DC voltage at this point, at the frequency of the flash rate (about one pulse per second). Again this was correct and Brett advised that he had also checked this but double-checking never hurts. That meant that the problem with the indicator lamp was in the instrument cluster itself. Undoing six screws gave us access to the circuit board which was now closely inspected. We didn’t have a circuit diagram for the board, so I began to trace the now-tarnished copper tracks from the plug pins to the repeater globe, then through the globe and on towards the base of the temperature gauge. As mentioned, this gauge had been indicating a problem, so it was somehow connected to the fault. I went back to the plug and observed that a nearby copper track had been very hot in the recent past. To get a better view, I undid the three screws that secured the economy gauge to the circuit board (this economy gauge is simply a mechanical vacuum gauge sensing the air pressure in the inlet manifold). Once this gauge was out, I could now see that this track had become detached from the board surface due to the excess localised heat. A closer examination revealed four or five small black marks (about the diameter of a pin), which had been hidden behind the vacuum gauge mounting point. What had caused these? The answer came when I looked at the back of the vacuum gauge mounting. This showed that two flat-headed screws had vibrated loose and were now capable of touching two adjacent copper tracks on the PC board. These screws were both threaded into the brass block of the vacuum gauge, thereby forming a complete current path between the two tracks and shorting them out The fix was simple. First the two screws were retightened and, for insurance, sealed in position with a drop of nail polish (a beautiful shade of pink). The floating track was then removed and the break bridged using a short length of tinned copper wire. And that fixed all the remaining problems. The indicator lamp now operated correctly and both the speedo and temperature gauge remained steady, with no tendency to flick in sympathy with the indicator signal. After that, it was just a matter of reassembling the instrument panel and the old Ford was ready for the road once more. SC siliconchip.com.au Now available: THE 5 5 DC POWER FOR CRITICAL COMMERCIAL AND INDUSTRIAL APPLICATIONS           Hospital theatre backup Portable medical instruments Portable computers & cameras Mining tools Oceanographic instrumentation Remote area power Railway signalling Rolling stock Aviation Military Systems Ph: 61 89 302 5444 or order on line <at> www.siomar.com March 2008  45 PICAXE VSM: It’s Time to PLAY! In the third part of our PICAXE VSM tutorials Clive Seager talks us through using some of the ‘virtual instrumentation’ included with the software – from a simple voltmeter to an advanced I2C protocol debugger! A fter you have designed a circuit using PICAXE VSM, you will naturally want to test it! Fortunately VSM has a wide range of ‘virtual instruments’ available for testing purposes. This article assumes you have worked through the tutorials in parts 1 and 2 of this series, so are familiar with drawing circuits in the VSM software. Voltmeter and Ammeter Voltage and current can be measured in two separate ways. As an example, open the ‘high command.dsn’ sample file from the /samples/picaxe/commands folder. You will then need to use the ‘File>Save As’ menu to save with a different filename so you can experiment and save modifications to it. Fig.1 shows the circuit with a traditional voltmeter connected across the LED. When run, the voltmeter will show the voltage when the LED switches on and off. An ammeter can be added by deleting the wire between the resistor and PICAXE pin. Right click and select Place>Virtual Instrument>DC Ammeter. Once dropped, right click on the ammeter symbol and edit the properties ‘Display Range’ from amps to milliamps. Then draw the Fig.2: virtual ammeter added to the circuit. Remember to change to mA range! two wires back in as shown in Fig.2. When run you will now have a display of both current and voltage. If you change any of the other component properties – eg, (changing the ‘Forward Voltage’ of the LED from 2V to 2.5V or the resistor from 330W to 270W) you will see corresponding changes in the current. The second, slightly simpler way of measuring voltage and current is to just add probes onto any component pin or wire. To do this, right click, select place and then either the voltage or current probes (see Fig.3). Once the simulation is run, the probes will show the current or voltage at the probe position. Oscilloscope Fig.1: simple LED circuit with voltmeter attached. 46  Silicon Chip On occasions you may wish to trace the voltage or a signal over a period of time. This is when the virtual oscilloscope is of use Open the ‘infrain.command dsn’ sample file and re-save with a different filename. This uses a ‘simulated’ IR LED and IR receiver (eg, equivalent to the TSOP4840). Two siliconchip.com.au Fig.3: right-click the mouse to add voltage and current probes. Fig:6: serial terminal demonstration. channels of the oscilloscope are connected across the LED output and the receiver output. When run, the oscilloscope display panel will appear on screen, showing the trace from the two channels. As can be seen from Fig.5 the top LED trace clearly shows the modulating signal, while the receiver trace shows the demodulated inverted output! The virtual oscilloscope includes all controls that you would expect to find on a real device, and so the position, timebase etc can all be adjusted as you require. Serial Terminal This time take a look at the ‘sertxd command.dsn’ sample file. This demonstrates the ‘Virtual Terminal’ which acts as an RS232 serial terminal for testing programs with serial data. When run, the serial data output from the PICAXE chip is displayed on screen within the terminal window. As with all serial systems, you do need to set the baud rate and polarity of the terminal to match the PICAXE settings (4800,n,8,1 [inverted polarity] in this case). This is carried out by right-clicking on the terminal symbol and selecting ‘Edit Properties’. COMPIM While we are talking about serial communication it is also worth mentioning the COMPIM (COM Physical Interface Model). This ‘symbol’ acts as a link between the Fig.4: two PICAXE chips communicating via a simulated infrared link. Fig.5: virtual oscilloscope trace. siliconchip.com.au Fig.7: remember to set the serial baud rate and other parameters, or you will see corrupt characters on screen! March 2008  47 simulator and the real serial port of the computer. This, amazingly, allows connection of real serial devices to a simulated PICAXE chip! As an example you could connect a serial GPS module to the serial port of the computer and then have the simulated PICAXE chip parse the NMEA serial data stream! The ‘COMPIM demo.dsn’ file demonstrates the COMPIM feature. Signal Generator The Signal Generator is demonstrated via the ‘count command.dsn’ file. When this simulation is run the Signal Generator control panel is displayed on screen. First make sure the generator is outputting a square wave (sawtooth, triangular and sine are also available) of around 5V and then try adjusting the frequency. The change in frequency should result in a different ‘count command’ value displayed on the serial terminal. An alternate, simpler, way of applying test signals to a wire is to just drop a generator probe onto the wire (as Fig.10: I2C debugger analysing data written to a 24LC16B EEPROM but fortunately the technicalities of the protocols are taken care of automatically in the PICAXE system, via use, as an example, of the writei2c and readi2c commands. Those interested in studying these protocols further may be interested in the function of the I2C and spi debugger instruments. For instance, the writei2c command.dsn’ file demonstrates how the ‘I2C debugger’ instrument is connected to the I2C bus. When the simulation is run the details of each I2C transaction – start signal (S), address (AO), data pulses, ack pulses (A), nack pulses (N), stop signals (P) etc – are clearly listed in sequence on screen. This makes it an in- Fig.8: demonstration of the COMPIM feature. with the voltage and current probes). This is carried out by right-clicking and selecting Place>Generator. SPI and I2C debuggers SPI and I2C are two different communication protocols used to link ICs together. The protocols are quite complex Fig.11: I2C debugger trace. This shows the time, and type, of all activity on the I2C bus valuable learning tool for those interested in understanding these protocols. Summary Fig.9: virtual signal generator. 48  Silicon Chip The software also contains a few other instruments such as a logic analyser – have a play with them! Using ‘virtual simulated’ instruments will never be quite the same experience as twiddling dials on real-life bench-top models but using these simulations is still a worthwhile process. PICAXE VSM incorporates an impressive array of virtual instruments – and you certainly wouldn’t be able to buy a new oscilloscope, signal generator or I2C debugger for anything like the price of a VSM licence! SC siliconchip.com.au MARCH PRE - CATALOGUE Kits for Kids Motorcycle Construction Kit Learn about mechanical & electrical construction principles while building your own electric-powered motorcycle. Everything's included, even tools to put it all together. The instructions Cat. KJ-8900 are excellent, with colour photos and a detailed parts list. $12.95 • 187 piece kit • Suitable for ages 10+ (contains small parts) • Measures: 210(L) x 147(W) x 56(H)mm 301 Piece Solar Construction Kit Build a solar-powered motorcycle, a front-end loader or whatever else your imagination can come up with. All parts, fasteners and tools are included as well as an illustrated instruction booklet with colour photos and a comprehensive Cat. KJ-8905 parts list. • Tools included $29.95 • Motor and solar panel included • Requires 1 x AA battery • 10yrs+ 153 Experiments in Electricity and Magnetism Kit Learn all the basic principles behind electricity. Cat. KJ-8835 153 different $39.95 experiments require only a 9V battery or no power at all. • Ages 9+. • 9V battery: SB-2423 $699 2.4GHz Baby Monitor with LCD Screen & IR Colour Camera Set up your own weather channel or connect to your computer for storage and analysis. The indoor receiver measures the indoor temperature, humidity, atmospheric pressure and receives weather data from the outdoor thermometer-transmitter sensor, wind sensor, and rain gauge. The receiver unit has USB interface output allowing data to be uploaded to a PC or laptop and a AV output so you can view the weather data on your TV. Was $299 This popular 2.4GHz wireless surveillance system has a specially designed indoor Hi-res colour CMOS camera and hand-held LCD monitor, that enables you to monitor your home, children or elderly residents even when it gets dark. You can link the monitor to a VCR to record what the camera captures or link it to a TV that has the 'Picture-in-Picture' feature to keep an eye on the baby while you watch your favourite TV show. • 2.4 inch colour TFT-LCD screen • Can work with up to 4 cameras Cat. QC-3258 • 10 IR LED illuminator $199 • Hi-Res colour CMOS camera • 4 channel selection • Low power consumption • 2 x PSU included • Monitor measures 65(L) x110(H)x 23(W)mm SAVE $100 NEW Watch high definition digital TV 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 Cat. XC-4859 • Antenna, cable and software included $99 NEW This wireless video system simply splices into the car's reversing light cable. It is automatically activated when you select reverse and gives you a clear view behind your vehicle. The camera is waterproof and can be mounted outside the vehicle. • Specifications: • 2.4" wireless colour LCD screen • Colour CMOS camera • 110° Camera viewing angle 250GB H INCLUD DD ED Weather Station with Wireless Sensors, Computer Interface & TV Out Reversing Camera Kit with Wireless Camera TELEPHONE> 1800 022 888 Cat. QV-3085 USB Digital TV Stick NEW FOR INFORMATION AND ORDERING SAVE $250 $199 Mains Adaptor 12VAC 2A Unregulated, 7 plugs included. • Approval number: N17582 $29.95 The DVR is fitted with a 250GB hard drive, can accommodate up to 4 cameras with power derived from the DVR and will allow you to record and view up to 4 cameras simultaneously. Package includes the DVR with 1 dome and 1 outdoor IR camera with bracket, mounting hardware, power supply, 14m of cable, software, USB interface lead and user manual. Additional cameras sold separately. Was $949 Cat. XC-0332 Mains Adaptor 12VAC 2A Unregulated Cat. MP-3057 DVR Camera Kit Preven Drivewat Acciden y ts 200W PA Combo Amp/Speaker A PA system in a box. 3 channels with balanced and unbalanced inputs, RCA inputs for an auxiliary source. The ideal small PA for schools, sports organisations, churches, weddings, conferences or solo acts. • 12" speaker • 2 channel equaliser • Line level RCA inputs • Tough moulded enclosure • Balanced and unbalanced line outs • 200WRMS power output • Dimensions: 600(H) x 410(W) x 325(D)mm NEW Cat. CS-2517 $399 Cat. QC-3725 $249 Better. More Technical INTERNET> www.jaycar.com.au Rear view 1 Wireless Weather Stations 38 Channel 1.5W UHF Pocket Transceiver Be Your Own Weatherman This high-quality light-weight UHF transceiver is ideal for use in many professional and leisure activities. • 1.5W output • Up to 8km range • Hi/lo power setting Weather Station with Wireless Sensors and Doorbell Anyone with a interest in the weather will love this station. It has an unbeatable range of features, it is great value, and best of all has no need for messy wiring. The system measures and displays inside and outside temperature, air pressure, rainfall, humidity, wind speed, direction, and chill factor. • Requires 7 x AA batteries Cat. XC-0293 • Indoor $149 display unit 140(W) x 170(H) x 40(D)mm Cat. DC-1040 $59 Dynamo Powered Splash Proof Radio with LED Torch Compact, portable, splash proof. 90 seconds winding gives 20 minutes operation. Has provision for battery operation if desired. Was $34.95 Cat. AR-1775 $28.95 SAVE $6 SAVE $5 RC Solar Pond Pump Uses latest solar technology , SAVE requires no $15 wiring, can be used a night and no running costs. Turns on/off via remote control. • Squirts 50mm high • 2 bright LEDs • 350mm (Dia.) Was $69.95 Cat. YH-5452 $54.95 Mini Digital Camera Keyring Always have a camera with you! • 100k pixels • Takes up to 80 photos (20 Hi-Res) • Use as a web cam • Includes easy-to-use software & cable Was $19.95 Cat. QC-3190 $14.95 2 Children's Weather Station Observe, learn and forecast the weather. This fully functional weather station is designed especially for children. Cat. XC-0308 • Shows wind direction $39.95 • Measures wind speed in kph & mph • Indicates relative humidity SAVE • Measures temperature in $10 Fahrenheit & Celsius degrees • Measures rainfall in inches & centimetres • No batteries required Suitable for children 8yrs+ Was $49.95 Mini Head Torch 3 Super Bright LEDs Professional Grade Outdoor Garden Lighting Quality Die Cast low voltage outdoor garden lighting range. Each fitting is die cast, powder coated and moisture sealed with neoprene gaskets. The spectacular range can be powered by 12 volt halogen lamps or a professional 24V for large installations where OFF EACH voltage drops would normally be a problem. Garden Flood Light • Size (length including spike) 310mm. • Dia. at globe 75mm. Cat. SL-2770 Was $14.95 Now $13.45 Focal Spotlight/Highlighter • Length: 320mm approx • Dia at globe: 65mm. Cat. SL-2772 Was $14.95 Now $13.45 General Purpose Spotlight / Highlighter • Size 100(H) x 96(dia) mm excluding bracket and spike. Cat. SL-2774 Was $14.95 Now $13.45 Wall Mount Step Light This light will mount on a wall, and is ideal for lighting a path, or steps. • Size 100(dia) x 50(D)mm. Cat. SL-2778 Was $9.95 Now $8.95 Pathway Illuminator A stylish contemporary design used to reveal a pathway at night. • Size 170(H)mm excluding spike which is 160(L)mm • Dia 60mm. Cat. SL-2780 Was $16.95 Now $15.25 Flushmount Illumination This lamp is designed to be embedded into a path or walkway. It can actually be walked on. • Size 100(H) x 96(Dia)mm. Cat. SL-2776 Was $14.95 Now $13.45 Pagoda Light • Size 300(H)mm excluding spike • Dia 140mm. Cat. SL-2784 Was $19.95 Now $17.95 10% Dynamo Wind up LED Torch Great gift idea for campers or hikers. Just one minute of winding will give you 30 minutes of light. Approximately Cat. ST-3337 130mm long. Was $19.95 $14.95 Easy to install - no wires, no fuss. Displays full clock and calendar functions, humidity, temperature readings, barometric changes as well as an SAVE audio and visual indication when the doorbell $20 is pressed. Can be desk or wall mounted. • Indoor display 225(W) x 260(H) Cat. XC-0336 x 27(D)mm $79.95 Was $99.95 SAVE $5 Excellent for outdoor activities. • Requires 2 x AAA batteries • Weatherproof and digitally controlled • Brightness levels 100% & 50% • 3 super bright LEDs Cat. ST-3280 • Flashing mode for $14.95 emergencies. Was $19.95 Mini Head Torch with 6 Super Cat. ST-3282 Bright LEDs also available $14.95 Was $19.95 Better. More Technical SAVE $5 Jumbo Display Indoor/Outdoor Thermometer with Memory This thermometer has one LCD that shows both the inside and outside temperatures simultaneously. It will record the minimum and maximum temperatures that are reached. The outside temperature sensor is waterproof and is on 3 metres of very thin cable, which helps when putting through a window seal. Has a tilting bail for standing as well as a screw hole for wall mounting. • Reads both °F/° C, selectable with switch • Measuring range: -39.9°C to 49.9°C • -39.8°F to 122°F • Size: 110(H) x 100(W) x 22(D)mm SAVE • Operates with AAA battery (supplied) $7 Was $35 Cat. QM-7205 $28 7 LED Diving Torch This torch is waterproof to 30m, and is very light and small. It features 7 high brightness Japanese made white LEDs. There is a rubber hand grip and rubber head which incorporates the rotary on/off switch, as well as a lanyard. Was $19.95 SAVE $5 LED Safety Band SAVE $5 Cat. ST-3076 $14.95 Traffic and other hazards can see you coming from afar. • Four red LEDs • Adjustable 30mm wide Velcro band SAVE $5 • Flashing or steady lighting mode • Visible up to around 300m Cat. ST-3026 Was $9.95 $4.95 FOR INFORMATION AND ORDERING TELEPHONE> 1800 022 888 INTERNET> www.jaycar.com.au Speakers Economy Car Alarm Wide range of speakers available for a multitude of home or car audio projects HOME AUDIO 6" Polycone Woofer • Nom impedance: 8 ohms • Power handling: 30WRMS Was $24.95 SAVE $5 Cat. CW-2108 $19.95 8" (200mm) Paper Cone Woofer • Nom impedance 8 ohms • Power handling 30WRMS Was $24.95 10" (250mm) Paper Cone Woofer • Nom impedance 8 ohms • Power Handling 40WRMS Was $29.95 An economy alarm that has many of the advanced features you would normally only expect to find on more expensive systems. Fantastic value. • Includes • Electronic black box controller • Shock sensor • Ignition cutout relay • Wiring looms Was $89 SAVE $5 SAVE $5 Cat. CW-2110 $19.95 Cat. CW-2119 $24.95 6.5" Driver Is capable of astounding bass extension. It will deliver incredibly deep bass that matches bigger sized woofers in a good enclosure design. Suitable for Hi-Fi or home theatre applications. • Nominal impedance: 8 ohms • Power handling: 60WRMS • Sensitivity: 85dB 2.83V at 1m SAVE $10 Cat. LA-9000 $79 MP3 Player Cassette Adaptor Lets you play your favourite MP3 tracks on any car cassette player. Excellent sound quality! • Built-in 3.7V 250mAh battery SAVE • Supports $20 SD, mini SD and MMC cards Was $69.95 Cat. AR-1764 $49.95 DIY Kits Cat. CW-2154 Ref: High Performance Electronic Projects for Cars - Silicon Chip Publications. $89.95 CAR AUDIO 4" Kevlar/Dome Tweeter Coaxial Car Speakers NEW New and improved! These Kevlar® cones are now paired with soft dome tweeters that provide cleaner and crisp sounds while maintaining natural and smooth balance. The 12dB octave crossover are now integrated into the speaker. • Nominal impedance: 4 ohms • Power handling capacity: 40WRMS • Dimensions: A 102 B 90 C 47 Cat. CS-2370 $79.95 7" TFT Touch Screen VGA Monitor Not only will you be amazed at the high resolution and audio clarity of this unit, but the added feature of touch screen capabilities enables use with a laptop/PCs , games consoles and endless other VGA operate devices. Was $499 Cat. QM-3749 $449 SAVE $50 Speedo Corrector MkII When you modify your gearbox, diff ratio or change to a large circumference tyre, it may result in an inaccurate speedometer. This kit alters the speedometer signal up or down from 0% to 99% of the original signal. With this improved model, the input setup selection can be automatically selected and it also features an LED indicator to show when the input signal is being received. Kit supplied with PC with overlay and all electronic Cat. KC-5435 components with clear English $49.95 instructions. Economy Adjustable Temperature Switch If you don’t need the display, or the huge operational range of the High Range Adjustable Temperature Switch with LCD, then this unit is a great alternative. It has an adjustable switching temperature up to 245°C, and it can be configured to trigger with rising or falling temperature. It has adjustable hysteresis (the difference between on/off temp) which is a great feature many other units do not possess. It can be used to operate cooling fans on a radiator or amplifier, over-temp warning lights or alarms, and much more. The small temperature sensor reacts quickly to temp changes. Kit supplied with PCB, Cat. KC-5381 NTC Thermistor, & all electronic $29.95 components. FOR INFORMATION AND ORDERING TELEPHONE> 1800 022 888 INTERNET> www.jaycar.com.au Auto Savings 2 Farad Capacitor with Coloured LED Display Cat. RU-6751 Was $149.00 Now $129.00 Save $20.00 1 Farad Capacitor with coloured LED Display Cat. RU-6752 RU-6752 Was $99.95 Now $89.95 Save $10.00 Digital Tachometer Cat. QM-1448 Was $69.95 Now $59.95 Save $10.00 Alcohol Breath Tester Key Chain Cat. QM-7293 Was $39.95 Now $29.95 Save $10.00 QM-1448 iPod® Car Charger Cat. MB-3650 Was $19.95 Now $14.95 Save $5.00 Auto Current Tester Cat. QP-2251 Was $29.95 Now $24.95 Save $5.00 Car Voltage Meter/In-Out Thermometer/Clock Cat. XC-0116 Was $39.95 Now $29.95 Save $10.00 Car Voltage Meter with Clock & Stopwatch Cat. XC-0118 Was $34.95 Now $24.95 Save $10.00 XC-0118 LED Globes for Vehicles Ideal replacements for your vehicles incandescent lamps. • 12 volt Note: Only suitable for show or off road use. 19 x White for car stop/tail lamp ZD-0311 19 x Red for car stop/tail lamp ZD-0316 19 x Yellow for car indicators ZD-0317 19 x White for car indicators ZD-0319 19 x Red for car tail (bayonette) lamp ZD-0318 Cat. ZD-0311 $19.95 Cat. ZD-0316 $14.95 Cat. ZD-0317 Cat. ZD-0319 $19.95 Cat. ZD-0318 $9.95 $14.95 120A Auto Circuit Breakers These circuit breakers feature a 3 digit LED voltage display so you can keep an eye on the battery's condition, a status LED which will illuminate only when there is a complete connection. High quality screw down connections. SZ-6002 Accepts: 1 x 0 gauge in 1 x 0 gauge out. Power Handling: 120 Amps Dimensions: 45(H) x 100(W) x 45(D)mm Was $39.95 Cat. SZ-6002 $34.95 $5 OFF SZ-6004 Accepts: 1 x 4 gauge in 2 x 8 gauge out Power Handling: 2 x 60 Amps Dimensions: 45(H) x100(W) x 70(D)mm Cat. SZ-6004 Was $44.95 $39.95 Better. More Technical $5 OFF 3 Dome & Ribbon Tweeters - Home Audio Dome Tweeters Cat. CT-2005 These tweeters offer great versatility and cater for just about any application. They feature ferrofluid injection cooling which increases power handling and greatly reduces failure to high thermal transients. Three models available • CT-2005 19mm Shielded Dome Tweeter • CT-2007 25mm Titanium Dome Tweeter • CT-2009 25mm High Performance Dome Tweeter Speaker Surround Kits 8” Speaker Surround Kit CF-2791 $19.95 • 2 x 8 inch rubber surrounds • 10ml bottle of special glue 10” Speaker Surround Kit CF-2792 $29.95 • 2 x 10 inch rubber surrounds • 10ml bottle of special glue 12” Speaker Surround Kit CF-2793 $39.95 • 2 x 12 inch rubber surrounds • 10ml bottle of special glue FROM $19.95 Cat. CT-2007 $24.95 Cat. CT-2009 $34.95 Loudspeaker Design Cookbook Sixth Edition Response Ribbon Tweeter The sixth edition of this world famous loudspeaker design "Bible" as used by manufacturers and amateurs alike! Totally updated and revised chapters, significantly more chapter footnote references and explanatory graphs. Includes new tutorials on woofer design, curvilinear vents, a brand new chapter on transmission line enclosures, CAD software, in car sound and 2 fully documented speaker designs. Will teach you all you need to know to design, construct and test loudspeakers for your home stereo, home theatre and car. • 233 pages Cat. BA-1400 • Softcover Was $69.95 $49.95 Ribbon tweeters are renowned for their smooth, natural response. Fast transient response, neodymium magnet, Cat. CT-2032 Kapton voice coil. • Nominal impedance: 6 ohms $49.95 • Power handling: 10 WRMS • Sensitivity: 92 dB 283mV <at> 1m • Recommended crossover frequency: >2500Hz Universal Crossover PC Boards Build Your Own Crossovers These 2 and 3 way crossover printed circuit boards have been designed as a versatile method of building your own customised crossover that will suit just about any speaker system. They can be used on 4 or 8 ohm speakers, and even with a combination of both. They can be wired to give a max. of 12dB per octave, or by leaving some components out, they could be 6dB or a combination of both. Full instructions on how to select the various components for different crossover frequencies are included, as well as an 2 Way CX-2605 3 Way CX-2606 attenuation table for tweeters. $17.50 SAVE $20 $13.95 2 x 100 WRMS Stereo Amplifier with Remote Control This is a good looking, no-nonsense stereo amplifier that is rated at a generous 100 watts RMS per channel and will form the heart of an impressive stereo system. • Inputs for Mic, Tape, Tuner, Cat. AA-0470 AV1, AV2, CD, Phono • Approx 420mm wide $199 Passive Direct Injection Box One of the most useful and versatile audio tools available, this DI Box is indispensable in providing easy interfacing and connection between a variety of audio equipment in Cat. AA-0402 numerous applications. $19.95 • Perfect for all live sound, permanent installations - club, church and practice PA systems, monitor systems, home and project recording studios, karaoke and DJ sound systems. • Rugged, roadworthy, all-steel construction will give years of continuous reliability. Five Way Speaker Switch Allows up to five pairs of stereo speakers to be connected to any Hi-Fi system. Each pair of speakers cay be individually turned on or off in any combination. Also features a separate headphone socket. 