Fullscreen HTML5Med Res (??MB)HTML4

SILICON CHIP DATA-LOGGING REMOTE WEATHER STATION Records rain and temperature for years on AA cells! SEPTEMBER 2007 PRINT POST APPROVED - PP255003/01272 8 $ 50* NZ $ 9 90 INC GST INC GST Advanced NiMH & NiCad BATTERY CHARGER: Build it just the way YOU want it! FEATURE: How to get into L-o-n-g Range (10km+!) WIFI! PROGRAMMABLE DISPLAY FOR YOUR PUSHBIKE! siliconchip.com.au P-O-V September 2007  1 SILICON CHIP If you are seeing a blank page here, it is more than likely that it contained advertising which is now out of date and the advertiser has requested that the page be removed to prevent misunderstandings.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 C o ntents Vol.20, No.9; September 2007 SILICON CHIP www.siliconchip.com.au The Art Of Long-Distance WiFi – Page 8. Features    8 The Art Of Long-Distance WiFi Want to create a WiFi (wireless network) link of 10km or more? Here’s how to go about it – by Rob Clark, Terry Porter & Robyn Edwards 13 Review: New Wireless PA System From Altronics Forget the hassle of running cables to your PA speakers. This new PA system from Altronics is “wire less” – by Ross Tester 20 How To Cut Your Greenhouse Emissions; Pt.3 Are alternative energy sources and carbon offset schemes all they are cracked up to be? – by Peter Seligman, PhD Pro jects To Build Spectacular Bike-Wheel POV Display– Display – Page 26. 26 Spectacular Bike-Wheel POV Display What’s POV? Well, it stands for “Persistence Of Vision” and this simple circuit is software-controlled to give spectacular displays – by Ian Paterson 34 A Fast Charger For NiMH & Nicad Batteries Easy-to-build unit can fast-charge up to 15 identical NiMH or Nicad batteries & can be configured to suit any cell capacity. Built-in safeguards are included to prevent overcharging – by John Clarke 58 Simple Data-Logging Weather Station, Pt.1 It records rainfall & temperature, is cheap & easy to build, operates completely unattended & runs for years on a set of AA batteries – by Glenn Pure 66 Building The 20W Stereo Class-A Amplifier; Pt.5 Fast Charger For NiMH & Nicad Batteries – Page 34. We described all the modules in the May-August 2007 issues. Here’s how to assemble them into a precision custom-made steel chassis – by Greg Swain Special Columns 44 Serviceman’s Log The blind leading the blind – by the TV Serviceman 77 Circuit Notebook (1) Alarm Clock With Day Selector; (2) DC-DC Converter Has Two Outputs; (3) IR LED Used As Remote Control Checker; (4) Battery Saver Under Micro Control; (5) Musical Doorbell Based On A Toy Piano; (6) Phone Call Alert For The Partially Deaf 90 Vintage Radio The HRSA’s 25th Anniversary Equipment Display – by Rodney Champness Simple Data-Logging Weather Station – Page 58. Departments   2   3 57 86 Publisher’s Letter Mailbag Order Form Product Showcase siliconchip.com.au 98 Ask Silicon Chip 100 Notes & errata 101 Market Centre Building The 20W Stereo Class-A Amplifier – Page 66. September 2007  1 SILICON SILIC 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 Kevin Poulter 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 ISSN 1030-2662 * Recommended and maximum price only. 2  Silicon Chip Publisher’s Letter Global warming is causing panic among politicians and the bureaucracy Whether or not you believe in global warming and whether or not you think human industrial activity is responsible, it seems that many of the proposed counter-measures will not help and may even worsen the problems. For example, federal and state governments are keen to give substantial financial incentives for people to install solar hot-water systems and solar cell arrays. All the environmentalists are very enthusiastic about these measures and they cheer on the politicians, albeit with the rider: “They’re not doing enough on climate change!” or “John Howard’s asleep on climate change!” or something similarly inane. In the face of such a barrage, is it any wonder that the politicians and bureaucrats are anxious to be seen to be “doing something”. However, as described in this and last month’s article on “How to Cut Your Greenhouse Emissions”, pushing solar hot-water and solar cell arrays is probably not the best way to go. Using solar cells to generate electricity in domestic installations is simply a poor economic decision. Similarly, a recent proposal to make some Sydney schools “carbon neutral” by installing large solar cell arrays is a crazy economic decision. It would make far more sense for those schools to do the best they can in cutting back energy consumption and then use their hard-earned budgets to improve their teaching resources. This is not to say that Australia should not invest heavily in solar power generation; simply that giving substantial financial incentives for small domestic installations is probably not the best allocation of scarce financial resources. Of course, to suggest this as alternative government policy is likely to bring forth catcalls from the environmentalists with such emotive labels as “climate change denier”. Similarly, setting up carbon trading schemes seems quite pointless when you think about it. Planting trees is fine and good for the environment. Trees do take quite a lot of carbon out of the atmosphere while they are immature but the trees must exist for all time for the carbon to have been permanently removed from the atmosphere. The only way to make a permanent carbon removal is to bury the tree after it dies – not very practical! Carbon dioxide geo-sequestration is also likely to be extremely costly, even if it does become workable on a large scale. To us, geo-sequestration seems to be a futile attempt to postpone the eventual acknowledgement that coal mining and coal burning do present serious problems. Ultimately, as pointed out in the Greenhouse Emissions articles, we really should make major cuts in carbon dioxide emissions from our existing coal-fired base-load power stations, particularly those using brown coal in Victoria. And while gas-fired and nuclear power stations could certainly lead to major cuts in emissions, a better way for the long term will be to use our huge geothermal reserves or so-called “hot rocks” such as in the Cooper Basin in South Australia. While this requires enormous investment to provide and exploit, the pay-off will ultimately be huge, both in economic terms and for the environment. Leo Simpson siliconchip.com.au MAILBAG Letters and emails should contain complete name, address and daytime phone number. Letters to the Editor are submitted on the condition that Silicon Chip Publications Pty Ltd may edit and has the right to reproduce in electronic form and communicate these letters. This also applies to submissions to “Ask SILICON CHIP” and “Circuit Notebook”. Is DAB+ making history or going into a blind alley? On Wednesday 25th July, Commercial Radio Australia (CRA) launched the world’s first DAB+ radio service (albeit labelled experimental) using Sir Ernest Fisk’s beloved 2CH, the once key station of the old AWA Network. 2CH switched from DAB to DAB+. But there is only one DAB+ receiver in Australia, sitting in the office of Richard Morris, CRA’s “Digital Expert”. It’s a UK Radioscape DAB+ Field Monitor dubbed by CRA’s boss Joan Warner as a “demonstration DAB+ receiver developed for the test”, costing 20,850 pounds ($50,000). On the days that Richard Morris is not in his office, no-one can be listening to Digital 2CH! There are currently no consumer DAB+ receivers in the world. PURE UK in September is releasing the Siesta clock DAB radio which will be upgradeable but the DAB+ upgrades won’t be available until next year, cost unknown. Joan now has positioned herself as the Deputy Chairwoman, Digital Radio Committee, of the Asian Broadcasting Union hoping to convince the region’s broadcasters that DAB+ is the future of Flashing CFLs make home like a disco I have just moved into my newlybuilt house, a Queenslander-style with verandas all around. To light these I have 12 wall-mounted coach lights around the perimeter with 9W CFLs installed. Every one of them flashes randomly during the night and it looks quite like a discotheque from the roadway. All the lights have a centralised switch (two 6-gang wall-plate switches) and then run in ‘twin Active’ cable to a 2-way switch located siliconchip.com.au radio, to get the production quantities up so that we Australians can purchase radios cheaper than the above. Joan’s CRA has set up a new company Digital Radio Australia Pty Ltd, using the CRA address. It’s website is: http://www.digitalradioaustralia. com.au/index.cfm?page_id=1001 Name supplied but withheld at the writer’s request. Comment: this appears to be another case of bureaucracy deciding on a product regime which is available nowhere else in the world. Hence there will be very large barriers to the adoption of digital audio broadcasting in Australia. It seems like another blind alley to us. Electrician had problems with three wires Here in Tasmania we use lots of simple electrical heaters. When they are fixtures, we enjoy a small discount on the cost of the power they use. I have several, all installed by professional electricians. One day, one developed a bad smell. It was never wonderful, so I decided to replace it. Oodles of shops can sell me a new heater and most have phone numbers of electricians “who can install them”. However, when I rang close to the actual light. The Neutral and Earth connections for each light are cascaded around the perimeter of the house in a separate cable. The problem is that while the light is off (at either switch) there is always one Active (live wire) parallel to the inactive (non-live) wire in the “twin Active” cable between the two switches. The capacitance along this cable is enough to continuously trigger the start circuits in the CFLs. I have been toying with the idea of an in-line Triac or relay between the last switch and the light to fully the local electricians I got a gamut of replies, some quite original, and all equivalent to: “too busy”. The new heater stayed in the garage for a few months and I left the smelly heater turned off. As winter encroached, this became increasingly less practical. After a few more failed attempts to find an electrician willing to install a heater, I decided, “It’s not rocket science; I’ll do it myself”. When I took the cover plate off the old one, I discovered a wire curled back onto the supply cables and with its end hidden by tape. The professional electrician had connected the Active and the Neutral but hadn’t known what to do with the “extra” wire, so had used some black tape to hide it. I’d been using an unearthed heater for years. Obviously, I am still here to write this, but as I enjoy the warmth of my heaters, I can’t help remembering that many of them have been installed by a professional electrician who when confronted by three wires and three sockets assumed that one of the sockets should be left empty and that one of the wires was a “spare” that should be taped out of the way! isolate the Active wire to the CFL, however it would have to be installed in the wall cavity behind the last switch and I don’t know what the electrical regulations requirements would be. The only solution at present is to fit incandescent bulbs and say to hell with the energy/environment saving so the family can get a good night’s sleep. There is nothing more disturbing than a blinking light shining on you, even with your eyes shut. Ray Hudson, Mareeba, Qld. September 2007  3 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 4  Silicon Chip Mailbag: continued Simple tank water level indicator Inspired by your “Publisher’s Letter” and the Greenhouse Emissions article in the July 2007 issue, I was prompted (without installing a special switch) to immediately turn off our air conditioner at the meter box. Moving on, I came to the “Tank Water Level Indicator” on page 32 of the same issue and voila! There was an opportunity to save on electrical components, construction and ongoing electrical energy use, except that I had already done it! I couldn’t even submit it for “Circuit Notebook” since there was no circuit. For those who appreciate alternative lifestyles, the “Energy Saving Tank Indicator” consists of a clear plastic pipe (13mm) attached vertically to the side of the water tank by three saddle clips using stainless self-tapping screws. The bottom end is a press-fit into a short length of clear plastic tubing which in turn is connected to some plumbing adapters to increase the diameter to match that of the tank outlet valve. One is a T-piece that goes in line between the outlet valve and the pump. Another 70mm length of the soft plastic tubing is fitted above the full level. Into that a bolt is screwed to I really hate to ask for “name withheld” but in this case I don’t want to alarm my insurance company unduly or to invite inspectors to visit. Name and address withheld at writer’s request. Comment: while we have respected your wish, perhaps it would be worthwhile to have a safety inspection, but perhaps not by a local electrician. Tip for low-cost SLA batteries A cost-saving method for purchasing SLA batteries is to buy from sales outlets for electric buggies (mobility aides). My local dealer finds that many owners will upgrade their buggies for a provide a dust-free air inlet. The bottom flexible tubing should not be looped, as it will create an airlock. The empty to full levels – eg, 1/2, 5/8, 3/4 – can be marked on the tank next to the vertical pipe. A flat-top cap from a red biro can be cut to about 15mm and dropped into the top of the pipe as a float to highlight the water level. This indicator is simple and 100% accurate and no access to the inside of the tank is required. John Williamson, Cheltenham, Vic. new model. The batteries in the tradedin old model are removed and new batteries fitted before it is sold again. The old batteries are checked and any that still have a reasonable capacity are sold at $22 each (well below the new battery price around $150). I have purchased six of these used batteries to power the rail-switching units at a local steam railway system and all batteries are still working after one year’s operation. Dave Jeanes, Banora Point, NSW. Street lighting and energy wastage At a time when many people are considering various ways of saving ensiliconchip.com.au ergy and do their bit towards reducing greenhouse gases, it is disheartening to find that some government departments are obviously wasting it. One such example is street lighting. Street lighting uses relatively efficient gas vapour lamps, consuming energy at a rate of between 80W and 400W per lamp. Most street lighting in residential areas uses individual light-sensitive switches to control the lamp but it seems that some of these switches have a very wide control margin. I measured a light level of around 2500 lux at the street level which turns many of them on. That appears to be ridiculous as it causes lights to turn on as early as 4.00pm in the afternoon and sooner if there is a reasonable cloud cover. Keep in mind that the average light level within a well-lit house is usually less than 200 lux, while the light level directly under an 8W street lamp is usually less than 4 lux at ground level, after sunset of course. In one area of Liverpool, at least half the street lights were on at around POSITIVE PEOPLE, POSITIVE FUTURES. Better speedo accuracy is possible but costly I noted your comments in the August 2007 issue regarding the wide speedometer tolerances stated in the ADR’s. You may be comforted to know that none of the Australian vehicle manufacturers would accept this level of accuracy from the instrument alone. The specifications given to the instrument suppliers are tighter and always have a positive error, as correctly pointed out by one of your readers. The act of measuring vehicle speed has a number of variables that may not be immediately obvious to most people and many mechanical variables need to be taken into consideration when applied to the various sub-groups of vehicles within a 3:30pm with an ambient light level of 2500 lux measured at the street level. Surely whoever is responsible for maintaining street lighting in a basic model type. The fact that the drive for the speedometer, whether mechanical or electronic, is basically mechanically derived – ie, it is taken from something spinning at a fixed relationship to the road – means that all possible vehicle options have to be taken into account. I am certainly not justifying inaccurate speedometers but pointing out that it is not all “beer and skittles”. Calibration of speedometers to each individual vehicle is technically possible. The only problem is that we as consumers would not be prepared to pay the considerable extra cost, particularly for lowerpriced vehicles. Warwick Woods, Glen Iris, Vic. particular area could do a better job of calibrating the dusk to dawn switches used in these street lights. My complaint to one such authority, Electrical Engineering Cadetships & Traineeships At EnergyAustralia, we’re proud of our 100-year history of providing the community with energy for life. And to continue our reputation for innovation and sustainability, we need talented people like you. Electrical Engineering Cadetships (University) A five year program combining full-time study for the Bachelor of Engineering (Electrical), specialising in Power Engineering, and work experience. We’ll pay your student contribution (formerly HECS) and give you a weekly salary. Upon completion, you’ll be eligible for a position as a professional engineer. Find out more and apply at www.energy.com.au/cadetships Electrical Engineering Traineeships (TAFE) Combining part-time study for the Electrical Technology Advanced Diploma at TAFE and work experience with us. You’ll earn while you learn, and develop your career with a team that’s only interested in seeing you succeed. Upon completion, you’ll be eligible for a position as an engineering officer with us. Find out more and apply at www.energy.com.au/traineeships For both roles, you’ll be completing your HSC this year, or already have completed it. You’ll also need to demonstrate strong academic results and your skills in the areas of leadership, communication, creativity, innovation and self motivation. To apply for these roles, visit our website or call Sumaira Cheema on (02) 9394 6663. Closing date: Friday 28th September 2007. All appointments will be subject to a Police Record Check. All qualifications will be verified with the issuing institution/s. Applicants with overseas qualifications must provide a statement of the Australian equivalent with their application. Further information on Australian equivalence may be obtained from www.energyaustralia.com.au/careers EnergyAustralia is an Equal Opportunity Employer and is committed to environment excellence. siliconchip.com.au September 2007  5 Mailbag: continued CFL promotions can be self-defeating It is interesting to read, in the media, views on energy wastage and the usually knee-jerk reactions to supposedly resolve these uninform­ed opinions! This publication has stated the same over several issues now. Sure, changing the light bulbs helps and people like myself have done this for years to save money on their energy bills. But government decisions to make this compulsory have, as you point out, not taken into account what we savers already know. Incandescent filaments in several forms need to be with us for some time yet! My local council was recently involved in a promotion to give away CFLs and energy-efficient shower heads by having stalls set up around the shopping precincts. This could Integral Energy, resulted in the answer that light sensitive switches are calibrated to the AS/NZ 1158 standard. If that is the case then someone should seriously look at the millions of watts of wasted energy and subsequent tonnes of greenhouse gases this standard causes. However, while ever these organisations are paid on the basis of maintaining street lighting and at the same time profit from the sale of energy, is it any wonder why little is done to reduce the problem? Heinz (Peter) Harle, Hinchinbrook, NSW. Unwanted electronic hardware from deceased estate My wife and I are currently sorting through the deceased estate of my wife’s parents. Her father was a television technician/repairmen and accumulated a lot of electronic hardware during the course of his career. We would like to find an electronic hobbyist who can make use of this material and we are willing to give it away free of charge to such a person. The material consists of a wide range of electronic components including 6  Silicon Chip have been alright except at least one location had an assistant with no understanding of how the various light fittings differed and every visitor left with wildly incorrect information! In fact, one woman went away expecting to just replace the globes in her recessed low voltage halogen units with the supplied CFLs! If the government wants to seriously conserve energy usage, they should ban all those outdoor gas heaters that the big hardware chains are promoting, along with outdoor solid fuel heaters/braziers, etc. Indeed, I saw one advertisement for an electric element device to do the same job. Running these (or any) heaters outdoors is an absolute waste, no matter what fuel source is used. Robert Graffham, Sanctuary Point, NSW. resistors, capacitors, valves, transformers, switches, fuses, various pieces of cabling with assorted plugs, speakers, power points, etc. Some of this material has been used but much of it is unused. We would be interested in hearing from interested persons on (03) 9495 0092. Just ask for Sandra or Jeff. Jeff Jeanes, Northcote, Vic. Lift mechanisms for LCD screens I wish to respond to an inquiry about a lift mechanism for an LCD Screen, by M. P., of Bellarine, Vic (Ask SILICON CHIP, July 2007). I would like to refer you to a manufacturer that specialises in such products: Linak Australia Pty Ltd, www. linak.com.au Bob Rigor, via email. Technics SL1600 turntable service manual On page 99 of the August 2007 issue of SILICON CHIP, you ask if any reader could assist with a service manual for a Technics SL1600 turnsiliconchip.com.au multimeter2 Car speedos really are meant to read high I read with interest the letter and the comments “Car Speedos Are Meant To Read High” in the Mailbag pages of the August 2007 issue. Having been the engineer responsible for speedos and other instruments at one of our major Australian car companies, I believe that there are some other comments and observations that need to be added. In the first instance, cruise controls vary enormously. I have driven with cruise control since 1986 and I do a great deal of country travel. Some are easy to set and provide very close control, while others (like my latest) are hard to set and exhibit considerable overshoot. Even so, they provide no help in close suburban driving, where attention focused on a traffic sign or adjacent traffic conditions can lead to momentarily exceeding the speed limit. Cruise controls are a help but not “a doddle”. What is of more importance is that the car manufacturers cannot control all the circumstances and must ensure that they are not in any way liable to legal action if a driver does exceed the speed limit. Hence a manufacturer will always calibrate the instrument to the “apparently faster” end of the range. A classic example is the 4X4 I wore out and changed last year. 118km/h on the clock was a genuine 110km/h across the ground. On one of my sixhour trips, I found that I would take 30-45 minutes longer by observing the speed limits on the speedo. After wondering why this regular trip was taking so long, I found I could travel another 330,000km (in that vehicle) safely and legally by making the appropriate mental adjustments. Remember that the extra 45 minutes on that typical trip is at the least safe time – right at the end of six hours behind the wheel. table. I found this one: http://www. vinylengine.com/download_centre/ index.php?technics_sl1600mk2_service.pdf This site is a vast repository of sersiliconchip.com.au 14/8/07 10:04 AM Why such a difference? It’s not an error. There are a variety of tyres that can be fitted legally and properly to the vehicle and of course, the factory tyres are the least expensive and have the smallest rolling radius. Even different brands on a sedan can produce the same effect but perhaps not to the same extent. This means that almost every vehicle on the road will show fast on the speedo. Later in the life of that 4X4, I fitted properly specified tyres of a different brand and type and it made 5km/h difference to the speedo reading, for the same speed over the ground. That is not all. Overhead speed indicators on highways are not free of error but they do provide a reasonable guide. The vehicle mentioned above showed 109km/h on such an indicator on the Hume Highway when heavily loaded at midnight, with the ambient temperature about 3°C and the tyres cold. At midday on a hot day, unloaded, and with hot tyres, the same speed (as per the vehicle speedo) produced 113km/h reading from the same overhead speed indicator. If you take into account the effects of load and temperature, and the variations in tyres that can be legally fitted, this vehicle chewed up 9m/h of the allowed variation. Add in the manufacturing tolerances on the parts and then add in the “legal protection factor” for the manufacturer, and you will see that the precision of the complete system is an order less than the precision available with the instrument technology itself. Really, we do need to keep the ADR limits. They have been established by careful people with good professional training and knowledge of the whole system, including driver behaviour, vehicle design and the law. Let us at least respect their work! Max Williams, Ringwood, Vic. vice manuals and user manuals for turntables: http://www.vinylengine. com/library.shtml Franc Zabkar, Barrack Heights, NSW. September 2007  7 Page 1 This article will show you how to use wireless networking (WiFi) gear to make a network link of 10km or more. The Art of Long D M ention WiFi and most people – at least those who know what WiFi is – think of a wireless link between a couple of rooms in the home or maybe a couple of offices in a building. That’s mainly because that’s all they are used to and all that they expect. But WiFi can go much further than this: the current world record for a “naked” (ie unamplified) 802.11g (WiFi) terrestrial link is (we believe still!) 280km (see SILICON CHIP, February 2007). But that was using some pretty esoteric gear including large, high-gain dishes, equipment that would probably be illegal to use here. Even so, you could use off-the-shelf and legal gear in Australia to set up a reliable, fast 2.4GHz link of perhaps tens of kilometres. The link could be used for anything a Local Area Network (LAN) connection can be used: Internet access, file sharing, Voice over Internet Protocol (VoIP), Video Surveillance and many more applications. But isn’t WiFi rated only up to 100m? Most WiFi equipment has a com- VISIBLE LIGHT ment somewhere that the effective range is something like 100m or less. That figure assumes a lot of worst case conditions, such as: • you only use the small antenna that comes with the unit • the other end of the link (a laptop?) has no external antenna and • this is all operating inside a building with walls and people in the way. By changing some or all that, much greater ranges can quite easily be achieved. Art – or Common Sense? If you think you don’t already know WiFi Transmitting end Bright light bulb (ie, high power) A reflector behind the bulb to focus the signal in the direction we want Clean bulb and reflector so we don’t lose light Aimed at the receiving end Strong transmitter power An antenna which can focus the signal in the direction we want Quality antenna cable so we don’t lose valuable signal Aimed at the receiving end Path between the two ends No trees or other obstructions in the way Low light levels (ie, dark night) No trees or other obstructions in the way Low WiFi noise Receiving end A good eye! A lens to focus the signal from the direction we want – maybe binoculars or telescope Clean Optics Aimed at the transmitting end A sensitive receiver An antenna to focus the signal from the direction we want – maybe a compass or GPS co-ordinates to help aim Quality antenna cable, so we don’t lose valuable signal Aimed at the transmitting end Table 1: it’s easy to see the similarities between visible light and WiFi signals when you compare them like this! 8  Silicon Chip siliconchip.com.au By Rob Clark, Terry Porter and Robyn Edwards (VK6XRE) www.Freenet-Antennas.com Distance WiFi how to do this, think again. What if someone asked you to use visible light to make a signalling beacon over 10km from rooftop to rooftop? We’re sure you would conclude you needed something like that in first column of Table 1. The second column in the table shows what we need for our 10km WiFi link. Notice the similarities? Let’s go through them individually: Transmitter Power The transmitter/receiver unit in the WiFi world is referred to by the all encompassing term Access Point (AP). Obviously the stronger the transmitted signal, the further it will go. Power, at least as far as WiFi is concerned, is expressed in either milliwatts (mW) or dBm. dBm is often confusing to the novice but is simply a ratio of the power with respect to 1mW. A 1mW transmitter would therefore have an output of 0dBm; a 100mW transmitter would have an output of 20dBm. Most mass-market APs have low transmitter power – as they are for the ‘50m’ market. Powers of 15 or 30mW (12 or 15dBm) are common but these are usually too low for long distance WiFi. Avoid them. At the other end of the scale you can get high power APs with transmit powers of 100mW or more. Amplifiers can boost that even further but there are legal limits on how far you can go. See the “Keeping it Legal” box for more information. The Freenet Antennas UltraWAP AP is available in a number of power siliconchip.com.au Cable Type CFD200 CFD400 RG-58/U One Bare Copper Wire 1.12mm Celled Foam 2.95mm Sealed Aluminum Mylar Aluminum Tape Tinned Copper Wire (88% coverage) Polyethylene (PE) 4.95mm 0.037kg/m 12.7mm RG8/U JIS 8D One Copper Clad Aluminium 2.7mm Celled Foam 7.24mm Sealed Aluminum Mylar Aluminum Tape Tinned Copper Wire (88% coverage) Polyethylene (PE) 10.3mm 0.108kg/m 25.4mm 50W 83% 80.4pF/m (24.5pF/ft) 19.6W/km 16.0W/km dB/m 0.540 0.493 0.424 0.326 0.228 0.159 0.130 0.075 0.058 50W 85% 78.4pF/m (24.0pF/ft) 4.56W/km 5.41W/km dB/m 0.220 0.196 0.168 0.128 0.089 0.061 0.050 0.029 0.022 Physical Properties Mechanically similar to Conductor Qty Material OD Dielectric Material OD Shield Binder Braid Jacket Material OD Mass Minimum Bend Radius Electrical Properties Nominal Impedance Velocity of Propagation Capacitance DC Resistance Inner Conductor Outer Conductor Attenuation MHz 2400 2000 1500 900 450 (~70cm band) 220 150 (~2m band) 50 30 Table 2: typical properties for high quality, low loss antenna coax suitable for WiFi. September 2007  9 levels from 60 to 200mW. The 90mW unit is a good all-rounder for long distance links that remain within the ACMA limits for directional antennas. Antennas Antennas are analogous to lenses in optics. They neither create nor destroy energy but rather focus it into a smaller beam – giving the impression of more power. The focusing power of an antenna is called “gain” and is measured in dBi. This abbreviation stands for gain (in decibels) over a theoretical isotropic (point source) antenna. But don’t let that worry you: simply remember that the higher the gain, the more focused the beam and the more accurately it must be pointed. There are lots of commercially available WiFi antennas. There are even more home-brew designs available on the web (some excellent, some not!) and some great ones have been published in SILICON CHIP (see Stan Swan’s article in November 2002; Rob Clark’s in August 2003 and Stan Swan’s WiFry antenna in November 2004.) Antenna Cable Just like a dirty lens wastes valuable light, a lossy antenna cable wastes valuable WiFi signal. But there’s another wrinkle with antenna cable: the higher the frequency, the lossier a cable becomes. Cable that is perfectly acceptable for long runs at, say, 144MHz (the Above: PC (PCMCIA) WiFi adaptor and (below) USB WiFi adaptor, both with external antenna connectors. These usually perform much better than the more usual adaptors which have the antenna “built in”. 