4 $19.95 NEW Speaker Stand These speaker stands are made of tough, steel construction, featuring three strong tubular supports and can be filled with dry sand and/or lead shot with a suitable sealant applied to the base to prevent leakage. Produce a cleaner, more lively sound from your existing speakers. • Dimensions: • Base Plate - 280(D) x 210(W)mm • Speaker Plate - 210(D) x 170(W)mm Cat. CW-2846 • Height: 400mm $99 • Black in colour • Sold as a pair Kits Theremin Synthesiser Kit The Theremin is a Cat. KC-5295 weird musical $59.95 instrument that was invented early last century but is still used today. The Beach Boys classic hit "Good Vibrations" featured a Theremin. By moving your hand between the antenna and the metal plate, you create strange sound effects like in those scary movies. Kit includes a machined, silk screened, and pre-drilled case, circuit board, all electronic components and clear English instructions. Three Stage FM Transmitter 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 includes a microphone but you can transmit other material as well. Includes a mic, PCB with Cat. KJ-8750 overlay and all other parts. $19.95 • Requires 9V battery Cat. AC-1643 $29.95 Better. More Technical Build Your Own Speakers Essential for multi driver speaker systems 2 WAY SPEAKER CROSSOVERS 3500Hz/6dB 3500Hz/12dB 5000Hz/6dB Cat. CX-2614 Cat. CX-2612 Cat. CX-2613 $10.50 $16.95 $10.50 3 WAY SPEAKER CROSSOVERS 800-5000Hz 6dB 700-53500Hz 12dB 1200-5000Hz 12dB Cat. CX-2615 Cat. CX-2618 Cat. CX-2621 $16.50 $34.95 $57.50 Accessories to finish off your Speakers SPEAKER EQUIPMENT FITTINGS Speaker Cabinet SpikesCat. HS-8002 $10.95 • Pack of 4 for 1 speaker box only Strap Handle Cat. HS-8022 $4.95 • Rubber strap is reinforced with steel • Total length 255mm x 27mm Cabinet Handle Cat. HS-8010 $9.95 • Dimensions 165(W) x 210(L)mm Metal Cabinet Handles • Recessed handle, rubber grip & spring return Silver Cat. HS-8015 $13.95ea Black Cat. HS-8016 $13.95ea Flared Speaker Box Cat. CX-2688 $4.95 • Flared to minimise air turbulence Angled Sub-woofer Cat. CX-2685 $14.95 • Angled at 30° to use in confined spaces Grey Speaker Carpet Cat. CF-2757 $19.95 • Size 1m x 1.4m x 2mm Black Speaker Carpet Cat. CF-2755 $34.75 • Size 1m x 1.8m x 3mm Spray-on Contact Adhesive Cat. NA-1504 $14.95 • 400g • Great for laying speaker carpet in/on speaker cabinets Grille Cloth 1.5 x 1m Cat. CF-2752 $17.50 • Protects expensive drivers • Allows all sound to get through Speaker Sealant 2m Cat. CF-2762 $5.45 • Gets airtight seals between drivers and cabinets FOR INFORMATION AND ORDERING TELEPHONE> 1800 022 888 INTERNET> www.jaycar.com.au Security Accessories to Enhance your Alarm System 8-Zone 2-Partition Alarm Panel 8 protection zones and 2 zones for panic and duress alarms. Designed for home and office protection, the system gives local alarm warnings. Supplied with one alarm control panel and one master control keypad. Programmable user codes, delays and alarm duration. Specifications: Cat. LA-5361 • Operating voltage: 16.5VDC • Entry delay: 15 - 90 seconds $199 • Exit delay: 60 seconds • Alarm duration: 3 - 5 minutes or unlimited • Alarm outputs: 12VDC, 2.5A • Dimensions: Control panel - 168(W) x 168(H) x 78(D)mm • Keypad - 117(W) x 117(H) x 27(D) mm • Suitable backup battery: 12V, 7.2Ah available separately - SB-2486 • Suitable 17VAC plugpack: MP-3022 NEW Due Mid March AV-Gad Brako Glass Breakage Sensor Cat. LA-5550 $59.00 Detects shock signal and glass breaking for a false alarm-free glass break detector Eyespy 11 PIR with Auto Temp Compensation Cat. LA-5532 $49.95 Increased performance in warm temperatures and reduced false alarms in cold temperatures Plastic Siren Cover Cat. LA-5112 $19.95 Rust proof and protects an external siren speaker from tampering. Has pre-drilled holes for strobe mounting and an internal speaker bracket. 12 Volt Photoelectric Smoke Detector Cat. LA-5045 $19.95 This unit is ideal for permanent wiring in boats, caravans or motorhomes etc. Fitted with N.O & N.C. contacts to trigger an external alarm. Dual Infra-Red & Microwave Motion Detector Cat. LA-5039 $79.95 This dual technology sensor provides the highest detection reliability by combining both IR and microwave motion detectors in one compact and attractive unit. NO & NC Reed Switch and Magnet Cat. LA-5070 $6.25 You have both types of contacts on the one unit. Normally open (NO) and normally closed (NC) per pair. Flush Mount Piezo Siren Cat. LA-5257 $12.95 Modern day replacement for the traditional top hat screamer. Mounts flush in the ceiling making it less noticeable. Output: 108dB <at> 1m 47mmdia. Professional Surveillance Cameras - CCD Only • For reliable, quality installations • Fit either C or CS mount lens • Feature Auto-Iris output for an Auto-Iris lens, which adjusts to widely changing lighting conditions • Top and bottom mounting threads for fitting on a standard mounting bracket or indoor/outdoor enclosure • Use specified regulated 12VDC plugpacks: MP-3011 - $17.95 or MP-3032 - $24.95 • Connections: 2.1mmID/5.5mmOD DC power socket, RCA audio socket and BNC video socket High Resolution Colour with Auto-Iris B&W CCD Camera - Pro Style Full range of professional surveillance DVRs 4, 8 & 16 channel with 250GB HDD From $499 Day/Night Camera with Sony Super HAD CCD Sensor Pro Style - Hi-Res ExView HAD Colour CCD Camera Cat. QC-3310 $69 Type QC-3310 QC-3309 QC-3307 QC-3810 QC-3300 QC-3301 QC-3298 QC-3299 B&W Colour Colour Colour Colour Colour Colour Colour Sensor Brand Samsung Sony HAD Sony HR SuperHAD Panasonic HR Sony SuperHAD Sony HR SuperHAD Sony ExView HAD Sony ExView HAD HR Resolution Pixels (H x V) 500 x 582 500 x 582 752 x 582 753 x 582 500 x 582 752 x 582 500 x 582 752 x 582 Security Installing Home Security Systems Book Installing home security can be a daunting task but this guide will almost certainly save you time and frustration. It clearly explains how to plan positioning of motion detectors for maximum efficiency, how to identify potential entry points for thieves, using sensors and switches plus basic cabling and installation. If you're looking to purchase and install an alarm for the first Cat. BI-8205 time, this guide is $2.00 essential reading. A4 8 pages. Large Alarm Sticker Cat. LA-5102 $2.25 Oval Alarm Window Sticker Cat. LA-5104 $2.95 Horizontal TV Lines 380 350 520 480 380 470 380 470 Min Lux 0.05 0.3 0.25 1 0.1 0.2 0.05 0.07 Shutter Speed (sec) 1/100,000 1/100,000 1/100,000 1/100,000 1/110,000 1/110,000 1/110,000 1/110,000 S/N Ratio >48dB >48dB >48dB >48dB >48dB >48dB >48dB >48dB Current Draw 120mA 180mA 160mA 100mA 250mA / 3W 290mA / 3.5W 295mA / 5W 295mA / 5W $290 Weight 630g 630g 290g 250g 610g 610g 610g 610g Dimensions (mm) 118 x 62 x 50 118 x 62 x 50 118 x 62 x 50 117 x 60 x 50 130 x 60 x 51 130 x 60 x 51 130 x 60 x 51 130 x 60 x 51 Recommended Retail Price $69.00 $149.00 $249.00 $199.00 $199.00 $249.00 $249.00 $299.00 Recommended Power Supply Cat. MP-3011 Cat. MP-3011 Cat. MP-3011 Cat. MP-3011 Cat. MP-3032 Cat. MP-3032 Cat. MP-3032 Cat. MP-3032 2.4GHz Transmitter for Video Cameras Active Matrix TFT Security Monitors This compact transmitter simply plugs in-line with an ordinary security camera and turns it into a wireless unit which can broadcast on one of four standard channels. The transmitter operates with all cameras that have a BNC signal socket and uses the camera's existing power supply, eliminating additional wiring. Cat. QC-3594 • Power jumper lead and fixed $69.95 antenna included • Measures 35(W) x 40(H) x 60(D)mm These rugged high performance TFT monitors are purposebuilt for demanding security applications and feature a toughened screen to Toughe prevent n damage. The Glass ed monitors will Screen accept VGA, S-Video, or composite video input and have Interlaced to Cat. QM-3419 Progressive scan. • Up to 1280 line resolution $549 • Accepts VESA 100 mounting • Don't confuse with cheaper non-protected LCD screens!! Cat. QM-3420 19" model also available QM-3420 $649 Commercial Grade Door Entry Beam 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 Cat. LA-5193 plugpack. • Optional counter also available $89.95 Drill not included FOR INFORMATION AND ORDERING TELEPHONE> 1800 022 888 Cat. QC-3299 $249 $249 Quick Reference Cat. Cat. QC-3301 Cat. QC-3307 INTERNET> www.jaycar.com.au Better. More Technical 5 VoIP VoIP or Voice over Internet Protocol is a method for taking analogue signals and turning them into digital data that can be transmitted over the Internet. Perhaps the biggest incentives of VoIP for the home users are price and flexibility. With VoIP, you can make a call from anywhere you have broadband connectivity and by using some of the free VoIP software available you can bypass the phone company all together. Both phones compatible with Skype, MSN, Yahoo Messenger, Xten, Dialpad, MediaRing, and Net2Phone. USING A VOIP HANDSET USB Wireless Phone Broadband Internet Connection • Also use as handset for MSN and Yahoo Messenger's voice service • Plugs into computer USB port • Echo eliminating technology • 30m range USB VoIP Phone with LCD & Hands Free VoIP Handset • Plugs straight to a spare USB port on your computer • Mobile phone design and crystal clear sound quality • Hands Free Function PC/Laptop Cat. XC-4968 Cat. XC-4966 $129.95 $49.95 Broadband Router Memories on Show - 12" Electronic Photo Frame Display your digital photos or videos with an MP3 file for background music if you like. The files can be loaded via a compatible memory card or via a USB cable (available separately) .You can control the display for individual images, a slide show or thumbnails with the remote or with the built-in keys. A huge 12.1" screen size for maximum impact. • Supports SM, SD, XD, MS & MMC Cards • PSU supplied Cat. QM-3774 VGA to VIDEO Converter Use your TV as a computer monitor. Great for watching DVD movies, PC gaming, presentations, educational applications or Internet viewing on TV. SAVE • No software required $10 Was $99.95 $349.95 Cat. XC-4870 $89.95 3.5" HDD Enclosure with PC Button Back-Up This tough aluminium enclosure provides 480Mbps USB2.0 high speed data transfer with hot swappable, plug and play. • Suits most 3.5" IDE hard drives. • One button backup software for PCs included. • Hard drive not included Was $59.95 SAVE $20 Cat. XC-4660 $39.95 Wireless Networking 6 $50 Cat. YN-8067 $39.95 SAVE $10 PCMCIA Wireless Network Adaptor Was $49.95 Cat. YN-8068 $39.95 SAVE $10 PCI Wireless Network Adaptor Was $49.95 Cat. YN-8066 $34.95 SAVE $15 Better. More Technical Everything you would expect from a modern network attached storage device and more! Includes a built-in BitTorrent client that can be used to download and share files over the BitTorrent network without the need to have your computer turned on. Cat. XC-4677 • Hard drive not included $149 More homes and offices are being networked without wires. Here’s the affordable way to be part of the trend. A range of wireless networking cards to suit all Book computers and provisions. This book covers both the MAC and PC Common specifications: environments and will help you set up your • IEEE 802.11g wireless network compatible. wireless network like the Interoperation with IEEE 802.11b 11Mbps networks Pros. It includes hints on • 64 / 128 Bit WEP encryption network security and how to • 54Mbps high speed transfer rate prevent outside attack. • 40 - 100m indoor range • Soft cover • 100 - 300m outdoor range • 560 pages Cat. BP-7100 • Low power consumption $49.95 • Plug and Play compatible • Compatible with Win98SE/2000/ME/XP USB 2.0 Wireless Network Adaptor Router SAVE Was $49.95 This router allows communication with up to four wireless and networked computers. It includes support for WAN, web based and remote management, auto detection and configuration of ISP, built in firewall, and more! • Static and dynamic routing Cat. YN-8086 • VPN pass through $79.95 Was $129.95 NAS Device with Built-in BitTorrent Client Multi-Network Cable Tester with Pin out Indicator This multi-network cable tester is designed to quickly test UTP/STP/Coaxial/Modular network cables by manually or automatically scanning the wires for continuity, incorrect wiring and polarisation. It will sequence each connection and indicate the connections via two 9-way LED bar graphs. Cables can be checked before or after installation by using the Remote Terminator (included). This ingenious cable tester also allows ground- testing of shielded twisted/pair cables. • Main Unit: 104 x 62 x 26mm (LxWxD) • Active Terminator: 100 x SAVE 30 x 25mm (LxWxD) $10 • Requires 1 x 9V battery • Note: Not suitable for Live circuits Cat. XC-5076 Was $39.95 $29.95 Pro Computer Tool Kit The ideal kit for the computer service professional. Includes • 3 solder aid tools SAVE • Chrome vanadium $20 screwdrivers • Crimping tool • Shifting spanner Cat. TD-2041 and much more! $58.95 See our website or catalogue for full listing Was $78.95 FOR INFORMATION AND ORDERING TELEPHONE> 1800 022 888 INTERNET> www.jaycar.com.au 200 Watt Wind Turbine Generators These units are quite massive and ruggedly built. They will generate 200 watts at wind speeds as low as 8 metres per second. They will deliver useful power at a gentle 3 metre/sec breeze or give up to 300W at higher wind velocities. There are two units available: one for 12V systems and another for 24V systems. The 12V unit has a 16V output and the 24V models has a 28V output which will charge an appropriate battery bank. Specifications: • Rated Power: 200 watts • Max Power: 300 watts Cat. MG-4510 • Output Voltage: 12V model: 16V 24V model: 28V $499 • Output Current at Rated Power: Cat. MG-4512 12V model: 16.66A 24V model: 8.33A $499 • Turbine Start Speed: 3m/s • Max Wind Speed: 40m/s • Rotor Dia: 2.1 metres • No of Blades: 3 • Recommended Minimum Tower Height: 4.5 metres • Shipping box dimensions: Box 1: 74 x 44 x 26cm (weight 50kg) Box 2: 154 x 24 x 13cm (weight 30kg) • Total shipping weight: 80kg Dual Stage Lead-Acid Battery Float Chargers Fully automatic switchmode battery chargers that will efficiently charge high capacity sealed and unsealed lead acid batteries then properly maintain them. Just connect and forget. Specifications: Cat. MB-3610 MB-3612 MB-3614 • Max. Current: 6A / 3A +/- 5% 12A / 6A +/- 5% 6A / 3A +/- 5% • Wattage: 85W 160W 160W • Equaliser Charge: 14.4V +/- 0.1V 14.4V +/- 0.1V 28.8V +/-0.2V • Floating Charge 13.8V +/- 0.1V 13.8V +/- 0.1V 27.6V +/-0.2V • Dimensions WxHxD: 168 x 72 x 45mm 162 x 96 x 48mm 168 x 96 x 48mm • Weight: 650g 850g 850g • AC input: • Efficiency: 5 Volt 3400mAh Li-ion Battery Pack Lithium Iron Batteries Take this back-up battery pack with you and charge your digital devices when you are away from home or office. Suitable for many devices including iPod®, PSP® and mobile phones. The pack is charged via USB and includes 7 output adaptor plugs to suit the most popular digital devices. Lithium Iron (Li Fe) batteries pack 5 - 6 six times the capacity of ordinary alkaline cells and give a 40-60% cost saving when comparing energy delivered to price paid. • SB-2364 1500mAh AAA twin pack • SB-2366 1200mAh AA twin pack • Ten year storage life • 4 x battery pack also available Note: These are not rechargeable Cat. SB-2366 $7.95 $69.95 NOTE: iPod® and phone not included Solar Power System with Lights 10% OFF EACH $7.95 Eclipse Lithium 9V 1200mAh Batteries Cat. MB-3300 Great value! Wide variety of sizes! On electrical specifications alone, these quality polycrystalline panels not only stand up to the name brand solar panels but also feature good efficiency and panel size to power rating ratios. They also feature tempered glass protection for harsh environments, and integrated waterproof junction boxes with cable glands that are amongst the best we've ever seen. $99.95 $99.95 $79.95 Cat. SB-2364 Powertech Polycrystalline Solar Panels Cat. MB-3614 Cat. MB-3612 Cat. MB-3610 110/220VAC switchable 47 63Hz >85% Everything you need to get a basic solar setup off the ground. All the components needed are included in the kit: 5 watt solar panel encapsulated in tempered glass, 7Ah SLA battery and 2 x 12V 5W energy saving fluorescent lights. The battery is housed in a sturdy metal enclosure with DC sockets for all the connections, so it's straightforward to set up and use. Cat. MP-4551 $179 Essential for smoke detectors, wireless alarms, garage remotes etc. Very dependable. For the sake of your family fit your smoke detector with Lithium batteries. Note: These are not rechargeable 2 Pack SB-2396 $22.95 Wind Powered Generator Experimenters Kit Learn all about this green energy source, and the mechanics of wind generators. It is supplied in kit form, so you get to assemble the whole thing before you start learning about how it works. Cat. KJ-6696 $49.95 12 Volt Battery Charging Regulators for Solar Panels Maintain your battery system in peak condition with one of our solar charge controllers. They are available with a range of features to suit various installations. Voltage 12V 12V 12V 12V 12V 12V Power 5W 10W 20W 65W 80W 120W Cat ZM-9071 ZM-9073 ZM-9074 ZM-9076 ZM-9078 ZM-9079 Was $99.95 $149 $239 $549 $699 $1050 Now $89.95 $134.10 $215.10 $494.10 $629.10 $945 12V 5A Cat. AA-0348 $29.95 FOR INFORMATION AND ORDERING TELEPHONE> 1800 022 888 INTERNET> www.jaycar.com.au 12V 1.5A Cat. AA-0258 $22.95 12V 6A Cat. MP-3128 $39.95 12V 20A Cat. MP-3126 $74.95 Better. More Technical 20A 12V with LCD Cat. MP-3129 $139.95 7 Kits UHF Remote Controlled Mains Switch PIC Based Water Tank Level Meter Kit Ref Silicon Chip November 2007 This PIC-based unit uses a pressure sensor to monitor water level and will display tank level via an RGB LED at the press of a button. The kit can be expanded to include and optional wireless remote display panel that can monitor up to ten separate tanks (KC-5461) or you can add a wireless remote controlled mains power switch (KC-5462) to control remote water pumps. Kit includes electronic components, case, screen printed PCB and Cat. KC-5460 pressure sensor. $99.95 Telemetry Base Station for Water Tank Level Meter Ref Silicon Chip February 2008 Commercial remote control mains switches are available but these are generally limited to a range of less than 20m. This UHF system will operate up to 200m and is perfect for remote power control systems etc. The switch can be activated using the included hand held controller or our KC-5461 water tank level sensor base station. Kit supplied with case, screen printed PCB, RF modules and all electronic components. Ref Silicon Chip January 2008 This Base Station is intended for use with the telemetry version of the KC-5460 water tank level meter. It has an inbuilt 433MHz wireless receiver and can handle data transmissions from up to 10 level meters and display the results on a 2-line 32-character LCD module. Kit includes electronic components, case, screen printed PCB and RF module. Cat. KC-5462 Cat. KC-5461 $99.95 $79.95 Save on Digital Multimeters Computer Connect Auto Range DMM Sensational Value DMM With the ability to analyse and store information on your home or notebook computer, this meter is ideally suited to laboratory or fieldwork. The software features data logging, with information displayed on a graph or simple list. When recording, you have the option of recording continuously or in preset time gaps. Min/max/avg information can also be displayed. The information can be exported to spreadsheet programs such as Excel for further analysis. • 3.7 Digit • Diode Test • 10 Amp AC & DC current • Data Hold Cat. QM-1538 • Software included $29.95 Was $39.95 SAVE $10 SAVE $40 $7.95 QM-1564 Mini AC/DC Current Clamp Meter with Non-contact Voltage Sensor available separately Was $99.95 Now $79.95 Save $20.00 SAVE $40 QM-1290 SAVE $15 QM-1462 Cat. QM-1290 QM-1462 QM-1541 QM-1539 Ideal for car stereo installations and electrical trades people. • 200A AC/DC • Frequency • Capacitance • Autoranging • Auto power off • Data hold • Zero function • Duty Cycle • Continuity Buzzer Cat. QM-1562 • Carry case included $99.95 • 4000 count Was $139.95 Cat. QM-1500 SAVE $50 Description Protek 506 USB Computer Connect IP67 Harsh Environment Cat III DMM AC/DC Current Clamp Meter Excellent budget digital multimeter packed with features. • 3.5 Digit • 12.5mm high LCD • Transistor test • Diode test • 10 Amp current • Plug-in leads Safety Category Cat III 600V Cat IV 600V Cat IV 600V Cat III 600V SAVE $20 QM-1539 Display 4000 Count 4000 Count 4000 Count 4000 Count QM-1541 Features 20A Current, TrueRMS, RS232 20A Current, USB Interface Large Display, IP67 Large Display Was $198.00 $139.95 $99.95 $59.95 Now $148.00 $99.95 $79.95 $44.95 See our website or ask in-store for full specifications 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) 8 6021 9699 9709 9678 9369 9905 4620 4365 9439 9476 4965 9683 4721 8831 6788 4699 2822 9669 3899 4130 7155 3433 4799 6221 3799 3377 8337 3151 Silverwater Sydney City Taren Point Tweed Heads Wollongong VICTORIA Coburg Frankston Geelong Melbourne Ringwood Springvale Sunshine Thomastown QUEENSLAND Aspley Cairns Better. 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Card expiry date: Signature_____________________________ 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, March Australia 20972008  57 03/08 A Digital VFO with Graphics Display This DDS VFO uses a widely available recycled Nokia cellular phone LCD to display analog and digital frequency readouts, text, and VFO status messages F or several years, I’ve wanted to build my own DDS (Direct Digital Synthesis) VFO (Variable Frequency Oscillator). Analog Devices makes one of the most popular ranges of DDS chips which digitally generate precise sine waves covering frequencies from practically “DC to daylight”; well, up to many hundreds of MHz. Some time ago I managed to obtain several samples but, for some time afterwards, that was as far as things went. I was just too busy with work and family to devote any time to the project. In addition, I couldn’t locate a suitable design to build. Practically all existing designs use one of the PIC microprocessor family. Others use several PIC microprocessors; yet others use a further large bunch of ICs to interface displays and keypad functions. With my microprocessor development tools all focused on the 8051 family – and being fundamentally of a contrary nature – I was determined to use an 8051 chip in my DDS VFO rather than mess about gearing up for another microprocessor, and keep the chip count minimal. Underlying this was a feeling that if I wrote my own software, I could customise it to suit my precise requirements and be better placed to develop one or two other DDS-based projects I have in mind. Of course, that naively assumes I’ll find the time to complete those new designs. Fig.1: the promise of things to come? The DDS VFO with its cellular phone “readout” mounted inside an HF transceiver the author is currently working on . . . 58  Silicon Chip siliconchip.com.au h LCD CLOCK fc by Andrew Woodfield ZL2PD ADDRESS COUNTER n bits SINEWAVE LOOKUP REGISTER DIGITAL TO ANALOG CONVERTER fOUT DIGITAL TO ANALOG CONVERTER fOUT Fig.3: basic Direct Digital Synthesis system. FIG 3: BASIC DIRECT DIGITAL SYNTHESIS SYSTEM PHASE ACCUMULATOR TUNING WORD M 24–48 bits n bit carry  n bits PHASE REGISTER 14–16 bits PHASE TO AMPLITUDE CONVERTER SYSTEM CLOCK fc Operator interface Let’s not forget the operator interface. Practically all existing designs use a standard 2 line x 20 character alphanumeric display. An earlier popular design used high current seven segment LED displays. The size of both of these displays and the limited information presented to the operator didn’t seem ideal to me. They certainly weren’t well suited for the small HF transceiver I’ve also been building. This led to another delay while I looked for alternative displays and a series of experiments with some small cheap, graphical LCD modules. These monochrome LCDs were used in many older cellular phones, as well as in some current low cost entry-level models. I built several small projects using one of the most commonly used Fig.2: the readout, from a Nokia cellular phone, is capable of displaying simple graphics . . . siliconchip.com.au Fig.4: a typical Direct Digital Synthesis system. FIG 4: TYPICAL DIRECT DIGITAL SYNTHESIS SYSTEM graphical LCDs, the Nokia 3310 LCD module. This LCD turned out to be very useful – It offers a 84 x 48 pixel display with a visible area of about 35mm x 25 mm. DDS Oscillators Direct digital synthesis (DDS) is a digital method to generate waveforms, usually sine waves. In contrast to the more common phase locked loop (PLL) approach which uses a voltage controlled oscillator, digital dividers and a phase detector to generate frequencies in defined steps, data stored in an internal DDS chip table is passed to a digital to analog (D/A) converter at a specific clock rate. If the table contains values equivalent to the amplitude of a sine wave, then a sinewave at a frequency related to the clock rate will be produced. One such basic DDS is illustrated in Fig.3. By changing the clock speed, a wide range of sinewave frequencies can be generated. If the clock is fast enough, frequencies can readily be generated across wide ranges, and at sub-Hz increments. The completely digital nature of the DDS oscillator and its ability to generate very fine frequency increments are the main advantages over PLLs. In practice, a DDS device uses the arrangement shown in Fig.4. The tuning word, which is usually 32 or 48 bits wide, is used to modify a phase accumulator. This outputs a 14-16 bit word for onward signal generation. With this approach and with a 32-bit tuning word, it is possible to generate more than 4 billion specific frequencies. For more information on DDS chips, the introductory documents on the Fig.5: and here it’s shown mounted on the back of the PC board, along with the six control switches. There are minor differences to the correct layout shown in Fig.8. March 2008  59 bands. The LCD modules the current operating frequency and mode of the VFO. A key feature of this design is an analog-style graphics-driven dial displayed on the LCD which sweeps up and down just like a conventional mechanical dial while tuning the VFO. The VFO also features two independent VFOs, a programmable receiver IF offset capability, full RIT, and VFO locking. All of this software is handled within a single 20-pin low cost Atmel 89C4051 microprocessor. The DDS drivers within the microprocessor are quite compact, but much of the space within the 4K bytes of flash program memory is actually required for lookup tables to handle the Nokia 3310 LCD. Unlike standard 2 line x 20 character alphanumeric displays, all of the information displayed has to be generated, dot by dot, by the 89C4051 microprocessor. Each and every character, every graphical feature, all resides within the 4K of program memory. The VFO code itself amounts to less than 1.5Kbytes, the balance taken up by the graphics tables. There is also some room in the program memory to permit other builders to add features to suit individual Fig.6: there are two ways to construct the DDS VFO – cut the board and “sandwich” the two sections as shown here, or leave the board intact (the tracks for the two sections are provided). As you can see from this photo, the component side of the PC board(s) is a groundplane, formed by using double-sided PC board blank. Analog Devices website at www.analog. com are highly recommended. The most significant problems with DDS oscillators are noise and spurious emissions. These can be minimised by using D/A converters with relatively long digital words. Many DDS devices are limited to 10-bit words but newer devices more often use 12-bit or 14bit words. This DDS VFO uses an Analog Devices AD9850 chip which uses a 10-bit D/A. This delivers a spurious emission level of -50dB. Frequencies are selected using 32 bits of a 40 bit tuning word, allowing better than 0.03Hz frequency steps 60  Silicon Chip At right is the optical encoder, made from a surplus mechanical mouse with the 80MHz DDS clock used in this design. The balance of the 40 bit word is used for phase and control functions. Since this level of resolution exceeds most requirements, many DDS VFO designs use a larger step size. In this VFO design, the user can select 10Hz, 100Hz or 1kHz steps to give three tuning rates – slow, medium and fast. Functionality The DDS VFO covers all amateur radio bands between 160m and 10m in 10Hz, 100Hz or 1kHz increments, and will happily tune outside of these requirements. The code uses no special features of the AT89C4051 and so it may be used with almost any 8051-type processor possessing adequate memory. One option might be the addition of country-specific frequencies, for example, not currently supported by the present VFO software. To that end, the fully commented source code is available from my website, as well as the Intel hex file for direct programming of blank microprocessors. The Design In contrast to other designs, this DDS VFO design is almost minimalsiliconchip.com.au siliconchip.com.au March 2008  61 LOCK VFO A/B PTT RIT 4 IC1b 22pF 22pF 10k +5V 7 IC1: LM393 1 X1 8.866MHz 22k 5 6 8 IC1a 10k RST 5 4 12 16 15 14 13 X2 X1 P1.0 P1.4 P1.3 P1.2 P1.1 7 P3.3 INT1 6 P3.2 INT0 1 GND 10 IC2 AT89C4051 Vdd 20 P3.0 P3.1 P3.4 P1.5 P1.6 P1.7 P3.7 A A A Vo CS 5 8 7 9 7 2 IC3 80MHz OSC 8 3 14 100nF 7 +5V 8 Rset D2 Vddd 2 5,24 Dgnd CLKin 22 10,19 Agnd RST IoutB 20 12 3,4, 6,23 100nF 56 100 10 F IN 150pF 33pF L2 330nH* IN 100pF 100nF 1 2,4 3 A A K OUT 100nF RFC3 100 H 120 K 12V DC RF OUT 2 3 ERA-4 LEDS ADJ BEVELLED 4 END 1 IN – + LM317LZ RFC4 100 H 1N4148 47 F IC5 ERA-4 LCD MODULE PINOUTS (REAR VIEW) 1 8 OUT GND IN 7805 GND OUT REG1 7805 * L1: 13 turns on T25-10 L2: 12 turns on T25-10 100pF 10pF L1 390nH* 100nF ADJ OUT REG2 LM317LZ RFC2 100 H 470 10 F 330  LED1 330 3.9k 4.7 F 10k +3.3V K A IC4 Iout 21 AD9850 DDS+DAC Wclk Fu/d SDin 11,18 Vdda RFC1 100 H GND 6 RST NOKIA 3310 LCD MODULE V+ 1 25 100nF 3x 10k NOT USED 1 F SDA SCL 4 D/C 3 2  LED2 1k 8 9 K A 3x 10k D1– D3 1N4148 17 K 18 K 19 K 11 100nF DDS DRIVEN VARIABLE FREQUENCY OSCILLATOR BAND 2x 10k STEP  2 3 10k 10 F Fig.7: the complete DDO VFO circuit diagram. Using the cellphone display certainly simplifies things! 2008 SC  TUNING OPTICAL ENCODER   560 100nF +5V 12V DC IN 14 IN TO IC1 PIN 3 2x 22pF NOT USED 10k 100nF IC1 LM393 10k 560 IC3 80MHz OSC 18030340 OFV SDD A K ENCODER LED 5V 22k 10k 4148 D1 4148 D2 4148 D3 + 100nF REG1 100nF REG2 10 F 10k 10k 10k S3 S2 S4 S5 1 2 3 4 5 6 7 8 330 470 + 1 F + 10 F + 4.7 F S1 NOKIA 3310 LCD MODULE S6 1k 28030340 LED1 OFV SDD LED2 = BOTTOM LAYER COPPER (TRACKS) = TOP LAYER COPPER (GROUNDPLANE) Fig.8: component overlay for the top (ground plane) side. Here the two parts of the PC board are shown still connected; the links (shown in green) are only required if you split the board and “sandwich” it. ist, using just four chips (excluding the regulators): the microprocessor, the optical encoder interface chip, the DDS, and the RF amplifier chip. This avoids the approach used in a number of other designs which requires a microprocessor dedicated to the encoder and display and a second processor dedicated to the DDS. The microprocessor is also operated at a very leisurely 8MHz. I actually used a PAL TV colour-burst crystal of 8.866MHz but any crystal from 8 to 12MHz will likely work fine. The top speed for this micro is 24MHz, so clearly nothing much is being pushed hard in this design. This might suggest that the 8051 is significantly more efficient than other 8-bit microprocessors used in similar designs. My software is all written in handcoded assembler, often far more effi- A NOTE TO SILICON CHIP SUBSCRIBERS Your magazine address sheet shows when your current subscription expires. Check it out to see how many you still have. If your magazine has not turned up by the first week of the month, contact us at silchip<at>siliconchip.com.au 62  Silicon Chip + 47 F 330 IN TO IC1 PIN 5 TO/FROM OPTICAL ENCODER – RFC4 10k 8 100nF + 10k 1 + RFC1 RFC2 100nF 100pF 56 100 100pF 7 10 F 10k 10k X1 8.866MHz 33pF 10k 10k 3.9k 150pF IC2 AT89C4051 120 L1 L2 100nF 100nF RFC3 10pF RF OUT cient than higher level languages and the code possibly also makes a little better use of interrupts. This approach allows the optical encoder (the main tuning control) to be very rapidly read without causing any measurable delays in the main DDS and display routines despite the fairly intensive data transfers required by the Nokia 3310 LCD whenever it is being updated. Interrupt-driven routines tend to be a little more complex to write but are necessary here to handle rapid updating of the digital display and the analog dial graphics, while also reading the dial and checking for any pressed buttons. These functions can add up to quite a lot of work for this modest 8051 microprocessor to manage but it is made possible by minimal mainline software functions and a relatively fast background interrupt cycle. This interrupt cycle is focused on reading the encoder, the most time-critical function. When power is applied to the VFO, the microprocessor begins by initializing the LCD module. These feature a brief animated set of graphics which illustrate some of the flexibility of the display and makes use of some spare ROM space. The 89C4051 then initialises the DDS VFO to the bottom of the 80m band in receive mode, with an offset assuming an IF of 8.467MHz, and with RIT (receiver incremental tuning) turned off. These parameters are all set by the software, and are very easy to change to suit other applications and user preferences. These settings are all very clearly highlighted in the source code. The DDS requires a 40-bit serial word transfer from the microprocessor. As the encoder is rotated, the DDS frequency is updated, the new frequency displayed and the dial graphics dynamically changed according to the direction of tuning knob rotation. The 40-bit word sent to the DDS is calculated from a series of predetermined lookup values, one for each digit in the 7-digit frequency of the VFO, the values depending on the DDS clock used. In this case, they assume an 80MHz clock, the highest frequency crystal Fig.9: soldering that SMD-mount chip requires a steady hand and a fine iron (see the SMD article in this issue!) siliconchip.com.au oscillator I could buy locally. The DDS output is filtered using a 5th order elliptical low pass filter with a cutoff frequency of about 35MHz. The output from the filter is then amplified with a ERA-4 surface mount MMIC. This gives a output level of about 1V peak-to-peak or +13dBm into 50W from the VFO, ideal for diode mixers. Since the DDS output level follows a sinx/x envelope, the output reduces to 0.8V peak-to-peak by 30MHz. This 2dB rolloff is of little concern in transceiver applications but should be borne in mind if this software is used for signal generator applications. The 80MHz DDS oscillator is the reference for the VFO’s output frequency. By contrast, the microprocessor crystal is a nominal 8MHz crystal and, as noted earlier, its exact frequency is not critical. Since output frequency accuracy and stability depends on the 80MHz DDS oscillator (and few of these have any external frequency adjustments available), any users requiring absolute output frequency accuracy can make the simple frequency alignment adjustments within the software. I found my VFO was accurate to a few hundred Hertz and quite adequate for my uses. The Nokia 3310 LCD module requires a 3.3V supply. While some 8051 chips will operate on the same 3V supply, the 80MHz oscillator demands a 5V supply. The decision was therefore made to run both a 5V (for micro and oscillator) and a 3.3V rail for the LCD. It’s a slight additional complexity but makes the design easier to convert to other types of 8051 chips should this prove desirable. The interface between the AT89C4051 and the display, necessary due to the different supply rails on these parts, is handled with three cheap isolating diodes. If you are able to purchase some 3.3V clock oscillators (a standard part but one I couldn’t buy locally), you can easily modify the entire VFO for single supply rail operation. The microprocessor interface for the LCD module uses fewer control lines than suggested in many references. Most suggest the need for five lines, including a reset line from the microprocessor. Careful reading of the datasheet revealed that the chip select (CS) line can be permanently tied to ground at the cost of a little more current. The VFO’s MMIC amplifier is fairly siliconchip.com.au Figs.10 & 11: here’s the full size artwork for both sides of the PC board with the top (ground plane) at right. We imagine most constructors will not bother etching a second layer (if they can!) but will simply remove the top-side copper around the holes with a small twist drill (eg, 5mm). It’s tedious but easy enough to do holding the drill in your fingers, putting the tip in the hole and twisting. The smaller holes in the ground plane are for the components which solder to both sides of the board – these should not be opened out. greedy, drawing around 65mA, so the modest constant 5mA consumed by the always-on LCD turned out to be of little concern. The datasheet also suggested the possibility of using a resistorcapacitor reset arrangement (10kW and 4.7mF), and that saved a further I/O pin. As a result, there is an additional delay of a hundred milliseconds or so at power-up, just to be sure the display has reset but this is of little importance in overall operation. The main dial knob uses connects to an optical encoder. This is interfaced to the microprocessor with an LM393 comparator to ensure clean rising and falling quadrature signals. The use of an optical encoder delivers improved long term reliability and allows users to set up the mechanics of the dial knob to suit individual taste. Construction The VFO can be built either as a single PC board measuring about 150 x 50 x 15mm (wxhxd) or in a sandwiched two-PC board configuration measuring 100 x 50 x 25mm (wxhxd). Those wanting a smaller version can convert the current layout to use SMD March 2008  63 Parts List – DDS VFO 1 double-sided PC board, 150 x 50mm, coded 06103081 (see text) 1 digital display ex Nokia 3310 cellular phone (see text) 1 surplus mechanical (ball-type) mouse for optical encoder parts (containing 1 LED and 2 phototransistors – see text) 1 8.866MHz crystal (X1) 6 PC mounting SPST pushbutton switches Semiconductors 1 LM393 (IC1) 1 AT89C4051 microcontroller (IC2) 1 80MHz oscillator (IC3) 1 AD9850 (IC4) 1 ERA4 (IC5) 1 7805 5V positive voltage regulator (REG1) 1 LM317LZ voltage regulator (REG2) 3 1N4148 silicon signal diodes (D1-3) 1 yellow LED 1 green LED Capacitors 1 10mF 16V PC electrolytic 3 10mF 10V PC electrolytic 1 4.7mF 10V PC electrolytic 1 1mF 10V PC electrolytic 7 100nF polyester 1 150pF polyester 2 100pF polyester or ceramic 1 33pF ceramic 2 22pF ceramic 1 10pF ceramic Inductors 1 390nH (L1) 1 330nH (L2) 4 100mH (RFC1-4) (code 0.1, 100n or 104) (code 150p or 151) (code 100p or 101) (code 33p or 33) (code 22p or 22) (code 10p or 10) (13T 33SWG ENCU on T25-10 toroidal former) (12T 33SWG ENCU on T25-10 toroidal former) Resistors (all 0.25W, 1%) 1 22kW 12 10kW 1 470W 2 330W 1 3.9kW 1 120W parts and reduce the dimensions by about 40%. While the present design uses a double sided PC board, the top side of the board is left unetched, forming a continuous copper ground. This allows the PC board to be etched in typical home workshops with ease as if it was a single sided PC board. That’s the method I used for the version pictured. While I’ve used standard components as far as possible, construction is not for the faint-hearted. The DDS chip, for example, is a 28 pin SMD device with very close pin spacing. The display connections are also challenging. Time and care allows both to be soldered into place but it does require a good soldering iron with a fine tip, steady hands, patience and good eyesight. I’d suggest building the keyboard/ 64  Silicon Chip 1 1kW 1 100W 1 560W 1 56W display PC board first. Install the jumpers first, the resistors, then the buttons, and finally mount the display. The Nokia 3310 display is supplied mounted on a plastic keypad frame assembly complete with speaker. Prise out the speaker – it’s just pressed into a rubber ring – and trim the surplus plastic away with a sharp knife, being careful not to disturb the plastic around the display itself. This is essential to maintain slight compression on the metallic springs which press onto the conductive tracks on the LCD glass. The display is then wired to the pads on the PC board. I was tempted to lay the PC board out to permit the display to be directly mounted on it but the current method offers a little more flexibility. However, it does require some delicate soldering of wire jumpers between the spring metal connections on the rear of the display and the PC board. I kept everything in place with a few dabs of hot glue and the display assembly was mounted a few millimetres off the PC board with three further strategic dabs of hot glue. This sounds crude – but it’s unseen and the glue forms a very rigid arrangement which can be easily adjusted with a little heat from a soldering iron. The display is extremely light, and the resulting mounting is very robust. There is also space beneath the LCD for the addition of backlighting, perhaps using some diffused LEDs, if desired, although the current PC board layout does not allow for component wiring. By the way, don’t be tempted to remove the white plastic material from the rear of the LCD. This improves display contrast and aids backlighting. I tried some green LEDs for backlighting and they worked very well, so I may add these to the final transceiver. An extra pullup resistor (10kW) can be seen in Fig.5 mounted next to the inter-PC board wiring on the top side of the keyboard/display PC board. This was caused by a minor change in pin connections when going from my Veroboard and wirewrap prototype to the final PC board version. This resistor IC1 PIN 1 IC1 PIN 7 ENCODER OUTPUTS WITH POSITIVE (CLOCKWISE) ROTATION IC1 PIN 1 IC1 PIN 7 ENCODER OUTPUTS WITH NEGATIVE (ANTICLOCKWISE) ROTATION Fig.12 : quadrature outputs from an optical encoder are used to tune the DDS. siliconchip.com.au siliconchip.com.au 54 95 28 59 8 44 Notes: 38 40 1. Red lines and dimensions in red text indicate details specific to the DDS VFO. All other dimensions may be varied to suit specific applications. 2. Panel material should be removed from the shaded area. 3. Dotted lines show outlines of LCD display and other panel-mounted components Fig.13 : same-sized diagram of the front panel of the transceiver on P58 showing where the VFO mounts. 4. All dimensions are in mm 40 21 54 28 has now been added to the PC board layout shown in Figure 8 and 9. Constructing the DDS/microprocessor PC board can start with the installation of the resistors and capacitors. Then proceed to add the jumpers and the various through-PC board connections if your board does not have plated-through holes. Mount the microprocessor socket (I strongly recommend using a “machine screw” IC socket for non-plated through PC boards), the LM393, crystal oscillator and crystal. The LM393 does not need a socket. Complete the board by soldering in the DDS chip and the ERA-4 MMIC. The optical encoder should be added next. Although you can use a commercial model, I made my optical encoder from parts salvaged from an old PC mechanical-type mouse. It’s not a difficult task – there are enough bits inside an old mouse for two such encoders. It is possible to monitor the two output pins of the LM393 interface to confirm correct quadrature waveforms using an oscilloscope (See Fig.12) while rotating the encoder. If you test without the microprocessor installed, which is best, you will need to add temporary pullup resistors on each open-collector comparator output. Any value from 4.7kW to 100kW works fine for testing. Remove these once encoder testing is complete. Fig.12 shows the ideal waveforms. Actual outputs have less perfect shapes, with variable width and timing but still do the job. The LCD module and pushbuttons are mounted on the solder side of the PC board. This allows the board to be mounted at the ideal distance from the front panel for display visibility and for the buttons to be depressed through a Lexan or similar flexible keypad/panel. Since my workshop facilities doesn’t run to Lexan production facilities, I made a workable flexible front panel from transparent plastic stick-on film from the local stationery shop and a laser-printed paper panel overlay. Unfortunately, my panel layout is too long to be printed here but it can be downloaded from my website (see references) or from www.siliconchip. com.au The film is layered over the paper on both sides and provides protection for the display while allowing the March 2008  65 buttons to be easily pressed under the appropriate keypad label. This panel will obviously wear out much faster than Lexan but it’s cheap and easy to make and replace. There are two indicator LEDs on the PC board. The green LED shows when DC is applied to the board and can be used as a power indicator (Top left hand corner of the front panel in Fig.10). The yellow LED was used during the software development to measure the time taken by the main software loop. It still does, changing state each time through the loop, flickering in varying degrees of brightness as buttons are pressed, the VFO is tuned, and the LCD updated. I located this LED at top dead centre over the main tuning knob. Yes, I confess, it’s purely for there for show, so just omit it if you don’t like it. The two PC boards are connected together using a total of 12 short wire links. There is a further short wire jumper which is run between the two boards for the +12V supply. This goes to the 120W resistor to power the MMIC. Operation With an 80MHz DDS clock, the VFO will operate with minimal spurious outputs up to about 30MHz. In transmit mode, the DDS VFO outputs the frequency displayed on the LCD. In receive mode, the receiver IF offset is added to the displayed output frequency until the actual DDS output frequency exceeds about 30MHz. At that point, the IF offset is subtracted from the nominal output frequency to keep spurious products to an acceptable minimum. The VFO keys have the following functions: LINE FUNCTION 1 Reserved for a 14 character string of text including the user’s callsign 2 Digital display of VFO frequency 3 Used by the VFO cursor which indicates the step size currently in use 4 Analog dial display 5 RIT frequency (Only shown in RIT mode) 6 Status messages including VFO lock, VFO A/B selection, and Tx mode Line 1 is the top-most LCD line. Incidentally, lines in the software are actually numbered from 0 to 5 to match the LCD controller’s addressing scheme. addresses the display using this linebased mode as shown above. Also mentioned earlier, the VFO has three tuning speeds, selected by the Step key. Some consideration was given to adding variable rate tuning to this VFO. This method is used on some commercial transceivers. As the dial is rotated more quickly, for example, the tuning rate will initially directly match the increased rotation speed. Then, if the tuning rate is sustained, the VFO frequency increment will be automatically increased, resulting in accelerated tuning, with the frequency being incremented at a much faster rate. When the dial is slowed, this is detected and the tuning rate switches to a slower rate. Having used it in one of the commercial transceivers I own, I’ve not found it particularly pleasant to use. Call me old-fashioned but I prefer the standard fast/slow tuning speed selection used in one of my older commercial transceivers. I did try a variety of variable rate methods during the development of this design but none really proved to offer any benefits over the scheme finally adopted. So, variable rate tuning VFO KEY FUNCTIONS: Step Selects VFO frequency increment (10Hz, 100Hz or 1kHz steps) Band Selects desired band (160m, 80m, 60m, 40m, 30m, 20m, 15m, 12m, 10m) RIT Changes dial to RIT control allowing the receiver frequency to be offset by ±5kHz in 10Hz steps VFO A/B Selects one of two independent VFO frequency banks Lock Locks the VFO frequency to the currently selected DDS output frequency Tx Removes the receiver IF and RIT offsets from the VFO output frequency As mentioned earlier, the LCD is addressed as a 6-line display, each 8 pixels high and 84 pixels wide. This is determined by the LCD controller chip bonded inside the Nokia 3310 display, a Philips PCD8544 or equivalent. The DDS VFO software therefore 66  Silicon Chip is not a standard feature in this VFO. Construction Options The split PC board layouts used in this design readily permit the use of other keypads and displays. In such cases, only the DDS/microprocessor board need be built. The relevant port lines are all available on the edge of this PC board. With minor changes in software, those standard two-line x 16 character alphanumeric LCD modules may be used, as may many different keypad arrangements and keypads. In most such cases, the software will readily fit in the smaller AT89C2051 (2K flash ROM) microprocessor which is 100% pin-compatible with the DDS/microprocessor board layout shown here. If there is sufficient interest, I will make schematics, connection details and software available on my website for this alternate version. Future Development Now that this design is complete, I want to find some time to build an RF signal generator using the more powerful AD9854 or AD9912 DDS chips. These DDS devices have higher quality quadrature outputs and are ideal for use with software-based receivers. Interestingly, a simple signal generator actually requires much less code than a ham-band transceiver VFO. But to compensate for this, I’d like to use one of the more complex full-colour cellular phone LCD modules. All I have to do is persuade my wife to let me borrow her new cellphone for a few minutes… SC References 1. The ZL2PD website can be found at www.zl2pd.com This contains all of the source code, assembled hex files, full size schematics and PCB artwork for free downloading 2. Analog Devices, ‘A Technical Tutorial on Digital Signal Synthesis’, 1999 (See www. analog.com) 3. Two websites offering Nokia 3310 LCD displays at time of writing include www.jelu. se and gsmserver.com, although I have no experience with either source. 