10  Silicon Chip Fig.1: download “NetStumbler” and run it on your laptop/notebook for a really good signal strength meter. On this screen grab, the red signal is WiFi noise while the green is the wanted WiFi signal. “two metre” amateur band) can be a poor performer at WiFi frequencies – 2.4GHz (2400MHz). As a rule, we must use short, low- Understanding dBm fusing. The dBm scale can be con positive the re mo the Just remember: nal. For sig the er ong str number, the than -70dBm er example, -50dBm is strong e. itiv because it is more pos bers: Here are some sample num dBm Power (mW) 10 0 -10 10 1 0.1 loss antenna cables. Less than 3m is a good rule. In some cases, this will necessitate installing the AP in a weatherproof enclosure close to the antenna, and running a weatherproof power/ethernet cable up to the external AP. The ethernet and power cables (or sometimes one cable serving both) can be much longer than the 2.4GHz cable without appreciable loss. Because cables look similar, don’t be fooled into believing they have similar performance. The popular RG-58 coax cable looks similar to CFD-200 but at 1dB per metre, has almost twice the loss. That loss could be critical. One more point – the standard cable used for all WiFi gear has a characteristic impedance of 50W (ohms). That means – don’t even think of using left over 75W satellite TV cable! Even if it is low-loss type, the impedance mismatch will cause you horrendous problems. Table 2 shows the properties of cable that is suited for WiFi use. The CFD200 is recommended for runs up to 3m (1.5 dB of loss). CFD400 is OK for runs up to 10m (2.2 dB). Cable loss can be partially compensated for with a higher gain antenna but remember that a bigger antenna boosts noise as well as the wanted signal so may not work in high noise (eg, urban) areas. Antenna Pointing The higher the antenna gain, the narrower the beam. That means we must accurately point both the transmitting and receiving antennas. Pointing by eye, especially over long distances, is usually out of the question but can work in some cases. The best way to point is to: • Aim the transmitting end as best as possible (By eye? By compass? By GPS co-ordinates?). In practice the transmitter is an AP (in Access Point mode) connected to the antenna. • Go to the receiving end and connect a signal meter directly to the antenna. Move the receiving antenna until the maximum signal strength is seen. Tighten the bolts. siliconchip.com.au The FreenetAntennas UltraWAP V2 is only 125 x 85 x 32 mm. (excluding the removable antenna). Think of it as a WiFi Ethernet Modem. • Have a buddy at the transmitting end slowly move his antenna. Tell him when signal is at a peak. Tell him to tighten his bolts. So what is this Signal Meter? No, you don’t have to go out and buy some very expensive test gear (and test gear for 2.4GHz is always expensive!). All you need is a laptop computer and a freeware program called Netstumbler (www.netstumbler.com). This software shows a running plot of signal (green) and noise (red) on the laptop screen. Connecting the antenna (b) the right polarity – there are male and female types and to the uninitiated, they look much the same. Obstructions A WiFi signal behaves much like visible light. It does not bend, nor penetrate most solid objects – but it does pass through untinted glass very well. In addition, 2.4GHz loves to heat up water – microwave ovens (which use 2.4GHz waves, albeit at a dramatically higher level) work the same way. Keep in mind that tree leaves will cause a significant loss of signal if you are expecting WiFi to pass through them because tree leaves are largely composed of water. A brick wall or wooden paling fence may only pose a minor problem to WiFi when dry – but will act like a solid barrier in the rain! WiFi Noise With few exceptions, in Australia any device capable of transmitting intelligence requires a licence to not only operate but to own. ‑Fortunately, WiFi is one of those exceptions. The good news is that you do not need an individual license for every installation because there is a shared range of frequencies in the 2.4GHz band allocated for WiFi. 2.4GHz is a very, very high frequency (not to be confused with The ‘Rootenna’ is a 14dBi antenna with a built-in enclosure for the AP. Two of these antennas will make a legal, 15km link with 130mW APs. The manufacturers got the name from the Kangaroo pouch. The black cable is weatherproof CAT5e and carries both 12VDC and the ethernet data. ers, remote-controlled toys and even But how do you connect the laptop wireless doorbells! You may have to the antenna? Good question! Most put up with them interfering with laptops do not have an external anyour WiFi. tenna connector; they use an internal One WiFi user we know has an AV antenna. extender so he can watch TV in anProbably the easiest (and most Keeping it Legal other room. But when it is turned usual) solution is to buy an extra on, the WiFi signal disappears The Australian Communicat ions and Media Authority WiFi interface for your laptop that (ACMA, www.acma.g completely. Even swapping chanov.au) is responsible for the laws comes with an external antenna in Australia for this tec nels doesn’t help much. The only hnology. connector. Fortunately, these are solution is to turn the offending In the frequency band use d by 2.4GHz WiFi equipquite cheap these days. ment (2.400-2.484GHz), AV extender off. the bottom line is that you do If your laptop has a PC slot not need a licence if: Even if you don’t suffer interfer(they were originally called PCence from these types of devices, • You are using DSSS (Direct Sequence Sprea d MCIA slots but are now becomSpectrum) equipment. (W you will still have to put up with iFi is DSSS). ing obsolete), you can get cards all the other WiFi transmissions • Your EIRP is less than 4W. to suit with external antenna in your area. In city areas it’s not sockets. uncommon to find ten, twenty or Today, the most common solution VHF!) – in fact, until a few years ago, it more WiFi setups within range is to get a USB WiFi interface with was thought fairly worthless. It’s way of yours. an external antenna socket. Again, above radio and TV station frequenWhile WiFi protocols are designed these are quite inexpensive. But in cies – in fact, it operates in the same using military technology that makes both cases you may also need variarea of the spectrum as radar and space it almost impossible to ‘jam’ (two ous cables, called pigtails, that adapt communications. WiFi links can co-exist on the same the laptop antenna connector to the The bad news is that there are now frequencies and not garble each other’s antenna you have. huge numbers of domestic devices data), the penalty is that both links A word of warning here: be careful also using 2.4GHz – everything from will run slower. when buying a pigtail to ensure it is (a) the previously mentioned microwave So how do you do your best to the right type – there are several and ovens through to AV signal extendeliminate unwanted WiFi noise? siliconchip.com.au September 2007  11 UltraWAP runs at full speed. So we can quote the Receiver Sensitivity as: -83dBm <at> 3.3kbps, and -63dBm <at> 23.5kbps. The significance here is getting a link to ‘work’ is one thing, but getting it to run as fast as possible will mean stronger signals are required. That may require a more powerful transmitter, a bigger antenna, better quality cable or combinations of these. Designing our Link Fig.2: “real world” receiver sensitivity performance measurements for the UltraWAP V2 Access Point. This graph tells us that the received signal must be better than -83dBm to work at all and better than -63dBm to work at a reasonable speed. Beware of Access Point manufacturer’s spec sheets which give a simple, bland sensitivity specification. Experience has shown that this figure is often little more than a twinkle in the designer’s eyes! • Use low-noise antennas. The better antenna designs reject as must signal coming from off-axis as possible. The higher the gain (ergo, the narrower the beam) the better an antenna will be at ignoring off-axis noise. • Use a quiet channel. WiFi has a number of pre-determined channels of operation. If all your neighbours are on channel 1, you might want to use Channel 11. Netstumbler will tell you what other signals are out there and their channel. • Use horizontal polarisation. Most urban WiFi noise comes from the home AP – which mostly use vertically polarised rubber ducky antennas. The simple act of turning the antennas through 90° for horizontal polarisation, (if you can) will automatically reject much of the urban noise. Transmit TX Power 19dBi grid antenna +19.0 dBi 10km -120.4 dB 19dBi grid antenna 5m CFD200 +19.0 -2.7 dBi dB UltraWAPV2 (worst case) -83.0 dB Signal Margin (>5 for reliable link) 14.7 dB Effective Isoptropic Radiated Power (EIRP) [<= 36 by ACMA rules] 35.8 dB Free Space Loss Reception Antenna Gain Cable Loss dBm dB Propagation 5m CFD200 (ignoring connectors) + 19.5 -2.7 Antenna Gain Computed Results Deaf people can not hear as far as those with good hearing. That’s called sensitivity and WiFi is much the same. A sensitive receiver can “hear” weaker signals, which generally means signals from further away. Unfortunately, you cannot rely on the manufacturer’s quoted sensitivity. While some quote receiver sensitivity that is accurate, some quote receiver sensitivities that are wishful thinking. Some are realistic – for example, the Freenet Antennas UltraWAP AP has “real world” receiver sensitivity measurements as shown in Fig.2. This tells us that if the received signal falls below -83dBm, we get no data through. If the signal is -63dBm or better, the 90 mW UltraWAP Cable Loss RX Sensitivity Receiver sensitivity Table 3: fill in the gaps on the chart for your installation, add the red, green and yellow figures (taking into account minuses!). Here they come to -68.3dB, which is almost 15dB better than the worst-case receiver sensitivity of -83dB. So this link will work!. The greater the difference, the faster it will run. 12  Silicon Chip So how do we put all this together? We do what is called a Link Budget. The table below is the link budget for our 10km link. It is based on the online version available at http://store. freenet-antennas.com/linkbudget. php How are the results computed? To get the Signal Margin, we simply add all the red, yellow, and green numbers (= -68.3dBm) and compare to the minimum signal needed (-83dBm). -68.3 is 14.7dB more than -83.0. See the box on Understanding dBm. EIRP (Estimated Isotropic Radiated Power) is the sum of the red numbers: in this case 35.8 dBm. How do we interpret these results? 1. We are legal. The EIRP is below the ACMA limit of 36dBm. 2. It will be reliable. For a reliable link, we need a signal margin of 5dB or more. This allows for things like rain and other problems. As we have more signal than we need, it means the link will run faster than the slowest speed. Table 3 predicts that we would still have 5db of margin if our RX sensitivity was about -73dBm. Fig.2 predicts that with a -73dBm signal we will see a data throughput on our link SC of 12Mbps or better. Special Offer for SILICON CHIP Readers! Freenet Antennas (www.freenet-antennas.com) specialise in long distance WiFi networks. They not only have the components required but also have a free design service. Purchase anything not already on special from Freenet-Antennas before December 31 2007 and you’ll receive a 10% discount if you mention this article! siliconchip.com.au New Wireless PA System has... LESS WIRES! “Hands on” Review By Ross Tester A ltronic Distributors are no strangers to the Public Address market. SILICON CHIP has reviewed several of their amplifiers and peripherals over the years, including at least two of their portable PA amplifiers. We’ve always found the Altronics equipment, sold under several “house” brands, to be extremely well made and, more importantly, to have performed very well under “real world” conditions. They are widely found in professional installations and have a good name in the trade. We’ve set up some of the Altronics gear at major sporting events and it has out-performed some significantly more expensive products. siliconchip.com.au For example, I’ve had to run PA amplifiers from small generators on occasions and where a couple of wellknown Japanese amplifiers didn’t like the less-than-perfect supply one bit (popped fuses were the order of the day), the “Redback” (Altronics) amplifier just kept going and going! Portable PAs Not long ago, Altronics’ General Manager Brian Sorensen rang to say they had just received the first shipment of a brand new range of Portable PA Amplifiers – and he’d like us to have a look at them. I have to confess at first I was of the “ho-hum, seen one, seen ’em all” mindset. But then Brian told me that, as far as he knew, these were unique in Australia because they had the option of being set up to cover a large area completely without wires. With a plug-in option, one box could transmit its program to the next box, which could receive and retransmit on yet a different frequency to the next box and so on. And with battery operation (as well as mains) that meant you could take a few of these to a venue, turn them on and be instantly “on the air”. As someone who has spent many an early morning and late night running speaker cables along beaches for surf carnivals, my “ho-hum” disappeared. I suddenly became very interested! Wireless Of course, wireless microphones September 2007  13 At left is one of the new Okayo portable PAs from Altronics (all models look the same from the front!) while at right is a fully-tricked-up model with two wireless mic receivers (top), CD/MP3 player (next down) wireless link module (2nd from bottom) and the common input/output/control unit (bottom). The units are designed to mate with Altronics heavy-duty tripods (C0521A) which fit into a “top hat” mount in the base of the box. are nothing new. And many portable PA systems have inbuilt wireless microphone receivers so you could talk through multiple boxes within range. That is the point: within range. What is new is that each of these boxes can be fitted with a “wireless link” transmitter as well as a receiver in the ~800MHz wireless microphone band. So all-of-a-sudden, the coverage area is as large as you want it to be – just keep adding boxes with transmitters and receivers and it doesn’t matter how far away the first box and wireless microphone are. Wireless mic coverage (or more correctly, wireless mic dropout as you approach their limit) is the bane of any PA operator. With this system, that has now ceased to be a problem: you just make sure the first box is within range and go from there. There are 96 channels to choose from (selected by push-button) so you’re not going to run out of available frequencies. And as the boxes are fixed in position (and usually mounted high on a stand or pipe) they are not going to suffer from another bane of wireless microphones: the user shielding the transmission with his/her body. Therefore, range between boxes will be significantly higher than using a “normal” wireless mic. Claimed range is 50-70m line-of-sight and we verified that this could be easily reached. 14  Silicon Chip During a couple of tests along a beach, we were able to reliably achieve 250300m range. And that was without mounting the boxes on their tripod stands, which almost certainly would have increased the range. The receivers and wireless links are options to the basic box (which we’ll look at shortly). My first question to Brian was “are the receivers and transmitters available as separate items” thinking about the portable PAs I already used (including SILICON CHIP’s “PortaPAL” from February/March 2003). Unfortunately for me, they’re only as an option; they were specifically made to suit the new systems. Oh well, Here’s the bit that made me sit up and take note: the wireless link transmitter. It has 96 channels (like the wireless mic receivers) and in fact looks similar from the front. This transmits to another PA system fitted with a wireless mic receiver, thus extending the range of the PA. can’t blame me for trying. The Altronics systems The portable PA system is available with several options. There are three standard models with various options and then you can add other goodies. The $749 base unit (Cat C7180) contains a 50W power amplifier with both balanced and unbalanced wired microphone inputs, stereo line in/line out, level controls for mic and line plus bass/treble controls. It has inbuilt batteries as well as mains power supply/charger and can operate from 3-4 hours from battery only. As we said, it is ready for nearinstant operation: just plug in a mic, turn on and talk. The first “optioned” model contains a UHF wireless microphone receiver. This is supplied pre-fitted and suits a range of wireless microphones. With the receiver, it becomes Cat C7182 and sells for $950.00. Note that the wireless microphone is extra. A second UHF wireless microphone receiver (C7187) can be added for $249.00 to give dual-channel operation (maximum of two receivers). The other “standard” option model is the $1299 C7184, with the UHF wireless mic receiver above plus a quality, anti-skip and MP3-compatible CD player. The C7187 wireless link add-on siliconchip.com.au transmitter is a simple plug-in option which sells for $249.00. So a fully tricked-up, dual channel radio mic model with wireless link and CD player would sell for $1797. If you regard this as the “master” unit, all you need for the add-on units in the system is the C7180 model with C7187 wireless receiver – $998.00 total. Those prices might sound expensive – until you start comparing the nearest equivalent models from other suppliers. And when we say “nearest” equivalent, we mean it – because as far as we know, there is nothing else out there which compares with the Altronics models with wireless link. Incidentally, there is also a Karaoke Echo module available with adjustable repeat and delay, plus provision for two (wired, 6.35mm) microphones. Wireless microphones Altronics have various microphones available for the system. The first is a traditional hand-held type (C7192) selling for $199.00 It’s a very nice mic to use – comfortable to hold and has a very nice sound to it – ideal for entertainment as well as speech. Its two “AA” cells give up to 14 hours use. Next comes a beltpack transmitter (C7195, $169.00) which accepts several different types of wired mics – a headset (lavalier) microphone (C7198, $69.00) which is ideal for sports/gym/ trainer use; a lapel mic (C7197, $55.00) One option not mentioned in the text is the C7199 soft carry case, designed to house a microphone, power lead and other accessories. siliconchip.com.au Here’s the range of wireless microphones suitable for the system. At left is the traditional handheld model, while above are a lapel (above left) and headset (above right) designed to plug into the beltpack transmitter shown at right. On the left edge (hidden) is a 3.5mm “aux in” socket – unfortunately, using this socket cuts out the microphone socket at top left of the beltpack unit. or virtually any of Altronics’ range of low impedance (dymanic) microphones which can fit, or be adapted to, a 3.5mm plug. The 3.5mm plug has a thread on it which matches that on the lapel or headset mics, making them captive. Nice touch! Ah, the beltpack I have to say it works very well indeed – but it hasn’t been completely thought through. I got excited when I first saw the beltpack transmitter because it also sported a “line in” socket. I thought that it might solve a long-standing problem I’ve had – the ability to plug in a music source (eg, MP3 player) and transmit it back to the receiver at the same time as speech. Alas, it can do so but only at the expense of the microphone input – in other words, one or t’other – not both. (That’s no better than the way I’ve done it until now using other beltpacks: throttle back the line-in and use the mic socket. But swapping plugs is a little less than convenient. And what if you want to commentate over the top of music?) When I explained why this was a problem for me, Altronics agreed and said they would see if the manufacturer could change the inputs to a “mix” rather than exclusive. The box We’ve neglected to give you the good oil on the amp/speaker itself. We mentioned before that the amplifier is rated at 50W RMS. The speaker setup is a 200mm woofer and high frequency horn. Sensitivity is 95dB 1W <at> 1m and maximum sound pressure level is 112dB. Frequency response is a very respectable 20Hz to 20kHz with a signal-to-noise ratio of <70dB. Overall box dimensions are 300 x 230 x 470mm and it weighs in at 12kg. That’s not overly light (especially if you have to carry it a long distance) but it is certainly light enough to be classed as “portable”. Construction is of tough ABS and the carry handle and feet are moulded into the case. Each box can also drive an 8-ohm external speaker if you want extended range without going to the expense of additional units. But that means running wires – something we’d try to avoid at all costs with this system! The verdict It’s a wee ripper! Performance of the system left nothing to be desired and that wireless link is like gold. Overall, we were very impressed. SC MORE INFO? Visit www.altronics.com.au or call 1300 797 007 September 2007  15 SILICON CHIP If you are seeing a blank page here, it is more than likely that it contained advertising which is now out of date and the advertiser has requested that the page be removed to prevent misunderstandings. Please feel free to visit the advertiser’s website: dicksmith.com.au SILICON CHIP If you are seeing a blank page here, it is more than likely that it contained advertising which is now out of date and the advertiser has requested that the page be removed to prevent misunderstandings. Please feel free to visit the advertiser’s website: dicksmith.com.au 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 Cut Cut Your Greenhouse Emissio The thinking person’s guide “If all Australians switched to clean, renewable energy (Green Power) today, Australia’s total greenhouse pollution would be cut by 30%.”– World Wildlife Fund Part III – by Peter Seligman, PhD E very problem is easy to solve if you know nothing about it. The statement above is on the World Wildlife Fund (Australia) website (www.wwf.org.au/act/takeaction /green-power-200603/). What was the writer thinking? Did he/she think that just by ringing our electricity suppliers a forest of wind turbines and solar panels would sprout up? Was he/she thinking that they had already been built and someone was just sitting by the phone waiting for us to ring up to throw the switch? Of course intelligent SILICON CHIP readers would not think like this. Renewable energy power sources are damn difficult to build. In Victoria, for example, a wind farm was held up for a year by the concern for the orange bellied parrot (by one assessment, it might kill one parrot every 1000 years). Progress is slow and bedeviled by obstacles technical, political and bureaucratic. But it is typical of the population at large to ignore these problems. Ideas that hydrogen or electric vehicles are the solution to CO2-induced climate change need very careful examination. Electric cars I’m not referring to hybrid-electric cars, which are a hi-tech way of improving petrol efficiency. This is about purely electric vehicles. There have been some around in the form of delivery vans for years and electric scooters are available. These vehicles are used for specific applications and with good reasons. As far as the general purpose car, as we know it is concerned, you probably realise that the pure electric car20  Silicon Chip which has the range, convenience and performance of a conventional car – is still way off in the future. Electric cars are often seen as a way of providing clean, pollution-free transport. However, that’s not what you get if the electricity comes from a fossil fuel-powered electricity grid. It just moves the pollution from one place to another. The dream is the car which derives its energy from the sun. Is this realistic – and is it a good idea? This question applies equally well to hydrogen, compressed air, flywheel and any other vehicles which store energy derived from electricity in the first place. Look at the energy . . . Let us look at the energy consumption of a typical car over a year. Let’s make an assumption of a car which does 10,000km over a year and has fuel consumption of 10 litres per 100km. Or you could assume a very efficient car using 5 litres/100km over 20,000km. Whatever assumption you make won’t affect the outcome. Let’s say it comes to 1000 litres per year. One litre of petrol contains about 10kWh of energy (that’s the energy used by a 100W light globe over 100 hours). So a 1000 litres of petrol provides 10 x 1000 = 10,000kWh of energy to the car’s engine over the year. Now let’s make another assumption. The efficiency of a car engine is about 25%. Only one quarter of the energy in the petrol gets to the engine’s output shaft. Again, you can make your own assumption, which won’t affect the outcome. For this case, the engine provides 0.25 x 10 = 2,500kWh siliconchip.com.au ons over the year. However an electric motor is not 100% efficient; nor do you get all the energy stored in a battery back out again. I’m assuming an efficiency of 90%. So we really need about 3000kWh a year. Imagine we are to provide these 3,000kWh each year from solar photovoltaic panels on our roof. How many solar panels would it take and how much would they cost? The cost of solar panels is about $10 per peak watt. A peak watt is what they output when they are directly facing the sun, with no cloud. Of course, in reality we need to take into account night time, cloud and the varying sun angle. Effectively, averaged over a year in south eastern Australia, the ratio between peak power and average power is about seven times. So the real cost of solar panels is about 7 x $10 or $70 per average watt. To calculate the cost of panels we would need to get our 3,000kWh in a year, we work out how many watts on average we will need to collect. There are 24 x 365 = 8760 hours in a year. To get the average watts, divide kWh (kilowatt hours) by hours in a year: 3000/8760 = 0.342kW (kilowatts) or 342W. What would this solar system cost? At $70 per average watt, we need about $70 x 342 = $24,000 of panels. Generally, in solar systems the cost of the panels is about half of the total cost when you include the mounting frames, labour, controllers, wiring etc. So the cost of the installation is likely to be closer to $48,000. However a good solar system will last 20 years or more. siliconchip.com.au One can image that when petrol is $2.50 a litre and solar cells are cheaper, (but at the moment they are not going down in price) that this is not beyond the realms of possibility. But is it a good idea? To answer this, we need to look at various scenarios from the carbon emissions point of view. These are: 1. Drive an ordinary petrol, diesel or LPG powered car. Let’s call it “Petrol” 2. Electric car – charged from the power grid operating predominantly on coal. Let’s call it “Elec/coal” 3. Electric car – charged from a home installed photovoltaic system (grid connected so that surplus can be put into the grid and deficiency is drawn from it. Let’s call it “Elec/PV” 4. Petrol, diesel or LPG car, with same photovoltaic solar system as above – called Petrol/PV Here is the information we need: From my electricity bill I can see that 888kWh resulted in 1.23 tonnes of CO2, that is 1.385 kg/kWh. From the Australian Greenhouse office – I can find that burning 1 litre of petrol results in 2.6 kg of CO2 being emitted. So for “Petrol” we multiply the litres per annum by 2.6 to get 2.6 x 1000 = 2,600 kg = 2.6 tonnes of CO2. For Elec/coal, we have put an extra load of 3000kWh per annum on the system resulting in 3000 x 1.385 = 4155 kg say 4.2 tonnes of CO2 For Elec/PV, there is no CO2 contribution. Finally, for Petrol/PV, the petrol car will contribute 2.6 tonnes of CO2 while the photovoltaic cells pump the same energy back into the grid saving 4.2 tonnes of CO2. The net result is that 4.2 – 2.6 = 1.6 tonnes of CO2 has been saved from entering the atmosphere. Here’s a graph: You can see that in our present situation, in which most electricity is generated from fossil fuel, electric vehicles combined with coal electricity generation are worse than the status quo. Electric vehicles combined with solar photo-voltaics are good but come with a double cost, that of setting up the solar system as well as the expensive batteries of the car. The winner, both CO2 and cost-wise, is the conventional car or hybrid-electric car, with independent renewable energy, supplied from solar, wind, geothermal or another renewable source. The good news and interesting thing is that this combiSeptember 2007  21 nation is already available, unlike the grid-charged pure electric car. Until the last greenhouse-gas-emitting power station is taken off line (don’t hold your breath!), there is no environmental advantage in taking energy out for the grid for powering cars. Niggling questions One of the questions a thinking person might ask is “what is the energy or environmental cost of energy saving measures themselves? It is not an easy question to answer. How can one calculate the environmental or energy cost of a compact fluorescent lamp? It has so many components and different materials in it. However, as far as energy is concerned, there is an easy way of thinking about it: if a CFL costs $5, at an absolute maximum it can only have used $5 worth of energy to make. Otherwise it couldn’t be sold for that price – and that’s ignoring any profit made by manufacturer, distributor or retailer. Of course you could argue that the energy was bought at a lower price. But the lamp was sold at a lower price from the factory than the retail price you paid. So let’s just compare retail with retail. A CFL has the potential to save say 80W for 5000 hours which is 400kWh. That electricity would cost about $50. So it could save up to ten times the maximum possible energy cost of its production. Even considering that it may not last as long as advertised and it might be left on longer than a tungsten lamp, that retail price is the maximum possible energy cost. So energy-wise it must be worth it. Another niggling question is the pollution aspect in the production of these lamps. I must say it concerned me too. However, here again there is a relatively simple way of thinking about it. Of course pollution is produced by manufacturing electronic goods and fluorescent tubes. But it is a little known fact that coal fired power stations put a lot of uranium into the atmosphere. And tungsten 5 lamps (ie, standard incandescent) need mining and energy to produce too. I can’t give you figures on this but you get the idea. Energy-saving devices do have their environmental costs but as a rule-of-thumb, the environmental payback period is similar to the economic payback period. It can be much better, when you are considering highlysubsidised energy, such as off-peak electricity. Carbon offset schemes per tree, that works out to 20/0.06 = 333. Please plant them! There is an organisation called Greenfleet that will plant and maintain 17 trees on your behalf for $40 to offset the CO2 for one car. Be aware, that these trees will not be mature for some years. And hope they will be cared for – and survive. See www.greenfleet.com.au/transport/technical.asp The main problem with a carbon offset scheme is that it can’t go on indefinitely. For decades we have been taking carbon out of the ground (from countless ancient forests) and putting it into the atmosphere. We can’t realistically expect to reverse this by planting trees. We aren’t going to put them back into the ground and we couldn’t if we wanted to. If you check CarbonSMART (www.carbonsmart.com. au/pdf/InformationSheet.pdf) you will see that part of the contract for people growing timber on their properties is “The carbon will remain on site for at least 100 years after the final trade of that carbon”. Another kind of carbon offset scheme is one where you pay for someone else’s energy saving or reductions of greenhouse gas emissions, where they wouldn’t have the funds to do it themselves. These are called Greentags. Examples are given in www.myclimate.org. This arrangement supports projects such as solar energy in Eritrea, electricity from Methane in South Africa and wind energy in Madagascar. Look at www.myclimate.org.index. php?lang=en&m=projects These project have a double benefit – to that community and to the environment in general. “Carbon offsetting” and “carbon neutrality” has suddenly sprung up as a growth industry (no pun intended). However as with any new industry, it is full of cowboys. There are now organizations which try to evaluate this, for example Total Environment Centre www.tec.org.au Where to from here? We have talked about how to reduce our energy use and how to offset the CO2 we do produce. However if we are ever going to make serious inroads into the looming climate change problem, we will have to do more. What we need is serious affordable alternatives to old fashioned coal. What are our best options for renewable energy? The main alternatives as we know them today are shown in the graph below. In the cases where there are greenhouse gas emissions, the cost of CO2 has been added at $60/tonne, to give a total effective cost. These are schemes that try to do good to make up for doing bad. Sounds OK – and planting trees is a great idea. If nothing else, it should at least increase the rainfall and habitat for wildlife – and that’s good. Just to spoil your warm, fuzzy feeling, let met tell you that one mature tree extracts about 60kg of CO2 from the atmosphere a year. If you have an average sort of household with an average energy use, you will be putting about 14 tonnes of CO2 into the atmosphere every year. The car accounts for another 4 tonnes and each overseas trip another 4. Let’s say 20 tonnes a year for the purpose of discussion – an order of magnitude type of calculation. What is 20 tonnes of CO2 in tree equivalents? At 60kg 22  Silicon Chip siliconchip.com.au A graph such as this is, of course, highly controversial and various camps will claim much higher or lower costs depending on their particular bent. It is interesting to note that in the media, Nuclear, Solar Wind and Geo-sequestration are frequently mentioned. How often is Geothermal mentioned in the press? Hardly ever. Why is this so? Maybe it is that both the coal and the uranium industries have powerful political lobbies associated with them. Geothermal obviously doesn’t carry much (any?) political clout. Now available: THE 5 Hot Fractured Rock Geothermal Unknown to much of the population, Australia has huge reserves of hot rock geothermal energy. This differs from “conventional” geothermal energy which is associated with volcanic activity (as used in New Zealand) In Hot Fractured Rock, (HFR) water is pumped down an injection well into heat-producing granites located three kilometres or more below the surface. Temperatures of up to 300° are obtained and the water is circulated through a heat exchanger. Australia’s recoverable HFR resources are capable of satisfying projected electricity consumption for over 450 years. 5 DC POWER FOR CRITICAL COMMERCIAL AND INDUSTRIAL APPLICATIONS           This illustration, courtesy of the International Geothermal Association (www.iga.igg.cnr.it) shows how Hot Fractured Rock Geothermal energy works. The website gives an excellent introduction to this very neglected subject. siliconchip.com.au 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 September 2007  23 Rockby Electronics Components Est. 1987 THIS MONTH’S SPECIALS Economy SPDT Toggle Switch Type: SPDT Rating: 3A <at> 250VAC Function: ON-OFF $0.80 #35924 2700mAh "AA" Ni-MH High Cap.Batt. (Pk2) $5.90 Rech.Cycle: up to 1000 times Package: Shrink wrap Pack size” 2 #35943 Hand Held pH Meter 3 Pin Chassis Mount Socket Rating: 10A 250VAC Suits panel thickness > 1.6mm Mounting depth: 25mm Colour: White #35895 $2.50 Sounds too good to be true? RJ45 & RJ11 Modular Cable Tester Quickly & easily checks for cable continuity, miswiring, open, short, straight-through or cross pinning. #36058 $13.50 12V 150W Power Inverter Input: 11 - 15VDC Size 40(w) x 158(h) x 34(d)mm $28.50 1 - 14 pH range / 0.1 pH res. $39.00 O/p Voltage: 230 AC 50Hz Output Waveform: Mod. Sine Wave +/- 0.2 pH accuracy DC Input Voltage: 12V DC Nominal 0° - 50°C oper. temperature #35616 #36096 USB All in 1 Card Reader Compliant to USB 2.0 Hot Swappable Supports: CF/MD,SD/MMC,MS/MS PRO/MD DUO/ MS ROM & xD/SMC. Win,98Se, ME, 2000, XP $13.50 #36074 Mini 4 Port USB 2.0 Hub Mini, lightweight design Complies with USB 2.0 specs Supports high speed 480Mbps Size: 60 x 47 x 12mm Plug & Play installation Lead Included #36073 $8.50 ******** Now Open New Large Showroom ******** For a Free Monthly Mailer Up-date Please Contact us Rockby Electronics Pty Ltd Showroom & Pick-up Orders: Mail Orders To: P.O Box 1189 Huntingdale 54-56 Renver Rd. Clayton Victoria 3166 Victoria 3168 Ph: (03) 9562-8559 Fax: (03) 9562-8772 Email: salesdept<at>rockby.com.au ABN# 3991 7350 807 ACN# 006 829 821 Web Address: www.rockby.com.au The Cooper Basin in South Australia alone could provide emission-free base-load electricity for 70 years. However, a chart on the International Geothermal Association’s website (www.iga.igg.cnr.it) shows that during the years 1995-2000, Australia’s installed capacity of geothermal generating capacity didn’t change (it remained a miniscule 0.15MWe), while worldwide the increase was almost 17%. Australia has a long way to catch up. Although it is technologically difficult, it is composed of solvable problems, mostly using existing oil drilling technology. When compared with nuclear with its multiple thorny issues of safe disposal, security against terrorism and accidents, it seems a very attractive proposition. The major advantage Geothermal has over wind and solar is that it suitable for base-load supply. It can be regulated to match the load, rather than being at the whim of the elements. A major advantage of the Cooper Basin is that it is a long way from any population centres. The Swiss city of Basel has a HFR geothermal power station pilot project, which has just recently been put on hold after three earth tremors, over three on the Richter scale, were experienced. Since then an argument has developed as to whether the drilling allowed minor slippage to occur (a practice used on the San Andreas Fault), thus averting a bigger earthquake, or if it is the cause of quakes which would otherwise never happen. Thorium fuelled nuclear power Thorium is a fuel that can be used in nuclear reactors but 24  Silicon Chip produces very little nuclear waste and what there is, has a half-life of hundreds of years, rather than millions. Thorium reactors are what is called sub-critical, so no runaway reaction can occur. Furthermore, Thorium is 10 times as abundant as uranium and Australia has huge reserves of it. Maybe, and certainly if you search on the web you can find plenty of criticism and opposition to the idea. Having said that, Norway, which currently bans the use of nuclear power, is now investigating it. Obviously the jury is out – but who knows, it might be that a more benign form of nuclear power will emerge. Our journey In the beginning I talked about how much energy various domestic appliances activities use and how we could reduce it. Some surprises included: • While taking a shower you are using the energy equivalent of 240 light bulbs. • Leaving a light on every night for a year uses as much energy as driving from Melbourne to Sydney. • All those devices on “standby” are huge wasters. • Electrically boosted solar water heating is worse than gas. • Fluorescent lights are not necessarily low energy! • Leaving them on never saves energy. • Low voltage halogen downlights are the worst. • “50W” low voltage halogens consume around 62W each when transformer losses are taken into account • “36W” fluorescents consume close to 50W each when ballast and other losses are taken into account. • Compact fluorescent lamps (CFLs) are efficient compared to incandescent lamps but perhaps not the panacea the government claims them to be. After having given you the bad news ,on how much energy everything uses, we saw how, by making the right choices and spending a bit of money, one could do a lot better. But we also learned about the dishonest practices of the electricity suppliers and how to get wise to their tricks. We learned that various “low energy” appliances use more energy sitting there doing nothing than doing their job. On the third leg of the journey, I introduced a real liability, space heating and how even there, improvements could be made. By using a combination of all tactics, our household managed to get its CO2 emissions down to one quarter of the “business as usual” scenario. On this last leg we have moved on to deal with energy usage over which we have less control by using methods such as carbon offsets. Even then, there are choices to be made and some of them make more sense than others. Finally we moved into the arena of government policy and discovered (surprise!) that the government actions and the technologies they support don’t make a lot of sense. I hope I have alerted you to some of the foibles we are led to believe. As informed citizens we can do a better job. SC siliconchip.com.au N A T A H G W N I Z A ! M R A OFFE Agilent Technologies Buy yourself one of the world’s most versatile digital multimeters – the incredible Agilent U1252A True RMS – between now and December 31 2007, and you’ll also enjoy a FREE 12-month subscription to SILICON CHIP – Australia’s world-class electronics magazine!