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. UHF IN 300 BR2 3.6k + TUNING 2.2 F IFo AFC BL AGC BH BU TUNING TUNER MODULE UVE 33–12 VHF IN 75 VR1 10k +42V + – 470 F 63V ~ BR1 VHFL BAND SELECT S1 2.2 F VHFH A UHF 1nF D1,D2: 1N4148 A A VR3 10k SENSITIVITY 9V AC ~ This TV field strength meter is based on a tuner module salvaged from an old Sharp TV although the circuit can be adapted to most VHF/ UHF tuner modules used in TVs and VCRs. The pin assignments are usually stamped on the cover of the tuner module or may be found on the bottom of the PC board. The Sharp tuner is an older model digital tuner, with a 75-ohm input for VHF and a 300-ohm input for UHF. Modern tuners now have a single 75-ohm input for the VHF & Q1 PN100 100–200 A + – METER VR3 10k B +12V METER – + C 100–200 A E OPTIONAL MOD FOR MORE SENSITIVITY K TV field strength meter 240V AC – VR2 10k 1000 F 16V K K D1 C B E 30V AC D2 PN100 S2 T1 ~ + +12V GAIN ~ UHF bands. Old VCRs can be picked up cheaply at flea markets and at kerbside rubbish collection times. The IF (intermediate frequency) pin produces a 45MHz signal (in the USA) and the IF output level varies with the incoming signal level. In fact, the frequency of the IF signal doesn’t matter as it’s simply rectified by diodes D1 & D2. Trimpot VR3 provides a sensitivity adjustment for the meter. The circuit is powered by a transformer with 8V and 30V AC secondary windings. The 8V AC is rectified by bridge BR1 and filtered to provide the nominal 12V DC rail for the tuner module while the 30V AC is rectified by bridge BR2 and fed to potentiometer VR1 is to provide a tuning voltage range of 0-30V DC. Potentiometer VR1 is connected to the AGC input to serve as a gain control. If you need more gain to obtain reasonable deflection of the meter, transistor Q1 can be added, as shown. As presented, the circuit will give a useful indication of TV signal strength and can be used as an aid for best antenna orientation. Henry Bowman, Parsons, Tennessee. ($50) 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 siliconchip.com.au Thyristor & Triac Analyser, with the compliments of Peak Electronic Design Ltd – see www.peakelec.co.uk You can either email your idea to silchip<at>siliconchip.com.au or post it to PO Box 139, Collaroy, NSW 2097. March 2008  67 D. Edw is this m ards onth’s winne Peak Atl r of a as Instrum Test ent Circuit Notebook – Continued S1 100 +5V 10k K REG1 7805 OUT ZD1 16V 1W 100 F IN GND A 2.7k SET VOLTS 2 VR1 2k LIN 3 LM311 B C 8 IC1 47k 7 E B 4 C 1 1k 4.7k Q1 BC557 ALTERNATOR + F 1k 10 F + 12V BATTERY Q2 2N2955 OR SIM 1M A POWER  LED1 CHARGING LED2 K GND – E K A D1 1N5404 A  – K 7805 2N2955 LEDS OUT IN GND BC557 K A ZD1 B E C A C 1N5404 K Alternator controller for charging deep cycle batteries A K B C E This controller is used for charging a bank of deep-cycle lead acid batteries from a 12V alternator driven by a Lister diesel motor. It provides three modes of charging: a hefty initial bulk charge, a pulse width modulated float charge to settle the voltage level and, when required, an adjustable high-voltage equalising charge. This latter mode is also useful to reactivate the sulphated batteries. The heart of the circuit is an LM311 comparator (IC1) and its reference voltage at pin 3 is provided by a 78L05 voltage regulator. The battery voltage is monitored during charging by a resistive divider which includes trimpot VR1. Its wiper is connected to the non-inverting input (pin 2) of the LM311. If the battery is below the set reference voltage level, the alternator field current is supplied by transistors Q1 & Q2, setting the alternator at its maximum charge current. When the set level is attained, nominally 13.8V to 14.2V, the circuit will switch to PWM mode, pulsing current into the battery bank at whatever rate is required to keep equilibrium. This pulse width modulation (PWM) is a function of the hysteresis of the comparator, as determined by the 1MW resistor between pins 3 & 7. At this point, the generating system can be shut down, as the best diesel efficiency can only be achieved if the engine is running almost fully loaded. The battery bank should be equalised several times a year. This is achieved by setting the cut-out voltage much higher than normal, usually around 15V and charging the batteries to this level. This will cause gassing in the cells which helps to mix the electrolyte which otherwise tends to settle into layers of varying acidic density. Any load connected to the battery bank should be disconnected during this procedure. D. Edwards, Taylorville, NZ. Emergency light uses 3W white LED and also prevents reverse current flow from the battery. 555 timer IC1 functions as an optical comparator and switch. LDR1 is the light-sensing element. When light intensity is high, LDR1’s resistance is low and as a result, the high level output from pin 3 will turn on transistor Q1 and disable the LM317 driving LED1 (in reality, it reduces the output of the LM317 to 1.25V). When the light intensity is low, LDR1’s resistance is high, the 555’s output switches low and the LM317 is enabled to drive LED1. (Editor’s note: this circuit has no provision to prevent over-discharge of the SLA battery if it is left to run for an extended period. Discharging an SLA battery below 1.8V per cell (ie, 5.4V for a 6V SLA battery) will destroy it. T. K. Hareendran, Kerala, India. ($35) This simple emergency light is based on one 3-watt white power LED. 12V AC is applied to a bridge rectifier and a 100mF filter capacitor to feed an LM317 voltage regulator. This is arranged to deliver 7.5V DC via diode D1 to charge a 6V 4Ah SLA battery. Diode D1 limits the maximum battery voltage to 6.9V 68  Silicon Chip siliconchip.com.au +5V 1k 100nF 4.7k 4 RESET RUN 17 15 UP 18 16 DOWN 1 14 +V IN0 4 OUT3 IN6 OUT2 IN1 OUT1 IN7 OUT0 IC1 PICAXE18X IN2 OUT7 OUT6 2 * 3 3x 10k SER.OUT OUT5 SER.IN OUT4 0V 5 3 9 6 2 8 1 7 7 6 5 13 16 Vdd BI Og LT Of DD Oe 14 7 x 47 Oc DB Ob DA Oa EL 9 9 1 10 f 2 11 4 12 6 13 7 b g e c Q1 BC557 B E C Q2 BC557 +12V A A  LEDS K A K 1N4004 B BC337, BC557 K A RLY1 D1 1N4004 READY  LED2 10k siliconchip.com.au c d 8 E B 330 K This PICAXE countdown timer uses two 7-segment displays to provide a maximum light box exposure time of 99 seconds. Three pushbutton switches are used to set the time (Up/Down) and to start the exposure (Run). A default time of 30 seconds is loaded the first time the software is run and after that the micro (IC1) stores the last time that was used, ready for the next run. The last used e 4 b 7 C TIMING LED1 PICAXE light box countdown timer 2 g 10k 330 * PROGRAMMING PINS: SEE PICAXE MANUAL f 8 10k 10 a 1 6 d 8 11 9 a Vss 12 DISP2 FND500 10 15 10 IC2 Od 4511B DC DISP1 FND500 A K setting is saved when the power is turned off. Four outputs from the PICAXE drive a 4511 BCD to 7-segment decoder (IC2). This drives the two 7-segment displays together with transistors Q1 & Q2 which drive the display’s common cathodes. The timing is controlled by ‘for next loops’ and the ‘pause’ command. The timer counts down from the selected time in seconds, to zero. There are two LEDs. Pin 11 drives LED2 (green) to flash at a 1-second Q3 BC337 E UV LIGHT SWITCHING B E C C interval to indicate that the timer is ready. Pin 10 goes high to turn on LED1 when the timer is counting down. The same output also drives transistor Q3 to operate the power relay to switch the lamps on an off. The details of the 240VAC mains wiring can be the same as for the Light Box Controller in the November 2007 issue of SILICON CHIP. The software (Countdown1.bas) will be available from the SILICON CHIP website. Cliff Wylie, Leumeah, NSW. ($50) March 2008  69 70  Silicon Chip This simple impedance bridge uses three twin-T oscillators based on Q1, Q3 & Q5 which are set to run at 100Hz, 1kHz and 15kHz. The oscillator outputs are taken from the resistive legs of the twin-Ts via FETs Q2, Q4 & Q6 which act as high impedance buffers (source followers). The oscillator fre- quencies can be trimmed by trimpots VR1, VR2 & VR3. The oscillator amplitudes are set by VR4, VR5 & VR6 and fed to switch S3 before being amplified by IC1, an LM380 amplifier. This drives transformer T1 which drives the switch ranges for the bridge circuit. Impedance bridge measures at three frequencies Finally, the null voltage from the bridge is amplified by the AC-coupled stages of Q7, Q8 & Q9 before being AC-coupled to the bridge rectifier (D1D4) and the meter movement. Diode D5 protects the meter movement from overload. In use, the unknown component is connected across the Z terminals and the range and multiplier switches S2 & S3 are adjusted to get a null reading (ie, minimum) on the analog meter. The impedance is then read off the switch settings for S2 & S3. Fritz Winkler, Bunbury, WA. ($60) Circuit Notebook – Continued siliconchip.com.au REG1 7805 OUT 7 6 470k 8 4 7 3 IC1 555 2 6 5 8 LED3 3 IC2 555 5 330 1 F 330 7805 IN GND A LED2  K K A A A 2 1 K Simple Mosfet tester This simple tester checks both N-channel and P-channel Mosfets. It checks for shorts between gate, drain and source and also distinguishes between N and P-channel Mosfets. IC1 is configured as an astable multivibrator to run at about 2Hz, as determined by the components at pins 2, 6 & 7. IC2, another 555 timer, is used simply as an inverter. Hence the two pin 3 outputs of IC1 & IC2 are in anti-phase. These two pin 3 outputs are fed out via 330W resistors and LEDs 1 & S1c 2 1 4 3 D1, D2: 1N4148 A 4 3 D2 LED1  A K D1 LEDS OUT  K 1 K 9V BATTERY A 4 2 1 GND GND 330 4.7k 10k S2 IN 4 3 2 1 S1b S1a SOURCE DRAIN GATE K 2, paralleled with diodes D1 & D2. From there, the anti-phase signals are connected to the Mosfet under test via a 3-pole 4-position rotary switch. The three switch wipers are connected to terminals labelled “gate”, “drain” and “source”. The switch settings correspond to the following tests: Test 1 checks for a short between the gate and source. If a short exists, alternating current paths are provided via LED1 and LED2 (ie, the LEDs alternately turn on and off). Test 2 checks for a short between the gate and drain. If there is no short, no LEDs will light. Test 3 provides a positive bias to the gate, while the drain and source are connected to the LEDs. If the Mosfet is N-channel, both LED1 and LED2 will blink. If the Mosfet is P-channel, only LED2 will blink. Test 4 provides a negative bias to the gate, while the drain and source are connected to the LEDs. If the Mosfet is P-channel, both LED1 and LED2 will blink. If the Mosfet is Nchannel, only LED1 will blink. If the Mosfet’s drain and source are shorted, both LED1 & LED2 will flash in tests 3 and 4, for both N-channel and P-channel Mosfets. Henry Bowman, Parsons, Tennessee. ($45) supply connector (use a Y-adaptor if necessary). The red wire is +5V, yellow is +12V and the two black wires are the common/ground leads. T. K. Hareendran, Kerala, India. ($35) PC cooling fan driver This circuit can be used to control a fan in a computer or equipment cabinet. It’s based on an LM35 analog temperature sensor which has an output voltage that’s directly proportional to temperature in °C. Its output signal is fed to a CA3130 op amp (IC2) which is connected as a comparator. IC2 switches on the fan via transistors Q1 & Q2 when the air temperature is above that set by VR1. LED1 lights whenever the fan is running. Power for the circuit comes from the +5V and +12V rails in a PC and can be derived from a spare 4-pin siliconchip.com.au March 2008  71 : IC 2 By JIM ROWE A Quick Primer Developed by Philips over 25 years ago, the I2C bus is now a well-established standard for low to medium-speed data communication between ICs. However, its basic operation still isn’t well understood, except by people in the chip design business. Here’s a quick primer to bring you up to speed. B ACK ABOUT 1980, when digital ICs were really starting to be used in consumer gear such as car radios, stereo systems and TV sets, Philips developed a low-cost interfacing technique for allowing the various ICs in a system to exchange data at a low to medium speed. They called it the “Inter-Integrated Circuit” or “Isquared-C” (I2C) bus and it rapidly became very widely used for data communication between ICs in all kinds of equipment. These days, I2C is found not just in consumer audio and video gear but in computer and industrial equipment as well. In fact, it’s now used in over 1000 ICs, made by more than 50 different companies worldwide. So it’s well worth knowing how this very versatile bus works. I2C is usually described as a 2-wire synchronous serial bus, although strictly speaking it’s a 3-wire bus because the PC board’s ground line is also an essential part of the communications link. The two nominal wires or “lines” are the data or SDA line and the clock or SCL line. Both of these lines are regarded as bidirec72  Silicon Chip tional and to allow this they are both used in wired-OR or “open drain/open collector” mode. This means that both lines are connected to the PC board’s positive supply rail only via pull-up resistors and can only be pulled down to logic low (or ground potential) by the circuitry inside the chips connected to the bus lines. So strictly speaking, any chip connected to the SDA or SCL lines can pull them down but if none of the chips does so, both lines are pulled high by the external resistors. This is known as the “idle bus” condition, incidentally. In its most basic form, I2C is used for “master-slave” communication – where one device takes control of the bus as the master, to send data to or request data from another device acting as the slave. It’s true that because both the SDA and SCL lines are bidirectional, any device on the bus can initiate a data transfer as the master and similarly, any device can play the role of the slave. So the I2C bus can operate as a multi-master bus and in fact its official specification provides for bus contention and resolution situations, where two devices try to take control of the bus at the same time. However, in most common applications, there is a single master device (usually a microcontroller) and the rest of the devices are used as slaves. These slave devices may be digital tuning chips, controlled-gain amplifier or filter chips, video switching or processing chips, EEPROM memories and LCD panels, etc. Fig.1 shows the basic master-slave I2C interface circuit. As shown, there are really three lines between the master and slave chips: SCL, SDA and ground. The external pull-up resistors (Rp) provide the only connections between the SCL and SDA lines and the positive supply rail (+V). In operation, the SDA line can be pulled down to ground by either the master or slave devices, via the opendrain Mosfets connected internally to their SDA pins. Similarly, both chips can monitor the logic levels on the SDA line, via the Schmitt trigger inverters which are also connected to their SDA pins. The circuitry connected to the SCL siliconchip.com.au Data transfer The master device controls all data siliconchip.com.au SLAVE DEVICE Rp SCL SCL CLOCK IN DATA IN SDA SDA DATA IN DATA OUT GND GND DATA OUT CLOCK OUT FIG.1: BASIC MASTER-SLAVE I 2 C INTERFACE +V MASTER DEVICE Rp Rp SCL SCL SDA SDA GND SCL SLAVE DEVICE 1 SDA GND SDA Before an I2C data transfer operation or sequence can take place, the master device must check to make sure that the bus is idle; ie, both the SCL and SDA lines must be at logic high. If so, it then takes control of the bus by pulling down the SDA line while leaving the SCL line high. This is described as setting up a “Start condition” and announces to all other devices on the bus that a data transfer is about to take place. The Start condition can be seen on the left in the SCL and SDA waveforms shown in Fig.3(a). We’ll look at the actual data transfer operations in more detail shortly. For the moment, let’s look at the way the master device signals the end of a data transfer sequence, by setting up a “Stop condition”. As shown on the right of Fig.3(a), this is simply the reverse of the Start condition. The master device releases control of the SCL line first, so that it goes high, then it releases the SDA line so this also goes high (ie, after the SCL line goes high). Both lines are then high, thus returning the bus to the idle condition. So this is the basic format of an I2C data transfer sequence: Start condition, the data transfer itself and then the Stop condition – all under the control of the master device. Now let’s look more closely at the fine details. Rp GND Starting and stopping +V MASTER DEVICE SCL pin inside each chip can be identical to that connected to the SDA pins. However, if only one device is to act as the master, it only needs an open-drain Mosfet connected to the SCL pin (as shown in Fig.1) because it will always be providing the SCL clock pulses. Conversely, when other devices are only being used as slaves, they only need the Schmitt trigger inverter to “receive” the SCL clock pulses. The next thing to note is that although Fig.1 only shows a master device with a single slave device, the I2C bus can be used to connect one or more masters to many slave devices – as many as 112 different devices in fact. These slave devices are simply connected to the SCL and SDA lines in “daisy chain” fashion, as shown in Fig.2. SLAVE DEVICE 2 2 FIG.2: I C BUS WITH ONE MASTER, MANY SLAVES transfer on the I2C bus, as this is the device that toggles the SCL line to produce clock pulses – one positive pulse for each data bit, as shown in Fig.3(b). The data bits themselves are conveyed on the SDA line, which must be stable when the SCL line is high. All logic level changes on the SDA line must occur between clock pulses, when the SCL line is low. Basically, all data is sent over the I2C bus this way, as serial eight-bit bytes with the most significant bit (MSB) first. This is shown in Fig.3(c), which also shows the next important thing you need to know about I2C operation: after each data byte is sent, the receiving device must “Acknowledge” that it has been received. This is normally done by the receiver pulling down the SDA line while the master device provides a ninth clock pulse on the SCL line. Which device pulls down the SDA line to acknowledge reception depends on the direction of data transfer: if the master is sending data to a slave, the slave device must acknowledge. On the other hand, if a slave is sending data to the master, the master itself must acknowledge. In other words not only is acknowledging mandatory after each byte but it is the receiving device which must do the acknowledging. As noted above, the acknowledge is usually done by pulling the SDA line low during the ninth clock pulse, known as “ACK”, but there are some situations where the receiving device acknowledges by leaving the SDA line high. This is known as “ACK-bar” and we’ll look at it more closely soon. Addressing By now you’re probably wondering how the I2C master device can selectively communicate with one particular slave device when there may be a number of slaves on the bus. That’s easy: the first data byte sent out by the master after it grabs the bus and sets up the Start condition is an address byte, specifying which slave device March 2008  73 SDA SCL BUS IDLE (DATA EXCHANGE & ACKNOWLEDGE) START CONDITION STOP CONDITION BUS IDLE Fig.3(a): BASIC I 2 C DATA EXCHANGE SEQUENCE SDA each device as having two addresses on the I2C bus – one address for writing data to it and the other for reading from it. For example, a device might have an effective write address of say 42h (01000010 binary) and a read address of 43h (01000011). This is really the same device address, with only the final read/write bit changing in value. By the way, the current I2C specification also provides for 10-bit extended device addressing as an alternative to the 7-bit addressing scheme. However 10-bit device addressing is apparently not used much yet. Single byte transfers SCL SDA STABLE WHEN SCL IS HIGH SDA CAN CHANGE WHEN SCL IS LOW (NEXT BIT TRANSFER) Fig.3(b): DATA (ADDRESS) BIT TRANSFER SDA B7 B6 B5 B4 B3 B2 B1 B0 SCL DATA (ADDRESS) BITS TRANSFERRED – MSB FIRST ACKNOWLEDGE BY RECEIVING DEVICE Fig.3(c): DATA (ADDRESS) BYTE TRANSFER WITH ACKNOWLEDGE it wants to communicate with. It also specifies whether it wants to write data to the device or read back data from it. Basically, the first seven bits of this first byte form the actual slave address, while the eighth bit specifies a read (1) or a write (0) operation. This addressing scheme is part of the I2C bus specification and devices designed to communicate via the I2C bus are given unique addresses (licensed to the chip maker by NXP, the current name for Philips Semiconductors). In some cases the address is built right inside the chip and can’t be changed, while in others it can be set to one of a number of addresses in a range allocated to that device, by tying one or more of its other pins to logic high or low. The latter arrangement is especially 74  Silicon Chip useful for devices like EEPROMs and other memories, where you might want to have a number of them on the same bus. Each device can be given its own unique address to prevent confusion. Because the I2C address code uses seven bits, this means that in theory you should be able to have a maximum of 128 (27) devices connected to the same bus. However, as part of the I2C specification, 16 of the possible address codes are reserved for either special or future purposes, so in practice you can only have a maximum of 112 different chips on the same bus. That’s still more than enough to handle the vast majority of situations. By the way, since the read/write bit effectively forms the eighth bit of the address byte, it’s quite valid to regard To make basic I2C operation a little clearer, let’s now take a look at Fig.4(a). This shows the sequence of operations involved in a master device taking control of the bus, addressing a particular slave device and then writing a single byte of data to that device. As you can see, the sequence begins with the master setting up the Start condition (S) and then sending the 7-bit address of the slave it wants to receive the data. It then follows with zero in the eighth bit (R/W-bar) position to indicate that it wants to “write” or send the data. If that particular slave device is present on the bus and ready to accept the data, it must then respond by pulling the SDA line low (A) before the master sends out the ninth (acknowledge) clock pulse. None of the devices on the bus with other addresses will respond. Following this acknowledgement, the master then sends out the eight bits of the data byte itself, after which the slave device must respond again with an acknowledge bit. Once the master detects this second acknowledge, it sets the Stop condition (P) to signify the end of the transfer and release the bus lines. Reading a single data byte from a slave device is very similar. Fig.4(b) shows the details. Here the master device again sets up the Start condition (S) and sends out the 7-bit address for the slave device it wants to read the byte from. Now comes the first difference, because in this case it sends out a ‘1’ for the eighth R/W-bar bit, to indicate that it wants to read back a data byte from the slave. If the addressed slave is present and ready to send back the data byte, it then siliconchip.com.au 7-BIT SLAVE ADDRESS S B6 B5 B3 B4 B2 B1 B0 R/W A DATA BYTE B7 0= WRITE S = START CONDITION A = ACKNOWLEDGE (SDA LOW) B6 B5 B4 B3 B2 B1 = FROM MASTER TO SLAVE B0 A P = FROM SLAVE TO MASTER P = STOP CONDITION Fig.4(a): MASTER WRITING A SINGLE DATA BYTE TO A SLAVE DEVICE 7-BIT SLAVE ADDRESS S B6 B5 B3 B4 B2 B1 B0 R/W A DATA BYTE B7 B6 B5 B4 B3 1= READ B2 B1 B0 A P A = NOT ACKNOWLEDGE (SDA HIGH) Fig.4(b): MASTER READING A SINGLE DATA BYTE FROM A SLAVE DEVICE 7-BIT SLAVE DEVICE ADDRESS S B6 B5 B3 B4 B2 B1 B0 R/W A 8-BIT SLAVE SUBADDRESS (STARTING) B7 B6 B5 B7 B6 B5 B4 B3 B2 B1 B0 B2 B1 B0 A 0= WRITE DATA BYTE B7 B6 B5 B4 B3 B2 B1 B0 A DATA BYTE B4 B3 A P Fig.4(c): MASTER WRITING MULTIPLE DATA BYTES TO SLAVE DEVICE SUBADDRESSES (IN SEQUENCE) S 7-BIT SLAVE DEVICE ADDRESS B6 B5 B3 B4 B2 B1 B0 R/W A 8-BIT SLAVE SUBADDRESS B7 B6 B5 B7 B6 B5 B4 B3 B2 B1 B0 B2 B1 B0 A 0= WRITE Sr 7-BIT SLAVE DEVICE ADDRESS B6 B5 B3 B4 B2 B1 B0 R/W A DATA BYTE B4 B3 1= READ Sr = REPEAT START CONDITION A P A = NOT ACKNOWLEDGE (SDA HIGH) Fig.4(d): MASTER READING A SINGLE DATA BYTE FROM A SLAVE DEVICE SUBADDRESS S 7-BIT SLAVE DEVICE ADDRESS B6 B5 B3 B4 B2 B1 B0 R/W A 8-BIT SLAVE SUBADDRESS (STARTING) B7 B6 B5 B7 B6 B5 B7 B6 B5 B4 B3 B2 B1 B0 B2 B1 B0 B2 B1 B0 A 0= WRITE Sr 7-BIT SLAVE DEVICE ADDRESS B6 B5 B3 B4 B2 B1 B0 R/W DATA BYTE B6 B5 DATA BYTE B4 B3 A 1= READ Sr = REPEAT START CONDITION B7 A B4 B3 B2 B1 B0 A DATA BYTE B4 B3 A P A = NOT ACKNOWLEDGE (SDA HIGH) Fig.4(e): MASTER READING MULTIPLE DATA BYTES FROM SLAVE DEVICE SUBADDRESSES (IN SEQUENCE) siliconchip.com.au March 2008  75 Table 1: I2C Timing and Electrical Characteristics Parameter Standard-mode Fast-mode Fast-mode Plus SCL clock frequency 0–100kb/s 0–400kb/s 0–1Mb/s SCL clock low time 4.7 s min 1.3 s min 0.5 s min SCL clock high time 4.0 s min 0.6 s min 0.26 s min Setup time, S or Sr condition 4.7 s min 0.6 s min 0.26 s min Hold time, S or Sr condition 4.0 s min 0.6 s min 0.26 s min Data setup time 250ns min 100ns min 50ns min Data valid time 3.45 s max 0.9 s max 0.45 s max Acknowledge data valid time 3.45 s max 0.9 s max 0.45 s max Rise time, SCL or SDA sigs 1 s max 300ns max 120ns max Fall time, SCL or SDA sigs 300ns max 300ns max 120ns max Setup time, stop (P) condition 4.0 s min 0.6 s min 0.26 s min Bus free time, P – S cond's 4.7 s min 1.3 s min 0.5 s min Low level output current 3mA min 3mA min 20mA min Output low volts (3mA sink) 0.4V max 0.4V max 0.4V max High level volts, SDA or SCL Vdd + 0.5V max Vdd + 0.5V max Vdd + 0.5V max 400pF max 400pF max 550pF max 10pF max 10pF max 10pF max Shunt C, SDA or SCL lines Capacitance for each I/O pin acknowledges the request by pulling the SDA line low (A) for the ninth clock pulse. Then when the master sends out a further eight clock pulses on the SCL line, the slave toggles the SDA line to transmit the data bits back to the master. Now comes the second change. Although it’s the master that now has to acknowledge that it has received the data byte from the slave, it doesn’t do this by pulling the SDA line down on the ninth clock pulse as before for a normal acknowledge (A). Instead, it leaves it high for a not-acknowledge (A-bar). Can you guess why? It’s because this is the only way the master can indicate to the slave that the transfer is ending and no further data bytes need be sent. Finally, the master ends the sequence as before by setting the Stop (P) condition and releasing the bus lines. Remember that in both Fig.4(a) and Fig.4(b), all the clock pulses on the SCL line are provided by the master device. It also sets the Start and Stop conditions, specifies the slave address and specifies whether the data byte is to be written to the slave or read from it. the I2C specification does allow it to have multiple secondary or subaddresses. This can be very useful where a device such as an audio or video processor chip needs to have many registers or latches to store its various control parameters, or in the case of a memory device, to store the data. Since a complete second byte can be used to specify the device subaddress, this means that a complex device can have as many as 256 subaddresses (28). This may sound like more than enough but some very complex video processing chips do need over 180 different subaddress registers to store their setup parameters and status bytes. Fortunately, devices which do have multiple subaddresses usually have an additional handy feature: a subaddress “pointer” register which automatically increments after each data byte write or read operation. This allows a master device to write a string of data bytes into successive subaddress registers, or read data bytes back from them, in a single multi-byte operation. All it needs to do is specify the starting subaddress first and then send or receive the data bytes one after the other. Device subaddresses Fig.4(c) shows the sequence of operations involved for a master device to write a number of data bytes into Although each device connected to an I2C bus has a single main address, 76  Silicon Chip Multi-byte transfers successive subaddresses in a slave device. As you can see, the sequence begins as before with the master setting up the Start condition (S), followed by the main address of the slave device which is to receive the data, plus an R/W-bar bit of zero to indicate a data write. When the addressed slave device acknowledges (A), the master then sends a second byte specifying the starting subaddress. Then, after the slave acknowledges again, the master simply begins sending the data bytes themselves, one after the other. The slave acknowledges the receipt of each data byte and saves them in consecutive subaddress registers, starting with the subaddress specified by the master. Finally, after the last data byte has been sent and acknowledged, the master sets up the Stop condition (P) and releases control of the bus. As before, all the clock pulses on the SCL line are generated by the master device. Reading back a data byte from a single slave device subaddress is similar but with a couple of noteworthy differences – see Fig.4(d). As before, the master sets up the Start condition (S) and sends the main slave address plus an R/W-bar bit of zero to indicate a write. Then, when the slave acknowledges, the master again sends a second byte specifying the slave subaddress and waits for the slave to acknowledge. But now things take a different course, because the master now has to set what is known as a “repeat start” condition (Sr), to signal that it is still controlling the bus (note: a repeat start condition is virtually the same as a normal Start condition except that it does not follow a Stop condition). It then sends the main slave address again but this time with an R/W-bar bit of “1” to indicate that it wishes to read a byte rather than write one. After the slave acknowledges this repeated slave address byte, it then sends back the data byte from the specified subaddress, toggling the SDA line as before in synchronism with the SCL clock pulses from the master. Following the last data bit, the master must acknowledge, of course, but if this is the one and only byte to be read back the master does so not by pulling the SDA line low for a normal acknowledge but by leaving it high for a NACK (A-bar). This is to indicate to siliconchip.com.au the slave that there are no more bytes to be read back. Finally it sets up the Stop condition (P) as before, to release control of the bus. The sequence of events when the master device wants to read back a number of data bytes from consecutive slave subaddresses is very similar. This is shown in Fig.4(e). Here the master sets the Start condition (S) and sends the slave device address first as before, followed by an R/W-bar bit of zero for writing. Then, when the slave acknowledges, it sends the starting subaddress and waits for the slave to acknowledge again. It then sets a repeat start (Sr) condition and again sends the slave device address, followed by an R/W-bar bit of one to indicate that data will now be read from the slave rather than written to it. After acknowledging (A), the slave then sends back the first byte of data from the specified starting subaddress. When the master acknowledges that it has received this first data byte by pulling the SDA line down (A), the slave continues to increment its internal subaddress pointer and send back data bytes from consecutive subaddresses. This continues until the master acknowledges the last byte it wishes to receive in the current transfer, by leaving the SDA line high during the ninth clock pulse (ie, A-bar) rather than by pulling it down as for the earlier bytes. This again signals the slave that no more bytes are to be sent back. Finally, as before, the last step is for the master to set up the Stop condition (P) and release control of the bus. Other bus events We have now looked at virtually all of the events that take place on a basic “single master/multiple slaves” I2C interface bus. As most common applications are of this type, you shouldn’t have much trouble with them if you’ve kept up so far. There are also other kinds of I2C bus events like “clock synchronisation”, “arbitration” and “clock stretching” but these mainly come into the picture with more complex multi-master systems – like 10-bit addressing. For the most part, you won’t need to worry about them, so I’m not going to try explaining them here. If you do need to find out more about them, they’re covered quite well in NXP’s I2C Bus Specification and User Manual, which can be downloaded from the NXP website (www.nxp. com/acrobat_download/usermanuals/ UM10204-3.pdf). I2C bus speeds When Philips first developed the I2C bus, it was only intended for lowspeed operation – up to 100kb/s (kilobits per second). However, over the years, the I2C specification has been revised and expanded and nowadays there are a total of four different allowable bus speed modes. The original 0-100kb/s mode is now known as “Standard Mode”, while the other three modes are designated “Fast Mode” (0-400kb/s), “Fast Mode Plus” (0-1Mb/s) and “High Speed Mode” (0-3.4Mb/s). Table 1 shows the most important electrical characteristics of the three speed modes in common use. If devices are to be used on an I2C bus running in one of the higher speed modes, they must be given SDA and SCL driver and buffer stages capable of working at those higher speeds. On the other hand, a device which does have higher speed drivers and buffers can always be used on an I2C bus operating in Standard Mode. In fact, this backwards compatibility is part of the I2C specification. Debugging & troubleshooting Debugging and troubleshooting of I2C bus circuits can often be done by monitoring bus activity using a dual-trace oscilloscope, with one trace watching the SCL line and the other the SDA line. If the scope is arranged to trigger on a negative-going edge on the SDA line, it will trigger for each Start condition. However, for tracking down more subtle problems, it may be necessary to use an I2C debugging program running on a PC, linked into the bus via a suitable hardware interface adaptor. This type of program usually allows you to do things like reading data from slave device subaddress registers, or writing data into them to program device operation “on the run”. There are various I2C debugging programs currently available, many of them designed to work with their own USB-I 2C hardware interface. These combined software and hardware pack­ ages can be fairly pricey though – up to hundreds of dollars in some cases. Fortunately, for quite a few years now, Philips/NXP has made available a freeware debugging program of their own, called “URD” – short for “Universal Register Debugger”. The current version of this is v3.12, which can run on any version of Windows up to Windows XP. It comes as a self-installing file called URD312.EXE and when it installs, it also unpacks two PDF files. These PDF files provide a User Manual for the program (URDUser.pdf) and a reference manual (URDLang.pdf) for its programming language, which seems to be derived from Microsoft’s Visual Basic for Applications. Hardware interface URD v3.12 is compatible with a very simple hardware interface which connects to one of the PC’s parallel printer ports and comes with a driver for this type of interface. Elsewhere in this issue, you’ll find a simple LPT/I2C interface of this type described, so you can build one up yourself to use with the URD program. Together they make a much cheaper alternative to commerSC cial I2C debugging packages. Issues Getting Dog-Eared? Keep your copies of SILICON CHIP 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. siliconchip.com.au March 2008  77 By JIM ROWE 2 LPT-to-I C A low-cost interface for debugging Tracking down problems in circuits which are programmed via an I2C bus can be tricky and time-consuming, unless you take advantage of a debugging program running on a PC. Here’s a low-cost, easy-to-build printer port to I2C interface designed to work with the Philips/NXP debugging program URD312.exe. TO PC PRINTER PORT (DB25M) 15 SCL IN SCL Q2 17 11 SCL OUT SDA IN Q1 9 SDA OUT 18-25 GROUND RETURN 78  Silicon Chip TO I 2 C BUS ON PC BOARD SDA BEING TESTED GND Fig.1: the basic arrangement for the LPT to I2C interface. Mosfets Q1 & Q2 pull down the SCL & SDA lines for outgoing signals from the port, while the inverters interface the incoming SCL & SDA signals from the circuit under test. J UST RECENTLY, I was trying to finish a project which uses a couple of video-processing ICs that are programmed via the I2C bus. However, I struck trouble with one chip. For some reason, it wasn’t responding correctly to the set-up data I was sending to it from the project’s microcontroller, even after I had been through my control program umpteen times searching for bugs (or programming errors). Even when I wrote a test program and captured the I2C bus activity with my digital scope, I still couldn’t track down the source of the trouble. siliconchip.com.au Fortunately, before tearing out the last few strands of my hair, I decided to seek help from the support people at NXP (formerly Philips Semiconductors) – not only because the chip concerned happened to be one of theirs but because it was Philips that developed I2C in the first place. After all, if anyone should be expert at solving I2C problems, it should be NXP. As it turned out, they were very helpful. An NXP support engineer promptly sent me an email suggesting several things to try. Then, when that didn’t fix things, he suggested I try analysing the problem using a debugging program running on a PC. Not only that but he also sent me a copy of the latest version of their free I2C debugging program (called “URD”), which they developed quite a few years ago. The current version turned out to be v3.12, which comes as a self-installing package called URD312.exe (more on this later). Along with the program, he also sent a device data register set-up file for the video processing chip I was working with, so the URD program could communicate with it sooner. And last but by no means least, he sent me a PDF file with the circuit of the original PC printer port/I2C interface card that the URD program was designed to work with, so I could build one up for the troubleshooting. That’s pretty good support from the other side of the world, don’t you think? As it happened, the original interface used a 74LS05 chip that I didn’t have, so I decided to update the circuit to use devices that are readily available nowadays. And that’s the project described here – it uses a 4011B quad NAND gate, a couple of Mosfets and not much else. How it works Like the original NXP/Philips interface, this unit is designed to allow the URD program to communicate with an siliconchip.com.au 4 7 TO PRINTER PORT OF PC DB-25M +5V 5 SCL PULLUPS ENABLE S1 IC1: 4011B 10 14 8 IC1c 9 11 IC1d K –SCL 100 3.3k S2 12 +3.3V 3.3k 13 SCL D1 17 10 F 100n 6 10k 12 15 IC1b D A Q2 G S 100k SDA 11 –SDA 3 IC1a 1 K 2 D3 9 –SDA 100 A 23 K 24 GND D4 A Q1 S K D2 25 D G A 100k Q1, Q2: 2N7000 D1 – D4: 1N4148 A SC 2008 K D G S LOW COST LPT –I 2 C INTERFACE FOR DEBUGGING Fig.2: the complete circuit for the LPT to I2C interface. It’s based on Mosfets Q1 & Q2, a 4011B quad NAND gate (IC1a, IC1c & IC1d) and just a few other parts. Diodes D1-D4 are there to protect the Mosfets. I2C bus on a development board via the PC’s parallel printer port (LPT). The basic arrangement of the circuit is shown in Fig.1. In operation, the URD program sends out the SCL pulses in inverted form via pin 17 of the printer port (originally used for the SEL-bar line). So the interface uses this printer port line to control Mosfet Q2, which is used to pull down the SCL line of the I2C bus. Conversely, the URD program monitors the I2C bus SCL pulses via pin 15 of the printer port, which was originally used for monitoring the printer’s Error-bar line. As a result, the interface feeds back the SCL line status to pin 15 via a pair of inverters which function as a non-inverting buffer. Similarly, the URD program sends out data to the SDA line (in inverted form) via pin 9 of the printer port, originally used to send parallel data bit 7 to the printer. The interface uses this printer port line to control Mosfet Q1, which is used to pull down the SDA line of the I2C bus. Finally, the URD program receives data from the SDA line (again in inverted form) via pin 11 of the printer port, which was originally used for monitoring the printer’s Busy/Readybar line. So, in the interface, we feed March 2008  79 Parts List 1 PC board, code 04203081, 55 x 61mm 1 male D25 connector, 90° PCmount (CON1) (Jaycar PP0843; Altronics P-3220) 1 10-pin (5 x 2) vertical IDC header, PC-mount (Jaycar PP-1100; Altronics P-5010) 1 10-way IDC socket (Jaycar PS0984; Altronics P-5310) 1 250mm length of 10-way rainbow cable 5 EZ-hook test clips, 40mm long 1 4-way DIL slider switch (S1,S2) 1 14-pin IC socket Semiconductors 1 4011B CMOS quad NAND gate (IC1) 2 2N7000 N-channel Mosfets (Q1,Q2) 4 1N4148 diodes (D1-D4) Capacitors 1 10mF 16V RB electrolytic 1 100nF monolithic ceramic Resistors (0.25W 1%) 2 100kW 2 3.3kW 1 10kW 2 100W the SDA line data back to pin 11 via a single inverter. So that’s the basic idea of the way the interface works. Let’s now take a look at the full circuit which is shown in Fig.2. Circuit details As shown in Fig.2, two low-cost 2N7000 N-channel Mosfets (Q1 & Q2) are used as the SCL and SDA pulldown transistors. Inverter stages IC1c & IC1d (part of a 4011B quad CMOS NAND gate) are used for interfacing the SCL line, while IC1a is used to interface the SDA line. The fourth gate (IC1b) is unused. Most of the rest of the circuitry is used to protect Mosfets Q1 & Q2 from possible damage due to electrostatic charge build-up on the printer port lines when the interface is not connected to a PC. That’s the reason for the 100kW resistors connected from each Mosfet gate to ground and for diodes D1-D4. The latter prevent each gate from being taken more negative than ground or more positive than the +5V rail which is used to power IC1. The 10mF capacitor on the +5V line provides supply line filtering, while the 10kW resistor ensures that pin 12 of the printer port is pulled high. This is a requirement of the URD program which expects to find a logic high on this pin of the printer port (originally used for monitoring the “Out of paper” line). Switches S1 & S2 can be used to switch in two 3.3kW pull-up resistors on the SCL & SDA lines respectively. This is necessary if the I2C bus lines on the PC board being tested don’t already have pull-up resistors. Note that the interface line marked “+3.3V” must be connected to the +3.3V line supplying power to the I2C chips on the board being tested, so the interface pull-ups can function correctly. As indicated, the interface pull-ups aren’t needed if the board being tested is already provided with pull-ups of its own. In that case, S1 and S2 are simply left open (and the interface’s +3.3V lead doesn’t need to be connected to anything). Building it Building the interface is very straightf­ orward, as all the parts are mounted on a small PC board coded 04203081 and measuring 55 x 61mm. These parts include the male D25 connec- From the publishers of SILICON CHIP PERFORMANCE ELECTRONICS FOR CARS NOT A REPRINT: More than 160 pages of new and exciting projects never published before – all designed to get top performance from your car. FASCINATING ARTICLES: 7 chapters explaining your car – engine management, car electronics systems, etc ADVANCED PROJECTS: You’ll build controllers for turbo boost, nitrous, fuel injection and much more! We explain the why as well as the how to! Available direct from the Publisher ($22.50 inc postage): Silicon Chip Publications, PO Box 139, Collaroy NSW 2097. Ph (02) 9939 3295; Fax (02) 9939 2648; email silchip<at>siliconchip.com.au or via our website: www.siliconchip.com.au 80  Silicon Chip siliconchip.com.au L CS 18030240 V5+ L CS AD S 9 10 100 4148 4148 100 100nF L CS- tor used to mate with the PC TO PC PRINTER PORT printer port. Fig.3 shows the parts layout. Install the single wire link CON1 D25M first, then install the resistors, 71 51 25 the four diodes and the two 1 9 21 11 1 capacitors. Be sure to orien10k ADState the diodes and the 10mF ADSelectrolytic capacitor exactly as shown. IC1 4011B Follow these parts with the two Mosfets (Q1 & Q2) and 4148 4148 the IC, again taking care to Q1 Q2 2N7000 2N7000 ensure they go in the right way 100k 100k 3.3k around. The assembly can then 3.3k CON2 be completed by fitting the D25 + connector (CON1), the IDC V 3. 3 + header (CON2) and the 4-way D N G 10 F S2 S1 DIP switch. Take care when installing 5x2 IDC CON2 – the slot in its body SOCKET 2 I C LEADS goes towards the bottom edge Fig.3 (right): install the parts on of the PC board. TURN OFF S1 & S2 the PC board as shown on this Note that switches S1 & S2 IF PC BOARD BEING layout diagram and in the above are part of a 4-way DIP switch, TESTED HAS PULLphoto. Each pair of external UP RESISTORS ON with the other two switches not leads from the 10-way cable can SCL & SDA LINES used. If you happen to have a be terminated in a small “EZ2-way DIP switch, this could hook” test clip as shown in the +5V +3.3V GND be used simply by fitting it in lead photo. SDA SCL the two righthand positions (nearer the 3.3kW resistors). The 10-way IDC header (CON2) provides the interface to the supply rail on the board. program, we are posting a copy of I2C circuit under test. This allows you If you’re going to be using the pull- URD312.EXE on the S ILICON CHIP to make up a test lead cable from a up resistors on the interface, you’ll also website (www.siliconchip.com.au). 250mm length of ribbon cable which need to connect the +3.3V lead to the If you download this and execute it, is fitted with a 10-way IDC socket at positive rail of the chips connected you’ll find that it will install on most one end to mate with the header. Each to the I2C bus – and close interface PCs running Win98, WinMe, Win2000 pair of wires in the cable can then be switches S1 and S2, of course. and WinXP. When it installs, it also terminated in a small “EZ-hook” test On the other side of the interface, loads the driver it needs for commuclip to make the connections to the PC all that’s needed is to plug CON1 into nicating with the interface via the board being tested. a printer port connector on a suitable printer port. PC, either directly or via a short D25MI had no difficulty installing and Putting it to use D25F extension cable if necessary. running the URD program on a maThere’s not a great deal involved After that, it’s simply a matter of run- chine running Win98 but it did have in using the interface, apart from ning the URD program and using it to a problem talking to the printer port connecting the I2C leads from CON2 check and/or modify the contents of when I installed it on a machine runto the appropriate points on the PC the I2C subaddress registers inside the ning WinXP/SP2. I still haven’t sorted board you’re debugging. This means chips on the board you’re working on. out that particular problem at the time connecting the SCL and SDA leads of writing this article but it may be to the same lines on the board to be Obtaining the URD program part of the tighter security enforced tested, the ground lead to the board’s To make it easier for you to get by WinXP when the SP2 patches are SC ground and the +5V lead to a suitable the NXP/Philips URD312 debugging applied. 