* SEE THE REVIEW IN APRIL 2 SILICON CH0I07 P! * offer valid only in Australia. If you are already a subscriber this can be made a gift subscription That’s right: a bonus valued at $89.50, yours free of charge when you buy the Agilent U1242A DMM! It’s so much more than just a DMM – look at these specs: FEATURES: * True RMS measurements * 20 MHz frequency counter * Up to 0.025% basic DCV accuracy * Programmable square wave generator * Frequency, temperature and capacitance measurements * 50,000 counts resolution on both displays * IR to USB connectivity (optional U1173A connectivity cable sold separately) * -20°C to + 55°C operating temperature * Category III 1000V OV safety compliance * 100 manual data storage points and unlimited data logging points when connected to a PC Resolution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50000 counts Basic DCV accuracy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.025% Displays (50,000 count) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Dual True RMS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . AC + DC Capacitance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10nF to 100mF Resistance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 500 MΩ Current . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10A Frequency . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.5Hz to 500kHz Math Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 Frequency Counter . . . . . . . . . . . . . . . . . . . . . . . . 0.5Hz to 20 MHz Programmable square wave generator . . . . . . . . 0.5Hz to 4800 Hz Data logger . . . . . . . . . . . . . . . . . . . . . . . . . . . 100 points (manual) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 200 points (interval) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Unlimited (PC) Operating temperature . . . . . . . . . . . . . . . . . . . . . -20 C to +55 C Safety compliance . . . . . . . . . . . . . . . . . . . . . . . . . . Cat III 1000V Battery . . . . . . . . . . . . . . . . NiMH Rechargeable with power adapter I/O interface . . . . . . . . . . . . . . . . . . . . . . . . . . IR to USB(optional) Dimensions . . . . . . . . . . . . . . . . . . . . . . . . 203.5 x 94.4 x 59.0mm Approximate weight . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 527g Here’s how to take advantage of this amazing offer! TRIOBY FAX:# SMARTCAL PTY LTD OR MEASUREMENT INNOVATION PTY LTD CALL! BY PHONE:* (02) 9939 3295 (02) 9939 2648 FAX! 24 Hours 9-4 Mon-Fri PHONE: 1300 8537 Days 407 FAX: 1300 853 409 sales<at>triosmartcal.com.au EMAIL! <at>siliconchip.com.au WRITE! 3 Byfield Street, North Ryde NSW 2113 PHONE: 08 9437 2550 FAX: 08 9437 2551 info<at>measurement.net.au S 2007  25 898 Anketell Road, Wandi, WA 6167 eptember • Support for In-Circuit Se rial Programming (ICSP) • 32 LEDs on each side of each PC board (64 LEDs per board , 192 LEDs total) • Displays a one-kilobyte image (32 LEDs x 256 radial “ra ster lines”) • All LEDs can be driven with 20mA at 100% duty indefinitely . This produces a very bright im age. • Firmware shuts the circui t down automatically when the voltage gets too low, to prevent damage to rechargeable battery packs • The PC boards fit 26-in ch bike wheels or larger. BIKE WHEEL POV DISPLAY This project uses POV to produce a spectacular glowing display on a rotating pushbike wheel as you ride along. So what is POV? It stands for Persistence Of Vision. It’s a term that’s applied to devices that rely on the human eye’s tendency to “see” an image for a short time after it has disappeared. Designed by Ian Paterson 26  Silicon Chip siliconchip.com.au H OW WOULD YOU LIKE to own the most talked-about pushbike in the school/street/suburb. . . galaxy? Build this POV display and you’ll be well on the way. You really have to see it to believe it – and we’ve even made it easy for you. As well as the images printed here, there are several more you can view online at www.ianpaterson.org/projects OK, you’ve now seen them and you’d have to agree that they look pretty spectacular, right? You want to do the same for your pushie? Just make sure you keep it chained up because everyone will want it . . . Persistence of vision You probably don’t realise it but you use POV every day – when you watch TV. Movies also take advantage of this phenomenon. The TV and movie picture is not continuous vision – rather (in the case of TV), 25 individual pictures are displayed every second. But your eyes and brain cannot follow the 25 individual frames of picture per second – instead, they “fill in the gaps” and you “see” full motion, non-jerky video. If you slowed those frames down to, say, 10 per second, you would be able to see the period between each frame and it would become jerky – just like the old-time movies where the hero moves like a Thunderbirds puppet. Let’s take this one step further. Say you had a moving light – we’ll make it a LED because they can be turned on and off very quickly – which you flashed on, very briefly, once per second. You’d see this as flashes of light moving along a path. If you changed that to, say, 10 flashes per second, you’d probably still see flashes but very much closer together. Make that 50 flashes per second and the flashes would all meld into one another. You’d see it as a continuous line of light – even though your brain knows full well that it is flashes you are viewing. That’s persistence of vision and this is the basic theory behind this project. Rows of LEDs are made to flash too quickly for your brain to process, so they appear to be permanently on. The rows of LEDs are mounted on PC boards fixed to a bicycle wheel, so they follow a circular path as the wheel rotates. By using some clever circuitry to switch the LEDs on and off at particular moments, a pattern or picture can be created – in fact, the display is almost unlimited. It can be everything from geometric shapes to text, cartoon characters and even very high contrast pictures (see examples below). In a nutshell . . . The display consists of three PC boards, each with a row of 32 LEDs on each side (a total of 64 LEDs). These boards are mounted radially in/on the spokes of a pushbike wheel and each has a battery pack mounted near the wheel’s hub. Talk about WOW! factor: this 3-high static display uses different coloured LEDs in each wheel to reveal three different patterns. The rider powers the one wheel & the second & third wheels are driven by friction between the tyres. A Hall Effect sensor measures the rotational speed of the wheel by sensing a small magnet fixed to the bike frame. This sensor sends speed pulses to a microcontroller, which then turns the individual LEDs on and off in such a way that a static image appears to float inside the wheel. Circuit description Fig.1 shows the complete circuit for one POV display module. Three such modules are required, arranged so that each is mounted 120 ° from the other around the wheel, between the spokes. With the exception of the trigger magnet and battery pack, all components mount on these three PC boards. Here are just a few of the images generated by the author: (from left) pagan star, ET, invisible unicorn, Saturn & evolution! siliconchip.com.au September 2007  27 28  Silicon Chip siliconchip.com.au SC 2007 1 1 OUT 3 RA6 RA3 RB0 Vss 5 RB5 RA7 IC1 PIC16F628A MCLR PGD PGC Vdd 14 1k 21 23 4 22 2 11 10k GND 3 10k 10 F 16V IN 16 15 2 100nF OUT REG1 LM2931AZ-5 BIKE WHEEL POV DISPLAY MODULE 2 GND (HALL SENSOR) HS1 DN6851 6 4 Vcc 13 2 12 3 4 ICSP SOCKET CON1 10k +5V 24 O7 O6 O5 O4 O3 O2 O1 O0 OE Rext LE CLK SDO SDI GND 1 O15 O14 O13 O12 O11 O10 O9 O8 IC2 STP16C596 Vdd 2 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 1 K K K K K K K K K K K K K K K K A K A K A K A K A K A K A K A K A K A K A K A K A K A K A K A K 3 DN6851 LED31                 LED1 A A A A A A A A A A A A A A A A CHAMFER LED32                 LED2 23 4 3 22 2 IN COM 24 Vdd OE Rext LE CLK SDO SDI GND 1 OUT O15 O14 O13 O12 O11 O10 O9 O8 O7 O6 O5 O4 O3 O2 O1 O0 IC3 STP16C596 LM2931AZ-5 21 1k +7.2 – +8.4V* 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 K K K K K K K K K K K K K K K K LED63                 LED33 A K A K A K A K A K A K A K A K A K A K A K A K A K A K A K A K A K 7.2–8.4V* NiMH BATTERY S1 POWER A A * DO NOT USE RED LEDS WITH 8.4V BATTERY A A A A A A A A A A A A A A LEDS LED64                 LED34 The modules, or PC boards, each contain 64 high-brightness LEDs, 32 on each side. A LED on one side is connected in series with a LED on the other, so that the same image is seen on both sides of the bike. The LEDs are under the control of a PIC16F628A microcontroller (IC1). It is this microcontroller which not only stores the image to be displayed but outputs it to two STP16C596 shift registers (IC2 & IC3) which in turn drive the LEDs. If each LED pair was driven with a dedicated output line, the microcontroller would have to have a very large number of output lines. Hence this circuit uses 16-bit constant-current LED sink drivers (IC2 & IC3) which can drive 16 outputs and allow multiple devices to be cascaded together. The STP16C596 also has a separate storage register that allows one set of data to be displayed while the next set is being loaded. Four lines are used to control the LED outputs: serial data input (SDI), clock (CLK), latch enable (LE) and serial data output (SDO). Each pulse of the clock line causes the data to be “shifted” over by one place and each pulse of the latch enable line causes the LED outputs to reflect the contents of the shift register. One kilobyte of image data is stored in the program memory area of the microcontroller and is read by way of a look-up table. The firmware uses four interrupt routines: • one to provide the time interval between radial raster lines; • one to increment a counter for timing the wheel rotation interval; • one to reset all counters and update the raster interval value every time the Hall Effect sensor is triggered; and • one that shuts down all LEDs when the battery voltage gets too low. In fact, after the initial start-up routine, virtually every part of the firmware’s execution runs inside an interrupt routine. We haven’t yet mentioned the DN6851 Hall Effect sensor. Its purpose is to measure the speed of the wheel Fig.1 (left): one POV display module – three are required for the whole project. With 64 LEDs per module it looks daunting but there are only 12 other components in each! siliconchip.com.au and supply the appropriate timing pulses to IC1. It is triggered each time it passes a small magnet attached to the bike frame. Its output pulse is sensed by input RB0 on IC1 Timing values for the radial raster line interval are retrieved from a look-up table that exists in the microcontroller’s program space. Data for the look-up table is generated with a QBasic program, although you only need to run this program if you want to experiment with different timing values. When using a 7.2V battery pack, it’s better to use a low dropout regulator such as the National Semiconductor LM2931AZ-5 than the commonly used 78L05. It will continue to provide a solid 5V for the microcontroller even when the battery is at 6V. This is important because if the supply voltage to the microcontroller drops, so does the internal reference voltage which would prevent the voltage sensing routine from working properly. A number of flow charts have been created to illustrate the logic in Spoke POV’s various firmware routines but since our space is limited, these can all be accessed on the website mentioned above. QBasic programs In addition to the microcontroller firmware, two Qbasic programs are required for setting the timing values and converting image data so they can be incorporated in the firmware. POVSLOPE.BAS creates the timebase look-up table. The table produced by this program is linear, so the only parameters one needs to be concerned with are slope and offset. Note that the timing data supplied in the sample firmware is reasonably accurate so you should only use POVSLOPE.BAS if you plan to experiment with different timing values. POVIMAGE.BAS is used to convert a raster image into radial data in the form of a series of “RETLW B’xxxxxxxx’;” commands that can be copied and pasted directly into the POV assembly code. The image data is read one pixel at a time as a series of 32 concentric rings. Each group of eight rings ends up occupying one memory page. Because of the limitations of QBasic, it has been made to read headerless RAW files. The images must be 700x700 pixels, eight bits per pixel, TRADE-IN Offer Any Brand – Dead or Alive Up to 20% trade-In Value towards your new Tektronix Instrument Enabling Innovation Trade-in*1 your Analog or Digital Oscilloscopes, Function and/or Waveform Generators or Logic Analyzers for the advanced Tektronix range. Trade-In*1 Any brand instruments – savings of up to 20% towards your New Tektronix instruments. ACT NOW! Equivalent instruments will be traded-in towards any of the following Tektronix models:  Digital Phosphor & Sampling Oscilloscopes (DPO7000/DSA8200)  Mixed Signal & Digital Phosphor Oscilloscopes (MSO4000/DPO4000/TDS3000B)  Digital Storage Oscilloscopes (TDS2000B/1000B Series)  Arbitrary Waveform Generators (AWG5000)  Arbitrary Function Generators (AFG3000 series)  Logic Analysers (TLA5000B/TLA7000) Offer expires on the 30th September 2007 *1 Conditions apply - Trade-In value may vary depending on instrument type, model & condition of trade-in instrument. Please call 02-99113888 or enquiries<at>tekmarkgroup.com to inquire Authorised Distributor in Australia: Certificate No: AU07/3011 TekMark Australia Pty.Ltd Suite 302, 18-20 Orion Road, Lane Cove, NSW 2066 Email: enquiries<at>tekmarkgroup.com Website: www.tekmarkgroup.com Phone: 02-9911 3888 Fax: 02-9418 8485 September 2007  29 30  Silicon Chip 1k 10k IC1 PIC16F628A (FACE DOWN) 1 RED DOTS INDICATE VIAS OR SOLDER-THROUGH LINKS 1 IC2 STP16C596 16109071 INNER COLUMN OF LEDS MOUNTED ON TOP OF BOARD & SOLDERED UNDER OUTER COLUMN OF LEDS MOUNTED ON UNDER SIDE & SOLDERED ON TOP IC3 STP16C596 1 10k GN D +V GN D Fig.2: the PC board component overlay (shown from the component side) with matching top and bottom-side photographs of the PC board. The fingerprints are an optional extra! Seriously, the boards should be coated with a PC board (ie, solder-through) lacquer immediately they are made to prevent this from happening – especially as these boards will be out in the weather on the pushbike. In fact, we’d even go so far as to give the whole thing a good spray once finished – making sure you don’t get it in the two connectors. 10F 100nF HS1 1k 1 CLK DAT MCLR GND (BEND DOWN 90o ) 10k REG CON1 siliconchip.com.au FIRMWARE Ian Paterson’s firmware for this project – 628h.asm, povslope.bas & povimage.bas can be down-loaded from his website at www.ianpaterson.org/projects with the pixels being either pure black (0x00) or pure white (0xff). Such a file can be created with Photoshop or many other graphics programs. When you’ve finished creating the image, the final file size should be exactly 490,000 bytes. To stop the LEDs from lighting up when the bike is stationary, the last raster line is always set to zero (off). Because the firmware stops incrementing the raster line counter when it reaches the last line in the image, having all LEDs off in that line will cause them to remain that way until the next trigger pulse from the Hall Effect sensor. Construction After checking the PC board, start with the three 10kW and two 1kW resistors, followed by the 100nF and 10mF capacitors. Of these, only the 10mF capacitor is polarised. As this is a double-sided PC board, we should mention that the components mount on the side with the writing in the copper! Next solder in the three IC sockets (the right way around!) and two connectors, followed by the polarised regulator (REG1) and Hall Effect sensor. For me, the most troublesome part of this project is soldering the Hall Effect sensors without damaging them. Because they are sensitive to both mechanical and thermal stress, you must use great care when attaching them to the circuit board. Their leads must be bent down 90° towards the face which has a chamfered edge on its top. This means that the face will actually be towards the PC board surface when fitted. When bending the leads, you must hold the sensor lead with needle-nose pliers between the plastic case and the point at which the lead is being bent. This is to prevent mechanical stress at the point where the leads enter the sensor’s case. When soldering, you must also use needle-nose pliers as a heatsink to prevent damage from excessive heat. Once the sensors have been successfully soldered onto the board, there is little risk of further damage. Soldering the LEDs You have probably noticed that we have left the LEDs until last. That’s because there are a lot of them and they too can be a bit tricky to solder. There are 32 LEDs to be soldered to each side of the PC board. Note first of all which is the anode and cathode of the LED – there is a flat spot on the bottom of the LED next to the cathode (labelled “K” on the circuit diagram). Also, the anode lead is longer. At right are the same PC boards shown opposite, this time fixed to their backing “plate”, ready for mounting on the wheel. Note the semi-circle notches at the bottom end to fit into the axle. The top end is rounded to fit against the rim. siliconchip.com.au September 2007  31 Parts List* 3 PC boards, each 50 x 245mm, code 16109071 3 18-pin IC sockets 6 24-pin IC sockets 3 7.2V or 8.4V 700mAh (or higher) battery packs (do not use 8.4V with red LEDs) – see text 3 magnets – see text Material for backing plates – see text Semiconductors 3 PIC16F628A microcontroller programmed with 628h.hex (IC1) 6 STP16C596 LED driver (IC2, IC3) – see alternatives below 3 DN6851 Hall Effect sensors (HS1) – see alternatives below 3 LM2931AZ-5 low-dropout regulators (REG1) 192 high brightness LEDs (LEDs 1-64) Capacitors 3 10mF 16V electrolytic 3 100nF MKT polyester or monolithic (code 100n, 104 or 0.1mF) Resistors (5%, 0.25W) 9 10kW (brown black orange gold) 6 1kW (brown black red gold) Alernative Parts ST Microelectronics STP16C596 LED driver alternatives: Allegro A6276EA Maxim MAX6969ANG Maxim MAX6971ANG Panasonic DN6851 Hall effect sensor alternatives: Melexis US5881EUA Allegro UGN3113 (may be discontinued) Allegro A1101LUA-T Allegro A1103LUA-T * This list is for all three modules On the top (component side) of the PC board, the LEDs are arranged with their cathodes oriented towards CON1 (the 4-pin connector) while on the bottom side, the reverse is true. The LEDs are controlled in pairs, one for each side of the board, thus allowing the POV image to be viewed from either side of the bicycle. The LED pairs are connected in series by way of small jumper wires through the 32  Silicon Chip In daylight, you can see the arrangement of the PC boards and batteries inside the spokes of the wheel. The PC boards, mounted 120° apart around the wheel, fit against the axle and are secured at the rim end via a couple of cable ties onto the spokes. It’s important to keep the battery packs (which ever form you use) close to the axle to prevent the wheel getting out of balance. PC board that serve the same purpose as a PC board “via” – connecting the copper on both sides of the PC board together where required. The biggest challenge in soldering these jumpers is that the heat from your soldering iron will travel along the wire and melt the connection on the other side of the board. I found it helpful to use those “Helping Hands” soldering aids with alligator clips to hold the wire in place. If you are able to obtain or make PC boards with vias, then these jumpers are not necessary. Finally, plug the three ICs into their sockets. Be careful to line up the notch in the end of the IC with the notch in the end of the socket. A second check is a small paint dot or indent beside pin 1 – make sure this goes where pin 1 is shown on the component overlay. Loading an image Since this POV design stores the image in program memory space, the microcontroller must be re-programmed every time you want to load a new image. The process is as follows: • Create a 700x700 pixel, 8-bit per pixel image and save it with an 8-character filename. • Edit POVIMAGE.BAS so that it references the new image and run the program. It will save its output with a .ASM extension. • Copy and paste the .ASM output into the POV firmware file (628h. asm). • Compile it to produce a .HEX file and program the POV board via the 4-pin In-Circuit Serial Programming (ICSP) connector. This connector does not supply power to the board during programming, so you must supply power from a battery pack or an external supply. Testing Test the operation of the POV board before fixing it to the spokes. It’s a lot easier to fix mistakes on the bench than on the bike! Of course, the microcontroller should be programmed at this stage Apply power and wave a magnet in front of the Hall Effect sensor. You should see the LEDs illuminate. They won’t make much sense (ie, there will be no picture to see) but at least you will know the microcontroller is doing its thing. If they don’t light up, turn the magnet over and try again. The faster you wave the magnet in front of the sensor, the faster the LEDs should flash. If this test siliconchip.com.au fails to illuminate the LEDs, the most likely causes are a defective Hall Effect sensor or a bad program. The batteries The battery voltage needs to be high enough to allow the regulator to provide 5V for the microcontroller and also just high enough to allow the LED drivers to deliver up to 20mA through each LED pair. Try using a 7.2V battery pack for LEDs with a low forward voltage (such as red) and 8.4V for other colours (such as white and blue). Be sure not to use a battery voltage that’s more than about 2V higher than 2x the forward LED voltage, otherwise the LED drivers may be damaged. In the prototype, battery packs were made up from AA NiMH cells. I used 700mAh cells but with 2500mAh now available, 1000mAh and even 1500mAh are becoming quite cheap. The larger the capacity, the longer your display will last. You can use six cells (for 7.2V) or, as long as you don’t use red LEDs, seven cells (8.4V) in your battery packs – it’s more a case of getting a suitable holder. All three packs should be the same weight to avoid unbalancing the wheel. An alternative, albeit a bit heavier, is to buy 7.2V or 8.4V battery packs intended for radio controlled models. High power (3500mAh+ ) ones are expensive but you can often find lower capacity types on eBay for less than $20. Just make sure you mount them so they can’t fly off! Wheel mounting The accompanying photo shows the position of the PC boards on the bike wheel. It’s important to note that the inner edge of the PC board sits right up on the axle and the whole thing is centred between the spokes, so that the board is right in the centre of the wheel. To mount the PC boards in the wheel, I made a protective backing out of 3mm sintra (often used as a rigid backing onto which printed material can be mounted), covered one side with anti-static plastic (cut from a motherboard bag), and attached it to the solder side of the PC boards using plastic cable ties. I’m not sure if the anti-static plastic is of any benefit but I used it as a precaution in case a static charge builds up on the sintra as the wheel spins. siliconchip.com.au RIGOL SCOPES SALE ... SAVE UP TO $300 Rigol DS5062MA 60MHz Rigol DS5102MA 100MHz 60MHz Bandwidth 1GS/s Real Time Sampling 2 Channels Mono LCD Display 4K Memory Per Channel 20 Automatic Measurements Advanced Triggering on Edge, Video & Pulse Built-in FFT Built-in USB 3 Year Warranty 100MHz Bandwidth 1GS/s Real Time Sampling 2 Channels Mono LCD Display 4K Memory Per Channel 20 Automatic Measurements Advanced Triggering on Edge, Video & Pulse Built-in FFT Built-in USB 3 Year Warranty ONLY $ 799 ONLY $ ex GST 1,099 ex GST 300 200 SAVE $ SAVE $ * Offer valid until 30th June 2007 or while stocks last. Sydney Melbourne Tel 03 9889 0427 Tel 02 9519 3933 Fax 03 9889 0715 Fax 02 9550 1378 email testinst<at>emona.com.au Brisbane Adelaide Perth Tel 07 3275 2183 Fax 07 3275 2196 Tel 08 8260 8166 Fax 08 8260 8170 Tel 08 9361 4200 Fax 08 9361 4300 web www.emona.com.au EMONA On one end of the sintra, I cut a crescent-shaped notch that matched the radius of my front hub shaft. On the other end, I cut a notch for the spoke nipple. All that is needed to secure a PC board to the wheel is two cable ties at the spoke nipple end – the other end stays put because the crescent-shaped notch engages around the wheel hub. To keep the hub end of the boards in place, I used two short sections of plastic hose, slit down one side, wrapped around the hub shaft and attached with cable ties. These act as spacers that prevent the boards from sliding laterally along the length of the hub shaft. Note: these boards will fit a 26-inch or larger wheel. Also, when using three boards, it’s easier to mount them in a wheel with a number of spokes that’s divisible by three (eg, 36 spokes). Mounting the magnet To trigger the Hall Effect sensors, I used a stack of four magnets from an old 3.5-inch hard drive. The stack of magnets was placed on the inside of one of the bike forks immediately above the region under which the Hall Effect sensor passed, then secured in place with a piece of tape. Other suitable magnets would be one or more of the rare-earth or so-called “super magnets” which are enormously powerful for their size. More information? There are a lot more notes, flowcharts, firmware and graphics on the author’s website: www.ianpaterson. SC org/projects September 2007  33 Select the features you want in this Fast Charger for NiMH batteries This is a truly versatile charger. It can charge up to 15 identical NiMH or Nicad cells. You can build it to suit any size cells or cell capacity and you can set the charge rate. It can fast charge, trickle charge and has safeguards, including temperature sensing, to prevent overcharging. S TANDARD NiMH and NiCad chargers are available just about anywhere, from hobby stores to supermarkets, the service station and even your local chemist or newsagent. However, they usually only charge two or four AA cells and at quite a slow rate – typically they will take between four and 15 hours to charge. But what if you want to charge at a much higher rate or more than four cells at a time? Or cater for C and D cells or battery packs? The only complete answer is to build the new SILICON CHIP Fast NiMH Charger. It can charge from one cell up to 15 cells simultaneously and battery packs up to 18V for both NiMH and Nicad types. Charging can be set from 34  Silicon Chip just a few milliamps up to 2.5A and it includes a reliable end-of-charge detection, with extra safeguards included to prevent over-charging. Safety is important when charging NiMH and Nicad cells and batteries because they can be destroyed, or have their life seriously shortened, if the charger is left on for too long after the battery pack has reached full charge. To see why over-charging can destroy a battery pack, have a look at Fig.1. This shows the typical voltage, temperature and internal pressure rise of a cell or battery pack with charge. by JOHN CLARKE Once charging goes past the 100% point, the temperature and internal pressures rapidly rise and the voltage initially rises and then falls. Continual overcharging will damage the cells due to the elevated temperature. This accelerates chemical reactions that contribute to the ageing process. In extreme cases during overcharging, excessive internal pressure can open their safety vents to release the pressure. These vents will re-close after the pressure is released but the cells will already have been damaged. Full charge detection Full charge can be determined in one of two ways. The conventional way has been to monitor the voltage siliconchip.com.au Main Features siliconchip.com.au Our new Fast NiMH Charger requires a small thermistor to be installed in the battery pack or cell holder, in close contact with one of the cells, so it can monitor temperature. The beauty of this system is that it will recharge any cell, regardless of whether it is flat or only partially discharged – you will not over-charge it. There is a proviso here and it applies when you charging very cold batteries – they may rapidly rise in temperature during charging. This could cause a false dT/dt end of charge condition. To circumvent this, the dT/dt measurement for end of charge detection is only enabled when the cell tem- perature is at least 25°C. Should the thermistor end-point detection fail, a timer is included that will switch off charging after a preset period. Further safeguards to protect the cells are also included. Charging will not start, or will stop, if the NTC thermistor for the cells is disconnected or if the temperature is under 0°C or over 55°C. Should the charger itself become too hot, charging will pause and the temperature is measured after two minutes to check if it has cooled sufficiently to restart charging. Select the features you want In its simplest form our new Fast NiMH Charger includes only the temperature detection feature. You 75 1.50 100 65 1.46 80 CELL VOLTAGE 1.42 60 1.38 40 35 1.34 20 25 1.30 55 45 PRESSURE across the battery pack and detect the point where the voltage begins to rapidly rise and then fall. This form of end-point detection is called dV/ dt (ie, change in voltage with respect to time). In practice, the critical end-point can be difficult to detect at low currents, particularly with NiMH (nickel metal hydride) cells. In fact, dV/dt end-point detection with NiMH cells is neither safe nor practical. The only safe way is to monitor the temperature of the cells. Very few chargers do this. This far more reliable method, especially with NiMH cells, monitors the temperature rise of one or two cells within the battery pack. During charging the cells do not heat up much because most of the incoming power is converted into useful stored energy. However, once the cells become fully charged, the charging current (and power) is converted to heat and so the cells rise quickly in temperature. Detection of this temperature change at the charging end-point is called dT/dt – change in temperature over time. The critical temperature rise is of the order of 2°C per minute. This is where normal charging should stop. Some chargers, ours included, may have a top-up charge after the endpoint to ensure full charging. After top-up, the cells can be trickle-charged to maintain full charge. In this situation, the cells are deliberately left connected to the charger, in the knowledge that they won’t be damaged but will be absolutely “full to the brim” when they are needed. TEMPERATURE (°C) These 1500, 1700 and 1800mAh ‘AA’ NiMH batteries were considered “state of the art” in our last NiMH charger (November 2002). Now 2500mAh are quite common (we’ve even seen claims of 3000+ ‘AA’). Our new charger will handle these as well as C and D cells and even battery packs. • Designed for NiMH cells but will handle Nic ads too • Charging timeout • dT/dt (temperature change) for end of charge detection • Over and under cell temperature detection • Power, charging and thermistor indication LEDs • Adjustable charging timeout limit • Adjustable dT/dt setting • Optional top-up and trickle charging • Adjustable charge current • Adjustable top-up and trickle charge curren ts • Over-temperature cut out for charger 0 0 50 100 STATE OF CHARGE (%) Fig. 1: typical charging curves for Nicad batteries (NiMH are similar). Cell temperature (green) and voltage (red) are most often used to detect the “end point” or 100% charge but in NiMH cells, the voltage is much less reliable. September 2007  35 Specifications Maximum input voltage.......................30V Maximum charge current.....................2.5A corresponding to 0-2.5V at Charge current adjustment...................From 0-2.5A, (in approximately 40mA steps) VR4 ...........................................................TP4 using , corresponding to 0-5V from Timeout adjustment.............................From 0-5 hours ...........................................................VR1 at TP1. x5 link installed (LK1) ............................................................0-25 hour with rise/minute, corresponding to dT/dt adjustment..................................From 0.5°-5° at TP2. ............................................................0.5-5V from VR2 once cells reach 25°C or more e minut dT/dt measurement..............................Once every when LK2 is installed, Top up and trickle charge.....................Top up available when LK3 is installed ............................................................Trickle enabled VR3 from 0-500mA, Trickle charge adjustment....................Adjustable using 0V to 5V at TP3 to g ondin ............................................................corresp ximately 5mA steps appro in ble ............................................................Adjusta g for 1 hour Top up charge......................................4 x trickle settin Cell over temperature cutout................55°C Cell under temperature detection.........0°C Charger over temperature cutout.........50°C can add top-up and trickle charging if you want (no extra components are required) and set all the charge parameters: full charge current, trickle charge, timeout period and dT/dt values. Full charge can be set from about 40mA up to 2.5A while trickle can be set from 10mA up to 500mA. Timeout can be set from between 0-25 hours while dT/dt can be selected from between 0.5°C rise per minute to 5°C per minute. More details concerning the adjustments are included in the setting up section of this article. Three LEDs indicate the status of the charger controller. The power LED is lit whenever power is applied to the