1 2 Resistor Colour Codes o o o o o siliconchip.com.au No. 2 1 2 2 Value 100kW 10kW 3.3kW 100W 4-Band Code (1%) brown black yellow brown brown black orange brown orange orange red brown brown black brown brown 5-Band Code (1%) brown black black orange brown brown black black red brown orange orange black brown brown brown black black black brown March 2008  81 Battery-powered aircraft creates aviation and technology history “Powered” Flight! T wo days before Christmas, a light aircraft took off from the Aspres sur Brec airfield near Gap in the French High Alps and flew for more than 50km without using a drop of petrol or avgas. It was the first flight of a fixed-wing, piloted plane powered only by battery and electric motor. The plane, named the “Electra”, was a single-seater Souricette woodand-fabric aircraft, built from a kit and modified for the purpose. It was fitted with a British-made 25hp electric motor (of the type used in golf carts) and 48kg of lithiumpolymer batteries. With test pilot Christian Vandamme at the controls, it flew a course through The Alps for 48 minutes. While electric-powered flight has been achieved before, it was either with ultralights, powered hang gliders or pilotless drones. In fact, SILICON CHIP featured such a flight more than fifteen years ago – in the October 1991 issue. And US inventor Paul MacCready, who developed the first man-powered plane, the Gossamer Albatross, has also pioneered electric-motor-powered microlights and ultralights, including a flight over the English Channel in 1981. However, a fixed-wing, conventional plane (one with an airworthiness cerby ROSS tificate) flying with only battery power 82  Silicon Chip has until now been a dream. A group founded to promote electric/green flight, the French “APAME” group, (rough translation Association for Promotion of Electric Aircraft), was behind the project, in collaboration with ACV Aero Services, Pegase, Capenergies and Onera. President of APAME, Anne Levrand, said that the flight showed that non-polluting, quiet, light aviation was within reach. “Fuel cost per hour of the Electravia was around one Euro, compared with about 60 Euro for an equivalent petrol-driven aircraft,” she said. “The motor and batteries will cost between ten and fifteen thousand Euro, roughly the same as current small petrol engines.” However, this comparison has started fierce debate amongst green and aviation groups, who maintain that when you take the cost and environmental impact of the batteries into account (especially the lithium) and then look at factors such as performance, petrol still wins hands-down. The debate highlights one of the major hurdles in electricpowered anything – but most importantly aircraft – the weight and weight-to-power ratio of the batteries. Typically, batteries produce just 2% of the energy of the same mass TESTER of petrol. siliconchip.com.au Some technical data: Aircraft: “ELECTRA” registration no F-WMDJ : One-seater Kit construction, in wood and fabrics Wing span : 9m Length : 7m Weight of the aircraft without batteries: 134kg Maximum weight for take off : 265kg Cruise speed : 90km/h Special ground-adjustable propeller from ARPLAST Electrical: Motor: 18kW disk brush type Batteries: Lithium - Polymer Total weight of batteries: 47kg Quick charge: 45 minutes And while huge reseach budgets in the battery field are currently producing exciting results (see the feature in the next issue of SILICON CHIP), they are still a long way behind the internal combustion engine. Moreover, with current and even foreseeable technology, battery power can only result in propeller-driven aircraft with all their current disadvantages over jet aircraft. But this flight demonstrates that electric flight is possible. The Times of London reported that Sonex, a leading US manufacturer of kit aircraft, is about to fly a 50hp electric plane that can carry two people at 220km/h for up to an hour before recharge. This puts the aircraft right into the recreational pilot market where modest-performing, light sport aircraft are in demand. The Times also reported that NASA and Boeing are currently researching hydrogen-fed fuel cells which will drive high performance and high power electric motors, capable of powering much larger aircraft for much longer SC flights. Earlier successes... Electric Ultralight Trike On August 25th 2007, the ultralight trike called “Electron Libre” (it means “free electron”!), powered by a 20hp electric brush motor and supported by APAME and ACV Aéro Service, performed a 22 minute flight in calm atmosphere conditions from Aspres sur Buëch airfield (Alpen). New powerful LIPO batteries allow such a performance. Of course the trike is almost noiseless. Flight with electric motor is now possible and affordable by all. siliconchip.com.au March 2008  83 Vintage Radio By RODNEY CHAMPNESS, VK3UG The batteries used to power vintage radios This view shows an assortment of old Eveready 1.5V cells and batteries, together with a 3V battery at far right. A Burgess 4.5V battery is also shown. Many valve radios were battery-powered but a lot of the battery types used are now obsolete and no longer available. However, with a little ingenuity, sets that would otherwise be static displays only can be restored to full working order. W HEN WE STOP to think about it, our civilisation would almost grind to a halt without batteries. Without them, there would be no iPods, no mobile phones, no handheld remote controls, no torches, no hearing aids, no battery-powered radios, no cordless mice or keyboards and no cordless telephones, to name just some of the equipment we now take for granted. Even worse, we would have to handcrank our cars to start them if we didn’t 84  Silicon Chip have batteries to do the job for us! Batteries were used to power many early valve radio receivers, particularly in areas where mains power was unavailable. These batteries consisted of both primary (non-rechargeable) and secondary (rechargeable) types. A primary battery is one that uses up its chemicals in an irreversible reaction and is disposed of after use (ie, after it has gone “flat”). By contrast, secondary batteries can be recharged because the chemical reactions that take place inside them are reversible. Primary cells Many types of primary cells had been developed by the early 20th century. These included the Fuller bichromate cell, Edison cell, Grenet Bichromate cell, Bunsen cell, Daniell cell, Gravity cell, Daniell gravity cell, Grove cell, Poggendorff cell, silver chloride cell, air depolarised cells and last but not least, Leclanche cells. Many of these cells were a variation on a theme and all were an attempt to provide electrical energy in an economical and convenient way. Because quite corrosive chemical solutions were used in many of these cells, considerable care was necessary when handling them. In fact, none of these cells were convenient to use in radios in their original format. However, the Leclanche cell was eventually modified to give us the now familiar “dry cell”. This is now the most common primary cell used in portable radios. Typically, a Leclanche dry cell has a positive carbon pole contained in a porous container filled with manganese dioxide which acts as a depolariser (the depolariser is used to remove the hydrogen gas that is developed on the carbon pole). This assembly stands in a container of ammonium chloride paste which also includes a negative zinc pole. It produces an output voltage of nominally 1.5V. One of the accompanying photos shows three glass-encased cells. The front one is an early Leclanche cell. However, we are more familiar with the normal torch cell in the same photograph, which is basically a refined version of the Leclanche cell and is much easier to use. Secondary cells By contrast with primary cells, secondary cells are a more recent development which occurred around siliconchip.com.au Dry batteries designed to power valve radio sets came in all shapes and sizes. The units shown here are now all obsolete. 1800. However, practical cells did not become available until about 1880. As stated above, secondary cells are rechargeable and include lead-acid car batteries and the nickel-cadmium (nicad) and nickel-metal hydride (NiMH) cells now used in many electronic devices. Because they are rechargeable, they can significantly reduce long-term battery costs in many applications. Early secondary cells include Plante cells, Faure cells and alkaline cells, with quite a few variations on a theme. During the early 20th century, secondary cells were classified according to their construction as follows: lead sulphuric acid cells, lead-zinc cells, lead-copper cells and alkaline zincate cells. The lead-acid cell is now the main secondary cell used in the automotive industry, while NiFe cells (nickel and iron electrodes) and, more recently, nickel cadmium cells are the main alkaline-based electrolyte secondary cells commonly in use. Maintenance Rather than being discarded, early primary cells were refurbished. The elements that were used up in the chemical reactions were replaced, after which the cell was again ready for use. However, this was a messy and quite often expensive exercise. Furthermore, the chemicals could be quite corrosive, so care was essential. siliconchip.com.au Almost without exception, primary cells now are thrown away when they become exhausted. Chinese “D” cells may cost from 25 cents upwards while high-quality alkaline cells may cost in the region of $2.00 each but will give superior service. It’s also interesting to note that some attempts were made to recharge primary cells back in the 1950s and early 1960s. During that era, a number of portable radio manufacturers installed a “re-activation” circuit into their radios. When the portable was connected to the mains, the set would work directly off the mains and the supply circuitry would also be used to “recharge” the installed dry batteries. In practice, various protocols had to be followed to recharge the batteries and the number of recharges the batteries could successfully take was decidedly vague. Usually, the instructions were not to use the batteries in the set to the point of being completely discharged before plugging the set into the mains again. Even four to five semi-successful “recharges” was considered good value, as the batteries were quite expensive. HMV recommended that the batteries in their sets be “re-activated” for six hours for every hour of operation. They believed that a set was typically used for around two hours a day, so an overnight charge would be the most convenient way of doing this. However, HMV also inferred that the batteries must be reactivated as soon as possible after any discharge, otherwise recharging would not be successful. Apparently, using the batteries on successive days without reactivation would make later attempts futile. I have no idea as to whether this idea would work with today’s dry cells, including alkaline types. However, High-discharge testers like this unit were used for checking lead-acid cells. The battery is shown for size comparison. March 2008  85 Another handy test tool was the hydrometer, used to test the specific gravity of the electrolyte in leadacid cells. An assortment of transistor radio batteries. These are mainly 9V types, the main exception being the 2510 at right which had 2 x 7.5V outputs. the instructions on many of these batteries indicate that it should not be attempted. Perhaps this is because people may endeavour to recharge the cells at too high a rate which could cause them to explode. You have been warned! During in the 1960s and 1970s, Astor and AWA also made some portable-cum-car radio transistorised receivers that used rechargeable nicad AA cells. These sets were rather advanced for their time and they were fairly expensive. Secondary cell problems A disadvantage of early lead-acid secondary batteries was that it was necessary to keep an eye on the charging procedure. This involved using hydrometer to check the charge condition of each unsealed lead-acid cell. A high-discharge cell tester was also commonly used with car batteries. During this procedure, it was very important not to smoke or create any sparks. This was to prevent the hydrogen gas given off during charging from exploding. It’s a warning that’s still valid today. Early valve radios Early valve radios commonly used the 201 or the later 201A triode valves. These required filament voltages of 5A at 1A and 5V at 0.25A respectively. In practice, these valves were commonly run from a 6V lead-acid battery with a rheostat in series with the filaments to reduce the applied voltage to 5V. By contrast, the high-tension (HT) voltage for the 201 & 201A varied from around 22.5V to about 135V, depending on the valve’s function in the circuit. The HT current drain was usually less than 25mA for the entire receiver. In the early days, miniature leadacid batteries were sometimes made up to supply the HT requirements of such receivers. Just imagine a bank of 60 cells supplying 120V to a receiver, then imagine having to check the electrolyte in each of these cells each time they had to be charged! That would really have been fun! I have only ever seen one example of these miniature batteries so I suspect that they weren’t all that popular. An alternative involved using a bank of dry cells to provide the necessary HT voltage and current for the receiver. For a 135V HT rail, this involved connecting 90 cells in series. It’s worth noting here that dry cell manufacturers standardised on the size of the cells used in their batteries at an early stage. For the HT batteries, they used A-size cells which are smaller than C-size cells. We don’t see them around these days but one is shown in the lead photo, standing alongside the cyclindrical No.6 cell. Dry cell deficiencies Eveready made a wide range of dry batteries for valve radios, the larger “B” units shown here delivering 45V. Diamond also made a range of dry batteries. 86  Silicon Chip Unfortunately, early dry cells did have some deficiencies. First, the insulation used between the cells in a battery was commonly cardboard and in a moist environment this became slightly conductive. As a result, the batteries would discharge and go flat over a period of several months, a problem that was particularly evident in hot, humid areas. In addition, some early dry cells had a “breather” vent and the moisture in the paste-type electrolyte evaporated over a period of several months. As a result, early dry cells had a rather limited shelf life. The earliest Traeger pedal radios (for the Flying Doctor Service) were commonly used in tropical areas and in an endeavour to overcome the discharge siliconchip.com.au A Clyde 2V lead-acid cell (circa 1930s-40s) is shown here, together with a Leclanche cell at the front and two Edison cells at right. problems in dry cells, only 9V of HT was used from two 4.5V batteries. The Australian army also initially had problems with dry batteries in their transceivers in the tropics during WWII. However, they were able to reduce the problems by completely sealing the batteries in wax. Of course, cost was not of prime concern in that instance. Dry batteries have changed enormously over the years and today’s batteries are considerably better than those used during the early valve radio era. In particular, the layer type method of construction was a major advance in packaging and was coupled with good insulation techniques and economy of manufacture. The subminiature overseas-made HT batteries, the Australian 490P & 482 types and transistor receiver batteries such as the 2761, 2362, 2510, 2364, 216 and 286, etc, all used this very efficient construction method. When Australian manufacture of transistor radios ceased, most of the “specials” for the Australian receivers quickly became hard to get and in some cases disappeared from the market. The 276P “evolved” and became a lower grade battery. The layer construction was dispensed with and six “C” cells in a holder were incorporated in its place. This was a backward step, as the contacts in the holder didn’t always make good contact and the electrical capacity of the battery was reduced. By contrast, large low-voltage dry batteries did not depart from the original concept of wiring multiple A, C, D, E & F cells in parallel (I’ve never found any reference to a “B” cell). An advantage here was that insulation was not a problem with such low voltages. We are all familiar with the “C” and “D” cell sizes and the “A” was basically a little brother to the “C” cell. Batteries such as the X250 and 745 1.5V types used the “F” cell. Towards the end of the valve era, siliconchip.com.au A collection of Stanmor dry batteries. There was nothing fancy about the packaging used for these units. portable receivers often used a combined low-tension (LT) and HT battery in the one case. Apparently, the HT sections were of layer construction while the LT sections were built using “D”, “E” or “F” cells. One such battery was the 759 which supplied 1.5V and 90V. This was suitable for household sets but was too big for portables. Another battery pack for use in rural areas was made by Eveready and contained one X250 1.5V battery and two 470 22.5/45V batteries. Although they were not all in the same case, they were all supplied together in the same delivery carton. Of course, using an “all in one” meant that if one section failed, the whole battery had to be replaced. Lead-acid batteries were predomin­ antly used for supplying valve heaters and for powering vibrator HT power supplies. In practice, 2V cells varied from 25Ah capacity to 130Ah, while 6V batteries varied between 60Ah and 160Ah in capacity. In 1937, these March 2008  87 Diamond made a large variety of dry batteries for valve radios, including 45V “B” batteries and 4.5V and 1.5V “A” batteries. varied in cost from about 17/6 ($1.75) to about £5/11/6 ($11.15). At that time the average weekly wage was about £4/10/- ($9.00), so they were quite expensive. The use of 2V lead-acid cells declined quite rapidly when 1.4V filament valves were introduced, replacing those with 2V filaments. However, 6V (and occasionally 4V) lead-acid batteries remained in use with vibrator-powered receivers until around the mid 1950s. Battery life Most radio batteries were rated for a 20-hour discharge rate. In practice, a typical 5-valve receiver using 2V valves draws 720mA. This meant that a fully-charged 25Ah cell would need recharging after about 35 hours, whereas a 130Ah cell would operate for about 180 hours. Similarly, vibrator-powered radios with efficient power supplies typically drew around 1A from a 6V battery. That makes the maths simple – a 60Ah battery would last around 60 hours and a 160Ah battery would last around 160 hours. As with lead-acid batteries, dry battery life depends on the battery capac- ity, the current drawn and the amount of time that current is drawn during each listening session. In practice, the battery life in transistor receivers varies from around 30 hours for a 9V 216 battery to about 300 hours for a 276P battery and up to 1000 hours for a 286 (as quoted by Kriesler for one of their sets). In typical valve portable receivers, the life of a 1.5V 745 battery allied with a pair of 45V 482 batteries was usually somewhere around 300 hours. The Australian “miniature” portables used two 950 cells to provide the filament current and a 467 67.5V battery to supply the HT current. In operation, the two 950 cells would last around 30-40 hours, while the 467 HT battery would probably last up to twice as long. By the way, if a restorer aimed to power the filaments of such a set from “D” cells, a pair of alkaline cells would give up to 150 hours before dropping to the cut-off voltage of 1V. The much larger dry battery packs designed for household receivers would have lasted much longer than the 745/482 combination. In fact, some combinations may have had an operational life of around 1000 hours or more. However, I have no means of being entirely sure of these figures (or the other figures quoted above), as I haven’t actually put this to the test. Battery receiver power Providing battery power for early portable transistor receivers is not Valve radio batteries were typically quite large and were not cheap. 88  Silicon Chip siliconchip.com.au an impossible task. For example, 216 batteries are still used in many transistor receivers and myriads of other electronic devices. They can often be used in transistor receivers where much larger batteries were originally specified. Of course, the life of the 216 will be noticeably less than the battery it is replacing. The 276P was a commonly used battery but is rarely seen these days. However, WES Components in Ashfield NSW have 276 batteries with adaptors to convert them to the 276P type. Alternatively, you can often use several AAA, AA, C or D cells in multiple cell battery holders if a 216 or a 276 battery is not appropriate. Battery-powered console, table and mantel radios that used 2V accumulators and three 45B dry batteries in series are a different story, as suitable batteries are no longer made. However, such sets can be operated from a mains power supply that’s been designed to deliver the necessary DC rails at the required current. Another way of powering such sets is via DC-to-DC inverters. These are typically designed to work from a 6V or 12V lead-acid battery. This method is closer to the original method of supplying power, as the receiver is independent of the mains. Valve portable receivers Valve portable receivers provide a much greater challenge. Certainly, a mains type power supply will do the job but this means that the set can no longer be used as a portable. A cumbersome method of supplying the HT voltage is to string together the requisite number of 216 batteries. Ten 9V batteries in series to supply 90V does look a bit odd though! Similarly, alkaline D cells can supply the filament voltage quite easily. A better method of supplying the HT rail is to use a DC-to-DC inverter that will fit inside the receiver. However, this can be quite a challenge with the small miniature receivers of the late 1940s, although the full-sized portables shouldn’t pose too many problems. The filament supply can still be supplied by heavy-duty alkaline cells, with the inverter supplying just the HT requirements of the receiver. Supplying bias to battery sets is comparatively easy as no current is usually drawn from these supplies. siliconchip.com.au Typical Eveready Battery Types For Valve & Transistor Radios Type Voltage Comments Bias Batteries 794 9V 714 4.5V W95 9V 761 4.5V Tapped bias battery Battery to suit “baby” pedal radio Bias battery tapped at -1.5, -3, -6 & -9V Bias battery tapped at -1.5, -3 & -4.5V; uses 3 ‘D’ cells, 100 x 35 x 87mm Low-Tension Batteries X250 1.5V 30 x ‘F’ cells; companion to the older and larger 470 745 1.5V 8 x ‘F’ cells, 270 x 34 x 97mm 739 9V 717 7.5V Battery for series-wired portable set filaments; uses 6 x ‘F’ cells Filament battery; 5 x ‘C’ cells ­­­– 1.5V Large battery; same size as the 45V 770 High-Tension Batteries 467 67.5V 45 layer type cells; 72 x 34 x 90mm 482 45V Layer type construction; 90 x 43 x 138mm 470 45V Large 45V battery, newer type; 126 x 100 x 148mm 770 45V Large 45V battery, 22 times the volume of the 467 Transistor-Radio Batteries 286 9V 2 x 276P batteries in parallel, 62 x 50 x 180mm 276P 9V 62 x 50 x 90mm 733 9V 57 x 52 x 90mm 2362 9V 33 x 25 x 76mm plus terminals 2364 9V 216 9V 2761 9V 2582 2 x 6V 2510 2 x 7.5V 2512 2 x 9V Miniature transistor battery General Purpose Batteries 742 1.5V 4 x ‘F’ cells 509 6V 4 x ‘F’ cells X-71 1.5V 1 x ‘F’ cell 703 4.5V Bias and general purpose battery – 3V A 1.5V 2 x ‘E’ cells cycle battery Small general-purpose cell C 1.5V Small general-purpose cell D 1.5V Medium general-purpose cell E 1.5V Medium general-purpose cell F 1.5V Medium general-purpose cell 6 1.5V Large telephone & general purpose cell; 17-30Ah capacity, depending on use Composite Batteries 759 1.5V & 90V Sometimes, the original batteries in 30-50 year old receivers still supply nearly the correct bias voltage (they will not supply any current though). Basically, it’s just a matter of using suitable small batteries to do the job (AAA or 216-size batteries may suit individual receivers). March 2008  89 Photo Gallery: AWA Empire State Radiolette PERHAPS THE MOST FAMOUS RADIO made by AWA, the “Empire State” Radiolette was first produced in 1934. It was housed in a bakelite case and came in a variety of colours including black, brown, marbled white and dark green. A black Model 28 (1934) and a marble Model 32 (1936) are shown here. Both are 5-valve superhet receivers and the valve line-up was as follows: 6D6 RF amp, 6A7 converter, 6B7 IF/AF amplifier/detector, 42 audio output and 80 rectifier. Photo supplied by the Historical Radio Society of Australia Inc (HRSA), PO Box 2283, Mt Waverley, Vic 3149. www.hrsa.net.au Most portables use 1.5V, 7.5V or 9V on the filaments, while the HT requirement is usually either 67.5V or 90V. Obtaining a battery eliminator An assortment for bias batteries from Eveready, Diamond and Impex. Note the multiple output terminals on each battery, to enable the correct bias voltage to be selected. A mains power supply or a DC-toDC inverter supply can also be used to power non-portable battery-operated valve radios. This should be relatively straightforward, as space is not usually a problem in such sets. 90  Silicon Chip In practice, a mains supply can either be designed specifically for particular receiver or designed to supply a range of voltages to suit many different receivers from the 1920s to the 1960s. The same goes for DC-to-DC inverters. So where do you obtain a suitable mains-powered battery eliminator to run a vintage radio? Well, I currently have a suitable design on the drawing board to be published later in the year. This unit will supply filament voltages of 1.4, 2, 3, 4, 5 & 6V at 1A or so and 7.5-9V at 50mA. It will also supply HT voltages ranging from 22.5V to 135V and there will be a good selection of bias voltages as well. Suitable DC-to-DC inverters were rather thin on the ground until Tony Maher of the Historical Radio Society of Australia (HRSA) designed a number units in 2001. His first item was designed to replace a 467 battery. It fits into the same space as the battery and is powered by four nicad or NiMH cells. He has since added a 2V supply for sets using 2V valves and is about to publish a 90V version of his 467 battery-sized supply in Radio Waves SC (the HRSA in-house magazine). siliconchip.com.au Simple add-on board mates with the GPS Frequency Reference 1pps Driver For Quartz Clocks By JIM ROWE This simple add-on module for the GPSBased Frequency Reference is designed to drive the escapement coil of a low-cost quartz clock movement. It uses the 1Hz GPS pulses available at the rear of the Frequency Reference so that the clock can display local time with GPS-based accuracy. I F YOU BUILT the GPS-Based Frequency Reference described in the March-May 2007 issues, you’ll know that it provides a continuous readout of “Universal Time Coordinated” (UTC) on its LCD. This time is derived directly from the GPS satellite system and is therefore very accurate. In practice, it’s not all that difficult to mentally convert UTC into local time. In most cases, you simply add or subtract a certain number of hours, depending on the nominal longitude of your local time zone and, of course, your time of year. For example to convert UTC into Eastern Australian Standard Time, you simply add 10 hours, or 11 hours during the summer months when we’re on “Summer Time” (daylight saving). So 05:15:00 UTC becomes 15:15:00 (3:15pm) EAST, siliconchip.com.au or in summer 16:15:00 (4:15pm). That’s all well and good but most people would find a direct readout of their local time a little more useful. And that’s where this project comes in. It uses the 1pps (one pulse per second) output from the GPS system to drive a quartz wall clock. All you have to do is set the display for local time at the start, after which the clock will be accurately controlled via the GPS seconds pulses. It turns out to be very easy to interface the GPS Frequency Reference to a standard ‘analog’ quartz clock movement. First, you have to remove the existing circuitry from the clock (usually just a chip and a crystal on a tiny PC board) and bring out the connections to the clock’s escapement coil. That done, the coil can be pulsed instead by the little driver module described here. This driver module is small enough to fit inside the clock (next to the movement) and gets its power from the GPS Frequency Reference, along with the 1Hz (1pps) pulses. How it works If you remove the back from a standard ‘analog’ quartz clock movement and take a look inside, you’ll find a small PC board with a single IC chip and a tiny quartz crystal (usually 32.768kHz). This drives a simple stepper motor coupled to a multi-stage reduction geartrain. Inside the IC there’s an oscillator stage which uses the crystal to generate the 32.768kHz ‘clock’ pulses plus a counter chain which divides these pulses down to 1Hz (one per second). These 1Hz pulses are then used to drive the movement’s stepper motor so that it gives an increment of rotation every second. The geartrain then steps down these increments in the motor spindle’s rotation to drive the spindles for the clock’s second, minute and hour hands. The stepper motor is basically the interface between the electronic and mechanical sections of the clock movement. And that makes the motor quite March 2008  91 ANTRIM TRANSFORMERS manufactured in Australia by Harbuch Electronics Pty Ltd harbuch<at>optusnet.com.au SOFT IRON STATOR LAMINATIONS A STATOR COIL WINDING B Toroidal – Conventional Transformers Power – Audio – Valve – ‘Specials’ Medical – Isolated – Stepup/down Encased Power Supplies MULTI-POLE PERMANENT MAGNET ROTOR WITH PINION GEAR S S N N (a) BasicN Stepper Motor – At Rest A CURRENT PULSE B (N) Encased Power Supply 9/40 Leighton Pl, HORNSBY 2077 Ph (02) 9476 5854 Fax (02) 9476 3231 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. 92  Silicon Chip N A CURRENT PULSE B (S) MAGNETIC FLUX IN STATOR DURING PULSE N (N) (N) N 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. (b) After First 'Odd' Seconds Pulse S 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. (S) S Want a real speed controller kit? (S) N Harbuch Electronics Pty Ltd S S www.harbuch.com.au MAGNETIC FLUX IN STATOR DURING PULSE (c) After Next 'Even' Seconds Pulse Fig.1: a clock stepper motor uses a multi-pole permanent magnet rotor which rotates inside a circular gap in a soft-iron stator. It’s made to step in the same direction by reversing the polarity of the current pulse at each step. interesting, especially as it’s surprisingly simple in construction. In most cases, the motor is similar to the arrangement shown in Fig.1. As can be seen, it has a multi-pole permanent magnet rotor which is free to rotate inside a circular gap in a soft-iron stator. The latter has two pole pieces which are driven by a single coil. The trick is to get this very simple motor to rotate in 1-second steps, all in the same direction. That’s done by applying the pulses to the stator coil with alternate polarity, as shown in the diagram. Basically, ‘odd’ pulses are applied with one polarity, while ‘even’ pulses are applied with the opposite polarity. As a result, the rotor clicks around through an angle equivalent to the distance between its permanent magnet poles each second – see Fig.1. The geartrain steps down these 1-second jumps to drive the clock hands! siliconchip.com.au REG1 78L05 +5V OUT GND 47 F 16V 100nF +12V IN 47 F 16V 0V (GND) IC1: 4093B 1pps INPUT 14 5 8 4 10 9 6 IC1b 100k IC2: 4013B Q CLK Vdd 13 Q CLK R 10 S Q IC1d 11 D Q R Vss S 4 7 6 6 8 3 10nF 1 CLOCK COIL +5V 1 2 7 IC1a 3 7 6 8 3 IC4 555 2 5 10nF 78L05 SC 2008 1PPS CLOCK DRIVER COM IN Circuit details Refer now to Fig.2 for the complete circuit details. It can basically be divided into two logical sections. The first section comprises the NAND gates of IC1 and flipflop IC2a. This section separates the stream of 1Hz pulses coming from the GPS Frequency Reference into two streams of alternating ‘odd’ and ‘even’ pulses. The second section comprises 555 Semiconductors 1 4093B quad CMOS Schmitt NAND (IC1) 1 4013B dual CMOS flipflop (IC2) 2 555 timers (IC3,IC4) 1 78L05 low-power 5V regulator (REG1) Resistors (0.25W, 1%) 1 100kW 1 390W OUT Fig.2: the circuit uses NAND gates IC1a-IC1d and D-type flipflop IC2a to separate the incoming 1Hz pulses into alternating “odd” and “even” pulse streams. These pulse streams then drive IC3 & IC4 which in turn drive the clock coil. This means that using the 1Hz pulses from the GPS Frequency Reference to drive such a clock movement is quite easy. All we have to do is provide a simple driver circuit which accepts the 1Hz GPS pulses and in turn applies brief current pulses to the stepper motor coil in the same alternate-polarity manner as the normal clock electronics. And that’s exactly what we do in this project. 1 PC board, code 04103081, 46 x 38mm 5 PC board terminal pins Capacitors 2 47mF 16V RB electrolytic 1 100nF monolithic ceramic (code 104 or 100n) 2 10nF monolithic ceramic (code 103 or 10n) 4 1 8 390 5 2 2 12 4 IC3 555 1 IC2b 11 7 13 IC2a 5 D 12 14 3 9 IC1c Parts List timers IC3 & IC4. These drive the stepper motor coil using the two separated pulse streams. In greater detail, the incoming 1Hz pulses are first fed through IC1b which is connected as an inverting input buffer. Note that pin 6 of IC1b is tied to ground via a 100kW resistor to prevent it from ‘floating high’ if the input cable is disconnected from the Frequency Reference. IC1b’s output appears at pin 4 and is fed in two directions – to pin 9 of IC1c and to the clock input (pin 3) of IC2a. IC1c simply re-inverts the signal and its pin 10 output is then fed to pin 12 of IC1d and to pin 1 of IC1a. IC2a is one half of a 4013B dual D-type flipflop (the second flipflop in the IC is not used here). As shown, its Q-bar output is connected back to the D input, so the flipflop is configured in toggle mode. As a result, its Q and Q-bar outputs (pins 1 & 2 respectively) toggle back and forth in complementary fashion, in response to the incoming pulses. IC2a’s Q output is fed to pin 13 of IC1d, while its Q-bar output goes to pin 2 of IC1a. As a result, IC1d and IC1a separate the 1Hz pulses into two alternating streams, each controlled by the toggling outputs of IC2a. The ‘odd’ 1Hz pulses (inverted) emerge from pin 11 of IC1d, while the ‘even’ pulses (also inverted) emerge from pin 3 of IC1a. These two separated pulse streams are then used to trigger 555 timers IC3 & IC4 which are used here simply as inverting drivers. As you can see, the clock’s stepper motor coil is connected between their two pin 3 outputs via a 390W current limiting resistor. During the gaps between the pulses, both IC3 and IC4 are in their ‘off’ state, with their pin 3 outputs both switched low. As a result no current flows through the stepper motor coil. However, each time a pulse arrives at IC1b’s pin 6 input, either pin 11 of Resistor Colour Codes o o o siliconchip.com.au No. 1 1 Value 100kW 390W 4-Band Code (1%) brown black yellow brown orange white brown brown 5-Band Code (1%) brown black black orange brown orange white black black brown March 2008  93 IC2 4013B 100k IC1 4093B IC3 555 390 47 F + REG1 78L05 + +12V ERJ 1PPS 10nF CC1 FROM GPS FREQUENCY REFERENCE 1PPS GND CC2 TO CLOCK COIL IC4 555 100nF 1 8 0 3 01 4 0 10nF GND +12V 47 F Fig.3: install the parts on the PC board as shown in this layout diagram and the photo at right. Take care with component orientation when installing the ICs and the electrolytic capacitors. IC1d or pin 3 of IC1a will pulse low, depending on the current state of flipflop IC2a. This causes either IC3 or IC4 to trigger, pulsing its output pin to the +5V level for the duration of the pulse (about 100ms) and hence driving a pulse of current through the stepper motor coil in one direction or the other. The next pulse (about 900ms later) then triggers the other 555 output driver, resulting in a current pulse through the coil in the opposite direction. Power for the circuit can be derived from any 12V DC source, including the 12V DC rail used to power the GPS Frequency Reference. This is applied to a low-power regulator (REG1) which delivers a +5V rail to power the circuit. The two 47mF capacitors and the 100nF capacitor provide supply decoupling and filtering. Building the module All of the driver module circuitry is mounted on a small PC board coded 04103081 and measuring just 46 x 38mm. This is small enough to mount in the back of most wall-type quartz clocks, alongside the movement. Fig.3 shows the assembly details. No particular order need be followed but we suggest that you install the wire link first, followed by PC stakes at the five external wiring points. The two resistors and the capacitors can then go in. Take care to ensure that the two 47mF electrolytics are orientated correctly. That done, you can install regulator REG1 and then complete the assembly by soldering in the four ICs. Be sure to orientate the ICs as shown on Fig.3 (ie, with pin 1 at lower left) and be careful not to get IC1 (4093B) and IC2 (4013B) mixed up. The two terminal pins on the left marked CC1 and CC2 are used to terminate the leads from the clock’s stepper motor coil (see below). In addition, you have to make three connections to the GPS Frequency Reference – ie, +12V, GND and the 1Hz GPS pulses. A length of 2-pair telephone cable can be used for these connections. Modifying the movement It’s not difficult to modify the quartz clock movement so that it can be driven by this module. The first step is to remove the back and then the clock’s PC board. The latter usually fits into a slot at one end of the movement’s case. If the battery contacts are attached directly to the PC board, these can be removed as well. As you are removing the PC board, you’ll find that there are two fine wires from the stepper motor coil soldered to it. These two wires must be carefully desoldered from the board, after which the board can be discarded. The next step is to connect a short length of light-duty 2-core cable (eg, a 200mm length of rainbow cable) between the coil wires and the CC1 & CC2 terminals on the driver board. This should be done in such a way that neither the joints nor the coil wires The leads from the clock coil are soldered to two pads on a piece of scrap PC board as shown in the above photo (see text). These pads also terminate the leads from the driver board. The photo at right shows the completed driver module mounted in the back of the clock case. 94  Silicon Chip siliconchip.com.au The driver board can be connected to the GPS Frequency Reference via a length of 2-pair telephone cable fitted with a DB-9 plug. This can plug into a matching DB-9 socket mounted on the rear panel, just above the “GPS 1Hz” output socket. will be strained if the lead wires are accidentally pulled. The way to do this is as follows. First, cut a small rectangle from an old PC board, making it exactly the same size as the clock PC board (so that it will slide into same case slot). That done, cut a 3mm hole into the side of the movement case near the board slot, then bring the ends of the lead wires in through the hole and solder them to two pads on the new “termination board”. Finally, solder the coil wires to these same pads and refit the back to the clock movement. The driver module itself can be mounted next to the clock module. In our case, the module was attached to the wooden dial ‘plate’ using a pair of 6G x 9mm self-tapping screws, with an M3 nut and flat washer under each to act as spacers. GPS reference connections As mentioned above, a length of 2-pair telephone extension cable is used to connect the driver module to the GPS Frequency Reference. To do this, we suggest fitting an extra DB-9 socket on the rear panel of the GPS Frequency Reference, just above the holes for the GPS 1Hz and phase error pulse outputs – see photo at left. That done, use three short lengths of hook-up wire to make the connections inside the unit to three of the pins on this added socket. One lead goes from the socket to the main board ground, another to the +12V line and the third wire to the rear of the “GPS 1Hz” output socket. Now fit a matching DB-9 plug to the end of the cable from the clock driver module. Be sure to connect the leads to the correct pins on this plug, to mate with those on the new DB-9 socket. It’s now just a matter of testing it out. Connect the DB-9 plug to the socket, apply power and check that the clock immediately starts ticking. Its second hand should step in time with the flashes from the “GPS 1Hz” LED on the GPS Frequency Reference. All that remains when you get to this stage is to set the clock movement to the current local time. If you want the second hand to read correctly as well, the easiest way to do this is to first unplug the clock connection from the rear of the GPS Frequency Reference when the seconds hand is in the 12 o’clock position. That done, set the minutes and hours hands manually for the start of the next minute and then, as soon as the UTC seconds display on the Frequency Reference’s LCD reaches “59”, plug the connection back in again to restart the clock. If you time this reconnection correctly, the clock will now display local time accurately (to the second) – and will continue to do so as long as GPS SC 1Hz pulses keep arriving. “I’ll GO THE RIGOL ... UNBEATBLE FOR PRICE AND PERFORMANCE” Rigol DS5062MA 60MHz Rigol DS5102MA 100MHz Rigol DS1202CA 200MHz Rigol DS1302CA 300MHz 60MHz Bandwidth, 2 Ch 1GS/s Real Time Sampling 4k Memory Per Channel Advanced Triggering Built-in USB 3 Year Warranty 100MHz Bandwidth, 2 Ch 1GS/s Real Time Sampling 4k Memory Per Channel Advanced Triggering Built-in USB 3 Year Warranty 200MHz Bandwidth, 2 Ch 2GS/s Real Time Sampling 10k Memory Per Channel Advanced Triggering Built-in USB 3 Year Warranty 300MHz Bandwidth, 2 Ch 2GS/s Real Time Sampling 10k Memory Per Channel Advanced Triggering Built-in USB 3 Year Warranty ONLY $799 Sydney ex GST 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 ONLY $1,099 Brisbane ex GST Tel 07 3275 2183 Fax 07 3275 2196 ONLY $2,036 Adelaide Tel 08 8363 5733 Fax 08 83635799 ex GST Perth Tel 08 9361 4200 Fax 08 9361 4300 web www.emona.com.au ONLY $2,620 ex GST EMONA March 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 Query on PC board layout Looking at the power supply PC board for the Studio Series Preamplifier (SILICON CHIP, October 2005), why do the tracks from REG1 & REG2 go to the external terminals first and then back to D5 and D7? Why don’t D5 and D7 connect directly to REG1 & REG2, as shown in Fig.10 on page 31? (J. E., Silverwater, NSW). • This is an interesting question, J. E., and it highlights the fact that many aspects of the topology of our PC board designs never get a mention in the articles – we simply don’t have the space. In this case, notice that diodes D5 & D7 are in parallel with the 100W sense resistors for the adjustable regulators and it is the connections of the 100W resistors which are important, not the diodes. By connecting the 100W resistors to the output terminals in the way depicted, any small voltage loss in the copper tracks from the OUT pins of the regulators to the external connectors is automatically compensated for. This is a small point, admittedly, but it does improve the circuit performance. And since the diodes need to be in parallel with the 100W resistors, they are connected to the same PC tracks. Normally of course, the diodes do nothing. Puzzlement with kit assembly I recently bought a kit for the 20W Class-A Amplifier from Altronics in Auburn and have so far put everything together quite easily. However, there are a couple of anomalies which I hope you might throw some light on. First, the power amplifier circuit shows a 150nF 250VAC capacitor and this is also printed on the amplifier boards (near the inductor). The one supplied with the kit is marked 150nF but 100VAC Vishay. Is this a problem? The hole centres suit the (smaller?) supplied cap, so I’ve installed it, assuming it will be OK. Can you please advise? Ignition System For A 1939 Packard I bought a High-Energy Ignition kit (SILICON CHIP, December 2005 & January 2006) for use in a 1939 Packard which is running a 6V negative-earth system. Can you tell me if it is suitable for this and if so, is there anything special I need to do to make it run? I built the kit but have had problems with the engine cutting out after about 10 minutes. This has happened three times, coincidentally cutting out after running around 10 minutes each time. I have LK1 in the normal position, LK2 in the 0.5ms position and LK3 in normal. I have also tried it in the point’s position. Are there any bench and in-car tests I can perform which will help verify that the circuitry is OK? (S. L., via email). 96  Silicon Chip • This ignition system was not specifically designed for 6V but it should work with minor circuit changes. In particular, the 100W 5W resistor for the base of transistor Q1 should be 47W 5W instead. Insufficient base current for Q1 when using the 100W resistor (at 6V) may be the cause of the cutting out. We also recommend using a 47W 5W resistor for the points’ resistor. One possible problem could be that the collector is arcing across to the case. Check that Q1’s collector (the metal tab) is isolated correctly, using the washer and bush. Check that there are no sharp protrusions that may puncture the washer. The hole in the box must be chamfered so there are no sharp edges that can cause an arc-over. Second, could you please explain how to use the tiny little links LK1, 2, 3 & 4 on the preamplifier board (SILICON CHIP, August 2007, page 20)? All four supplied in the kit appear identical. I’ve not encountered this type of component before and don’t understand from the instructions exactly how they’re meant to fit or in fact, exactly what they do. The instructions mention the headers have pins but those supplied do not, just a little sliding socket which can be pushed out. Is LK2 on top while LK1 is underneath? Similarly, is LK3 on top and LK4 below? Your help would be greatly appreciated, as I don’t understand the instructions. On page 18 of the August edition, links are mentioned and the photo on page 21 shows what looks like a gold pin sticking up from underneath. (K. P., via email). • The 100VAC capacitor is fine. You install the four 2-pin headers as shown on the PC board. Then, the link itself is the little top sliding section – this shorts the two pins of the header together. Defective brownout protection A while back I built the Appliance Energy Meter (SILICON CHIP, July & August 2004). I built it with the added brownout protection but the device doesn’t seem to restore to normal function once battery operation has been activated. I have just disconnected the battery and it seems a waste not to use the relay. (A. R., via email). • Make sure the 9V battery is an alkaline type and is fresh. Standard 9V batteries do not seem to be able to supply the necessary current. Better transistors for the class-A amplifier For the 20W Class-A Amplifier, is it possible to use MJL1302A & MJL3281A transistors instead of the specified MJL21193 & MJL21194 desiliconchip.com.au Electronic Tacho For A Motorbike I went to a Jaycar store with the intent of purchasing your electronic tachometer. The salespeople allowed me to read the directions/ information that accompanies this kit but it was not obvious if I could use the tachometer because the salespeople and the article were vague about how the tacho picks up the signal from the coil. I want to use it with a Suzuki DR650 motorbike. As far as I know it has electronic ignition because everything does these days. It has no engine management system and I doubt that it has electrical connections for adding a tacho. Any help would be appreciated. I don’t want to pay about $60 and not be able to use it. (R. B., via email). • The tachometer detects rpm signal either from the ignition coil or from the ignition pickup sensor. In cars, the sensor is usually a reluctor, Hall Effect device, optical pick-up vices? I presume the transistors I have are genuine On Semiconductor as they have a circle printed with “ON”. (N. J., via email). • Yes, these are ideal substitutes. Offset problem in Studio 350 amplifier I have constructed two Studio 350 amplifier modules (SILICON CHIP, January/February 2004) from kits supplied by Altronics. For each kit, adjusting VR1 never brings the output to 0V; rather it adjusts between 120mV to 10mV from one extreme to another. Curiously, one kit stays positive with respect to ground (+120mV to +10mV over VR1’s range) and the other stays negative (-10mV to -120mV). With VR1 in its centre, the offset is about +35mV in both cases. VR2 adjusts the idle current just fine. I have not yet tried removing the 470W set-up resistors and applying a signal, as I am not particularly keen on using something that hasn’t passed its tests. I have checked all the voltages against those printed on the schematic in the article and they’re all within about 20%, although some only barely. siliconchip.com.au or points. With a motorcycle, things are different and often the ignition is a very basic Capacitor Discharge Ignition (CDI) that comprises a high voltage magneto coil and a magneto pickup. The high voltage is used to charge a capacitor which is ultimately dumped into the coil by a signal from the magneto pickup. A small electronic circuit comprising the capacitor and an SCR is used to dump the capacitor’s charge. The tachometer can generally be used if it connects to the magneto pickup. Although the tachometer has been used on these CDI motorcycle ignition systems we cannot guarantee that it will work with all motorcycles. The tachometer will not operate on the coil side because of the short firing pulse from CDI ignitions. Note that most motorcycles already include a tachometer as standard equipment. The power rails measure 72.5V rather than exactly 70V and I have not yet hooked up both amplifier modules at the same time. I am considering swapping the 2SA1084 transistors from the long-tailed pair in case they’re poorly matched enough to cause this issue. (M. J., via email). • This is a question of input transistor matching. Try swapping in some different input transistors to see if you can get a better match. However, if you can get the output offset down to 10mV that really is good enough – far better than most amplifiers. It is really only important if you are driving a transformer-coupled loudspeaker such as an electrostatic. Short circuit in NiMH charger I recently built the NiMH Charger from the September 2007 issue. It made all the settings/adjustments OK with the trimpots but when I connect batteries (2 x AA) for charging, the voltage regulator (LM317), trimpot VR6 and IC1 all overheat and fail. The DC power supply is rated for 22V <at> 3A. My previous Nicad charger projects from SILICON CHIP are still going strong. Helping to put you in Control Controllers We have a selection of Controllers for managing your processes. N322 Electronic Thermostat Budget priced ONOFF temperature controllers. Models for Thermistor, PT100 RTD and J Thermocouples. The NTC model is provided with a 2m waterproof NTC Thermistor to get you up and running immediately. From $89+GST N1100 PID Process Controller Popular controller features a