charger (obvious!) while the Thermistor LED lights if the thermistor is disconnected or if there is an over or under-temperature detection. For over-temperature (>55°C), the Thermistor LED will flash once a second (1Hz) while for under-temperature (<0°C) the LED will flash once every two seconds (0.5Hz). Over heating of the charger itself causes the Thermistor LED to flash once every four seconds. Finally, the charging LED is continuously lit during the main charging cycle and switches off when charging is complete. If top-up and/or trickle charging are selected, the charging LED will flash at 1Hz during top-up and at 0.5Hz during trickle charge. Note that if the thermistor LED is lit or flashing, the charging LED will be off, indicating that charging has paused or stopped. A view inside our new NiMH Fast Charger. As you can see, the PC board sits in the bottom of the diecast box, as normal. But when the lid is screwed on, it becomes the base and the whole thing is turned over so the PC board is actually upside-down. 36  Silicon Chip siliconchip.com.au 7–30V DC IN D2 1N4004 POWER A K REG1 LM317T IN S1 OUT ADJ 220 F 50V 220nF 120 VR1 T/t (5V=5°C/min) TRICKLE (5V=500mA) VR2 10k +5V CELL/BATTERY TEMP 18 TH1 RB3 AN3 VR4 1 10k AN1 12 IC1 PIC16F88I/P RB4 10 AN2 RB5 11 LK2 LK3  SC 1k TH2 S K Q1 IRF540 A 0.22  5W TOPUP ENABLE D1, D2 TRICKLE ENABLE AN4 A 470 8 A OUT K K ADJ AN6 RB1 7 Vss 5 THERMISTOR LED2 IN OUT 470 LM317T LEDS A 2007 G ZD1 16V 1W 4 TIMEOUT D 1k 7 10k 13 HEATSINK TEMP IC2 6 LM358 ZD1 RB2 100nF 10 F 16V 8 LK1 TP5 3 5 1k RB6 TP4 D1 1N5822 K 8.2k 9 TP3 10k VR5 20k 47 2 VR3 CHARGE (2.5V=2.5A) AN0 A 100 F 10V 100nF Vdd TP2 9.1k CON1 14  K +5V 17 10k A POWER LED1 TP1 CON2 + TO BATTERY – 470 TPGND VR6 500 TIME OUT (5V=5h) TP +5V 10 F 16V  K A CHARGE  LED3 K D K A G D IRF540 S NIMH BATTERY CHARGER Fig.2: the circuit is based on a PIC16F88 microcontroller and apart from the components used to set and monitor the current, there’s not much more to it. Circuit details The circuit for the Fast NiMH Charger is based around a PIC16F88I/P microcontroller, IC1. Apart from the complexity of the software for IC1, there is not much else to it. Two NTC thermistors are used in the circuit. NTC stands for “negative temperature coefficient” and this means that the resistance of the thermistor is progressively reduced as the temperature rises. Thermistor TH1 monitors the cell or battery pack being charged. It is connected via a 2-way terminal block (CON1) and forms a voltage divider with 20kW trimpot VR5 across the 5V supply. VR5 is adjusted so that the voltage across the thermistor is 2.5V at 25°C. The voltage across the thermistor is monitored at the AN4 input (pin 3) of IC1 via a 47W resistor and 100nF filter capacitor. These are included to siliconchip.com.au remove radio frequency (RF) signals and noise that could be present due to the thermistor being connected remotely from the circuit. The voltage at the AN4 input is converted into a digital value and the values are compared against the over and under temperature values and for dT/dt changes. Trimpots VR1, VR2 and VR3 are used to set the timeout, dT/dt and trickle charge values. The wiper of each trimpot connects to the AN0, AN3 and AN1 inputs respectively and these inputs can receive between 0V and 5V, depending upon the setting of the trimpot. For the full charge current input at AN2, VR4 connects to the +5V supply via a 9.1kW resistor. This restricts adjustment to a nominal 2.5V maximum (for a 2.5A maximum setting). The voltage inputs are all converted to digital values within IC1 so that the settings can be processed in software. Test points TP1, TP2, TP3, TP4 & TP5 are provided for setting the trimpots when using a multimeter. There is also a TP GND terminal for the negative probe of your multimeter. The voltages measured at each test point directly relate to the setting’s value. For example, setting VR1 to give 4V at TP1 will set the timeout to 4 hours. The timeout value can be multiplied by a factor of five if jumper link LK1 is inserted. This ties pin 12 to ground. With LK1 out, pin 12 is pulled to +5V via an internal pullup resistor within IC1 and timeout is set at x1. Links LK2 and LK3 work in a similar manner. LK2 enables the top-up and LK3 enables the trickle charge modes. Outputs RB1 and RB2 of IC1 drive the Thermistor and Charge LEDs respectively via 470W resistors. September 2007  37 CHARGE LED3 LED2 100nF 8.2k D2 1k 1k ZD1 5W VR6 500 – 10 F DC IN VR2 10k VR4 10k TP2 TP4 TP5 100nF IC1 PIC16F88-I/P 120 + TO BATTERY LK2 LK3 LK1 220 F VR5 20k 100 F 10 F 470 9.1k 470 470 IC2 LM358 17090140 1k 0.22  5822 D1 Q1 (UNDER BOARD) LED1 47 TP GND TO THERMISTOR POWER THERMISTOR REG1 LM317 10k S1 TP1 TP3 VR1 10k VR3 10k TP +5V 220nF RE GRA H C H Mi N TH2 Fig.3: full-size component overlay – compare this with the photograph of our prototype at right. If the 220mF capacitor you have is higher than 14mm, it will have to be laid over to fit within the case. Constant current source Op amp IC2 and Mosfet Q1 are connected to provide a controlled current source to charge the battery (connected via CON2). Op amp IC2 compares the voltage across the 0.22W resistor (at pin 6) with the DC voltage derived from the RB3 output of IC1 (at pin 5). The output from RB3 is a 5V 500Hz pulse-width-modulated signal which is fed to a divider and filter network comprising 8.2kW and 1kW resistors and a 10mF capacitor. The filter network smooths the pulse output to give a DC voltage. It is this smoothed DC voltage which effectively sets the current level provided by Q1 to the battery. Diode D1 is included to prevent the battery from discharging via the intrinsic reverse diode inside Mosfet Q1, when the power is off. D1 is a 3A Schottky diode, specified because it has less than half the forward voltage of a normal power diode. Typically, it has about 380mV across it (at 2.5A) compared with a standard diode which has 0.84V across it at 2.5A. The lower voltage drop also means less power loss in the diode; 0.95W at 2.5A compared to 2.1W in a standard diode. Power for the circuit is taken from a DC plugpack supply via diode D2. This diode provides reverse polarity protection for the following capacitor and regulator REG1. An LM317T is used to provide a 38  Silicon Chip regulated 5V supply to IC1 and the trimpots. This was chosen in preference to a standard 5V regulator because it can be adjusted to supply a precise 5V, using trimpot VR6, to make the settings of VR1 to VR5 more accurate. Voltage requirements To fully charge a battery you will require up to 1.8V per cell from your plugpack even though the nominal terminal voltage shown on the battery pack is 1.2V per cell. Hence, to charge a 6V battery which has five cells, you will need a DC input voltage of 9V (5 x 1.8V). Similarly, an 18V battery will have 15 cells and you will need 27V (15 x 1.8V) to charge it fully. However, while the voltage requirement for charging one, two or three cells is less than 7V, in practice you need more than 7V at the input to ensure that the LM317T regulator operates correctly, ie, remains in regulation. You can operate the charger in a car, in which case the input voltage will be around 12V with the engine stopped and up to 14.4V with the engine running. With 12V in, you can charge up to six cells (ie, a 7.2V battery). With 14.4V (ie, engine running), you can charge up to eight cells (ie, a 9.6V battery). Note also that using a supply voltage that is significantly higher than required to charge the cells will cause the charger to heat up more than necessary. For example, at 2.5A and with 10V higher than the battery voltage, there is going to be 25W dissipated in the charger. The heatsink will certainly become hot and the charger will shut down when it reaches 50°C. So you may have to reduce charge current if the supply voltage is high compared to the battery voltage. Charge current Maximum charging current is limited by the mAh capacity of the cell or battery (as can be seen in the accompanying table) and the rating of the DC plugpack or power supply. So if you charge at 2.5A, the power supply or plugpack must be able to deliver this current. Note that most “transformer” type plugpacks cannot supply this amount of current while some “electronic” plugpacks (ie, those with a switchmode supply) may be able to. Construction The Versatile NiMH Charger is constructed using a 98 x 53mm PC board, coded 14109071. It is housed in a diecast box measuring 111 x 60 x 30mm. A fan heatsink (that’s fanshaped, not a heatsink with a fan!) measuring 55 x 105 x 25.5mm mounts on the case to ensure that the charger runs reasonably cool. Begin construction by checking the PC board for any defects such as shorted tracks and breaks in the copper. Check also that the hole sizes are correct. Holes for the DC socket and the 2-way screw terminals will need to be larger than the 0.9mm holes required for the other components. Also check that the corners have been shaped to clear the internal corner posts of the box and that the 6mm diameter access semicircle for Q1’s screw has been cut from the edge of the PC board. Install the resistors first. Use the resistor colour code table as a guide to each value or use a digital multimeter to check each resistor before inserting it into the PC board. Next, install the wire link, the diodes, the IC socket (for IC1) and IC2, taking care to orient each with the correct polarity. The capacitors can go in next. Note that the electrolytic types must be oriented with the polarity shown. If the 220mF 50V capacitor is higher siliconchip.com.au The complete charger, reproduced close to life size. Q1 is mounted under the PC board – you can just see its tab poking out the left side (between the terminal blocks). Inset below is the wiring of the NTC thermistor which attaches to the side of the box, monitoring temperature rise. 2-WAY HEADER PLUG HEATSHRINK SLEEVES (2) OVER WIRE CONNECTIONS OUTER HEATSHRINK SLEEVE OVER THERMISTOR, SPADE LUG & CONNECTIONS than the 14mm-high type we used, it may need to be mounted on its side (over ZD1 and D2) to allow room to fit into the box. Follow these parts with the 2-way and the 3-way headers for the jumper links, then install PC stakes for test points TP1-TP5 and for the TH2 connection. Also, install the PC stakes for S1, TP GND and TP +5V. The bases of each of the three LEDs should be 15mm above the surface of the PC board. Orient them with the anode (longer lead) toward the left of the PC board. LED1 and LED2 are the green LEDs while LED3 is a red LED. They ultimately are bent over at right angles at a point 10mm above the PC board, so that they fit through their matching holes in the side of the box. Next, solder the trimpots in place. They have different values so be sure to install the correct unit in each position. Note that the 10kW trimpots may be marked with 103, the 20kW with a 203 and the 500W with a 501 instead of the actual (Ohms) value. Regulator REG1 lies flat on the PC board with its leads bent over to insert into the appropriate holes. It is secured using an M3 screw and nut. Now install the DC socket and 2-way terminal screw connectors. At this point, apart from Q1, the PC board assembly is complete. This close-up of our prototype shows how Q1’s legs are bent up and soldered to the underside of the PC board. And here’s how the thermistor (TH2) is “heatshrinked” to a spade lug and then secured to the box side. siliconchip.com.au Mounting Q1 Q1, an IRF540 MOSFET, is not actually mounted on the PC board – it screws to the case 6mm underneath the board. As shown in the photo, its legs are bent up 90° and are soldered to the underside of the board (they just poke through the upper surface, underneath the 0.22W 5W resistor). You need to get the MOSFET into the right position so that when the completed PC board is placed in the box, a hole can be drilled through the NTC THERMISTOR (TH2) SPADE LUG case and heatsink. This is a little tricky to achieve because the centre leg, the drain, is actually shorter than its gate or source legs. Bend the drain up 90° 5mm out from the body of the MOSFET and similarly bend the source and gate legs up 90° 7mm out from the body. Now solder Q1 in position and turn the board over. The hole through Q1’s heatsink should be right in the middle of the access semicircle cut in the edge of the PC board. Boxing it Insert the PC board into the box and mark out the corner mounting holes in the base of the box and also the hole position for Q1. Drill these out to 3mm in diameter. Now place the heatsink squarely onto the base of the box and mark out the four corner mounting holes and the Q1 hole onto the back of the heatsink. Drill these out using a 3mm drill bit. The battery temperature thermistor (TH1) is mounted inside a modified battery holder so it contacts two cells. September 2007  39 the centre terminal of the switch and it doesn’t matter which terminal the other goes to – if it appears to work “upside down” (ie, off in the down position), you simply turn the switch through 180°. Assembly This view shows the mounting positions for the LEDs and switch (front) plus DC socket and thermistor (rear). Deburr the holes with a larger drill bit and in particular, make sure that the area around the hole inside the box for Q1 to mount on is smooth so that the insulating washer will not be punctured. Holes need to be drilled in the side of the box as shown in Fig.5. These holes are for the three LEDs and power switch on one side and the DC socket and TH2 thermistor mount on the other side. The end of the box adjacent to Q1’s hole needs a 9.5mm hole for the cable grommet (our photos in fact show a 12.5mm grommet – because we had one – but a 9.5mm grommet would be better). TH2 is mounted on a spade terminal using a 4mm length of heatshrink tubing. This then mounts on the box to detect heatsink temperature. First, cut the thermistor leads to 5mm length and solder two 50mm lengths of light-duty insulated wire to it. Insulate the joints with 1.5mm heatshrink tubing. Now attach the two free wire ends to the 2-pin header connector. The thermistor can be attached to the spade terminal with the heatshrink tubing. While you are about it, cut, solder and insulate a similar pair of wires for switch S1. These wires should be roughly 70mm long. One connects to Beware sheep in wolf’s clothing! Be careful if you buy NiMH batteries over the ’net – you might not quite get what you think you’re getting. We’ve seen several warnings about the ratings of rechargeable batteries coming from suppliers in Hong Kong and China (among other places) and readily available on eBay, for example. It seems some of Asia’s inscrutable manufacturers or distributors simply print whatever they think will sell their cells without too much angst. If that means labelling a 1500mAh cell (which of course is much cheaper to produce), as a 2500mAh, then so be it. Another source has warned about ‘C’ and ‘D’ cells which are actually ‘AA’ cells inside a ‘C’ or ‘D’ case. Even if you do pay a little more to buy your NiMH or NiCad cells from retailers in Australia (and that’s not always the case anyway), you have the availability of recourse if your purchase isn’t what it appeared to be or what you thought it should be. Try doing that with an email address in, well, where? The old maxim applies: if it looks too good to be true, it probably is! 40  Silicon Chip The heatsink and PC board are screwed to the bottom of the box, which (when completed) is then turned over and becomes the top side. The lid then becomes the base. Before mounting the heatsink, apply a thin smear of heatsink compound to its base. Then attach the heatsink to the box bottom with the M3 x 10mm screws and 6.3mm threaded plastic standoffs. Next, secure Q1 to the base of the box, along with its silicone insulating washer and insulating bush. We used an M3 x 10mm from the inside and a 6mm M3 tapped spacer on the outside. You could use just an M3 nut here but the exposed screw thread does not look as neat as the spacer – and besides, the spacer is easier to grip when tightening it up! The PC board is secured to the Nylon spacers using four M3 x 5mm screws. Before going any further, check to make sure that the metal tab of Q1 is in fact isolated from the metal box. With your multimeter on a mid-range ohms scale, connect one lead to the box and the other to Q1’s tab (or the cathode [striped end] of diode D1). The reading should be above 1MW. If it is low ohms, check that the insulating washer and bush are installed correctly and that the washer is not punctured. If you get a low reading, correct the problem before proceeding. Attach the side panel label to the box and bend the LED leads over to just protrude through the holes in the side of the box. The previously-prepared thermistor (TH2) attaches to the side of the box with an M3 x 5mm screw and nut. Its wires connect to the PC board as shown. The roughly-70mm-long wires from switch S1 (which sits directly over IC2) connect to the appropriate PC stakes and both the switch itself and the PC stakes are insulated with heatshrink tubing. Wire the terminals on the PC board for the battery and thermistor (TH1) using medium-duty wire. We used red siliconchip.com.au Parts List 1 PC board, code 14109071, 98 x 53mm 1 diecast box, 111 x 60 x 30mm (HB-5062) 1 fan type heatsink, 55 x 105 x 25.5mm 1 mini SPDT toggle switch (S1) 2 2-way PC-mount screw terminals 1 PC-mount 2.5mm DC socket 1 18-pin IC socket 5 2-way headers 1 3-way header 3 jumper shunts 4 PC stakes 1 2-way jumper connector 2 NTC thermistors (10kW <at> 25°C (TH1, TH2) (Jaycar RN-3440 or equivalent) 1 4-way (or 6-way) automotive connector 1 9.5mm grommet 4 small adhesive rubber feet 1 50mm length of 1.5mm diameter heatshrink tubing 1 50mm length of 4mm diameter heatshrink tubing 4 6.35mm Nylon M3 tapped spacers 6 M3 x 5mm screws 5 M3 x 10mm screws 1 M3 x 6mm tapped spacer 2 M3 nuts 1 6.4mm spade lug chassis hole mounting 1 TO-220 silicone insulating washer 1 3mm TO-220 insulating bush 1 battery holder to suit cells to be charged 2 cable ties 30mm length of 0.8mm tinned copper wire 120mm lengths of red, black, green and yellow medium-duty hookup wire 120mm lengths of red and black light-duty hookup wire Heatsink compound for battery positive, black for battery negative and yellow and green wires for the thermistor wiring. These pass through the cable grommet and into the terminals. Because we wanted to make the charger adaptable to other batteries, the other ends of the wire connect to an automotive connector plug and socket which then connects to the battery holder and thermistor. For a permanent connection, the connector could be omitted, with the battery holder/thermistor wires going straight to the appropriate places on the battery holder. Ensure the connections to the thermistor are sleeved with heatshrink tubing to prevent any shorts to the battery holder terminals. The thermistor needs to be mounted in the battery holder so it contacts at least one of the cells under charge. We drilled a hole in a 4xAA cell holder so that the thermistor is sandwiched between the cells in the holder (see photo). Depending on the type of battery holder you use (or none at all) your cells may need to have the thermistor mounted with some hook and loop tape (eg, Velcro) around the cell body. siliconchip.com.au Semiconductors 1 PIC16F88-I/P microcontroller programmed with NiMHCharger.hex (IC1) 1 LM358 dual op amp (IC2) 1 IRF540 Mosfet (Q1) 1 LM317T adjustable 3-terminal regulator (REG1) Setup With IC1 still out of its socket, connect your plugpack to the DC socket (positive to the centre of the plug) and turn on. The power LED should light. Connect a multimeter between TP +5V and TP GND and adjust VR6 for a reading of 5.0V. Now check that there is 5V between pin 14 and pin 5 of the IC1 socket. If this is correct, switch off power, wait a short time and then install IC1. Adjustments The thermistor is adjusted using VR5, so that the voltage between TP5 and TP GND is 2.5V when the thermistor is at 25°C (ie, if the ambient temperature is 25°C, adjust VR5 so that the voltage between TP5 and TP GND is 2.5V). If the ambient is 20°C, set it for 2.8V or to 2.2V for 30°C. Both the timeout and dT/dt values are adjusted using trimpots VR1 and 2 3mm green LEDs (LED1,LED2) 1 3mm red LED (LED3) 1 16V 1W zener diode (ZD1) 1 1N5822 3A Schottky diode (D1) 1 1N4004 1A diode (D2) Capacitors 1 220mF 50V PC electrolytic 1 100mF 16V PC electrolytic 2 10mF 16V PC electrolytic 1 220nF MKT polyester (code 0.22mF, 220n or 224) 2 100nF MKT polyester (code 0.1mF, 100n or 104) Resistors (0.25W, 1%) 1 10kW 3 470W 1 9.1kW 1 120W 1 8.2kW 1 47W 3 1kW 1 0.22W 5W Trimpots 1 500W horizontal trimpot (code 501) (VR6) 4 10kW horizontal trimpots (code 103) (VR1-VR4) 1 20kW horizontal trimpot (code 203) (VR5) VR2. Test points have been included to allow easy measurement. The timeout can be set from 0-25 hours. In its simplest arrangement, the voltage at TP1 gives the timeout in hours. So, for example, if the VR1 setting gives 5V between TP1 and TP GND, the timeout is 5 hours. If you need longer than this time period, then you can install LK1. This acts as a x5 multiplier so that the time period is increased. So, for example, with LK1 installed and VR1 set so that TP1 is 5V, the timeout will be 25 hours. Similarly, if TP1 is 1.2V, then the timeout will be six hours (5 x 1.2). Refer to the “NiMH charger settings” section to work out the timer value required. The table at the end of this article also shows typical settings for various capacity cells. Temperature rise detection (dT/dt) can be adjusted from between 0.5°C per minute rise to 5°C per minute rise. This is done using VR2 and measuring between TP2 and TP GND. There is a direct correlation between the voltage and the setting: a setting of 2.5V at TP2 will set the dT/dt value September 2007  41 10mm LONG M3 MACHINE SCREW 4 x 5mm LONG M3 SCREWS PC BOARD INSULATING BUSH 4 x 6.35mm M3 TAPPED SPACERS Q1 SILICONE WASHER 6.35mm LONG M3 TAPPED SPACER 4 x 10mm LONG M3 SCREWS FAN TYPE HEATSINK Q1 MOUNTING HOLE HOLE FOR CABLE GROMMET 9.5mm DIAM 3.0mm DIAMETER 6.0mm DIAMETER 10.5 6 37 LID SIDE 48 CL LID SIDE 59 Q1 MOUNTING HOLE 70 Q1 MOUNTING HOLE 3.0mm DIAMETER 6.35mm DIAMETER ALL DIMENSIONS IN MILLIMETRES Fig.4 (top) shows the way the PC board assembly and Q1 are mounted in the box, while Fig.5 (above and right) gives you all the drilling details for the case. to 2.5°C per minute rise. Initially set VR2 so that the voltage at TP2 is 2.5V. Option Installing links LK2 and LK3 enable top-up and trickle charge respectively. If you want top-up only, install LK2; if you want both top-up and trickle charge install LK2 and LK3; if you want trickle without top-up, install LK3 only. If any of these two links are selected, 3.0mm DIAMETER 9.0 8.0 LID SIDE you will need to set the trickle charge rate. The top-up charge is fixed at four times the trickle charge. Trickle charge, trimpot VR3 allows adjustment from 500mA down to less than 20mA. Note that some battery packs have a thermistor already installed. This should not be used unless it has the same resistance characteristics as the one specified. The thermistor should measure about 10kW at 25°C and the 32 71 resistance should fall with increasing temperature. NiMH charger settings Before setting up the charge, timeout and trickle settings you need some extra snippets of information. You will need to know the Ah rating (or mAh) of the cells or the battery – this will normally be printed on the side of the cells or battery. You also need to know the nominal Resistor Colour Codes o o o o o o o o No. 1 1 1 3 3 1 1 42  Silicon Chip Value 10kW 9.1kW 8.2kW 1kW 470W 120W 47W 4-Band Code (1%) brown black orange brown white brown red brown grey red red brown brown black red brown yellow violet brown brown brown red brown brown yellow violet black brown 5-Band Code (1%) brown black black red brown white brown black brown brown grey red black brown brown brown black black brown brown yellow violet black black brown brown red black black brown yellow violet black gold brown siliconchip.com.au Battery or cell capacity Trickle Current (LK3 in) Top up with LK2 will be 4 x trickle setting Slow Charge (15h) Standard Charge (5h) Fast Charge (1.5h*) (* at or below 2.5A) (VR1 <at> 1.5V, LK1 out) (VR1 <at> 3V, LK1 in) (Do not select top-up) (VR1 <at> 5V, LK1 out) (Top-up not recommended) 200mAh 10mA (VR3 <at> 100mV) 20mA (VR4 <at> 20mV) 60mA (VR4 <at> 60mV) 200mA (VR4 <at> 200mV) 400mAh 20mA (VR3 <at> 200mV) 40mA (VR4 <at> 40mV) 120mA (VR4 <at> 120mV) 400mA (VR4 <at> 400mV) 700mAh 35mA (VR3 <at> 350mV) 70mA (VR4 <at> 70mV) 210mA (VR4 <at> 210mV) 700mA (VR4 <at> 700mV) 900mAh 45mA (VR3 <at> 450mV) 90mA (VR4 <at> 90mV) 270mA (VR4 <at> 270mV) 900mA (VR4 <at> 900mV) 1000mAh 50mA (VR3 <at> 500mV) 100mA (VR4 <at> 100mV) 300mA (VR4 <at> 300mV) 1.0A (VR4 <at> 1.0V) 1500mAh 75mA (VR3 <at> 750mV) 150mA (VR4 <at> 150mV) 450mA (VR4 <at> 450mV) 1.5A (VR4 <at> 1.5V) 2000mAh 100mA (VR3 <at> 1.0V) 200mA (VR4 <at> 200mV) 600mA (VR4 <at> 600mV) 2.0A (VR4 <at> 2.0V) 2400mAh 120mA (VR3 <at> 1.2V) 240mA (VR4 <at> 240mV) 720mA (VR4 <at> 720mV) 2.4A (VR4 <at> 2.4V) 2500mAh 125mA (VR3 <at> 1.25V) 250mA (VR4 <at> 250mV) 750mA (VR4 <at> 750mV) 2.5A (VR4 <at> 2.5V) 2700mAh 135mA 270mA 810mA (VR3 <at> 1.35V) (VR4 <at> 270mV) (VR4 <at> 810mV) 2.5A (1.6h) (VR4 <at> 2.5V) (VR1 <at> 1.6V, LK1 out) 3000mAh 150mA 300mA 900mA (VR3 <at> 1.50V) (VR4 <at> 300mV) (VR4 <at> 900mV) 2.5A (1.8h) (VR4 <at> 2.5V) (VR1 <at> 1.8V, LK1 out) 3300mAh 165mA 330mA) 990mA (VR3 <at> 1.65V) (VR4 <at> 330mV (VR4 <at> 990mV) 2.5A (2h) (VR4 <at> 2.5V) (VR1 <at> 2.0V, LK1 out) 4000mAh 200mA 400mA 1.2A (VR3 <at> 2.0mV) (VR4 <at> 400mV) (VR4 <at> 1.2V) 2.5A (2.4h) (VR4 <at> 2.5V) (VR1 <at> 2.4V, LK1 out) 4500mAh 225mA 450mA 1.35A (VR3 <at> 2.25V) (VR4 <at> 450mV) (VR4 <at> 1.35V) 2.5A (2.7h) (VR4 <at> 2.5V) (VR1 <at> 2.7V, LK1 out) 250mA 500mA 1.5A (VR3 <at>2.5V) (VR4 <at> 500mV) (VR4 <at> 1.5V) 2.5A (3h) (VR4 <at> 2.5V) (VR1 <at> 3.0V, LK1 out) 5000mAh 450mA 900mA (VR3 <at>4.5V) (VR4 <at> 900mV) 9000mAh 2.5A (5.4h) (VR4 <at> 2.5V) (VR1 <at> 1.08V, LK1 in for x5) 2.5A (5.4h) (VR4 <at> 2.5V) (VR1 <at> 1.08V, LK1 in [x5]) This table shows typical settings of our Fast NiMH Charger for a range of cell capacities. battery voltage or the number of cells connected in series, the plugpack voltage and the plugpack current rating. Note that when using slow charging rates (eg, charging over 15 hours) the top-up current will be greater than the charge rate. In this case, do not enable top-up. At faster rates (eg, charging over five hours) the top-up may be similar to the charge rate and again top-up is not recommended. the charge current. So a 2500Ah battery charged at 1A should be charged after 2.5 hours, which means that the timeout is set to 3.75h. This would be a 3.75V setting at TP1. Any changes to the timeout value when charging will not take effect until power is switched off and on again. This includes changes to the LK1 setting. Any changes to other settings will be incorporated in the charging. Timeout Trickle Timeout should be set to 1.5 times the Ah rating of the battery divided by siliconchip.com.au The trickle charge requirement is calculated by dividing the amp hour rating of the cells by 20. So, for example, if the cells are 2400mAh, then the trickle current should be 120mA. When testing, the charger may stop before full charge or it may tend to overcharge the batteries. Under-charge will be evident if the charging period is too short and the batteries do not deliver power for the expected period. In this case, turn VR2 further clockwise to increase the dT/dt value. If the battery pack appears to get hot after full charge has been reached, turn VR2 back anticlockwise for a lower SC dT/dt value. September 2007  43 SERVICEMAN'S LOG The blind leading the blind Remote-controlled security blinds are not normally my scene but I’ll give anything a go once. So was this a case of the blind leading the blind or was it simply blind man’s bluff? Some years ago, a friend of ours had a large house fitted with security sun blinds. These are all remote controlled and block out the sun as well as the burglars. In all, there are 17 of these babies installed, some as large as 2 x 2m. They look great, are easy to use and work quietly and efficiently. What’s more, you can control each window or door shutter individually or all simultaneously with a master remote control. The only problem was that these 44  Silicon Chip had now all stopped working. And because they would be very expensive to replace, I volunteered to see if I could help. The first problem we encountered was how to disassemble them, as there were no service manuals available. That meant that we had to figure it out as we proceeded. Removing four rusty screws from the top cover gives access to the top of the roller shutter. We then found that when 240V power was applied to the blind, it would emit a whistling noise but nothing else happened. We then discovered that there was one rivet at one end which had to be removed and we did this by drilling it out. This rivet can be at either end, depending on whether the motor is at the lefthand end or the righthand end. Once it’s removed, you can push the plastic end in, drop the motor case off its axle and let it drop out of its case. Next, making sure that the 240V is off, you remove a Philips screw on the other end to release a plastic core. This is then slid out, after which you can unplug the motor and power input and remove a clear plastic tube containing the control electronics. This consists of two interconnected PC boards – one is the RF remote control receiver, while the other is the power supply and controller. Now that we had the boards out on the bench, it was time to find out what was wrong. Both were doublesided boards with surface-mounted components and were nicely made. I tried drawing out a circuit diagram but because of the surface-mounted ICs, it was bit crude. However, I did establish that the 240V went through a capacitor and resistor before being rectified and smoothed to run a couple of 12V relays. It also provided a 5V rail to run all the microchips and the remote receiver. There was also a little piezo buzzer on board, as well as a light sensor and wheel which worked with a counter to establish where the motor was in relation to the blind. I checked that the motor was OK and then measured the power supplies. These were low, so I replaced the electrolytic filter capacitors. In most cases these had no effect though some improved matters a little. Next, I checked the series resistor for the 240V rail and this too was OK, I then looked at the axial tubular capacitor in series with it. This was a 680nF polyester capacitor rated at only 220V AC (the mains voltage used in Italy where these units are made). A quick check confirmed that this capacitor was low in value and that proved to be the case with all the other units. Replacing it restored the voltage rails to their correct levels. The only problem was that I couldn’t get a capacitor rated at 240V to fit in the tight space (only 40mm in diameter). In the end, we got some large chunky capacitors and then slots in the plastic tube and hotsiliconchip.com.au Items Covered This Month • Loewe Calida 56847 TV set, Q2300 chassis • Philips 15PF9936/69 Flat TV set, LC03A chassis • Grundig Xentia 42PW1105510 TOP TV set (P6 chassis type H8X) glued each one to the case after fitting a couple of extension leads. Re-assembly wasn’t much fun. It all had to be done in-situ, balancing on top of a ladder with very little room and using your third hand to do the work. In practice, the two boards had to be shoe-horned back into the small clear case and all the leads, including the aerial, threaded through. The worst part involved assembling the geared propeller to fit in between the photoelectric sensors. There were also problems when it came to connecting the earth lead as it is all slid back inside the motor cylinder. And on some of them, the rivets that held felt spacers in place had to be removed so that the assembly could slide out of the case in the first place. Afterwards, these had to be riveted back in place. In most cases, it required two people to refit the motor cylinder back onto the axles. A self-tapping screw was used to replace the original rivet that had to be removed in order to remove the motor. In some cases too, once the whole thing was back together, the remote siliconchip.com.au control had to be reprogrammed to set the end stops up properly. This required pressing a sequence of buttons on the remote for a period of time, to allow the blind to go up and then down (fortunately, we had the instructions for these). An additional small problem was that a lot of the remote controllers wouldn’t work because the negative contact for the battery had become corroded. Cleaning these contacts was all that was required to fix these remotes. In the end, we were quite proud of ourselves for having diagnosed and fixed all the problems in these blinds, especially as we hadn’t had any previous experience with them. It’s amazing how quickly we were able to do this rather complex job by the time we got to the 17th blind! Upside down computer I recently received a phone call from a rather frantic lady, the problem being that the picture on her computer monitor was upside down. It turned out to be a good friend of ours who had just gone back to work after being retired for a few years and this was her first day in the job. She wasn’t all that proficient with computers and was in fact rather hesitant with them but felt that she could manage – it would just be a matter of gaining some experience. Adding to her stress on this day was the fact that this was her boss’s virtually brand new computer. Anyway, there she was, alone in charge of the business and doing pretty well on the computer when the phone rang. As she picked it up, the cord became entangled with a stack of books which fell onto the keyboard. She picked them up but didn’t notice until after the telephone conversation had finished that the picture on the monitor was now upside down! As she soon discovered, trying to use a mouse when the display is upside down is pretty tricky and sitting upside down is not really an option either – at least not in the long term. She tried to work out what keys had been pressed but was unfortunately unable to retrace the sequence. She then decided to turn the computer off and reboot it and was very relieved to see that the opening messages on the screen were all the correct way up as the machine went through the BIOS routines. However, much to her dismay, as soon as it reached the XP log-on screen, it was once again upside down. September 2007  45 Serr v ice Se ceman’s man’s Log – continued That was when she phoned to see if I could help. Unfortunately, this was a new one to me but I agreed to see what I could do! From the information she had given so far, I could eliminate the monitor itself and any other hardware. It just had to be a software problem. I asked what she was doing just prior to the accident and she replied she was looking at emails in Outlook Express. I initially thought that maybe she had opened an email with malicious software. However, this computer had a firewall, anti-virus and malware software protection and it was all enabled. The computer, in fact, was almost brand new and had hardly been used. It was getting too hard for her to check the various software settings while the display was upside down, so I got her to actually turn the monitor upside down. That made her life much easier and I now told her to look in the display settings for some button or tick box that would rotate the display upside down. We went from menu to menu and even went into the advanced settings but nothing showed up. I then remembered that some display cards have their own display manager utility. This is normally shown in the system tray at the right46  Silicon Chip hand end of the toolbar. We checked that but again drew a blank so I then got her to launch the System Configuration Utility (Start –> Run –> msconfig) and switch off all the Start-Up programs. The machine was then rebooted but still no joy. While she was doing this, I “Googled” the symptoms and was immense­ ly cheered to see a lot of hits (507,000). At least we were not alone. The information showed we had been on the right track but just hadn’t quite gone far enough. In this case, under the advanced display settings, you have to go to the “Intel Extreme Graphics” tab, then to “Properties and Display Settings”. And that’s where the setting is – just uncheck “Enable Rotation” and that fixes the problem. You could imagine my friend’s relief but how did it happen? Well, there is a “Hot Key” sequence to enable this setting, involving CTRL, ALT and an ARROW key. However, she wasn’t game to try it again and I don’t blame her. Now who would ever want to use such a feature? It sure beats me. The recall job As Loewe service agents, we have been busy dealing with a factory safety recall to all models using the Q2300 chassis. It is only a minor service recall check involving the reseating and resoldering of C0541, so that it is 1mm above the PC board. While we are at it, we normally resolder C0531, C0542 and C0544 as well. Because it is a free service, we have had a few people try to take advantage of the recall. In particular, these people have had other unrelated faults and have demanded that they be fixed for free – even though the symptoms have absolutely nothing to do with the safety recall. Recently, we had a service call booked for a Mrs Johnston (not her real name), to just do the service recall check on a Calida 56847. When I arrived, I switched the set on in front of Mrs Johnston, just to make sure that the set was otherwise working OK. To my surprise, the set was stone motherless dead and the initial silence was stunning. My look must have said it all, at which point she confessed unashamedly that the set hadn’t been switched on since it stopped working over six months ago. Despite this, I took the back off and did all the modifications but I could also see that the power supply had failed, which meant it would have to go back to the workshop. I informed her of this and the likely charges involved and she indicated that she was quite happy for us to go ahead with the repair. Back at the workshop I did the full repair to the switchmode power supply and the line output transistor but when I switched it on, there was a loud bang due to massive arcing from the ultor cap. Replacing tuning capacitor C0531, capacitors C0542 & C0544 and the flyback transformer stopped the arcing but the set still had an east-west pincushion fault. I then replaced transistor Q0586 and coils L0590, L0537 & L0538 but there was still no east-west correction. A check with the scope showed the waveform coming into the Q0582 differential pair but no output waveform at 8D or 8E. I then checked every component in the east-west circuit but could find nothing wrong with any of them. Further checks revealed that there was no DC voltage on Q0586’s collector, nor on Q0585’s collector or Q0593’s emitter. I also expected pulses from pin 2 of the flyback transformer (T0531) to be rectified by diodes D0589 & D0590 and smoothed by capacitor C0590. However, the CRO showed that the waveform on pin 2 was negative with respect to ground, which meant that this circuit couldn’t possibly work. It was then that I noticed that the earth track to pin 9 of the flyback transformer had been deliberately cut at some time in the past – obviously by someone using a hobby knife. Bridging this cut finally produced the required positive pulses and voltages and completed the repair. By why had this been done? It was definitely not a production modification. While all this had been going on, Mrs Johnston had been phoning regularly to ask “Is it ready? Is it ready?”