universal Input accepts: Thermocouples , RTD, 4-20mA, 50mV and 0-5Vdc. Outputs include Relay, 4-20mA and pulse for SSR From $175+GST USB I/O Controller The KTA-220 allows PC's to control real world applications. It features 8 relay outputs, 4 Isolated Inputs, 2 Analog inputs and a PWM output. Multiple modules can be connected to a single PC. $135 +GST Serial I/O Controller KTA-108 is a Serial Port Controlled I/O module. It features 8 relay outputs, 4 Isolated Inputs $112.50+GST Pixel Controller Card Using the PICAXE 28X microntroller. It features 8 relays, 8 digital Inputs, 4 analog inputs. Programmed in Basic $129.50+GST Solid State Relays High quality SSR’s with 4-32VDC, 80280VAC, 4-20mA and potentiometer inputs. DIN Rail and Panel Mount Heatsinks for SSR’s also available. Contact Ocean Controls Ph: 03 9782 5882 www.oceancontrols.com.au March 2008  97 Comparing Rechargeable & Non-Rechargeable Cells I have a question regarding conventional (non-rechargeable) batteries versus rechargeable batteries. Just taking standard “over the counter” cells as an example (AAA, AA, C & D), rechargeable cells always come with a mAh rating, whereas conventional batteries (heavy duty, alkaline, etc) do not. I know rechargeable cells are 1.2V and conventional batteries are 1.5V. But what I’m not clear on is which type of battery would produce the highest short-term peak current? Obviously, if the internal resistances were identical, then 1.5V would “push” more current into a given load than 1.2V but is it that simple? Are the internal resistances similar in each type of battery? Why don’t conventional batteries have an mAh rating and why do some toys say not to use rechargeable batteries? In my case I am looking at modifying a launch controller for model rocketry clustering. Launch controllers in rocketry are used to supply current to a Nichrome wire Circuit board/components checked OK. Any assistance would be appreciated. (R. R., via email). • It appears there is a problem with the LM317. To destroy the adjustment trimpot and IC1 would suggest that there is a high current flow in the adjust terminal or the output is somehow shorting to the drain of the Mosfet. Check that the Mosfet is isolated from the box and that the regulator tab is not shorting to the case with the securing screw. Digital instrument display for fire truck I want to use the Digital Instrument Display (SILICON CHIP, August & September 2003) to convert the analog temperature display on the engine of a fire brigade truck belonging to a volunteer brigade, so that I can provide a remote idiot light at the rear of the appliance to shut down the engine in the event of an over-temperature condition. The problem is that the vehicle is 24V. Could you please advise on the 98  Silicon Chip igniter-head, which in turn ignites the rocket motor. When clustering (ie, igniting more than one rocket motor simultaneously), it is essential that the controller provides a high current for a short period (1-3 seconds), otherwise the situation could arise where one or more motors may not ignite before lift-off occurs, which could lead to serious damage to both the rocket and the pocket, to say nothing of the potential hazard to spectators! This leads to my final question: for a given number of cells (most controllers hold four AA cells), would the best solution be alkalines, rechargeables or the “newer” non-rechargeable Lithium cells? Any assistance would be greatly appreciated. • Non-rechargeable cells and batteries do not have their capacity stated because it really depends on how you use them. If used for a short time each day, they will provide more capacity than if used continuously. The cur- mods required to run the display from 24V? (J. C., Mt. Dandenong, Vic). • Change zener diode ZD1 to 30V rating and the 100mF capacitor at the input to REG1 to 35V. Change the 1kW resistor at the collector of Q6 to a 2.2kW 0.5W resistor and make sure C1 and C2 are 35V. Serial I/O controller kit is a slave I am really keen to build the Serial I/O Controller kit but there’s one question that has been plaguing my mind for months now. Is there any way to interface this card with a computer and have the card control functions of software on the computer? What I am trying to achieve is finding a method of utilising this card to run batch files on my computer to do automated tasks should a condition change on the card’s inputs. Is this possible? If so, what modifications would I have to make. (J. H., via email). • The Serial I/O Controller published in the November 2005 issue is a slave device. This means that it sits and rent draw also changes the available capacity. Rechargeable cells state the capacity because this information is needed to be able to recharge them and their capacity is fairly consistent over a wide range of applications. Some toys cannot be used with rechargeable cells because they are voltage sensitive and may not work well with the lower voltage available from rechargeables. Rechargeables can also damage toys with motors because high current delivered to a stalled motor can burn it out. In general, rechargeables can deliver higher currents than non-rechargeable cells. The current available from a cell depends on the chemistry and the manufacturer. Generally, Nicad cells can deliver the most current but these days NiMH cells can deliver high currents as well. In general, if you have any device which can accept rechargeable cells and you use it a lot, then rechargeables are the better proposition. waits for commands from the host PC. Once it receives a command, it executes it, and optionally sends data back to the PC. It does not initiate data transfers with the PC. The set of commands that are available are explained on page 78 of the November 2005 issue. For the application that you have in mind, a simple C program could be written that will run on the host PC. It would continuously monitor some condition, by periodically sending commands to the Serial I/O Controller, and it would analyse the received data. It would then take action, such as executing another program, if some condition is met. In other words, the application you have in mind can be implemented but you will have to: (1) Write a C program (or equivalent in some other high level language) to poll the Serial I/O Controller periodically and analyse its output; (2) This program must run on the host PC and must be always running - the host PC will have to be on for a start. (3) This program will preferably be loaded automatically by the OS siliconchip.com.au (operating system) and work in the background. As you can see, it can be done, yet the solution is not ideal, mainly because polling is an inefficient way to implement your application. PIR Sensor Triggered Mains Switch, February 2008: the O11 output mentioned in the text on pages 58 and 59 and on the circuit should be the O10 output. Laptop recording & software Multi-Message Voice Recorder, December 2007: the resistor from pin 7 of the HK828 should be 47kW and the parts list should show nine 47kW resistors and only one 10kW. I was interested in the article on PC recording (SILICON CHIP, November 2007) as I am about to buy a new laptop computer for audiovisual work. You mention the audio testing software “Rightmark Analyser” but how would I test a new computer before purchase, to see if it is suitable? What are the preferred specs for a laptop? Few of them appear to be media-orientated with AV sockets fitted. My old Pentium 400 had a separate Pinnacle sound card in one of the motherboard slots – this had a full set of RCA in/out connectors on the rear metal bracket. I have spoken to four different computer suppliers and they say that any late model should do but can’t be sure. They’re a bit vague, refer me to someone else or don’t reply. Even a consultant who specialises in recording has not replied. Yet I’ve seen concerts being recorded straight into laptop computers. Enquiries to the PC user group for technical specs are for members only. So maybe I should join then investigate this recording aspect. (P. S., Albert Park, Vic). • Any salesman will tell you that any laptop will do the job but like anything else (cars, stereo systems, washing machines), some are better than others. Some laptops have sound quality UHF Remote Mains Switch Transmitter, February 2008: Transistor Q1 is a BC327 (PNP) as listed in the parts list. The circuit labelling is incorrect. In addition, the parts list should have 5 10kW resistors not 4. Notes & Errata Electricity Saving Box, November 2007: the formula published in Fig.6 (page 26) should read: q' = tan-1 (w (L - w2CL2 - CR2))/R = 59.98° which leads to cos(q') = 0.5. which is atrocious (hum and noise, poor frequency response etc) while others are exemplary – it all depends on the manufacturer and the model. Generally, cheap laptops have cheap and dirty sound circuitry but a high price is not always a guarantee of high quality. However, there are a number of ways of making sure you get a good one: (1) Take a copy of the analyser program with you and ask to test it before you buy it. Most places will allow this and if they don’t then try (2) below. (2) Make sure you get a “money back guarantee if returned within X days” deal and simply purchase the laptop. Take it home and analyse it. If it’s no good, take it back and demand one that works properly or you want a refund. (3) In the unlikely event that both of the above are not possible, then get a high-quality music sampler CD that you know intimately and a set of highquality headphones – the best you can get, even if you just borrow them. Play the CD and listen to it on a known system of high quality. Then try it on the laptop in question. If you have good ears, then it should be readily apparent if the laptop is not up to spec – if you don’t, then the whole matter is rather moot anyway. Chances are that if the manufacturer has gone to the trouble of designing a good audio playback stage in the laptop, then the recording section will also be good. As to what constitutes good specifications, just compare its performance with that of high-quality amplifiers: 20-20kHz within ±1 or 2dB; less than 0.1% distortion; -70dB hum and noise or better. There is no need to go overboard on specifications. The main thing is that the finished result sounds good. A poor quality laptop will soon reveal itself in this regard because results will simply not be pleasing to the ear, even when everything else is SC done correctly. 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. siliconchip.com.au March 2008  99 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* 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. 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. 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, PROGRAMMING 32-bit MICROCONTROLLERS IN C By Luci di Jasio (2008) $79.00* 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. PRACTICAL GUIDE TO SATELLITE TV 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. 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. 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. See Review March 2010 See Review Feb 2004 SWITCHING POWER SUPPLIES A-Z 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. 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. 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 Ian Hickman. 4th edition 2007 $61.00* by Douglas Self 2nd Edition 2006 $69.00* by Carl Vogel. Published 2009. $40.00* 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 PAYPAL (24/7) INTERNET (24/7) MAIL (24/7) PHONE – (9-5, Mon-Fri) eMAIL (24/7) FAX (24/7) To ilicon Chip Use your PayPal account www.siliconchip. Call (02) 9939 3295 with silicon<at>siliconchip.com.au Your order and card details to Your order to PO Box 139 Place100  S com.au/Shop/Books silicon<at>siliconchip.com.au Collaroy NSW 2097 with order & credit card details with order & credit card details (02) 9939 2648 with all details Your You can also order and pay for books by cheque/money order (Mail Only). Make cheques payable to Silicon Chip Publications. Order: 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* 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. 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. 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, PROGRAMMING 32-bit MICROCONTROLLERS IN C By Luci di Jasio (2008) $79.00* 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. PRACTICAL GUIDE TO SATELLITE TV 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. 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. 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. See Review March 2010 See Review Feb 2004 SWITCHING POWER SUPPLIES A-Z 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. 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. 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 Ian Hickman. 4th edition 2007 $61.00* by Douglas Self 2nd Edition 2006 $69.00* by Carl Vogel. Published 2009. $40.00* 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 PAYPAL (24/7) INTERNET (24/7) MAIL (24/7) PHONE – (9-5, Mon-Fri) eMAIL (24/7) FAX (24/7) To siliconchip.com.au 2008  101 Use your PayPal account www.siliconchip. Call (02) 9939 3295 with silicon<at>siliconchip.com.au Your order and card details to Your order to PO Box 139 March Place com.au/Shop/Books silicon<at>siliconchip.com.au Collaroy NSW 2097 with order & credit card details with order & credit card details (02) 9939 2648 with all details Your You can also order and pay for books by cheque/money order (Mail Only). Make cheques payable to Silicon Chip Publications. Order: ALL TITLES SUBJECT TO AVAILABILITY. PRICES VALID FOR MONTH OF MAGAZINE ISSUE ONLY. ALL PRICES INCLUDE GST MARKET CENTRE Cash in your surplus gear. Advertise it here in Silicon Chip. CLASSIFIED ADVERTISING RATES 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 credit card details, or fax (02) 9939 2648, or post to Silicon Chip Classifieds, PO Box 139, Collaroy, NSW, Australia 2097. Enclosed is my cheque/money order for $­__________ or please debit my o Visa Card   o Master Card Card No. Signature­­­­___­­­­­­­­__________________________ Card expiry date______/______ Name _________________________________________________________ Street _________________________________________________________ Suburb/town ______________________________ Postcode______________ Phone:______________ Fax:______________ Email:___________________ FOR SALE MicroByte Electronics: PIC Micros – Development Board – Development tools & Components. Phone: (03) 9378 4288. info<at>microbyte.com.au; www. microbyte.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 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 12V Batteries, <6mths use. 5, 7, 9A/h, $1 per A/h. Ongoing availability. Pickup only, Highbury, SA. petria<at>adam.com.au LEDs! I NOW HAVE good stocks of Nichia superbright oval LEDs, as well as 5mm Agilent (HP) LEDs. These are fantastic, bright brand-name qual- Circuit & Design Ideas Wanted Do you have a good circuit idea? If so, sketch it out, write a brief description of its operation & send it to us. Provided your idea is workable & original, we’ll publish it in Circuit Notebook & you’ll make some money. We pay up to $100 for a good circuit idea or you could win some test gear. Silicon Chip Publications, PO Box 139, Collaroy, NSW 2097. 102  Silicon Chip ity LEDs at Chinese LED prices! Also Osram surface mount range and other NOS standard and superbright brand name LEDs from just a few cents each. Also Cree X-Lamps, 5 and 10 watt power LEDs, LED drivers, kits and all sorts of other stuff. www.ledsales.com.au KIT ASSEMBLY KEITH RIPPON KIT ASSEMBLY & REPAIR: * Australia & New Zealand * Small production runs. Phone Keith 0409 662 794. keith.rippon<at>gmail.com WANTED CUSTOMERS: Truscotts Electronic World – large range of semiconductors siliconchip.com.au ELNEC IC PROGRAMMERS VIDEO - AUDIO - PC High quality Realistic prices Free software updates Large range of adaptors Windows 95/98/Me/NT/2k/XP distribution amps - splitters digital standards converters - tbc's switchers - cables - adaptors genlockers - scan converters bulk vga cable - wallplates CLEVERSCOPE USB OSCILLOSCOPES DVS5c & DVS5s High Performance Video / S-Video and Audio Splitters 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 MD12 Media Distribution Amplifier QUEST ® IMAGECRAFT C COMPILERS ANSI C compilers, Windows IDE AVR, TMS430, ARM7/ARM9 68HC08, 68HC11, 68HC12 Quest AV® HQ VGA Cables GRANTRONICS PTY LTD www.grantronics.com.au AWP1 A-V Wallplate Come to the specialists... Satellite TV Reception 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°. 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 C O N T R O L S You get results faster with the world’s easiest controllers! best v alue! Developer’s Kit $193 includes programming cable & software Made in Australia - enthusiastic users world-wide splat-sc.com 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: EARLY HIFIs, AMPLIFIERS, siliconchip.com.au ® ® Quest Electronics Pty Limited abn 83 003 501 282 t/a Questronix Products, Specials & Pricelist at www.questronix.com.au fax (02) 4341 2795 phone (02) 4343 1970 email: questav<at>questronix.com.au Do you have wireless problems? Telelink has wireless solutions! If you want the right ‘wireless’ ingredients for a successful project recipe, THINK Telelink! Don’t want to be confused by wireless gobbledegook and confusing buzz words? TALK to Telelink! We will give you honest advice so that you can make the right purchase decision for your OEM low power wireless requirements. Browse our website for more information about our products. If you have any questions speak with a Telelink Communications representative. At Telelink we sell solutions, not problems! 01010101 MS120OEM216 $149 1-off VGA Splitter VGS2 Telelink Communications www.telelink.com.au e-mail Jack Chomley – jack<at>telelink.com.au or call (07) 4934 0413 or 0428 199 551 Speakers, Turntables, Valves, Books, Quad, Leak, Pye, Lowther, Ortofon, SME, Western Electric, Altec, Marantz, McIntosh, Tannoy, Goodmans, Wharfedale, radio and wireless. Collector/ Hobbyist will pay cash. (07) 5471 1062. johnmurt<at>highprofile.com.au 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. PICmicro Programmers And Compilers: microEngineering Labs USB programmers, adapters, and Basic Compilers, DIY (Kitsrus) USB programmers, MikroElektronika Basic, Pascal, DSpic Pascal Compilers, CCS C, FED C, Hi-Tech C, MikroElektronika C, disassembler and hex tools. CAN: Lawicell CANUSB, CAN232 FTDI: USB Family of IC ‘s. FT232RL, FT2452RL, also BL and others. 4DSystems LCD/Graphics: Add VGA monitor, or OLED LCD to your micro. Simple Serial I/F. Heaps And Heaps Of USB Products: TTL, RS-232, RS-485, modules, cables, analyzers, CRO’s. Popular Easysync USB To RS-232 Cable: Works when the others fail. Only one recommended by CBUS. Money back guarantee. www.dontronics-shop.com March 2008  103 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. SPK360 3/5/06 1:10 PM 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. Page 1 DOWNLOAD OUR CATALOG at 20 years experience! www.iinet.net.au/~worcom HI-FISPEAKER REPAIRS WORLDWIDE ELECTRONIC COMPONENTS PO Box 631, Hillarys, WA 6923 Ph: (08) 9307 7305 Fax: (08) 9307 7309 Email: worcom<at>iinet.net.au Specialising in UK, US and Danish brands. Speakerbits are your vintage, rare and collectable speaker repair experts. Foam surrounds, voice coils, complete recone kits and more. Original OEM parts for Scan-Speak, Dynaudio, Tannoy, JBL, ElectroVoice and others! SPK360 YOUR EXPERT SPEAKER REPAIR SPECIALISTS tel: 03 9647 7000 www.speakerbits.com RETAIL MANAGER: PERTH STORE Altronics is a dynamic national company involved in retailing and wholesaling a wide range of electronic equipment to the trade and enthusiast markets. We are searching for a motivated manager to join our Perth team. The successful applicant will have several years experience in retail, preferably with management experience and a background in the electronics industry. Excellent communication and customer service skills are essential. This is a hands-on position which involves serving customers, processing orders, merchandise control and supervision of our retail team. A generous salary and bonus scheme will be provided. To register your interest, forward your resume to Dean Stephens via email at: dean.stephens<at>altronics.com.au 174 Roe St. Perth WA 6000. Advertising Index 555 Electronics............................. 43 Alternative Technology Assoc...... 92 Altronics.........................loose insert Alvin Electronics........................... 13 Amateur Scientist CDs............... IBC Av-Comm................................... 103 BitScope Designs........................... 3 Computronics............................. 102 Dick Smith Electronics............ 18-21 Dontronics.................................. 103 Ecowatch.................................... 103 Emona Instruments...................... 95 Grantronics................................. 103 Harbuch Electronics..................... 92 High Profile Communications..... 103 Instant PCBs.............................. 104 Jaycar........................ IFC,49-56,104 JED Microprocessors..................... 5 Keith Rippon............................... 102 LED Sales.................................. 102 Microgram Computers.............. OBC Microzed Computers...................... 6 Microbyte Electronics................. 102 Ocean Controls............................ 97 Ozitronics..................................... 41 Prime Electronics......................... 11 Quest Electronics....................... 103 RCS Radio................................. 102 RF Modules................................ 104 Sesame Electronics................... 102 Silicon Chip Binders......... 77,92,104 Silicon Chip Bookshop........ 100-101 SC Perf. Elect. For Cars.......... 37,80 Silicon Chip Subscriptions........... 57 Siomar.......................................... 45 Soundlabs Group......................... 79 Speakerbits................................ 104 Splat Controls............................. 103 Telelink....................................... 103 Tenrod Australia........................... 83 Truscotts Electronic World.......... 102 Trusys......................................... 102 Vaf Research.................................. 7 Wagner Electronics...................... 41 Worldwide Elect. Components... 104 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. Ph: 1300 797 007 Fax: 1300 789 777 Internet: www.altronics.com.au 104  Silicon Chip siliconchip.com.au STIC FANTAIDEA GIFT UDENTS FOR SFT ALL O S! AGE THEAMATEUR SCIENTIST An incredible CD with over 1000 classic projects from the pages of Scientific American, covering every field of science... THE LATEST VERSION 4 – WITH EVEN MORE FEATURES! Arguably THE most IMPORTANT collection of scientific projects ever put together! This is version 4, Super Science Fair Edition from the pages of Scientific American. As well as specific project material, the CDs contain hints and tips by experienced amateur scientists, details on building science apparatus, a large database of chemicals and so much more. ONLY 62 $ 00 PLUS $10 Pack and Post within Australia NZ P&P: $AU12.00, Elsewhere: $AU18.00 “A must for every science student, science teacher, science lab . . . or simply for those with an enquiring mind . . .” Just a tiny selection of the incredible range of projects: ! Build a seismograph to study earthquakes ! Make soap bubbles that last for months ! Monitor the health of local streams ! Preserve biological specimens ! Build a carbon dioxide laser ! Grow bacteria cultures safely at home ! Build a ripple tank to study wave phenomena ! Discover how plants grow in low gravity ! Do strange experiments with sound ! Use a hot wire to study the crystal structure of steel ! Extract and purify DNA in your kitchen !Create a laser hologram ! Study variable stars like a pro ! Investigate vortexes in water ! Cultivate slime moulds ! Study the flight efficiency of soaring birds ! How to make an Electret ! Construct fluid lenses ! Raise butterflies as experimental animals ! Study the physics of spinning tops ! Build an apparatus for studying chaotic systems ! Detect metals in air, liquids, or solids ! Photograph an ant's brain and nervous system ! Use magnets to make fluids into solids ! Measure the metabolism of an insect . . . ! and many, many more (a thousand more, in fact!) See the V2 review in SILICON CHIP, October 2004. . . or read on line at siliconchip.com.au This is the ALL-NEW Version 4 . . . it’s even BETTER! HERE’S HOW TO ORDER YOUR COPY: BY PHONE:* (02) 9939 3295 9-5 Mon-Fri BY FAX:# <at> (02) 9939 2648 24 Hours 7 Days BY EMAIL:# silicon<at>siliconchip.com.au 24 Hours 7 Days BY MAIL:# BY PAYPAL:# PO Box 139, Collaroy NSW 2097 silicon<at>siliconchip.com.au 24 Hours 7 Days * Please have your credit card handy! # Don’t forget to include your name, address, phone no and credit card details. BY INTERNET:^ siliconchip.com.au 24 Hours 7 Days ^ You will be prompted for required information There’s also a handy order form inside this issue. Exclusive in SILICON Australia to: CHIP siliconchip.com.au siliconchip.com.au March 2008  105