. Well, we finally phoned to inform her that it was indeed ready and advised her as to the service cost. She reluctantly accepted this and we arranged for the set to be re-delivered. However, after the set had been siliconchip.com.au No picture A beautiful 38cm LCD TV was brought in with the complaint that there was no picture. This set was a 4-year-old Philips 15PF9936/69 Flat TV using an LC03A chassis. Apparently, the problem started with the set being difficult to start. It would only come on by repeatedly pressing the power switch on the remote control but now even that no longer did the trick. I stripped it down to find it was structurally all OK. In particular, I carefully checked the screen because I am only too conscious of the price of spare parts. This set cost over $700 new but could probably now be replaced for about half this price. This Philips set had an XGA active matrix cold cathode TN-type TFT panel giving a 1024 X 768 resolution but it is only a 38cm 3:4 display. The display is actually an LG Philips LC151X01 (C3PI). The sound and remote control were both OK and the LED display was a solid green; ie, showing no error codes. In fact, apart from the obvious no picture, the only other clue I had was a faint ticking noise emanating from deep inside the unit. I could also see no sign of the backlights coming on. I started by measuring the voltage outputs from the power supply, comparing them with those shown in the service manual. All were OK (12V, 5V, 8.3V, 5.4V, 3.5V, 3.3V, 2.5V & 1.8V), except that I noted that PAN-VCC +5V would only come on for a few seconds from the 7005 and then disappear. The 7005 is unusual in that it is a switchable FET inside an 8-pin DIL IC case. It switches the +5V rail and its gate (on pin 4) is driven by transistor Q7004, the latter turned on by a PANEL-PWR-CTL signal from pin AD22 of a Jay RF_SiliconChip_60x181mm.qxd 30/3/07 2:12 PM Page 1 ASM SCALAR microprocessor (IC7402). www.ajdistributors.com.au reinstalled, Mrs Johnston’s attitude suddenly changed. She was no longer prepared to pay and was complaining that the set had never worked properly and that it had blown up with “sparks and explosions”. We told her about the bodgy “repair” by someone else but she denied all knowledge of this. Furthermore, she had actually phoned Loewe with her complaints while we were on the way to reinstall the set. We phoned Loewe and they said they would pay for the repair which we thought was rather generous. On the other hand, we were pretty disgusted with Mrs Johnston and her antics, I can tell you. » MULTI-LAYER CAPACITORS » BROADBAND CAPACITORS » SINGLE LAYER CAPACITORS » RESISTIVE PRODUCTS » TRIMMER CAPACITORS » AIR TRIMMERS » HIGH VOLTAGE » NON-MAGNETIC TRIMMERS » CERAMIC CHIP TRIMMERS » GLASS/QUARTZ » MINIATURE TRIMMERS » MRI & NMR INDUSTRIES » CURRENT SENSE » RESISTORS » NON-INDUCTIVE » HIGH VOLTAGE ISTRIBUTORS CONTACT US FOR OUR LINE CARD OR DATA SHEETS Fax.+61 8 8281 2427 Ph.+61 8 8285 4889 11 Acrylon Road PO Box 62 Salisbury South SA 5106 Salisbury South SA 5106 sales<at>ajdistributors.com.au www.ajdistributors.com.au This IC also switches the backlight, as well as switching the backlight inverter power supply from pin AF22. There are two known modifications for this set, one being C2920 (470mF 25V) which filters the 11V rail to IC regulator 7920 which produces +3.5V (this capacitor has been known to leak onto the TV tuner board). This modification was unnecessary in this set as indeed was the second modification for the IPS inverters (R49 is now 3kW and R29 a link) – the set here is a TN type and uses a different circuit. Despite the ticking, I could find no short circuits. I unplugged socket 1506 supplying the LVDS data to the display panel and immediately the 5V rail stayed on and ELECTRO CHEMICALS Chemical Technology siliconchip.com.au • Dust Off • Freezing Spray • Electronic Cleaning Solvent No. 1 • Electronic Circuit Board Cleaner • Electrical Contact Cleaner Lubricant • Video Head Cleaner • Ultrasonic Bath Cleaner • Isopropyl Alcohol • Protek • Contact Treatment Grease • Contact Treatment Oil • Solvent Diluted Oil • Contact Cleaning Strip • Circuit Board Lacquer • Q43 – Silicon Grease Compound • Heat Sink Compound Contact us to find your nearest distributor: sales<at>rfoot.com.au Tel: 02 9979 8311 Fax: 02 9979 8098 Richard Foot Pty Ltd, 14/2 Apollo Street,Warriewood NSW 2102 September 2007  47 Serr v ice Se ceman’s man’s Log – continued the backlights also came on permanently. In addition, the ticking noise stopped. This wasn’t looking good as it pointed to the display. As a further test, I reconnected socket 1506 and shorted out the 7005 FET IC pins 1, 2 & 3 to pins 5, 6 & 8. This brought the picture back on, so the display was possibly OK after all! Next I tried shorting the NPN driver transistor (Q7004). This also brought the picture back on! And if I released the short, more often than not the picture stayed on! This gave me the opportunity to get into the Service Alignment Mode (SAM) via the remote (062596 and i+ [info]). This reported errors 22 and 29 and the service manual told me that these are due to scalar protection being active (IC7351) and a scalar microprocessor I2C error from IC7753 or IC7064. However, when I followed this up, I soon realised that these error codes were due more to the way I had switched the set on rather than an actual fault. When the errors were cleared, the set would then run for hours but when I switched it off, it wouldn’t start unless I overrode the FET switch – and then the same error codes would reappear. My feeling was that the problem was in the display itself, so I removed the LG Philips LC151X01 (C3PI) TN and removed the metal cover over its PC board. I then reconnected it to the rest of the set and switched it on in the normal way. This time I could hear the ticking from the display panel more loudly than before. I now checked for shorts but could find none. Unfortunately, no circuit diagram is available for this panel but I could see a fuse on the 5V PAN-VCC rail from pin 40 and various surface mounted components but couldn’t work out what might be causing the problem. Was it something as simple as a decoupling capacitor arcing over? Who knows? Subsequent enquiries revealed that the panel is just not available and even if it were, it would probably be too expensive. In the end, I reassembled the set with a lead connected to the base of Q7004 sticking out the back. Touching the bared end of this lead against one of the case screws allowed you to switch the picture on but as time went by it became harder and harder to turn it on. And so, after all my work, the set was a write-off. Grundig plasma TV Recently, I did a service call somewhere near the back of Bourke on a Grundig plasma TV. Now normally, I would just pick up the set and bring it back to the workshop. However, this set was a Grundig Xephia 42PW1105510 TOP (P6 chassis type H8X) and the owner was insistent that I try to fix it in-situ. The fault symptom was that the set was trying to start but was cutting off. Issues Getting Dog-Eared? Sometimes, however, a complete picture and sound would come on before it cut off and this was good news for me because I was able to photograph the picture using a digital camera and study it for any display problems. I found none. As is usual these days, it is the logistics that take all the time. First, you have to find a large enough work space with sufficient padding to lay the 106cm screen face down. That done, an electric screwdriver is necessary to remove about 50 screws in order to remove first the stand and then the back. Once the back was off, I reconnected the power supply and propped up the edge of the screen so that I could monitor the picture using a strategicallyplaced mirror. I then switched the set on and it immediately began pulsating intermittently. It was time for some percussive diagnostics. I found that by tapping the boards gently, I could accentuate the problem and eventually tracked the source directly to the sub-power supply board. I removed this board (R84.194R-3) and it was immediately apparent that diode D1014 was getting very hot and was, in fact, dry jointed. In fact, it was so bad that I could remove it using just a pair of pliers. The diode still actually measured OK but I didn’t want to risk it so I fitted a brand new 1N4007. This diode supplies 12V to the power relay and drive circuit and replacing it fixed the fault. I left it working. However, a couple of hours later, the client phoned me to say that the symptom had reoccurred. I went back the next day but the fault was now in hiding. When I got it back to the workshop, it took two hours to show up and the same diode was overheating. I replaced the 12V zener diode after the 10W resistor but it made no difference. But when I replaced the 1mF smoothing capacitor at the same point, it brought the voltage up to 12V and SC finally fixed the problem. Keep your copies safe with our handy binders 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. 48  Silicon Chip siliconchip.com.au 4 Way HDMI Multimedia Splitter Connect a High Definition HDMI device to up to four displays. Supports HDCP compliant devices and 720 or 1080p resolution. It accommodates up to a 5m length cable, has a single link range of 1920 x 1200 and a vertical frequency range of 60Hz. Plugpack included. Cat. AC-1696 $299 New Car Amplifiers This new range features insert-type connectors, pass through RCA outputs, variable high and low pass filters and variable bass boost. See website for full specifications. 4 x 100WRMS Full Range Car Amplifier • 4 x 130WRMS <at> 4 ohms • 4 x 490WRMS <at> 4 ohms • 2 x 380WRMS <at> 2 ohms Produces 550W when bridged. Cat. AA-0456 $399 5 Channel Full Range Car Amplifier • 4 x 60WRMS + 1 x 225WRMS <at> 4ohms • 4 x 90WRMS + 1 x 340WRMS <at> 4 ohms • 2 x 180WRMS + 1 x 340WRMS bridged <at> 4 ohms Cat. AA-0458 $499 Windows Media Centre Remote Control New Kit Fast Ni-MH Battery Charger Kit Refer: Silicon Chip Magazine September 2007 A truly versatile charger, capable of handling up to 15 of the same type of Ni-MH or Ni-Cd cells. Build it to suit any size cells or cell capacity and set your own fast or trickle charge rate. It also has overcharge protection including temperature sensing. Ideal for R/C enthusiasts who burn through a lot of batteries. Kit includes PCB & all specified Cat. KC-5453 electronic components. Heatsink, case & battery holder not included. $39.95 Adaptive Turbo Timer Refer: Silicon Chip August 2007 Ordinary turbo timers with a fixed time setting don't adapt to engine use and can turn off too early if the car has been driven hard, or run your engine overtime if the car has only been pottering about. This excellent kit overcomes the problem by constantly monitoring engine load and adjusting the timer run-time to suit the turbo's cooling need. Maximum cool down can be adjusted from a few seconds to 15 minutes and the timer will automatically work within this range. Indicators show when the timer is in operation, cooling period, and sensor level. Cat. KC-5451 Kit supplied with silk screened $44.95 PCB and all electronic parts. OUR BONDI STORE IS RELOCATING 1000WRMS Monoblock Amplifier • 1 x 1000WMRS <at> 1 ohm • 1 x 600WRMS <at> 2 ohms • 1 x 1800WRMS <at> 2 ohms linkable 125 Bronte Road, Bondi Junction Phone: (02) 9369 3899 $399 TELEPHONE> 1800 022 888 New 5.8GHz Wireless Cameras Avoid the clutter on the 2.4GHz band with these 5.8GHz cameras and receivers. The system has a range of about 100m (clear line of sight) and also has audio capability. Plugpacks supplied. Not ACMA approved. Wireless CMOS Camera with 4 Ch Receiver Plugpacks for both camera and receiver included. • Dimensions: 25(L) x 24(W) x 24(H)mm • Sensor: CMOS 628 x 582 pixels Cat. QC-3570 $269.95 Wireless CMOS Camera This camera is suitable as a spare or replacement for our Cat. QC-3571 QC-3570 (shown above) $179.95 5.8GHz wireless system. CMOS IR Camera with 4 Ch Receiver Cat. QC-3572 This system's camera has an IR illuminator for low light and night use. • 78(L) x 45(Dia) x 83(H)mm • Sensor: 1/3" CMOS 628 x 582 pixels $299 Wireless CMOS Camera with IR Illuminator Suitable as an additional or spare camera for our QC-3572 or QC3570 (shown above) camera with receiver systems. • 78(L) x 45(Dia) x 83(H)mm Cat. QC-3573 • Sensor: CMOS 628 x 582 pixels $199 This new large premises has ample off street parking Cat. AA-0460 FOR INFORMATION AND ORDERING A Windows Media Centre PC can revolutionise your home entertainment and this remote will put you in control. The remote will let you control the system as easily as you now control the TV. • Instant playback Cat. XC-4889 • Control the Media Center's $24.95 TV and video functions • Requires 3 x AAA batteries, available separately • 210mm long. Better. More Technical INTERNET> www.jaycar.com.au Wireless IR CMOS Camera Suitable as a spare or additional camera to suit: QC-3572 or QC-3570 camera and receiver systems. • 41(L) x 35(W) x 39(H)mm • Sensor: CMOS 628 x 582 pixels Cat. QC-3575 $169.95 1 Digital Video Recorder Package Deals Digital Surveillance Event Recorder Surveillance on a budget. It works by recording images to an SD memory card as JPEG or video AVI when motion is detected. View the events on a monitor or any media player that accepts SD cards. Two cameras are included with IR LEDs for low-light use, are housed in extremely robust Cat. QV-3098 aluminium cases and are mounted on ball swivel brackets. $349.95 AV-GAD 5 Zone Alarm Package AV-GAD's known reliability and advanced technology make this system sought after by commercial and domestic installers. This 5 zone alarm is ideal for a complete advanced home security system and has everything to do it yourself. It has a built-in dialer for remote alarm notification and includes the panel, keypad, 2 x PIRs, glass break sensor, 2 x reed switches, backup battery, mains power supply, internal siren, strobe light, external siren with cover, warning stickers, 100m roll of alarm cable and 30m roll of figure 8 cable. Cat. LA-5484 $599 Active Matrix TFT Security Monitors These rugged, high performance TFT monitors are purpose-built for security applications and include a toughened front panel to protect the TFT panel from damage. They can display up to the maximum resolution defined by CCIR standards (720 x 576 / 525 x 625TV Lines) via the incorporated I/P (interlaced to progressive scan) converter. See website for full specs. Two models available: QM-3419 17" Version QM-3420 19" Version s version 8 Zone vailable also a 8 $999 LA-548 Cat. QM-3419 $499 Toughened Glass Protected Screen Quad Processor with 2 CMOS Colour Cameras & Remote Control Add a monitor and you have a complete surveillance system. With 2 colour IR cameras, this processor turns any standard TV or monitor into a mulitplexer. It can display a single camera view, or combinations of different camera views including Cat. QV-3095 one or two picture-in-picture, $349 or automatic sequencing. DVR Camera Kit with Colour Dome and IP56 Camera 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 a dome and outdoor IR camera with bracket, mounting hardware, power supply, 14m camera connect cable, software, USB interface lead & user manual. Cat. QV-3085 Was $999 SAVE $50 $949 Includes 250GB HDD Colour may vary QC-3086 Extra Colour Weatherproof IR Camera Was $199, Now $159, Save $40 QC-3087 Extra Colour Mini Dome Camera Was $149, Now $119, Save $30 Steelmate Car Alarm with Remote It features code hopping remotes, a shock sensor, door and boot trigger and a 125dB battery backup siren and more! It also has a valet parking or car wash feature that enables the system to remain disarmed, but the door and boot release will work normally. • Compatible with most factory and Cat. LA-9008 aftermarket central locking and $149 remote boot release systems. • Extra circuits for fuel and ignition cutout. 2 Cat. QM-3420 $599 B&W Video Door Phone Identify callers without them even knowing. The system can accept up to 3 optional monitors. With the optional electronic door strike, (LA-5078 $44.95) you can unlock the door at the touch of a button, with a 1.5 second latch, so your visitors have time to get in. Other features include a Panic button, Silent monitor feature, AV out option, 15m interconnecting cable, volume and contrast controls, and plugpack power supply included. See our full range in-store Pan Tilt Day/Night Vision Camera System with Hand Held Monitor Is small enough to be carried and features audio, and an AV output for interface with a recording device. The 380TVL camera has an operating range of 100m (line-of-sight) and up to 5 metres night vision capability. Mains plugpacks are provided for both the camera and monitor. • Monitor size: 68(W) x 130(H) x 26.5(D)mm • Approx. camera size: 105(W) x 120(H) x 110(D)mm Remotely pan/tilt the camera from the hand-held monitor Cat. QC-3602 $149 Cat. QC-3279 Colour CCD Camera Pro Style $399 Delivers a flickerless digital colour image via a Sony CCD image sensor. Suitable for high-end surveillance installations, See our the flickerless ability makes it catalogue for ideal for applications that lenses to suit demand a high quality, stable, no compromise picture. Also features Cat. QC-3309 a high sensitivity microphone plus $149 auto iris lens controller. Remote Controlled Central Locking System Unlock your car doors as you approach. This system is easy to install and comes complete with wiring loom, two remote keyfobs and is backed with a 12 month warranty. Was $59.95 SAVE $10 Cat. LR-8839 $49.95 Better. More Technical Mini Colour Dome CCD Small in size (only 72mm diameter) this tiny camera is excellent value for money and has specifications comparable to some of our higher priced dome cameras. It features a SENSOR 1/4" Sharp CCD sensor and 350 TV Cat. QC-3291 line resolution. • 72(dia) x 52(H)mm $69 2.4GHz Colour Mini Wireless Camera Kit The camera transmits audio and video up to 100m (line of sight) to the receiver. It can be powered by a plugpack or by its in-built rechargeable battery, and has 4 transmission channels to minimise interference. The receiver has composite video out and is powered by the supplied plugpack. Kit includes camera with bracket, power supplies, AV lead and receiver unit. • Camera Cat. QC-3569 67(L) x $199 22(W)mm • Receiver size 78(L) x 68(W) x 16(D)mm FOR INFORMATION AND ORDERING TELEPHONE> 1800 022 888 INTERNET> www.jaycar.com.au USB Missile Launcher Mk II USB Desktop Bouncer This tough looking guy with a cockney accent will turn away any would be punter trying to interfere with your desktop stuff. He'll warn them off with one of his six tough-guy quotes. •1.2m USB lead included • Can use 3 x AAA batteries (not included). Cat. GE-4088 • Stands 210mm high "Your cruising for a bruising" $59.95 $24.95 Gaming Backphones with Built in Bass Shakers and Microphone USB Exercise Bike Mouse with LCD Word Counter These backphones have a built-in bass shaker that adds depth and realism to your gaming experience. The bass shaker massively enhances low frequency response and it feels like you are listening to the music through high powered Hi-Fi speakers. They include a concealed microphone so they're perfect for network games and are also useful in VoIP applications such as Skype®. This hard working mouse will pedal one revolution and increment the counter each time you type a word on your keyboard. Loads of fun and great for essay writing, articles and projects etc. • 140mm high Cat. GE-4086 $24.95 This USB to 9 pin Serial (RS-232) converter allows a computer with a USB port to use SAVE any RS-232C serial device via the USB port. $5 Suitable for digital cameras, modems, Cat. XC-4834 POS systems, ISDN terminal adaptors etc. Powered by the USB port. $34 Was $39.00 VGA to Video Converter Cat. XC-4870 $99.95 Composite Video to VGA Converter Included in this service kit is an IC inserter/extractor, pearl catch, tweezers, 1/4" nutdriver, 3/16" nutdriver, double ended 10/15 TorxTM driver, parts tube for Cat. TD-2040 storage, #1 Phillips $24.95 screwdriver, #0 Phillips screwdriver, 1/8" slotted screwdriver, 3/16 slotted screwdriver in a black 55pc Pro Computer zipper case. Tool Kit also available • Case measures TD-2051 $65 220 x 155 x 38mm Cat. XC-4969 $49.95 Make or answer Internet calls just like using a regular phone. Utilise the many benefits of VoIP without being confined to your computer. The transmitter plugs into a spare USB port so you can chat away on the handset. It is compatible with Skype, MSN, Yahoo Messenger, Xetn, Dialpad, MediaRing, and Net2Phone and is perfect for home or office use. • Up to 30m Bluetooth range Cat. XC-4968 $129.95 Cat. YN-8084 $49.95 Network Cable Tracer This tone generator is a highly practical network installation and troubleshooting tool and allows cables to be easily traced by the probe, even when cables are in a bundle or hidden in SAVE punch down blocks or wall plates. $30 • The probe is 205mm long and approximately 35(H) x 35(D)mm. Cat. XC-5083 • Both operate from 9 volt batteries $99 (sold separately) Was $129.00 USB to IDE and SATA Hard Drive Adaptor This clever device will allow you to use an ordinary IDE or SATA disk drive on a USB-2 interface. The adaptor can be powered from the existing computer power supply or from the supplied mains adaptor. The adaptor has plug and play support for Windows ME, 2000, and XP. Cat. XC-4833 • Win98 supported via $79.95 downloaded software • Interface cables included External 2.5" HDD Case for SATA Drives Instantly add gigabytes of storage to your computer or move large amounts of data from one computer to another. Accepts a standard 2.5" hard drive and connects via your computer's USB port. Just 127mm long. Cat. XC-4681 Presentations Without a Computer! eFlash allows you to present common Microsoft Office applications without the need for a computer. It connects easily and intuitively to a projector or TV with simple cable connections and is operated by the included remote control with integrated laser pointer. Store your presentations on a memory card and leave the computer at the office. An essential for corporate trainers and teachers. $199 MPEG4 Media Player with Remote Control Boasting composite, S-Video, component and RGB video output with stereo and digital (SPDIF) audio output, it is compatible with almost any home theatre system. With up to 500GB of hard drive storage (IDE HDD not supplied), you can keep a large library of movies and music on the device to entertain for days. PC connection is made easy with the USB 2.0 interface and supplied USB cable. The unit features a cool blue LCD and backlit control panel and is supplied with a slim line remote control that allows for full playback functions, zoom and slideshow control. The included stand allows for vertical mounting. Cat. XC-4866 $29.95 FOR INFORMATION AND ORDERING TELEPHONE> 1800 022 888 Everything you would expect from a modern network attached storage device and more! Includes a Cat. XC-4677 built-in BitTorrent client that can be used to download and share files $199 over the BitTorrent network without the need to have your computer turned on. • Full specifications on our website. Cat. XC-5405 This neat device converts all region video signals into a noninterlaced VGA signal for monitors. With features such as, an on screen display and a slim line remote control, this converter box is user friendly and easily connected to your PC, video source & video Cat. XC-4872 game consoles without any $99.95 software installation. Computer Service Tool Kit Expand your connections! Network your computers or share your ADSL connection, and avoid hassles with file sharing and internet access. Operates up to 10 / 100 mbps. NAS Device with Built-in BitTorrent Client VoIP USB Wireless Phone 8 Port 10/100 N-Way Switch USB to DB9M RS-232 Converter Use your TV as a computer monitor. Great for watching DVD movies, PC gaming, presentations, educational applications or Internet viewing on TV. • No software required With full directional movement, you can now declare war on someone up to 7m away! It uses a burst of air ejecting the foam missile instead of a spring loaded mechanism. USB powered, the launcher comes with software, 3 soft foam missiles, target, sound Ready, Aim, Fire effects and USB lead. • Base measures 110mm(Dia.) Cat. GE-4074 • Stands 120mm high INTERNET> www.jaycar.com.au $199 Better. More Technical 3 Solar LED Outdoor Umbrella Light New Wireless Weather Stations Provide light at any time for your outdoor setting. The solar panel screws onto the top of the pole to charge during the day and connects into the light fixture via the 1m power lead included. • Light dimensions Cat. ST-3293 200(Dia.) x 59(H)mm Computer Interface Weather Stations The indoor receiver measures the indoor Cat. XC-0330 temperature, humidity, atmospheric pressure $249.95 and receives weather data from the outdoor wind sensor and rain gauge. The receiver unit has a USB interface output allowing data to be uploaded to a PC or laptop. The XC-0332 unit has an additional AV output so you can view the weather data on your TV. Mains adaptor and View software supplied. weather data See website for on your TV full details. $39.95 Rechargeable 11W Fluorescent Work light With an 11 watt tube, this light provides plenty of illumination for any purpose. It’s rechargeable, portable and has a hanging hook. Charger included. • Battery: Ni-MH 2200mAh • 450(L) x 75(dia)mm Cat. ST-3127 $69.95 Solar Powered Thermometer Wireless outdoor temperature & hygrometer sensors transmit data to the LCD receiver which displays temperature, humidity, heat Index and dew point levels, the time, barometric pressure with comfort index and forecasts the weather through Cat. XC-0342 5 weather icons. $149.95 7" Four Input In-Car TFT Colour Video Monitor This stylish monitor is an excellent choice for in-car applications from DVDs to game consoles or SAVE reversing cameras $50 and GPS navigation systems etc. Can also be used with multiple cameras on larger vehicle and trucks. Supplied complete with mounting bracket, input and power leads, and infrared remote control. Was $299 See our full 4 i.2i Wireless Colour LCD Weather Station We have a huge range of Head Torches range of Monitors in our 2007 Catalogue Wireless Weather Station with Coloured Display and Projection Clock $99.95 A head torch for the adventurous type! With flashing mode to attract attention in an emergency, you'll never get lost wearing this 6 super bright LED head torch. • Requires 3 x AAA batteries (not included) $39.95 Remote Controlled Mini Helicopter Cat. XC-0340 6 LED Super Bright Waterproof Head Torch Cat. ST-3282 $39.95 $299 This LCD desktop weather station has an alarm clock that will project the time onto the wall or ceiling. Cat. QM-3772 $249 Motorcycle Headset for UHF CB Radios Designed to fit into a full-face helmet with the included self-adhesive Velcro mounts, it can be easily removed when not in use. Add a second set and use it as a bike to bike or rider to pillion intercom. Handlebar-mounted push-to-talk button included.Compatible with the following UHF CBs: DC-1025, DC-1028, DC-1040, DC-1045 & DC-1060. Cat. DC-1037 • Headset cable length: 1.6m $99 • PTT button cable length: 1.3m Better. More Technical Made of hard styrene, this remote control plane is almost indestructible. It is small enough for indoor use or it can whiz around the backyard. Flying time is around 8 minutes per charge. • Wingspan 260mm • Twin engines Was $49.95 SAVE $10 Cat. GT-3218 Cat. XC-0332 Stick this to your home or office window to give you an instant temperature reading of the outdoor environment. Choose your measurement in either Celsius or Fahrenheit and it will appear on the easy to read LCD. The solar cell keeps it powered with no need for batteries and the strong adhesive tape will keep it firmly Cat. QM-6328 fastened to your chosen area. $24.95 • Size: 100(H ) x 11(W)mm Mini RC Aeroplane 27MHz The twin rotor design of this chopper makes it very easy SAVE to fly and $10 very stable. The infrared remote unit has a range of about 15 metres and has throttle, rudder and stability trim controls. It recharges in about 10 minutes from the remote unit, giving about 8 minutes of flying time. • Requires 6 x AA batteries (not included) • Remote: 130(L) x 120(W) x 45(D)mm Cat. GT-3215 • Helicopter: 170mm long, weight 10g $39.95 • Suitable for ages 8+ Was $49.95 Air Powered Water Rocket Kit Fill the rocket half full of water, pump it up then fire with the cable release. It flies up to about 30 metres. Everything is in the kit - pump and one rocket included. Adult supervision recommended. • Suitable for ages 10+ • Launcher: 260(dia) x 250(H)mm • Rockets: 370mm long • Pkt 3 spare rockets: GT-3602 $29.95 Cat. GT-3600 $49.95 38 Channel 1.5 W UHF Pocket Transceiver This high-quality light-weight UHF transceiver is ideal for use in many professional and leisure activities. Up to 8km working range with a hi/lo setting to conserve power. Was $79 See our full range of CB Radios In-store SAVE $20 Cat. DC-1040 $59 3 Watt 38 Channel UHF CB Radio The radio has a massive 12km transmission range (clear line of sight) and features CTSS sub-channel calling, automatic muting, scrambling and much more. It has a high gain antenna (168mm) with an SMA connector for use with external antennas. Supplied with a rechargeable Cat. DC-1060 1200mAh pack with mains $169 charger. FOR INFORMATION AND ORDERING TELEPHONE> 1800 022 888 INTERNET> www.jaycar.com.au Test & Measure Temperature & Humidity Datalogger This USB datalogger logs up to 3200 readings (1600 Cat. QP-6013 temperature, 1600 humidity) $99.95 in intervals of 2 seconds to 2 hours per reading. It records at the prescribed intervals and will flash an alarm LED if the user-defined minimum or maximum temperature is exceeded. A mounting bracket is included with screw or self-adhesive attachment. • Range: -40-70°C (-40-158°F), 0-100% relative humidity, • Accuracy: ±1°C (1.8°F), ±3% relative humidity • Resolution: 0.1°, 0.1% RH AC/DC Current Clamp Meter This small clamp meter will measure up to 200 amps DC. It is ideal for car stereo installations and electrical trades people. It has a one touch zero adjustment for DC current measurement. • Jaw opening is 23mm. Cat. QM-1562 $139.95 2 Channel USB Oscilloscope At last! A genuinely affordable computer connect oscilloscope. Using the Plug 'n Play USB technology and providing full optical isolation from the computer, this oscilloscope is easy to setup and use, as well as providing protection for the computer. The software (again developed in Europe) is a fully featured chart recorder, function generator, logic generator, logic analyser, and spectrum analyser all in one easy to Cat. QC-1930 use package. See website for $299 specifications. 153 Experiments in Electricity and Magnetism Kit Learn all the basic principles behind electricity. 153 different experiments to keep the junior mad scientist occupied for hours without burning the house down. All the experiments require only a 9V battery or no power at all • Ages 9+ Cat. KJ-8835 $39.95 OBD II LCD Scan Tool If you have a late model car, it will probably have an OBD (On-Board Diagnostics) connector. If it was manufactured after 1996, it will support the OBD II protocols. This OBD II Scan Tool supports the CAN (Controller Area Network) protocol and can be used to Can be diagnose prior to repair and to used to check the verify a repair Cat. QP-2294 VIN number on after service. late model cars! $129 Digital Megohmmeter Megohmmeters generate high voltage, low current signals for testing the breakdown strength of electrical insulation. Includes a rubber holster, test leads with alligator clips, 200M and 2000M Ohm ranges and simple, one button 'push to test' operation. Cat. QM-1492 $99.95 With a wide temperature range and laser sighting, this portable thermometer is easy to use for quick and accurate temperature checking of any surface. The backlight allows for low light temperature readings and the unit has an 8:1 distance to spot size. Belt holster supplied. • Temperature range: -50 to +550°C (-58 to +1022°F) Cat. QM-7223 • 160(H) x 82(W) x 41.5(D)mm • 9V battery included $97.95 Meteorology 25 experiments to help the junior meteorologist understand all about weather. Tornadoes, lightning, clouds, wind and air pressure are all covered - even make your own rainbow or a flash of lightning. Colour instruction book included. • Suitable for ages 8+ • 155 x 155 x 155mm 30 experiments what will allow you to observe fundamental principles of air, temperature, wind and water. Everything's included in the kit and only a few extra household items are needed comprehensive colour instruction book included. • Ages 8+ • 155 x 155 x 155mm Life in Nature Cat. KJ-8820 $29.95 The pliers feature serrated jaws and a box joint to provide a precise action and strong grip. The coil spring ensures smooth, fatigue-free use. Insulated soft touch handles. These quality tools are made in Japan from the same High Carbon Steel that is used to make professional chef's knives INTERNET> www.jaycar.com.au Cat. TH-1885 $24.95 150mm Precision Side Cutters These cutters are designed for sharp cutting in precision wiring' . They have insulated soft-touch handles and a coil return spring for fatigue-free use. Cat. TH-1891 $27.95 Heavy Duty Coax Crimping Tool For crimping F, N, BNC, TNC, UHF, ST, SC & SMA connectors onto coax cable for TV and communications applications. It also has adjustable crimp force and 3 hex dies: 2.54mm, 9.12mm & 10.3mm. Cat. TH-1832 $24.95 Super Pro Gas Soldering Tool Kit It features an adjustable tip temperature up to 580°C and ignition is achieved by the internal piezo crystal mechanism. Run-time is around 2 hours on a 30 second refill. The protective end cap also acts as a safety gas shut off when replaced. The kit includes a quality storage case, cleaning sponge & tray, 2.4mm double flat tip, 4.8mm double flat Cat. TS-1328 tip, hot knife tip and a hot air deflector. $139 • Replacement tips available Multifunction ESD Duratech Soldering Station Cat. KJ-8822 $29.95 With 29 experiments this cube will help you understand how plants live and grow, contains a series of experiments that will show you how life is dependent on water and how the environment effects growing things. Cat. KJ-8824 • Suitable for ages 8+ $29.95 • 155 x 155 x 155mm FOR INFORMATION AND ORDERING TELEPHONE> 1800 022 888 125mm Precision Long Nose Pliers Six titles to choose from... Rules of Nature See our full range of Meters in-store Compact Non-Contact Thermometer Kits Experimental Cubes for Kids Precision Japanese Made Carbon Steel Tools Complete SMD working at your fingertips! This robust unit features a soldering pencil, and hot blower for all rework applications. The soldering pencil and hot blower have individual temperature adjustment, and the air Cat. TS-1570 flow can also be varied. It is ESD safe $299 for sensitive components, and is ready to tackle a myriad of tasks. See our website for details. See all our Aerosol Service Aids Aerosol Dust in-store Remover Blow dust out of keyboards and other difficult places with this handy Cat. NA-1018 duster in a can. CFC free. $16.95 • 250g Better. More Technical 5 10" Electronic Photo Frames Display your digital photos or videos in various ways from landscape to thumbnails. You can even select and play a sound track. The files can be loaded via CF, MS, SD, MMC, SM, XD memory cards 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. NOW ONLY QM-3768 Black Acrylic QM-3769 White Acrylic $299 ea SAVE Were $399 each $100ea New Party Speakers 12" 200WRMS Party Speaker This speaker provides good performance in difficult locations such as backyards, tents, party rooms or halls etc. Cat. CS-2514 Power handling: $199 200WRMS <at> 8 ohms. • Size approx 650(H) x 370(W) x 450(D)mm NEW CONTEMPORARY OK! LO 12" Foldback Speaker 7” photo frames also available: White QM-3765 or Silver QM-3759 Was $179 Now $149 Save $30 2.4GHz Wireless A/V Sender This audio video sender is even more compact and features 4 frequency channels complete with phase-lockedloop (PLL) technology to prevent signal drift and provide assured picture and sound quality. Pack includes a transmitter, receiver, AV leads, power supplies and instruction manual. • Additional receivers sold separately Cat. AR-1842 AR-1843 $39.95 $59.95 • Also available with IR remote control extender AR-1844 $69.95 Limited stock 5.8GHz Wireless A/V Sender Wireless LAN, Bluetooth,cordless Not C tick approved phones, etc, can cause overcrowding and interference for items that transmit on the 2.4GHz band. Beat the congestion with this 5.8GHz unit and ensure crystal clear reception no matter what audio video device you choose. Complete with built-in IR remote control repeater, AV leads, Cat. AR-1840 power supplies and instruction manual. $249 • Additional receivers AR-1841 $159.95 Ribbon Tweeters Spectacular US stock purchase Affordable at last! All audiophiles know that ribbon tweeters are the ultimate speaker for smooth high frequency performance. These dynamic type tweeters are made Quantities in Japan by Foster and have multiple are strictly ribbon 'diaphragm' components in limited same phase configuration. Each speaker is supplied with a datasheet Cat. CT-2023 and securely packed. $49.95ea • Size: 89 x 74mm • Type: Regular-phase 100mm ribbon tweeters Or buy as • Power: 20 watts RMS, 50W max. a set of 4 for $179.60! That's • SPL: 92dB/ watt only $44.90 • Freq Resp: 6K-40KHz +/-2dB each! • Impedance: 8 ohms • Crossover Freq: 6,400Hz (12dB/Octave) 6 Rated at 300WRMS this 4 ohm wide range speaker is ideally suited for use as a foldback speaker on stage or as reinforcement in an existing system. • Enclosure Size: 650(W) x 330(H) x 440(D)mm Cat. CS-2516 $129.95 Specifically designed for the 2nd generation iPod Shuffle, this stereo speaker is still ideal for use with any iPod or MP3 player. Its Cat. XC-5189 1W+ 1W output power produces quality $19.95 sound, and its protective cover makes it fantastic for use at the beach. • Requires 4 x AAA batteries (not included) ABS Roadie's Case A sturdy case to take all the bits and pieces musos and roadies take to gigs. It has ample room for leads, manuals, tools, spare strings etc, and is foam lined to provide protection for spare valves. Solid pintle Cat. HB-6379 hinges and cam closures. • 520(L) x 428(W) x 200(D)mm $69.95 Heavy Duty Ceiling Projector Mount 12" Subwoofer High performance subwoofer. Finished in leather carpet, the cabinet houses a 12" 4 ohm sub-woofer rated at 300WRMS. Cat. CS-2518 • Enclosure Size: 480(W) x 580(H) $169.95 x 440(D)mm 2 x 100WRMS Stereo Amplifier with Remote Control A nononsense stereo amplifier that will form the heart of an impressive entertainment system. Rated at a generous 100WRMS per channel, this two-channel amplifier features a Cat. AA-0470 microphone input and quality $199 screwdown speaker terminals. Wireless Microphone UHF Dual Channel Features two separate channels, one for each microphone. The system includes 2 microphones and batteries, receiver unit, 14VDC plugpack and 1m Cat. AM-4078 6.5mm mono plug to 6.5mm mono plug lead. Ideal for schools, churches, $199 karaoke, weddings etc. DVD Maker - USB 2.0 iPod Shuffle (Gen.2) Speaker with Aux In Turn your VHS video tapes into exciting video productions or record live video straight to your DVD or CD burner. Editing software lets you add effects as well as sound tracks and titles to your work. PCI version also available. • Requires PC with suitable burner. This bracket does not affix to the top of the projector like many models but provide a secure platform for ANY projector with a width of 34cm to 47cm and a weight of not more than 15kgs. • Vertical arm measures: 500mm adjust able to 700mm Was $99.95 Cat. CW-2818 $89.95 SAVE $10 In-Car Multimedia Player with Detachable Face Play DVDs, VCDs, CDs, you can even use files off an SD card or other media via the mini USB port. The MOSFET amplifier stage is rated for 45WRMS per channel. It also has a sub-woofer output, composite video and line level audio outputs. Supports DVD, CD, VCD, SD, USB Cat. QM-3785 • Full function remote control included $249.95 • 182(W) x 169(D) x 53(H)mm 7" LCD In-Car TV/Monitor Featuring a motorised 7" TFT LCD screen, this unit fits into a standard automotive DIN opening and in addition to the TV function, it takes two extra video inputs and an input for a reversing camera. It also has composite video and audio output. • Full function remote control included Cat. QM-3782 $299 Cat. XC-4809 $99 Better. More Technical FOR INFORMATION AND ORDERING TELEPHONE> 1800 022 888 INTERNET> www.jaycar.com.au Solar Powered Garage LED Light Pure Sinewave Inverters A great new range of pure sinewave inverters at breakthrough prices. They have 100% short-term surge capacity, heavy duty screw down terminals, temperature controlled cooling fans, and a strong aluminium case. Cat. MI-5153 MI-5155 MI-5157 MI-5159 Volts 12VDC to 230VAC 12VDC to 230VAC 12VDC to 230VAC 24VDC to 230VAC Watts 300 600 1,000 1,500 Price $199.00 $349.00 $449.00 $799.00 Ideal for garages, gazebos and greenhouses, the 360° adjustable solar panel will allow for custom positioning. It's waterproof, features a cord-switch to operate, and is simple to install. Pack includes solar panel and mounting bracket, 2.4m cable & rechargeable enclosed Ni-Cd battery. 2 year manufacturer warranty and a 20 year warranty on efficiency! Cat. SL-2715 $39.95 Four Pack Ni-MH Rechargeable Batteries Modern digital devices require high current high drain performance cells. These high capacity batteries will provide the best in portable power. Price gh rou a e r B kth SB-1738 2500mAh AA SB-1735 2400mAh AA SB-1737 2000mAh AA SB-1739 900mAh AAA 12V Powertech Polycrystalline Solar Panels $19.50 $15.95 $13.95 $11.95 They feature tempered glass protection to ensure they are not easily damaged in the harsh environment which solar panels exist in. Each solar panel has an integrated waterproof junction box with cable glands, cooling fans and strong aluminium cases. Cat Watts Price ZM-9071 5 $99.95 ZM-9073 10 $149.00 ZM-9074 20 $239.00 ZM-9076 65 $549.00 ZM-9078 80 $699.00 ZM-9079 120 $1050.00 Rugged 16 Amp 12 Volt Car Battery Charger This fully automatic, switchmode, car battery charger utilises a four stage rapid charge design to optimise the life and performance of your car or GEL battery. Includes a top mounted Cat. MB-3620 carry handle and cable storage for the battery leads & clamps. $169 • 270(W) x 220(H) x 120(D)mm 150W Inverter with USB Outlet This compact inverter plugs directly into your vehicle's cigarette lighter socket. This 150W modified sinewave inverter comes complete with a USB port to charge or power your MP3 player or other USB operated devices. Cat. MI-5125 $79.95 600VA Uninterruptible Power Supply Protect your valuable computer system and critical data from black-outs, brown-outs, and power surges. Battery back time is 10 minutes which lets you power down SAVE without loss of data! The UPS is $20 supplied with a 7AH SLA battery, USB interface cable, and software. See our website for full specifications. • 100VA also available MP-5202 $199.00 Cat. MP-5200 Was $129 $109 0 to 30VDC/0 to 3 Amp Regulated Variable Lab PSU Provides a stable voltage and current with a regulated output voltage which is adjustable from 0 to 30VDC. Output current is adjustable from 0 to 3 amps. The unit has a uncluttered control panel with LCD, voltage and current adjustment knobs. See our website or catalogue for full specifications. Wind Generators 200 Watt Wind Turbine Generators 12V and 24V models available. They will generate 200 watts at wind speed as low as 8 metres per second and will deliver useful power with a gentle 3 metre/sec breeze or give up to 300 watts at higher wind velocities. Features a 3 phase permanent magnet alternator with 2.1 metre diameter 3 blade rotor and new solid state regulator with auto detection of battery voltage to control charge levels. The units will withstand wind speeds of 40m/sec (144km/hr). Some skill is required in construction e.g. concreting, mechanical assembly and rigging. Units are shipped in 2 boxes, with a combined weight of 65kg. NB. Due to the weight and size not all stores will have these in stock. The store can order the unit for you & have it delivered to your site (freight costs are New improved solid additional). See state control website or catalogue for box further specifications. Cat. MG-4512 24V Model Cat. MG-4510 Both Types (ea) Cat. MP-3086 $499 $199 FOR INFORMATION AND ORDERING TELEPHONE> 1800 022 888 12V Model INTERNET> www.jaycar.com.au Solar Power Controller Maintain your battery system in peak condition with this excellent charge controller. It features 30A capacity, temperature compensation, and full overload protection. Multi-mode operation. See website for details. Cat. MP-3124 $229 10 LED Solar Powered Torch Featuring 10 high brightness LEDs and internal rechargeable batteries that are charged by the solar panel on the handle. Leave it basking in the sun during the day for a light filled night. • Solar panel measures 120(L) x 28(W)mm • Torch 210mm long Cat. ST-3077 $24.95 Digital Mains Timer Switch Modules Automate your heating, lighting, or other switching applications. The hard wired timers have eight on/off settings that can be programmed to function on any day, or combinations of days across the week. The setting process is simple and intuitive. Two models available: AA-0361 12VDC switching capacity 16A <at> 240VAC AA- 0362 240VAC switching capacity Each 30A <at> 240VAC $49.95 Better. More Technical 7 Speaker Protector Kit MKIII Subwoofer Controller Kit Refer Silicon Chip August 2007 Using this kit to control your external speaker and sub-amplifier can give you loads of bass without taking up much space. The kit has all the features you could want, including low and high pass filters, parametric equaliser and auto-turn on for external equipment. The controller is 12 volt DC powered and can also be used in automotive applications. Cat. KC-5452 • Kit supplied with silk screened $99.95 PCB and processed panels. YOUR LOCAL JAYCAR STORE Freecall Orders: Ph 1800 022 888 NEW SOUTH WALES Albury Ph (02) 6021 6788 Alexandria Ph (02) 9699 4699 Bankstown Ph (02) 9709 2822 Blacktown Ph (02) 9678 9669 Bondi Junction Ph (02) 9369 3899 Brookvale Ph (02) 9905 4130 Campbelltown Ph (02) 4620 7155 Erina Ph (02) 4365 3433 Gore Hill Ph (02) 9439 4799 Hornsby Ph (02) 9476 6221 Newcastle Ph (02) 4965 3799 Parramatta Ph (02) 9683 3377 Penrith Ph (02) 4721 8337 Silverwater Ph (02) 9741 8557 Sydney City Ph (02) 9267 1614 Taren Point Ph (02) 9531 7033 Tweed Heads Ph (07) 5524 6566 Wollongong Ph (02) 4226 7089 VICTORIA Coburg Ph (03) 9384 1811 Frankston Ph (03) 9781 4100 Geelong Ph (03) 5221 5800 Melbourne Ph (03) 9663 2030 Ringwood Ph (03) 9870 9053 Springvale Ph (03) 9547 1022 Sunshine Ph (03) 9310 8066 Thomastown Ph 1800 022 888 QUEENSLAND Aspley Ph (07) 3863 0099 Cairns Ph (07) 4041 6747 Ipswich Ph (07) 3282 5800 Mermaid Beach Ph (07) 5526 6722 Townsville Ph (07) 4772 5022 Underwood Ph (07) 3841 4888 Woolloongabba Ph (07) 3393 0777 AUSTRALIAN CAPITAL TERRITORY Belconnen Ph (02) 6253 5700 Fyshwick Ph (02) 6239 1801 TASMANIA Hobart Ph (03) 6272 9955 SOUTH AUSTRALIA Adelaide Ph (08) 8231 7355 Clovelly Park Ph (08) 8276 6901 Gepps Cross Ph (08) 8262 3200 WESTERN AUSTRALIA Maddington Ph (08) 9493 4300 Northbridge Ph (08) 9328 8252 NORTHERN TERRITORY Darwin Ph (08) 8948 4043 NEW ZEALAND Christchurch Ph (03) 379 1662 Dunedin Ph (03) 471 7934 Glenfield Ph (09) 444 4628 Hamilton Ph (07) 846 0177 Manukau Ph (09) 263 6241 Newmarket Ph (09) 377 6421 Palmerston Ph (06) 353 6738 Wellington Ph (04) 801 9005 Freecall Orders Ph 0800 452 9227 8 Refer: Silicon Chip July 2007 The primary function of this versatile project is to protect your expensive speakers against damage in the event of catastrophic amplifier failure such as a shorted output transistor. In addition, the circuit also banishes those annoying thumps that occur when many amplifiers are switched on or off, especially when the volume is set to a high level. The design also incorporates an optional over temperature heat-sensor that will disconnect the speakers if the output stage gets too hot. Configurable for supply voltages between 22VDC - 70VDC. Supplied with a silk screened PCB, relay and all Cat. KC-5450 electronic components. 4 Channel Guitar Amplifier Kit Refer: Silicon Chip May 2007 Cat. KC-5448 $99 This is an improved version of our popular guitar mixer kit and has a number of enhancements that make it even more versatile. The input sensitivity of each of the four channels is adjustable from a few millivolts to over 1 volt, so you plug in a range of input signals from a microphone to a line level signal from a CD player etc. A headphone amplifier circuit is also included for monitoring purposes. A three stage EQ is also included, making this a very versatile mixer that will operate from 12 volts. Kit includes PCB with overlay & all electronic components. $29.95 Battery Zapper Kit MKII Refer: Silicon Chip May 2006 Like its predecessor this kit attacks a common cause of failure in wet lead acid cell batteries: sulphation. The circuit produces short bursts of high level energy to reverse the damaging sulphation effect. Kit includes machined case with screen printed lid, circuit board, alligator clips and all electric components. • Suitable for 6, 12 and 24V batteries • Powered by the battery itself odel ved m Improor 2007 f Cat. KC-5427 $99.95 Digital Multimeter Kit $69.95 Interface your computer to the real world. There are five digital and two variable gain analogue inputs. Eight digital and two analogue outputs Cat. KV-3600 are available. Supplied with all $69.95 components, silk screened PCB, assembly manual and software. Outstanding Educational Kits Speedo Corrector MKII Kit Refer: Silicon Chip December 2006 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 PCB with overlay and all electronic components. • Recommended box UB5 use HB-6013 $3.50 Better. More Technical Refer: Silicon Chip May 2007 Accurately monitors audio signals to prevent signal clipping and ensure optimum recording levels. This unit is very responsive & uses two 16-segment bargraphs to display signal levels and transients peaks in real time. There are a number of display options to select, and both the signal threshold and signal-level calibration for each segment are adjustable. Kit supplied with PCBs, LCD and all electronic components. Accuracy within 1dB for signals above -40dB. • Requires 9V-12VDC power supply use: MP-3147 $17.95 • Case not included Cat. KC-5447 Short form kit. use HB-6082 $9.95 Case sold separately USB Experimenter's Interface Kit Learn everything there is to know about component recognition and basic electronics with this comprehensive kit. From test leads to solder, everything you need for the construction of this meter is included. All you'll need is a soldering iron! Cat. KG-9250 • 67(W) x 123(H) x 25(D)mm $19.95 Improved Model for 2007 Stereo VU/Peak Meter Water Level Indicator Kit MKII Refer: Silicon Chip July 2007 This simple circuit illuminates a string of LEDs to quickly indicate the water level inside a rainwater tank. The more LEDs that illuminate, the higher the water level is inside the tank. Now back in t Ten sensors located in the water tank and stock! Ran our la connected to the indicator unit via lightpu po to e du duty figure-8 cable provide the input signal. demand. Kit includes PCB with overlay, machined case with screen-printed lid and all electronic components. • Requires: 2.5mm PVC hose/pipe (length required depending on depth of tank) • Requires 12-18V AC or DC plugpack Cat. KC-5435 $49.95 Cat. KC-5449 $34.95 FOR INFORMATION AND ORDERING TELEPHONE> 1800 022 888 Prices valid until September 30th 2007 INTERNET> www.jaycar.com.au SILICON SILIC CHIP Order Form/Tax Invoice Silicon Chip Publications Pty Ltd ABN 49 003 205 490 www.siliconchip.com.au PRICE GUIDE: SUBSCRIPTIONS YOUR DETAILS (Note: all subscription prices include P&P). (Aust. prices include GST) Your Name________________________________________________________ (PLEASE PRINT) Organisation (if applicable)___________________________________________ Please state month to start. Australia: 1 yr ...................... $A89.50 1 yr + binder ....................... $A105 NZ (air): 1 yr ....................... $A96 Overseas (air): 1 yr ............. $A135 2 yrs ...................... $A172 2 yrs + 2 binders .... $A203 2 yrs ...................... $A190 2 yrs ...................... $A260 Address__________________________________________________________ PRICE GUIDE: OTHER PRODUCTS __________­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­___________________­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­____________________________________ Postcode_____________ Daytime Phone No. ( )_____________________ Email address (if applicable) ___________________________________________ Method of Payment: (all prices include GST on Aust. orders) *SILICON CHIP BACK ISSUES in stock: 10% discount for 10 or more issues or photocopies. Australia: $A9.50 ea (including p&p). Overseas: $A13 each (including p&p by air). *ELECTRONICS AUSTRALIA: project photocopies. Australia: $A9.50 each (including p&p). Overseas: $A13 each (including p&p by air). *BINDERS: BUY 5 or more and get them postage free. (Available in Aust. only): $A13.95 each plus $7 p&p per order. o Cheque/Money Order o Visa Card o Master Card Card No. *ELECTRONICS PROJECTS FOR CARS, VOL.2: Aust. $A14.95; Overseas $A18.00. (Prices include p&p & GST where applicable). Card expiry date: Signature_____________________________ *PERFORMANCE ELECTRONICS FOR CARS: Aust. $A22.50; Overseas $A26.00. (Prices include p&p & GST where applicable). 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, September Australia 20972007  57 09/07 It’s cheap & simple to build, operates completely unatt Simple DataWeather Sta 58  Silicon Chip siliconchip.com.au ended & will run for years on a set of AA batteries If you need to record weather data at a remote location, there are very nice professional logging weather stations out there that do the lot, with solar panels for power and the ability to record rainfall, temperature, humidity, barometric pressure, wind speed and direction, sunlight hours etc. While it would be nice to have all that capability, I had a need that was a lot simpler. Like many people, I only wanted to record rainfall and temperature. More importantly, I couldn’t justify the cost of the professional systems, which typically run to four or five figures. There are plenty of hobbyist weather stations out there too – and at much better prices. They appear very capable but none can log data unattended for an extended period (well, I did find one but even it was well over a thousand dollars). SILICON CHIP has published weather station projects in the past, including a PICAXE-based system that recorded temperature and humidity (December 2004). There was also an electronic rain gauge but again, neither project was suitable for unattended remote logging for months at a time. A bit of research convinced me that it wouldn’t be too hard to build my own, including a suitable rain sensor. So that’s just what I did! -Logging ation siliconchip.com.au Part 1 – by Glenn Pure September 2007  59 O N THE ELECTRONICS SIDE, a low power microcontroller was the way to go. With the right device and a bit of care in design, current consumption has been kept down to an average of around 10mA, meaning a set of three AA batteries should last for years – virtually their shelf life, in fact. In terms of logging capability, with half-hourly readings, it is capable of storing just under a year’s worth of rainfall and temperature records, utilising the 64 kilobytes of on-board EEPROM memory. The firmware can easily be modified for reading at more frequent intervals. With sixminute logging frequency it has over two months capacity. At the other extreme, with hourly recording, it will store almost two years of data. The data is accessed through an on-board RS232 interface, enabling easy downloading straight to a laptop or desktop computer. If, like me, you don’t own a laptop, there is a simple solution. The controller is cheap and easy enough to build that you can make two and simply swap one out and take it home to dump the data at your leisure. In fact, the most time-consuming part about the project isn’t the electronics – it’s the hardware. Building the rain sensor will probably take the most time and effort. But if you don’t have the time or inclination, at modest cost you can even solve that little problem too. While unsuccessfully looking for a suitable commercial weather station, I found a good quality rain sensor for a few hundred dollars that will interface with the weather station. More on this later. Circuit description & operation As mentioned, the circuit is based around a microcontroller (IC1). Since low power consumption and simplicity were paramount, I chose a PIC16F88 “nanowatt” microcontroller. Here’s a close-up view of the data-logging weather station. The rain gauge is at top right, while the temperature measurement housing is at bottom left. The box containing the “works” (shown above) is housed in the lower right container. 60  Silicon Chip This has pretty-much all the peripheral interfaces needed already integrated into the device, including an on-board oscillator, a serial interface driver and A/D converters. While the A/D converter was used in an earlier version of the design for temperature sensing, it’s not actually needed in the final design since analog temperature sensing was abandoned. Instead, sensing is done by a Dallas DS1621 digital sensor (IC5). This greatly simplified the circuit, which previously required an accurate voltage reference for the A/D converter and a circuit to switch this on and off. Better still, the DS1621 is an I2C bus device (like the two 24C256 serial EEPROMs – IC3 & IC4), which further simplified design and software development. The DS1621 has a low-power standby mode when not in use, helping further to save power. A brief comment on the I2C devices is warranted. These devices require two lines for communication – a clock line and a data line. The data line is normally held high by a 10kW pull-up resistor. An active device pulls the data line low when it needs to during transmission. Hence, if two devices attempt to transmit at the same time, the worst that can happen is that they can pull the shared data line low. This is unlikely to present any risk of damage but could lead to unpredictable power consumption in some cases. So there are 390W resistors in series between the PIC (pin 7) and each of the data lines to the three I2C devices. The PIC actually has a synchronous serial port for I2C siliconchip.com.au +4.5V 100nF 220k RAIN SENSOR 6 S3 RB0 CLOCK CORRECT RA0 +4.5V 10k 8 Vdd 3 10 A2 5 SDA 2 A1 IC3 1 A0 24C256 6 SCL 7 WP Vss 4 390 S2 RESET S1 10k 6 7 SC 2007 A2 A1 A0 IC5 DS1621 SDA Vss 4 SCL 1 2 RB4 1 F 7 9 3 RB1 RB5 RB3 RB6 RA4 1k A RA1 RB2 6 RB7 18 8 11 10k 10k 10k 3 4 IC2 MAX232 1 F 1 F 5 TO PC CON1 8 9 12 13 11 14 1 2 3 4  LED1 5 K bus interfacing but this hasn’t been used here since it has more limitations than benefits. Instead, the I2C interface is implemented fully in the firmware of the weather station. The asynchronous (RS232) serial port on the PIC is connected through a standard MAX232 serial interface driver (IC2), providing suitable voltage levels for serial communication. The MAX232 part of the circuit is manually switched on and off by the user (using S4 ) when a data dump is needed. Getting this part of the circuit to work proved more difficult than it might appear because even when switched off, the MAX232 would sometimes stay in a partially running state. It appeared to be drawing power parasitically through its three I/O connections to the PIC. Resistors (10kW) between the PIC and each of these I/O lines solved that particular problem. The RS232 interface is set up for 2-way communication but only transmission from the PIC is built into the firmware since this is all that is needed. However, the capability is there for the device to receive serial communication for anyone who wanted to extend the capabilities of the design. Interfacing the rain sensor is simple. The rain gauge is a tipping bucket type and operates by closing a switch momentarily each time the bucket empties. The PIC detects this through an interrupt and increments an internal rain counter by one. The rain sensor input on the PIC is normally held high 6 7 8 9 5 12 13 DB9F 15 X1 32.768kHz Vss DATA LOGGING WEATHER STATION siliconchip.com.au 1 F 16 1 RA2 IC1 PIC16F88 390 10k 1 F 10k 3 390 A2 5 SDA 2 A1 IC4 1 A0 24C256 6 SCL 7 WP Vss 4 5 17 2 1 8 Vdd 8 Vdd 'DUMP' S4 14 Vdd LED 33pF 33pF K A Fig.1: there are just five ICs and a handful of other components in the Weather Station circuit. by a 220kW resistor when the switch is not closed. A high value was used for this resistor because there is a small risk that the tipping bucket could stick in the centre position and keep the switch closed. If this occurs, the battery would The control box from the rear, showing the battery pack (three AA cells) and the 5-pin DIN connector, along with the hanger bracket at the top. September 2007  61 17090140 IC1 PIC16F88 SW 33pF RST 33pF P11 32.768kHz X1 CLKADJ K 27090140 + +V 10K 10k 10k 100nF P12 quickly drain if a smaller (say 10kW) pull-up resistor had been used instead. There are two extra features included in the circuit. One is a small pushbutton switch (S2) on the PC board that is only accessible when the case is open. This is used to calibrate the clock in the controller. You may wonder why this is needed. To achieve low power consumption, the PIC spends most of its time “sleeping”. Even though the 16F88 has an on-board oscillator that could potentially run a real time clock, this shuts down when the device sleeps. Hence, an external crystal oscillator, using a 32.768kHz “watch” crystal was necessary. The PIC keeps driving this crystal even when it is sleeping. Even though these crystals are pretty accurate, they aren’t perfect and can be out by maybe five seconds a day. In the worst case, over a year, this can add up to an error of half an hour. Details on using switch S2 can be found later in this article. A second pushbutton switch (S1) is accessible from the front panel. This is used to reset the weather station. “Reset” in this case does not mean a hardware reset of the PIC. Instead, the reset button is used to zero the address pointer for the EEPROM memory. The user would normally do a reset after data is dumped so that all the memory in the device becomes available again for logging. If a reset is not done via this button, the weather station will keep logging from where it last left off. This will happen even if the device is powered down or re-boots itself due, for example, to a fault condition. There is no way to wipe the EEPROM memory in the weather station. This has been done deliberately to enable data to be recovered even if the address counter has become corrupted. If a data dump is performed just after a reset, the entire contents of the EEPROMs will be dumped – all 64kB or 16,384 records (four bytes per record). Normally, only the records up to the last one recorded will be transmitted through the serial port during a data dump. The way the data is recorded also enables breaks in the recording to be detected if a full data dump needs to be done – but more on that later. The weather station is very reliable and I’ve never had a need to do a full data dump (except for testing) but the feature is there just in case. Finally, there is a LED on the front panel to indicate status. This flashes very briefly every four seconds during normal operation. It comes on permanently during a data dump and it quickly flashes three times when a reset is performed by the user. A high-intensity LED is used to improve visibility since it is only on for about three milliseconds each flash – again, this was done to help keep power consumption down. 62  Silicon Chip -V P9 1k 390 IC3 24C256 IC4 24C256 390 +V 220k 1 F P12 10k P11 10k SW 10k A LED1 1 F –V + 390 Rain 1 F MAX232 IC2 1 F + +V 10K –V SDA SCL + Fig.2: two PC boards are used: (1) a main board, containing the PIC16F88 (IC1) and the two 24C256 serial EEPROMs (IC3 & IC4); and (2) an RS232 interface board which holds the MAX232 (IC2). The DS1621, is not mounted on a PC board but is housed inside the temperature measurement container. + 1F P9 Pin 1 TO S4 Four I/O pins on the PIC are not used at all, including an analog input for the A/D converter. Hence, there is scope to expand the capability of the weather station for those who may need additional sensing. The following table summarises the I/O pin usage on the PIC. Pin I/O port,bit 1 Port A,2 2 Port A,3 3 Port A,4 4 Port A,5 6 Port B,0 7 Port B,1 8 Port B,2 9 Port B,3 10 Port B,4 11 Port B,5 12 Port B,6 13 Port B,7 15 Port A,6 16 Port A,7 17 Port A,0 18 Port A,1 Allocated to… ‘Reset’ switch input (unallocated analog input or digital I/O) LED output (unallocated, digital I/O) Rain sensor switch input I2C bus data line (SDA) RS232 port receive (input) I2C bus clock output (SCL) Clock calibration switch input RS232 port transmit (output) Clock crystal Clock crystal (unallocated, digital I/O) (unallocated, digital I/O) Data ‘dump’ request input RS232 ‘communication ready’ input Putting the controller together The project is assembled in a small plastic utility box (second smallest size is used). Looking first at the externally visible parts, the front panel of the box has holes for the LED and the Reset switch, plus a larger cutout for the DB9 female serial port connector. There is also a single-pole, single-throw slide switch (S2), used for powering up the MAX232 when preparing for a data dump. The battery holder (3 x AA) is stuck to the back of the box with double-sided tape and the wires from this run through two small holes in the box. The only battery holder I could find for three AA cells was one with a plastic cover and an on-off switch. Unfortunately, the case opens on the opposite side to the switch. Hence the switch is inaccessible when the case is stuck to the utility box – and in fact the switch actuator had to be cut flush with the surface of the battery case to enable mounting. Since the switch is now inaccessible, to minimise the risk of failure, I broke open the battery case behind the switch and soldered a link across the terminals to bypass it (so the switch is effectively permanently on). Of course, a 4 x AA flat battery holder could also be used with either a dummy cell or shorting wire replacing one of siliconchip.com.au And here are those two PC boards, shown slightly over-size for clarity, which match the diagrams at left. Note that there are also connections underneath the boards – the underside of the main PC board is shown below. the four cell positions. If you use this method, don’t forget which cell you’ve replaced or you could end up putting one into the shorted position! One end of the utility box has a socket for connecting the temperature and rain sensors. The temperature sensor requires four connections (Vcc, ground, data & clock), while the rain sensor has a 2-wire connection (ground & signal). A 5-pin DIN audio connector was chosen for the task, with the ground connection shared between the temperature and rain sensors. A range of other socket types would be suitable, including separate sockets for the temperature and rain sensor if this is desirable. The main consideration should be ensuring a reliable connection. Inside the box, there are two PC boards, on which all components are mounted except the slide switch for dumping data and the rain and temperature sensors. The PC boards slide into the mounting slots provided in the utility box, with the component side of both facing towards the socket that connects the temperature and rain sensors. I’ve included solder pins on the PC boards for the interconnections that are needed. Those pins on the main controller (PIC) board that are needed for connection to the MAX232 board should be mounted on the copper side of the board so they point towards that board, enabling easier connection. Six connections are needed between the two boards (including +V and ground). The overlay of both boards (Fig.2) makes it clear where the interconnections should occur (‘SW’ to ‘SW’, ‘P9’ to ‘P9’ and so on). There are two sets of positive and negative connection In the prototype, the on/off switch on the battery pack was shorted (see enlargement) because the switch was on the wrong side of the pack. You could use a 4 x AA pack with one cell shorted out. CLOSEUP OF BATTERY PACK WITH SHORTED SWITCH siliconchip.com.au points on each board. One of the sets on the MAX232 board (which should face out from the copper side) is for connection to the battery pack, while the second set connect power to the PIC board. The second set of power connection pins on the PIC board is for the temperature and rain sensor socket. The MAX232 board also has two pins marked “to switch” on the overlay which need to be run to the “dump” switch. Assembly is straightforward. As usual, watch for correct orientation of polarised components – besides the ICs, the only ones are the five electrolytic capacitors on the MAX232 board and the LED on the main board. There is one PC board link – sort of, anyway. The in-line DB9 socket solders directly on to the MAX232 board, with the edge of the board pushed between the two rows of pins The DS1621 temperature sensor chip is soldered to the end of a four-wire lead as shown at left and in the photo below. If using telephone or alarm cable, it makes sense to use red for +ve, black for -ve and the blue and white wires for data. September 2007  63 Parts list – Data Logging Weather Station 1 PC board, 63 x 37mm, code 04109071 1 PC board, 63 x 32mm code 04109072 1 130 x 68 x 43mm plastic utility box (UB3) 1 ~500mm length of 100mm diameter PVC sewer pipe (150mm length for rain sensor and 200mm length to house the controller) 3 PVC end caps to fit 100mm sewer pipe 1 180 x 360mm piece of 0.4mm galvanised steel sheet (for primary funnel) 1 260 x 15mm piece of 0.4mm galvanised steel sheet (for secondary funnel bracket) 1 80 x 125mm piece of 0.6 to 0.8mm thick aluminium sheet (for tipping bucket) 1 100 x 50mm piece of 0.6 to 0.8mm thick aluminium sheet (for secondary funnel) 1 95 x 25mm piece of 0.6 to 0.8mm thick aluminium sheet (for tipping bucket bracket) 2 M4 x 20mm machine screws and nuts, corrosion resistant 4 M4 x 12mm M4 machine screws (corrosion resistant) plus 1 nut 1 small piece of fine wire gauze (for primary funnel; also used on the discharge holes below the tipping bucket) 2 100 x 8mm galvanised steel bolts, plus nuts and washers for each (to make mounting brackets for rain sensor and controller housing) 1 steel strip, 70 x 25 x 3mm, for rain sensor mounting bracket 1 20 x 8mm galvanised steel bolt, plus nut and washers to suit (for rain sensor mounting bracket) 1 length of stainless or galvanised steel wire, 50mm long 1-2mm diameter Assorted pop rivets 1 AA battery clip (for three AA batteries) 1 1m length single-core shielded audio cable 1 1m length 4-core alarm cable 1 3 x 2mm disc-shaped rare earth magnet (or two 3 x 1mm magnets) 1 DB9 female socket (in-line solder type) 1 5-pin panel mounting DIN socket and line plug to match (plus mounting screws for socket) 1 right-angle PC-mount momentary close pushbutton switch (mini tactile) (S1) 1 PC-mount momentary close pushbutton switch (mini tactile) (S2) 1 glass-encapsulated magnetic reed switch (Jaycar SM1002 or equivalent) (S3) 1 SPST slide switch and mounting screws (S4) 21 PC solder pins 1 18-pin IC socket 1 16-pin IC socket 2 8-pin IC sockets 1 32.768kHz watch crystal (X1) Semiconductors 1 PIC16F88 microcontroller (IC1) programmed with “weather station.hex” 1 MAX232 serial (RS232) interface driver (IC2) 2 24C256 or 24LC256 serial EEPROMs (IC3, IC4) 1 DS1621 temperature sensor (IC5) 1 5mm super bright red LED Capacitors 2 33pF ceramic (C1, C2) 1 100nF ceramic (C3) 5 1mF electrolytic (C4-C8) (code 33 or 33p) (code 104 or 100n) Resistors (0.5W, 5%) 3 390W (colour code orange white brown gold [5%] 1 1kW (colour code brown black red gold [5%] 7 10kW (colour code brown black orange gold [5%] 1 220W (colour code red red yellow gold [5%] or orange white black black brown [1%]) or brown black black brown brown [1%]) or brown black black red brown [1%]) or red red black orange brown [1%]) Optional parts 1 steel star picket (1.2m long) Aluminium and galvanised (or Colorbond) steel sheet to make a louvred housing for temperature sensor 1 galvanised steel bolt, 100 x 8mm (and two nuts and washers to suit) for mounting the louvred housing 1 DB9 serial communication cable for computer connection See part II of this project (next month) for more details on materials for the separate temperature housing 64  Silicon Chip siliconchip.com.au on the socket. Pads are provided on the solder side of this board for pins 1-5 of the socket. Pins 6, 7 & 8, which sit on the component side, also need to be connected. A single pad and hole in the PC board is provided for this, just near pin 6 of the DB9. A wire link should be soldered into this pad and, on the component side, bent and soldered to pins 6, 7 & 8 (see photo). Don’t connect pin 9 of the socket. Wiring the DS1621 temperature sensor The DS1621 temperature sensor comes in an 8-pin DIP package. For use with this project, it is mounted on the end of a cable, so it can be placed in a housing or other suitable location where the temperature is to be measured. There are a few possible cable choices, including a length of 4-core alarm cable, telephone cable or Ethernet LAN cable. A length of about a metre was used for the prototype and this worked well. It’s likely to be feasible to extend the length but no testing has been done on longer lengths. The cable only needs to handle a digital signal at about 60kHz, so it shouldn’t be too demanding. The wires on one end of the cable are simply soldered Fig.3: it’s up to you which software you use for data logging – there’s a mountain of it out there, a lot of it freeware. This screen grab shows the “Eltima” RS232 software which the author uses. More on this next month. directly to the appropriate pins on the DS1621. Follow the wiring diagram and the photograph, which shows the underside of the DS1621. All DS1621 pins except pins 4 & 5 are trimmed before soldering so that they can be bent flat onto the back of the device without touching one another. Bending them back like this gives a more compact final result. After soldering, coat the DS1621 and the end of the cable in 2-part epoxy. Try to keep the amount of epoxy to a minimum – the more there is, the more bulk that has to heat up or cool down each time the temperature changes, thereby reducing responsiveness. Protecting the DS1621 like this should be fine for most uses. But be warned: experience has shown that it won’t tolerate extended immersion or prolonged exposure to wet or damp environments. If high water-resistance is needed, pot the DS1621 in silicone sealant (again, minimising the amount used) then use a short length of adhesive lined heatshrink tubing over this. After heating the heatshrink (and while the adhesive is still melted), pinch the open end closed until the adhesive re-hardens (use gloves or you could burn yourself!). It’s a good idea to apply white paint to the coated sensor to reflect any radiant heat that may reach it. If you don’t do this, you may measure heat from sources other than the surrounding air. The temperature sensor is accurate to 0.5° Celsius and SC is not adjustable. We’re getting a bit ahead of ourselves (mechanical details will be presented next month) but this shot shows how the control box is “hung” inside its PVC pipe with the hanger bracket riveted to the PVC pipe cap “lid”. siliconchip.com.au NEXT MONTH: Full construction details for the rain gauge and temperature measurement housing September 2007  65 Stereo Class-A Amplifier; Pt.5 By GREG SWAIN Ch as s is as s em b l y, w ir in g & a d j us t m en t de t a ils 66  Silicon Chip siliconchip.com.au In this article, we show you how to build a high-performance 20W Class-A Stereo Amplifier using the modules described over the last few months. The unit is available as a complete kit from Altronics and the assembly is straightforward. I N THE MAY & JUNE 2007 issues, we published the circuit and assembly details for our new high-performance 20W Class-A Stereo Amplifier modules, along with a suitable Power Supply module. Then in the July issue, we described a Speaker Protection & Muting module and followed that up in August 2007 with a LowNoise Preamplifier & Remote Volume Control. This month, we show you how to assemble everything into a custommade steel chassis that’s been designed by Altronics. This precision laser-cut chassis is supplied with all the holes drilled and with pre-punched front and rear panels with screened lettering. This case is similar to their “2U” deluxe rack cases (but is much deeper) and features a bevelled front panel. The completed amplifier looks very professional, although at 420 x 425 x 88mm (W X D x H) it’s really quite a siliconchip.com.au large unit. This size is necessary to accommodate the large finned heatsinks used for the power amplifiers and to allow the various modules to be logically placed (and separated) inside the chassis. The large chassis size is also important to aid ventilation, as the main heatsinks run quite hot in operation (about 30° above ambient). In addition, the bottom of the chassis and the lid have large ventilation slots which line up with the heatsink fins, to allow the air to circulate through them. That’s one of the drawbacks of a class-A amplifier – they generate lots of heat that has to be dissipated. OK, let’s assume that you’ve completed all the modules and that you’re ready to mount them in the chassis and install the wiring. Here’s how to go about it. Preparing the case As supplied, the case is finished in a tough powder-coating that’s also a good insulator. However, you must ensure that all sections of the case, including the side panels and the front & rear panels, are correctly earthed and that means ensuring they make good electrical contact with each other. There are two reasons for this: (1) all sections of the case must be connected to the mains earth to ensure safety; and (2) correct earthing is necessary to keep RF interference out of the audio circuitry. The first job is to ensure that the two side panels, the front & rear panels and the lid are all earthed to the bottom section of the chassis. This is done by using an oversize drill to remove the powder coating from the countersunk screw holes. Use a drill that’s slightly smaller in diameter than the screw heads and be sure to remove the powder coating right back to the bare metal. Don’t just do this for one or two holes – do it for all the holes in each panel. Provided you use a drill that’s not too big, the bare metal will later be covered by the screw heads. Next, scrape away the powder coating around the screw holes inside the panels, the underside of the lid and from the matching contact areas around the screw holes in the chassis. This includes the contact areas around the screw holes on the inside folded September 2007  67 OUTPUT + + – – E B C E B B C 17070210 E -NIKPSR C E B -NIKPSL +NIKPSL B B SPEAKER PROTECTOR BOARD + B C E CABLE TIE C E C +NIKPSR +TUOKPSL E C B E C E C C E B CON3 CON2 CON1 ~ RECTIFIER BRIDGE + SPKR– LEFT CHANNEL POWER AMPLIFIER E E B SPKR+ B + +22V C E +22V ~ SPKR– SPKR+ – E B + C C B E + C B E + GN D GND 1N 4148 1N 4148 CON1 LEFT AMPLIFIER INPUT C E B B C C E E B + – 22V + * B C E C B E C B E E B C B E + 1k + 68  Silicon Chip B * 7002 C Installing the hardware You can now start installing the hardware in the case – see Fig.1. Begin by securing the IEC power socket to the rear panel using the two 6g x 12mm countersunk self-tappers supplied. That done, mount the two insulated RCA input sockets and the two loudspeaker terminal panels. Note that the white (left) colourcoded RCA socket goes to the top, while the red (right) socket goes to the bottom. The loudspeaker terminal pairs go in with their red (positive) terminals towards the top and are again secured using 6g x 12mm countersunk self-tappers. The 35A bridge rectifier can go in next. Because it uses the chassis for heatsinking, it’s important to ensure good metal-to-metal contact. It’s mounting area should be completely free of powder coating but if not, mark out the area and remove the powder coating using a small grinding tool. Now smear the underside of the 35A bridge rectifier (BR1) with heatsink compound and bolt it to the chassis using an M4 screw, star washer and RIGHT SPEAKER OUTPUT +TUOKPSR sections of the front panel. That way, when the case is assembled, earthing takes place via the screws themselves and also via direct metal-to-metal contact between the various sections. The transformer mounting bolt must also be earthed and this means that you have to remove some of the powder coating from around the mounting hole on the outside of the chassis (ie, from under the bolt head). The same goes for all other mounting screws that go through the bottom of the chassis. In particular, make sure that you clear away the powder coating from around the six heatsink mounting holes. Once you’ve done all this, remove the front panel, wrap it up and put it to one side, so that it doesn’t get scratched or damaged. It doesn’t take much of an accident to spoil the panel’s appearance while you are installing the parts in the chassis and completing the wiring. LEFT SPEAKER 1N 4148 Fig.1: follow this diagram and the photos to install the parts in the chassis and complete the wiring. Note that the supply leads to the modules, transformer and mains switch are twisted together – see photos & text. –22V EARTHING LUG NOTE: ALL FEMALE SPADE QUICK CONNECTS MUST BE FULLY INSULATED (NOT SHOWN FOR CLARITY) LEFT CHANNEL HEATSINK * ADHESIVE CABLE TIE-DOWN POINT siliconchip.com.au IEC MAINS CONNECTOR (FUSED) * INSULATE FROM L EF T REAR PANEL GRN INPUT BLUE RIGHT INPUT B RN POWER TRANSFORMER G RN NYLON P-CLAMP EARTHING LUGS * GRN SLEEVE WITH HEATSHINK TUBING - SEE TEXT * NYLON P-CLAMP * +22V SPKR– +22V G ND – 22V SPKR+ NYLON P-CLAMP E +2 2V SPKR– B + E E + + B B C C + B E POWER SUPPLY BOARD E RIGHT CHANNEL POWER AMPLIFIER C SPKR+ B + + + SLEEVE SWITCH LEADS WITH HEATSHINK TUBING - SEE TEXT E + B C GN D GND + + R1 1N 4148 B B C C E B E E +22V E B C C E B GN D + C O N1 NYLON P-CLAMP LED1 LE D 2 K – 22V + RIGHT AMPLIFIER INPUT A K A TO AMPLIFIER(S) 1N 4148 B E C + + C –22V B B E +22V C –22V E 100k BEAD 22F NP 1F NP 100nF 22F NP 1F NP X1 REG1 22pF 1k 100F 16V 100F 16V REG3 100F 25V 10F 16V 1k 10 1k D1 RE G 2 LK2 LK 1 22pF 100 PREAMP & VOLUME CONTROL BOARD siliconchip.com.au 22 D2 100 B E AD 22k 560pF 100 25V 220F 1k 1k 1k 10k 1k 100nF 25 V 220F * VR 2 1R 0O 0nTFOM Q2 1k 100nF BEAD 4.7k 4.7k 22F NP Q4 Q1 IC3 PIC16F88-I/P 100k 270pF 100 Q3 CON6 CON5 100nF 560pF 22F NP CON4 IC2 NE5532 4.7k 4.7k 4.7F NP IC1 N E 5532 100k 270pF 100 CON3 100k CON2 100 4.7F NP B E AD CON1 10nF 22k OERETS ESION WOL REIFILPMAERP 17080210 –22V LK4 LK3 18k 100 100F 16V POWER SWITCH RIGHT CHANNEL HEATSINK September 2007  69 Fig.2: the Altronics case will come with the main earth lugs mounted in place. However, if you’re using a different enclosure, here’s how to install the chassis earth point. Two nuts are used to permanently lock the assembly in place. Make sure that it forms a sound electrical contact with the chassis. nut. Fig.1 and the photos show BR1’s mounting location and orientation. It’s mounted with its positive DC output at top right. Chassis earth lugs Fig.2 shows the mounting details for the main chassis earth lugs. This assembly consists of two double-ended quick-connect terminals which are bolted to the chassis using an M4 x 10mm machine screw, two star washers and two nuts. The second nut on top locks the first nut in place, so that there’s no possibility of the earth terminals coming loose. Altronics has indicated that the chassis supplied with the kit will come with the earth lugs mounted in position. However, if you are using a different case, then you will have to remove the powder coating yourself. To do this, temporarily bolt one of the double-ended quick connects to the chassis and use a pencil to outline the contact area. The quick connect can then be unbolted and the powder coating removed using a sharp implement or a small grinding tool. The two double-ended earth lugs can then be bolted in position. Be sure to do the nuts up nice and tight, to ensure a reliable earth. A second earth lug is mounted at the front of the chassis, to the left of the preamp board. This is a single-ended lug and is used to ensure a reliable earth connection for the body of the volume pot. Installing the modules The five PC-board modules can now 70  Silicon Chip be installed in the chassis. Note that these modules are all mounted on 10mm tapped stand-offs, except for the preamplifier module which mounts on three 25mm tapped stand-offs. Begin by mounting the left and right channel power amplifier modules. These should already be attached to the heatsinks and it’s just a matter of lining these up with their mounting holes in the chassis and bolting them into position using M4 x 10mm machine screws and star washers. The star washers go under the heads of the screws and bite into the chassis to ensure that the heatsinks are securely earthed. Note: do not over-tighten these screws. The heatsinks are made of aluminium and it’s all too easy to strip the threads if you are ham-fisted. Once the heatsink screws are in, the spacers fitted to the power amplifier boards can be secured to the chassis using M3 x 6mm screws and flat washers. Loosen off the heatsink screws under the chassis to get everything to line up if necessary, then do the screws up nice and tight. That done, the power supply board and the preamplifier module can be mounted. As previously mentioned, the preamplifier is secured using only three of its four mounting holes – the hole adjacent to the volume control pot is not used. This avoids placing strain on the pot’s soldered joints and in any case is unnecessary, since the pot’s ferrule is also secured to the front-sub-panel. Before mounting the preamp, fit a flat washer over the pot’s threaded ferrule. That done, fit the three 25mm tapped spacers, then slip the preamp board into position and secure it to the front sub-panel by fitting the nut and a shakeproof washer to the pot. Do this nut up firmly but don’t over-tighten it, to avoid stripping the thread. Finally, the three spacers can be secured to the chassis using M3 x 6mm machine screws and washers. The three indicator LEDs and the IR LED on the preamp board all go through a cutout in the front sub-panel. Provided you’ve installed them correctly, as shown in Pt.4 last month, they should all line up neatly with their respective holes when the front panel is later installed. Note that the photos show these parts going through separate holes in the front sub-panel. The chassis supplied for kits will feature a large cut-out in the sub-panel instead. Note also that if the infrared receiver module (IRD1) has a metal shield, then it must be insulated from the front panel (see p22, August 2007). The power supply board is next on the list but first you have to add some extra quick connectors. First, you need to install three extra single-ended connectors at the DC output end of the board, to go with the existing doubleended connectors. That done, install an extra double-ended connector at the GND terminal (to go with the existing single-ended connector) at the input end of the board. Make sure that the screws that hold these connectors in place are done up nice and tight. You will need a screwdriver to hold the head of each screw in place and a ratchet-driven socket to tighten up the nuts. Having added the extra connectors, the power-supply board can be mounted in position. Secure it using M3 x 10mm screws and flat washers. Leave the power transformer out for the time being – that step comes a little later, after you’ve installed the low-voltage DC wiring. Wiring up Fig.1 shows the wiring routes. It’s not nearly as intimidating as it appears at first sight as most of it simply consists of DC supply wiring to the various modules. In addition, there’s a small amount of audio signal cabling, plus the loudspeaker cabling and the mains wiring. As can be seen, most of the supply wiring is terminated using insulated female spade connectors. These simply plug into the quick connect spade terminals on the various modules. Screw terminal blocks handle most of the other terminations, the exceptions being the RCA input sockets on the two audio amplifier boards. By the way, a ratchet-driven crimping tool (see photo) is an absolute necessity when it comes to installing the crimp connectors. Low-cost automotive type crimpers are definitely not suitable here, as their use would result in unreliable and unsafe connections – particularly where the mains wiring is concerned. As shown in the photos, all the supply leads are tightly twisted together. This not only keeps the wiring neat but also minimises hum pick-up, siliconchip.com.au This chassis view clearly shows the routing of the loudspeaker cable from the right channel power amplifier. It runs along the bottom of the rear panel and is secured using adhesive cable tie mounts and cable ties. since the hum fields are effectively cancelled out. There’s an easy way to twist the leads together and that’s by using a hand drill. All you have to do is secure one end of the leads in a vice and the other end in the drill chuck. You then rotate the drill handle until you get a nice even lead twist along the full length of the cable. Make the twists reasonably tight but don’t overdo it – the wire will break through the insulation if you do. Once it’s done, trim the ends to remove any damaged insulation and fit spade connectors to the leads at one end of the cable only. The spade connectors are fitted as follows: (1) trim 6mm of insulation from the end of a lead and twist the wire strands together; (2) push the lead into the connector until the insulation siliconchip.com.au hits the internal collar; (3) crimp the connection using the crimping tool; and (4) check that the connection is secure and properly insulated, with no wire strands outside the connector (this is particularly important for the 240V AC wiring). The leads at the other end of each cable are also later fitted with spade connectors, after they have been run to their destinations and cut to the correct length. It’s best to install the low-voltage DC wiring first. This can go in as follows: (1) Install the supply wiring to the two power amplifiers. These cables should be run using extra heavy-duty red, green and black leads. Twist the leads together and initially fit spade connectors to the power supply ends only. That done, plug each cable into the power supply board and route it to its respective power amplifier board. When it reaches the amplifier board, cut the green lead to length, fit it with a spade connector and plug it in. The red and black leads then continue under the amplifier to the centre of the board. They then diverge at right angles and are routed to the +22V and -22V terminals. (2) Install the +22V, 0V & -22V supply wiring between the power supply board and the preamplifier. (3) Install the +22V and 0V wiring between the preamplifier and the loudspeaker protector module. Note that this wiring actually runs behind the bridge rectifier (Fig.1 shows it in front for clarity) and is tied down to one of the transformer ventilation slots. An adhesive cable tie mount at the front left corner of the power supply board September 2007  71 You Need A Ratchet Type Crimping Tool One essential item that’s required to build this amplifier is a ratchetdriven crimping tool, necessary for crimping the insulated quick-connect terminals to the leads. Suitable crimping tools include the Altronics Cat. T-1552, Dick Smith Electronics Cat T-3535 and the Jaycar TH-1829. These all feature doublejaws so that the bared wire end and the lead insu­lation are crimped in a single action. Don’t even think of using one of the cheap (non-ratchet) crimpers that are typically supplied in automotive crimp kits. They are not up to the job for a project like this, as the amount of pressure that’s applied to the crimp connectors will vary all over the place. This will result in unreliable and unsafe connections, especially at the mains switch and IEC socket terminals. By contrast, a ratchet-driven crimp­ i ng tool applies a preset amount of pressure to ensure consistent, reliable connections. provides a second anchorage point. (4) Install the ±22V wiring between the bridge rectifier (BR1) and the power supply board. (5) Install earth leads from the power supply board to the main chassis earth point and from the preamplifier board (near the volume pot) to its adjacent chassis earth. AC sense leads The two “AC-Sense” leads that run from the bridge rectifier to the loudspeaker protector are next on the list (these are the blue leads that run to BR1’s AC terminals in Fig.1). First, twist the two leads together and fit one end of each lead with a piggyback crimp connector (see photo). That done, plug these into the AC (~) terminals of the bridge rectifier, then route the leads to the loudspeaker protector and trim them to length. Finally, strip about 5mm of insulation from the ends of the leads and tin them before connecting them to the screw terminal block (CON2). If you route these leads as shown in the photos, they can be secured to the chassis using a cable tie that passes through one of the transformer ventilation slots. A second cable tie adjacent to the CON2 is also a good idea. Audio input wiring The audio input signal leads can now be run from the rear panel to the preamplifier. These leads should be run using figure-8 (stereo) audio cable (ie, with the inner conductor individually shielded). Route these leads exactly as shown and secure them using cable ties and adhesive cable tie mounts. The locations of the latter are indicated on Fig.1. Note that the shield leads are separately connected to their respective solder lugs on the insulated RCA input sockets. Do not connect these shield leads together or to chassis, otherwise you’ll get an earth loop. At the preamplifier end, trim each conductor to length, then strip about 14mm of the outer insulation away from each conductor in turn and care- Where To Buy Complete & Shortform Kits A kit of parts for the 20W Stereo Class-A Amplifier (Cat. K5125) is available from Altronics, 174 Roe St, Perth, WA 6000, Australia. The kit is complete and includes the five modules (unassembled) and a pre-punched steel chassis similar to that shown in the photographs. Alternatively, you can purchase individual kit modules (but not the chassis) separately. Check the Altronics website at www.altronics.com.au for further details. Note: the kit does not include an infrared remote control handpiece. This must be purchased separately. Almost any universal remote should be suitable; eg, Altronics Cat. A 1009. 72  Silicon Chip fully separate and twist the shield wire strands together. That done, strip about 10mm of insulation from each inner conductor, then double each bared end back on itself, twist it together and lightly tin with solder. The shield wires can also be “doubled up”, twisted and tinned. Now secure the audio input leads to the screw terminal blocks. Note that it’s important to do these screw connections up nice and tight, otherwise the signal-to-noise ratio will be compromised. Some of the left over figure-8 audio cable can now be used to make the two audio leads that run from the preamplifier to the power amplifiers. Separate the cable into two separate leads and fit an RCA plug to one end of each lead (red for the right channel, black for the left). Make sure that each shield wire connects to the “earthy” side of its RCA plug (ie, to the terminal that connects to the outer collar). The other ends of these cables can then be trimmed to length and connected to screw terminal blocks CON2 & CON4 on the preamplifier. Be sure to tin the leads as before and again make sure the connector screws are done up tightly. Loudspeaker cabling The loudspeaker leads, both to and from the loudspeaker protector, are run using heavy-duty 90/0.18 speaker cable. The cables are terminated at both ends using female spade connectors and must be routed exactly as shown in Fig.1 and the photos. In particular, note the path for the loudspeaker cable from the right channel power amplifier. This must be kept as far away as practical from the mains wiring between the IEC socket and the power transformer. As shown, it runs around the chassis earth terminal and then runs along the bottom section of the rear panel (behind the transformer) to the loudspeaker protector module. The cable is anchored in position using several adhesive cable tie mounts. Two of these are attached to the bottom of the rear panel, while the third sits in front of the chassis earth lugs. Mounting the transformer The toroidal mains transformer can now be bolted into position. This transformer is supplied with two siliconchip.com.au Parts List For Class-A Stereo Amplifier If your infrared receiver module has a metal shield like this one, then be sure to insulate it from the front panel as described last month. The “AC Sense” leads from the loud­ speaker protector are terminated in piggyback crimp connectors at the bridge rectifier end, as shown here. neoprene rubber washers – one sits under the transformer (ie, between the transformer and chassis), while the other sits on top. A metal cup washer is then placed over the top rubber washer and the whole assembly secured using a large bolt that passes up through the centre of the transformer. Before installing the mounting bolt, check that the powder coating has been cleared from around its hole at the bottom of the chassis (this is necessary to ensure the bolt is correctly earthed). That done, install the bolt and do the nut up finger tight, then rotate the transformer so that its yellow secondary lead is exactly in line with the GND (centre) connection on the adjacent power supply board. Finally, do the nut up firmly but don’t over tighten it, otherwise you’ll distort the metal chassis. (Note: Fig.1 shows both the transformer and the preamplifier module offset to the right, compared to their true locations in the chassis. This has been necessary to keep these parts clear of the magazine centre.) As previously mentioned, the trans­ former leads are all the correct length to reach their destinations and are siliconchip.com.au 1 custom pre-punched steel case with screened front & rear panels 1 32mm black aluminium knob with grub screw (Altronics H 6236) 1 16V + 16V 160VA magnetically-shielded toroidal transformer (Altronics MA 5417) 1 SPST 10A 250VAC rocker switch (Altronics S 3224) 1 chassis-mount fused male IEC socket (Altronics P 8324) 1 M205 4A 250VAC slow-blow fuse 1 240VAC 3-pin IEC mains power lead 3 6.3mm double-ended chassis-mount spade lugs (Altronics H 2261) 5 6.3mm single-ended chassis-mount spade lugs 40 6.3mm female spade fully-insulated connectors (Altronics H 2006A) 2 piggyback crimp connectors (Altronics H 2016A) 1 red RCA plug (Altronics P 0200A) 1 black RCA plug (Altronics P 0201A) 2 chassis-mount insulated RCA sockets (red & black) (Altronics P 0218 & P 0220) 2 2-way loudspeaker terminal panels (Altronics P 2016) 1 pot nut and washer 5 P-clamps (Altronics H 4211) 20 M3 x 6mm screws 20 M3 shakeproof washers 20 M3 flat washers 13 M4 x 10mm screws 1 M4 x 16mm screw (to secure bridge rectifier BR1) 22 M4 flat washers 1 M4 shakeproof washer (for bridge rectifier BR1) Heatsink compound for BR1 Modules 1 right-channel class-A power amplifier module (Altronics K 5126) 1 left-channel class-A power amplifier module (Altronics K 5127) 1 power supply module (Altronics K 5128) 1 preamp and remote volume control module (Altronics K 5129) 1 loudspeaker protector module (Altronics K 5124) Wire & cable, etc 1m brown 32/0.20 extra heavy-duty hook-up wire (Altronics W 2280) (mains rated) 2m red 32/0.20 extra heavy-duty hook-up wire (Altronics W 2283) 1m black 32/0.20 extra heavy-duty hook-up wire (Altronics W 2284) 2m green 32/0.20 extra heavy-duty hook-up wire (Altronics W 2285) (mains rated) 250mm 24/0.20 heavy-duty blue hook-up wire (Altronics W 2275) 1m figure-8 shielded audio cable (Altronics W 3022) 1m heavy-duty 90/0.18 speaker cable (Altronics W 2130) 40 small nylon cable ties 7 adhesive cable tie mounts (Altronics H 4107) 500mm of 10mm-diamter heatshrink tubing pre-fitted with female spade quick connects. We’ll deal with the secondary wiring first – all you have to do is twist the various lead pairs together and plug them into the relevant quick connect terminals on bridge rectifier BR1 and the power supply module. First, twist the white and black leads together (to form the 0V centre-tap) and connect them to the adjacent GND point on the power supply module. That done, twist the red and yellow secondary leads together and plug them into the piggyback spade connectors on the AC terminals of BR1. There’s one important wrinkle you have to watch out for when plugging in the transformer secondary leads – it’s all to easy to push the male lug of each piggyback connector down September 2007  73 The RCA input sockets must be fully insulated from the chassis. The audio cable shield wires go to the individual solder lugs – do not join them or connect them to chassis at this point, as this would create an earth loop. The transformer’s red and yellow secondary leads plug into the piggyback connector at the bridge rectifier (BR1) as shown here. They should then be strapped using cable ties, so that the connectors can not short against BR1’s metal case. so that it shorts against the metal case of BR1. To avoid this, bend each male connector upright after plugging in the transformer lead and secure it in this position using a cable tie (see photo). It’s also a good idea to fit cable ties at both ends of the twisted pairs to keep the wiring tidy. Mains wiring It’s now time to connect the transformer primary leads (brown & blue) and install the rest of the mains wiring. Take particular care with the mains wiring – your safety depends on it. In particular, be sure to use fully insulated spade connectors for all connections to the IEC socket and mains switch. 74  Silicon Chip As shown in Fig.1, the transformer’s blue primary lead connects to the Neutral terminal on the IEC socket, while its brown primary lead runs directly to the top terminal of the mains switch. In addition, you need to run a heavy-duty (32/0.20) mains-rated cable (brown) between the bottom terminal of the mains switch and the Active terminal of the IEC socket. The best place to start this wiring is at the power transformer. Here’s the procedure, step-by-step: STEP 1: run the primary leads straight down the side of the transformer to the chassis and secure them together at top, bottom and centre using three cable ties. STEP 2: cut a 600mm length of brown 32/0.20 heavy duty cable (this will be used to connect the IEC socket Active terminal to the mains switch). STEP 3: twist this lead together with the brown primary lead. Start of the primary lead’s quick connector and twist the leads together all the way back to the base of the transformer. STEP 4: Slip a 320mm length of 10mmdiameter heatshrink tubing over this twisted pair and lightly shrink it into place using a hot-air gun. Be careful not to apply too much heat – you don’t want the cable insulation to melt (gently does it)! STEP 5: Secure this cable in position using the Nylon P-clamps as shown in Fig.1. Note the orientation of the Pclamps – the cable should run adjacent to the power supply board, so that it is well away from the righthand power amplifier. The switch end of the cable runs under the preamp and must be routed exactly as shown. STEP 6: Trim the switch end of the added brown lead to the same length as the brown primary lead and crimp on a fully-insulated spade connector. Make sure that all the wire strands go inside the connector – a stand outside the connector will be dangerous. STEP 7: Attach the front panel to the amplifier chassis and clip the mains switch into position. The two switch terminals go towards the top of the panel. STEP 8: Connect the two spade connectors to the switch terminals. The transformer’s primary lead goes to the top terminal. Use a cable tie to secure the leads at the switch terminal. STEP 9: Twist the added brown lead with the blue primary lead all the way to the latter’s spade connector. STEP 10: Slip a 120mm length of 10mmdiameter heatshrink tubing over this twisted pair and lightly shrink it into place using a hot-air gun (gently does it). STEP 11: Secure this section of the cable in position using another two Nylon P-clamps. As before, these should be orientated exactly as shown in Fig.1. STEP 12: Trim the brown cable to length and crimp on a female spade connector. STEP 13: Plug the connectors into the IEC socket. The blue lead goes to the Neutral terminal while the brown lead goes to Active. STEP 14: Further secure the leads using cable ties – two between the transformer and the first P-clamp and one right at the IEC socket. STEP 15: Prepare a 100mm-long earth lead with female spade connectors at either end and connect it between the earth terminal on the IEC socket and a spare chassis earth lug. STEP 16: Fit a 4A slow-blow M205 fuse to the IEC socket. STEP 17: Secure all the wiring in the amplifier by fitting cable ties as shown in Fig.1. This not only improves the appearance by keeping everything tidy but ensures reliability as well. In particular, make sure that the 240V wiring is properly secured by the P-clamps and by fitting cable ties immediately behind the spade connectors at the IEC socket and the mains switch. Initial checks That completes the wiring but there are a few things to check before plugging in a mains cord and switching on. Just follow this step-by-step checklist: (1) Check the 240V wiring to the IEC socket, mains transformer and mains switch to ensure all is correct. In particular, the female spade connectors should all be tightly crimped, the connectors must be fully insulated and there must be no wire strands outside these connectors. In addition, all spade connectors should be a tight fit onto their lugs, especially at the IEC socket, the mains switch and the bridge rectifier. Retension any connectors that slide on too easily. (2) Check that BR1’s positive and negative terminals connect to the correct terminals on the power supply board. siliconchip.com.au Ditching The Preamp & Using A Conventional Volume Pot Instead One of the options that you have in building this unit is to ditch the Preamplifier & Remote Volume Control module and use a dual 10kW log pot as the volume control instead. This option would typically be used if you want to use a CD player to drive the power amplifier modules – the signal output from a CD player is usually (but not always) sufficient to drive the amplifier modules to full power output. The advantage of this scheme is that you save money (ie, the cost of the preamplifier) and construction time. But there are a couple of disadvantages. First, as mentioned last month, using a simple volume control varies the input impedance to the power amplifiers, thereby slightly degrading the signal-to-noise ratio. And second, your CD player may not be able to drive the amplifiers to full output power on CDs that give below-average output signal levels. Another disadvantage is that you no longer have the convenience of remote volume control. If you do want to omit the preamplifier, Figs.3 & 4 show how it’s done. As shown, the incoming left and right channel signals are fed to the top of the pot and the attenuated signals on the pot wipers are then fed directly to the power amplifier inputs. Fig.3 shows the circuit, while Fig.4 shows the wiring diagram. Fig.3: this circuit shows how to use a dual 10kW W log pot as the volume control. Fig.4: follow this diagram to wire the volume pot in place. External preamp If you intend using an external preamplifier (eg, the SILICON CHIP Studio Series Stereo Preamp­lifier), you can omit the volume control altogether and simply run the audio input leads direct to the class-A power amplifiers. What about all those blank holes on the front panel? Easy – just mount the necessary parts to fill in the holes but don’t wire them up. The LEDs can be secured at the rear using epoxy resin. (3) Check that all the electrolytic capacitors on the power supply board are installed with the correct polarity. These things have a nasty habit of exploding if they’re in the wrong way around. The same goes for other electrolytics across the supply rails on the other modules. In fact, it’s not a bad idea to wear safety glasses when switching on for the first time, just in case you do have a capacitor in the wrong way around or you accidentally reverse the supply polarity. Exploding capacitors and eyeballs generally don’t mix too well! (4) Use a multimeter to confirm that all the chassis panels are correctly earthed. Do that by checking for continuity between the earth terminal of the IEC socket and each of the panels in turn (remove some of the powder coating from an inside surface of each panel to make these checks, if necessary). siliconchip.com.au Similarly, check that the heatsinks are earthed to the chassis and that all external screw heads are earthed. (5) Use a multimeter to confirm that the output transistors (Q12 & Q14) are correctly isolated from the heatsink of each power amplifier module. Test & adjustment There are three basic procedures to go through here. First, you have to check that the power supply module is delivering the correct voltages. You then apply power to each power amplifier module in turn and adjust its quiescent current. And finally, you power up the preamplifier and loudspeaker protector modules and check their operation. Here’s the procedure: STEP 1: disconnect all nine spade connectors from the +22V, 0V, -22V terminals at the output end of the power supply module. STEP 2: disconnect the loudspeaker leads from the power amplifier modules. STEP 3: connect an IEC power cord to the amplifier and use a multimeter to confirm continuity between the earth pin of the plug and the chassis earth. That done, plug the cord into a mains socket and switch on. Warning: don’t go poking around the rear of the IEC socket with power applied. The metal strap that runs from the Active terminal to one end of the fuse has 240V AC on it. STEP 4: check the unregulated ±22V rails at the output of the power supply module. These rails should both be measured with respect to the 0V terminal and should be a little high at around ±24V (since they are unloaded). If the meter reads 0V, switch off immediately and re-check the connections to BR1. STEP 5: switch off and connect the September 2007  75 Adjusting The Quiescent Current Through The Power Amplifiers The quiescent current flowing in the output stage of each power amplifier is initially adjusted by installing 1.5W 5W resistors in place of the fuses. The voltage across one resistor is then monitored and trimpot VR1 adjusted for a reading of 1.68V – equivalent to a quiescent current of 1.12A. The easiest way to connect the resistors is to “blow” the supply leads (+22V, 0V, -22V) for the righthand power amplifier to the power supply module. STEP 6: remove the two fuses from the righthand power amplifier and install 1.5W 5W resistors in their place – ie, one in series with the +22V rail and one in series with the -22V rail. The best way to do this is to solder these resistors across a couple a spare M205 fuses, after first destroying the internal fuse wires. First, drill a hole in each end cap, breaking the fuse wire in the process. The resistor leads can then be bent to shape, fed through the end caps and soldered (see photos). The modified fuses with their resistors are now plugged into the fuseholders. These 1.5W resistors protect the output transistors by limiting the current through them if there is a fault, eg, if the VBE multiplier circuitry (Q10) is not functioning correctly. STEP 7: wind trimpot VR1 on the right channel power amplifier fully anticlockwise, switch on and check that the amplifier’s output voltage (ie, between the loudspeaker terminals) is less than ±50mV. If not, check the baseemitter voltage of each transistor in the amplifier; they should all be 0.6-0.7V. Check also that the correct transistor is installed at each location and that they are all the right way around. STEP 8: assuming the output voltage is OK, monitor the voltage across one of the 1.5W 5W resistors and wind VR1 slowly clockwise until the meter reads 1.68V. This is equivalent to a quiescent current of 1.12A. 76  Silicon Chip fuse wires in a couple of spare M205 fuses, then drill holes in the end caps and solder the resistors in place as shown. The original fuses can then be removed and the “modified” fuses clipped into place – see photos. That done, let the amplifier run for about five minutes or so and then check the voltage again. During this time the amplifier heatsink will become quite warm and the quiescent current will drift slightly. Readjust VR1 to obtain 1.68V again. STEP 9: switch off, remove the 1.5W 5W resistors and install the 3A fuses. STEP 10: repeat steps 5-8 for the left channel power amplifier. STEP 11: let the amplifiers run for about 30 minutes (so that the heatsinks get nice and hot), then check the voltage across one of the 0.1W 5W resistors in the right channel power amplifier. Adjust VR1 for a reading of 112mV. Now check the voltage across the other 0.1W resistor – these resistors have a tolerance of about 10%, so set VR1 so that the average voltage across them is 112mV. STEP 12: repeat step 11 for the left channel power amplifier. STEP 13: switch off and reconnect the preamplifier’s +22V, 0V, -22V leads to the power supply module. STEP 14: check the preamplifier and remote volume control for correct operation, as described in the August issue (skip this step if you’ve already done this). STEP 14: check the operation of the loudspeaker protector module if this hasn’t already been done. To do this, apply power and check that the relay turns on after about 5-7 seconds. If it does, temporarily short the temperature switch input – the relay should immediately switch off. Similarly, the relay should immediately switch off if you disconnect one of the leads to the “AC Sense” input. Now check that the relay switches off if a DC voltage is applied to the loudspeaker terminals (this simulates an amplifier fault condition). This is done by connecting either a 3V, 6V or 9V battery (either way around) between the LSPKIN+ terminal and the ground terminal of CON1. The relay should immediately switch off. Repeat this test for the RSPKIN+ terminal, then reverse the battery polarity and do these two test again. The relay should switch off each time the battery is connected (see also pages 74-75, July 1007). Note: the reference to testing the loudspeaker protector using a 1.5V battery in the July issue is incorrect. You need at least a 3V test battery to bias on the transistors in the DC detection circuit. STEP 15: switch off and reconnect the loudspeaker leads to the power amplifier modules. Watch the ventilation That’s it, your new 20W Class-A Stereo Amplifier is now ready for action. Just one final thing – as previously mentioned, the heatsinks get quite hot and the air must be allowed to flow freely through the bottom and top ventilation slots. This means the amplifier must sit out in the open on a hard, level surface. Do not enclose it in a cabinet and do not stack anything on top of it. SC 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. Alarm clock with day selector This circuit disables an alarm clock on Saturdays and Sundays when people like to sleep in but enables normal operation on Mondays to Fridays so that people rise in time for work or school. The core of the circuit is a 4017 decade counter which acts as the day counter and it is used in conjunction with a desk clock which acts the alarm and a watch module with alarm function which pro- vides one clock pulse very day to the 4017. In operation, the watch module feeds a day pulse via transistor Q3 to the clock input of IC1. This has seven outputs connected via day switches (S1-S7) and diodes D3D9 to Q1 which disables the alarm signal to the speaker via transistor Q2. LEDs1-7 indicate the actual day (if you forget!). To set the system, set the desk clock for the correct time and for the desired alarm time (eg, 6’o’clock). The watch module is set to the correct time and its alarm set to midnight. The day counter, IC1, is set to the correct day, as indicated by the LEDs, by pushing switch S12 and closing switch S8 or S9. S8 is normally left open to conserve the battery by leaving the LEDs off. As shown on the circuit, switches S1-S7 are set to sound the alarm on Mondays to Fridays and disable it on Saturday and Sunday. However, you can change the days to suit your work habits. Rasim Kucalovic, Liverpool, NSW. ($50) Issues Getting Dog-Eared? Keep your copies safe with these handy binders. REAL VALUE AT $13.95 PLUS P & P Available Aust, only. Price: $A13.95 plus $7 p&p per order (includes GST). Just fill in and mail the handy order form in this issue; or fax (02) 9939 2648; or call (02) 9939 3295 and quote your credit card number. siliconchip.com.au September 2007  77 Circuit Notebook – Continued DC-DC converter has two outputs This circuit was designed specifically to power the two separate panel meters for voltage and current measurements, featured in the March 2007 issue. The two separate supplies are required for independent LCD panel operation. In essence, the circuit is a 555 driving a step-up transformer with two output windings and associated rectifiers and filter capacitors. A 7809 3-terminal regulator provides 9V from a 12V-15V supply. The 555 timer is connected as an astable multivibrator operating at around 70kHz and with a duty cycle of 52%. The output from the 555 is fed via a 10nF capacitor to the primary winding of transformer T1. Fast recovery diodes D1 & D2 damp the positive and negative back-EMF swings from the transformer. Each transformer secondary wind­ing is fed to a 1N4148 signal diode (D3 & D4) which operates as a half-wave rectifier to feed a 22mF capacitor. The resulting DC is limited to 12V by the associated zener diodes, ZD1 & ZD2. The transformer is wound on a 15mm powdered iron toroid (Jaycar Cat. LO-1242). The primary was wound on first, with 10 turns of 28 SWG enamelled copper wire. The secondary windings are wound bifilar style, with 28 turns of 28 SWG wire. Roy Dickman, St. James, WA. ($40) 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 now there are four more reasons to send in your circuit idea. Each month, the best contri- 78  Silicon Chip bution published will entitle the author to choose the prize: an LCR40 LCR meter, a DCA55 Semiconductor Component Analyser, an ESR60 Equivalent Series Resistance Analyser or an SCR100 Thyristor & Triac Analyser, with the compliments of Peak Electronic Design Ltd www.peakelec.co.uk So now you have even more reasons to send that brilliant circuit in. Send it to SILICON CHIP and you could be a winner. You can either email your idea to silchip<at>siliconchip.com.au or post it to PO Box 139, Collaroy, NSW 2097. siliconchip.com.au IR LED used as remote control checker This circuit uses an infrared LED as a photo sensor while a 7555 timer is used in an unconventional way. The 7555’s pin 2 (trigger) is grounded, which normally would force the output at pin 3 to be permanently high. However, the IR LED (LED 1) connected to pin 4 (reset) forces the 7555 output low when there is no IR light present. Shining an IR remote control (with a button pushed!) on the IR LED releases the reset condition from pin 4 and causes LED 2 (red) to flash with each IR pulse. The circuit only works with the remote control in close proximity to the IR LED; ie, less than 100mm separation. The timer IC must be a CMOS type. An Intersil ICM7555 device was used in the prototype. Other CMOS 7555 devices may not work in this circuit if their pin 4 reset voltage threshold is much over 600mV. Geoff Nicholls, Hamburg, Germany. ($30) This circuit is about as simple as it gets when it comes to a remote control checker. Battery saver under micro control Many computerised devices like calculators and MP3 players have an automatic turn-off function which can save the battery from being accidentally fully discharged. One common method for doing this is to put the microcontroller and peripheral components into a standby mode. However, especially in larger microcontroller-based systems, it may not be feasible to power down peripheral components. And components like regulators draw quiescent current even when supply­ing minimal power to the circuit. This circuit allows the microcontroller to completely disconnect the power source. It supplies the standard regulated +5V for microcontroller circuits and uses an 8.4V NiMH rechargeable battery. The battery can be recharged by an external +12V DC input and charging is indicated by LED1. Pressing S1 temporarily comnects the battery via relay RLY1 to the regulator, powering up the microcontroller connected to the +5V supply. The first line of the microcontroller’s code must be written to set the “PowerControl” line high. This switches on Q1 and relay RLY1 which connects the battery to the regulator, effectively turning the circuit on. Pressing S2 shorts the base of Q1 to 0V, turning off the relay and siliconchip.com.au disconnecting the battery from the regulator. The +5V supply collapses, so when S2 is released, the relay cannot turn back on. This effectively turns the circuit off. Alternatively, the microcontroller can set the “PowerControl” line low, which performs the same function as pressing S2. This allows the microcontroller to turn the whole device off; for example, when the device has not received user input for a set period of time or if the microcontroller detects that the battery is low. The relay can be a small reed type unless the circuit draws a lot of power. In this case, the 78L05 may need to be replaced with a larger regulator and a larger relay may have to be used. It should be noted that switched power could also be drawn at near battery voltage from the input side of the regulator. The 150W resistor was selected to provide a trickle-charge current to a 9V-style NiMH battery and can be decreased in value if an AA batterypack is used. Roger Marley, Carbrook, Qld. ($40) September 2007  79 Circuit Notebook – Continued Musical doorbell based on a toy piano This musical doorbell plays a tune on a salvaged toy or electronic piano or organ. Ideally, the toy piano will have sustain so that notes sound “dinnnggg” rather than “tnk”. You will need to check its operation to find whether the common line for all the keys is high. The one used for this circuit was high (connected to battery positive). There was no on/off switch and the standby current is negligible. The circuit works as follows. IC1 is a 555 timer operating in monostable mode and gives a high output from its pin 3, lasting about 10 seconds. The time must be set using trimpot VR1 to cover just the time required to play the selected tune. IC1’s output at pin 3 supplies the toy piano and the rest of the circuit involving IC2, IC3 and IC4, etc. IC2 is a 555 timer operating in astable mode and producing a pulse train at pin 3 at about 1Hz. Since the 470kW timing resistor is connected to pin 3, the pulse duty cycle is close to 50%. These pulses are used to clock IC3, a 4017 decade counter which produces a series of high outputs which are used to turn on the piano notes. However, IC3’s outputs cannot be used directly since they overlap and typical toy pianos will not play another note while a previous key is still being pressed. Hence the outputs of IC2 (short) and IC3 (long) are gated together by NAND gate package IC4, a 4093. IC4’s outputs are low-going and used to turn on transistors Q1-Q4 which turn on the respective keys on the toy piano. IC3 and the transistors are set to play the Westminster halfhour chime, ie: F A G C rest F G A F. The diodes between IC3 and IC4 are included to prevent shorting the high on one pin of the 4017 to a low on another 4017 output pin. If your tune requires more than four notes, you will need another 4093 NAND gate package. If you analyse the diode connections, you will see that note F is played on outputs 1, 6 & 9, as required by the tune. Output 5 is not connected, to get between the first and second groups of four notes. A moment after the last note is played, IC1 is timed to turn off the circuit, ready for the next press of switch S1. If you want to run the entire circuit from an unswitched battery, IC1 should be a CMOS 7555. This can only source a limited current so the secondary positive rail will need to be switched by an additional BC337 PNP transistor, as shown in Fig.1. If your toy piano has the common of all keys negative, you will need to reverse the connections to the output transistors – see Fig.2. Finally, if you are using a toy organ which must have the keys held down to play (as distinct from a piano) you will need to lengthen the output pulses from the 4093 by changing the duty cycle of IC2. This can be done by using the standard two-resistor timing circuit of a 555. A. J. Lowe, Bardon, Qld. ($45) 80  Silicon Chip siliconchip.com.au Phone call alert for partially deaf If you are partially deaf, you may have trouble hearing the telephone ring, particularly on modern phones with relatively high-pitched electronic ringers. This circuit presents siliconchip.com.au an effective solution, using a loud reversing beeper (Dick Smith Electronics Cat L-7060). The beeper is controlled by the voice-operated relay project which was featured in the September 1994 issue of SILICON CHIP. It is powered by a 9V or 12V DC plugpack. The electret microphone is plac­ ed near the phone so it can be triggered when the phone rings. Note that the circuit will need to be manually switched off while you answer the phone. Dave Jeanes, Banora Point, NSW. ($30) September 2007  81 SILICON CHIP If you are seeing a blank page here, it is more than likely that it contained advertising which is now out of date and the advertiser has requested that the page be removed to prevent misunderstandings. Please feel free to visit the advertiser’s website: www.altronics.com.au/ SILICON CHIP If you are seeing a blank page here, it is more than likely that it contained advertising which is now out of date and the advertiser has requested that the page be removed to prevent misunderstandings. Please feel free to visit the advertiser’s website: www.altronics.com.au/ SILICON CHIP If you are seeing a blank page here, it is more than likely that it contained advertising which is now out of date and the advertiser has requested that the page be removed to prevent misunderstandings. Please feel free to visit the advertiser’s website: www.altronics.com.au/ SILICON CHIP If you are seeing a blank page here, it is more than likely that it contained advertising which is now out of date and the advertiser has requested that the page be removed to prevent misunderstandings. Please feel free to visit the advertiser’s website: www.altronics.com.au/ PRODUCT SHOWCASE eLabtronics flash microcontroller experiment board The eLab16m board from Adelaidebased eLabtronics, is a complete hardware and software solution for experimenting with flash microcontrollers. It includes a PIC16F819 microcontroller and there is a USB programmer and various external components to interface to the physical world. The kit, aimed at students from years 5 to 10, allows easy programming of the microcontroller through a dedicated graphical interface using the supplied CoreChart software. The programs are visualised in the form of a flow chart, and can be modified in an intuitive way through the dragging and dropping of icons. This kit is ideal for students and teachers interested in the application of electronics to scientific projects. The included CoreChart software allows programs to be written and programmed to the chip. The programs are visualised as flowcharts with icons representing typical program operations, like setting variables, jumping to subroutines and conditional branching. The software produces an assembler file of the program, which is then compiled and written to the PIC16F819 through the USB programmer. The USB programmer itself contains a PIC micro, the PIC16C745, which has an onboard USB port. The eLab16m board containing the target microcontroller can be powered through the USB programmer or externally by three AA alkaline batteries, giving around 4.5V. For scientific applications, the kit can be supplied with an interesting va- riety of sensors and peripherals including a thermistor, a light dependent resistor, as well as a motor and incandescent light bulb. A 16 x 2-line LCD screen can also be connected, as well as a switch, a buzzer and two LEDs. The eLab16m board has high current drivers to operate motors and light bulbs that can deliver up to 600mA and connects to the outside world through a row of terminal blocks. The great strength of the kit is the supplied software, which is aimed at simplifying the writing of programs. A microcontroller like this, with its limited memory, would normally be programmed directly in assembler. This would make it less accessible to a beginner audience. The main purpose of the CoreChart software is adding a higher level programming layer and it is quite successful at doing so. It is simple enough to be intuitive and not too simple as to lose its flexibility. In fact, any possible assembler program can effectively be written in the CoreChart software, so the latter is as powerful as it can be. The microcontroller can accommodate 2048 single word instructions in its flash memory and has 256 bytes each of EEPROM and RAM. It can become an I2C slave and has five 10-bit ADC channels. The eLab16m is a perfect introduction to flash microcontrollers and will provide many hours of instruction. This kit would make a great beginner’s course in microcontroller applications. It comes with a comprehensive and step-by-step guide to 6 example projects. Contact: eLabtronics 51 Byron Place, Adelaide, SA 5000 Tel: (08) 8321 5966 Fax: (08) 8231 5266 Website: www.elabtronics.com No, it’s not Jaycar’s Flying Saucer . . . Jaycar Electronics have come up with some pretty off-beat gadgets over the years – and when we first saw this one we thought “Oooh! A Flying Saucer!” But no – it’s nothing quite so esoteric. This is a handy LED flasher which is intended for emergency and warning applications – particularly automotive. It’s quite small (90mm diam) and is designed to be placed flat on a road to warn oncoming vehicles (it can even be driven 86  Silicon Chip over!). Three ultrabright LEDs flash at the right angle to warn drivers from a distance. Every car should have a couple in the glovebox. They are available from Jaycar stores for $9.95 (Cat ST-3185). Contact: Jaycar Electronics (all stores) 100 Silverwater Rd, Silverwater NSW 2128 Ph: (02) 9741 8555 Fax: (02) 9741 8500 Website: www.jaycar.com.au siliconchip.com.au Hills 850MHz Yagi ready for 3g/data links If you’re looking for extra perfomance from your 850MHz 3G system and/or need reliable data comms away from the crowded WiFi band, Hills Antenna have a new 11dB, 8-element Yagi that could be exactly what you’re looking for. Being such a high frequency, the antenna is nice and small – just 700mm long and the widest element (the reflector, of course!) is just 95mm. The models Hills supplied to SILICON CHIP for evaluation were black powder-coated and came complete with a 5m+ downlead and postmounting hardware. With the variety of cards out there, pigtails may be necessary to ensure the right connection. The Yagi can be mounted in either horizontal or vertical polarization and the folded dipole driven element is already fitted and connected to the downlead. These antennas are so new that they don’t yet appear on the Hills Antenna website. The 850MHz model has a catalog number of FB608559. There is also a 900MHz variant available (FB608558). Contact: Hills Antenna & TV Systems 10 Wiggs Road, Riverwood NSW 2210 Ph: (02) 9717 5210 Fax: (02) 9717 5209 Website: www.hillsantenna.com.au OLED display from Dontronics The micro-OLED (uOLED-128GMD1) is a compact and cost effective all-in-one ‘SMART” OLED Display with an embedded graphics controller that will deliver ‘stand-alone’ functionality to your project. The ‘simple to use’ embedded commands not only control background colour but can produce text in a variety of sizes as well as draw shapes (which can include user definable bitmapped characters such as logos) in 262,000 colours while freeing up the host processor from the ‘processor hungry‘ screen control functions. With full colour graphics OLED display it is suitable for just about any microcontroller project. It can be interfaced to any PIC, AVR, Basic Stamp, ARM or any other microcontroller as well as a PC. Typical applications include an electronic panel meter or gauge of any sort for instrumentation or automotive applications, advertising or point-ofsale. Its interface also suits a variety of medical, industrial and commercial siliconchip.com.au Getting his teeth into engineering . . . early! Recently Jaycar Electronics (NZ) sponsored a bunch of stickers promoting engineering as a career choice at New Zealand universities. Our intrepid Professor Picaxe (also known as Stan Swan, a kiwi who moonlights as an electronics engineering lecturer at Massey University in Wellington) was tickled pink to think they could finally attract students away from law, finance, accounting (or even worse) and into the “real” professions. And Stan was doubly chuffed to find 9-month-old Logan had already made up his mind which faculty to join when visiting the Wellington Jaycar Electronics store – so he snapped this pic to share with us! Contact: Jaycar Electronics (NZ) PO Box 9667, Newmarket, Auckland NZ Ph: (09) 377 6421 Fax: (09) 377 6422 Website: www.jaycar.co.nz STEPDOWN TRANSFORMERS 60VA to 3KVA encased toroids equipment. And at $99.00, it’s cheap enough for the hobbyist and student to use in their applications as well as the professional engineer in product development. Contact: Dontronics PO Box 595, Tullamarine Victoria 3043 Fax: (03) 9445 9202 Website: www.dontronics.com Harbuch Electronics Pty Ltd 9/40 Leighton Pl. HORNSBY 2077 Ph (02) 9476-5854 Fax (02) 9476-3231 September 2007  87 Into flight sims? Don’t fidget . . . Phidget! Perth-based OzzieSim is a supplier of components for home cockpit builders. Anyone interested in home-brewed flight simulation should browse their product line, which apart from including all sorts of flight controls, includes a number of Phidgets. Phidgets are small USB controlled electronic devices that form programmable building blocks for control and sensing projects. All are fully powered by the USB. We had a look at two such Phidgets, although many others exist. There is a 3-axis accelerometer Phidget, which continually monitors the sensor’s acceleration and provides the x-y-z components through the USB port. Software is freely available to interface to all the Phidgets through many common languages, such as VB and C/C++ on Windows, Macs and Linux. The accelerometer plugs into your USB port and is then ready to sense. It is sensitive to accelerations up to 29.4m/s2 or three times gravity. Another Phidget that we looked at was a simple servo which can be easily programmed to jump to a specific angle location. Again, it is fully programmable through the supplied API. Example source code is also available from the Phidget website www.phidgets.com age is included for a complete set of integrated virtual instruments on Windows or Linux PCs. Standard functions include mixed signal and digital storage scopes, a logic analyzer, baseband spectrum analyzer, X-Y phase plotter and an integrated data recorder. With BS100U the DSO introduces 2 GS/s equivalent time sampling with phase coherent full speed dual channel capture for HF eye diagrams, ISI and modulation analysis, a multi-band spectrum analyzer for RF and narrow-band signal analysis and sophisticated transfer function analysis applications using the built-in waveform generator. Engin is Australia’s leading broadband telephone company, with more than 60,000 customers making calls across their VoIP (Voice over Internet Protocol) network. Traditionally, VoIP technology has only been used by large corporations that can afford to invest in this cost saving technology. Since 2004 Engin has been offering this same technology directly to residential and small business customers. They were the first broadband phone service to be broadly available to Australian consumers and businesses, and the first on the shelves of major retailers. Today they provide services to almost half of the broadband phone market. Engin allows any broadband user to make and receive calls over the internet whilst using their existing telephone or an Engin Internet phone. The easy to use service drastically reduces customers phone bills, whilst offering a range of free included features enabling users to actively control their own calls. Engin’s latest Voice Box special offer is $29.95 on a 12-month contract. That lets you use your existing phone to make calls over the Internet. The Engin Voice Box 3102 (shown above) is the best choice for the home or small office customer. It can be connected to your existing landline (PSTN), which means you can continue to receive calls from your old phone number. Contact: Contact: Suite 3, 28 Chandos St, St Leonards 2065 Tel: (02) 9436 2955 Fax: (02) 9436 3764 Website: www.bitscope.com 431 Warringah Rd, Frenchs Forest 2086 Tel: (02) 9004 4444 Website: www.engin.com.au Contact: OzzieSim 151 Mill Point Rd, South Perth WA 6151 Ph: 0433 227 597 Fax: (08) 9369 2947 Website: www.ozziesim.com.au BitScope BS100U – USB Mixed Signal Scope and Waveform Generator BS100U is the newest member of BitScope’s popular family of PC based mixed signal oscilloscopes. It has an analog input bandwidth of 100MHz and supports real-time simultaneous analog and logic capture to 40MS/s. Unique to BS100U is its opto-isolation decoupling it from the PC. You can ground reference it independently and USB drop-outs due to ground-loops or glitches when looking at high power electrical or automotive systems are never a problem. It has a powerful DSP based flash programmable waveform generator. Operating independently of the scope’s capture engine it allows complex waveforms to be synthesised concurrently with waveform capture. Four inputs feed two analog channels plus eight concurrent logic channels, a ±5V adjustable external trigger input, a calibration output and low power modes for extended use on battery power in the field. The BitScope DSO software pack88  Silicon Chip Got broadband? Get Engin VOIP and start saving real $$$! Bitscope Designs Engin siliconchip.com.au NEW! R E V3 SUP FAIR E SCIENCION! EDIT THEAMATEUR SCIENTIST Two incredible CDs with over 1000 classic projects from the pages of Scientific American, covering every field of science... NEW UPDATED VERSION ALSO INCLUDES BONUS SCIENCE SOFTWARE LIBRARY! Arguably THE most IMPORTANT collection of scientific projects ever put together! This is version 3, 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 $7 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 HERE’S HOW TO ORDER YOUR COPY: BY PHONE:* (02) 9939 3295 9-4 Mon-Fri BY FAX:# (02) 9939 2648 24 Hours 7 Days <at> BY EMAIL:# silchip<at>siliconchip.com.au 24 Hours 7 Days BY MAIL:# PO Box 139, Collaroy NSW 2097 * 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 (see SILICON CHIP Bookshop pages). Exclusive in SILICON Australia to: CHIP www.siliconchip.com.au siliconchip.com.au September 2007  89 Vintage Radio By RODNEY CHAMPNESS, VK3UG Our radio heritage on display How many of us have had the opportunity to see working examples of equipment dating from the end of the 19th century? There was a lot of impressive equipment on display during the HRSA’s recent 25th anniversary celebrations in Melbourne. A special display of vintage radio equipment was recently held in Melbourne to mark the 25th anniversary of the Historical Radio Society of Australia (HRSA). That display took place over the weekend of 13-15th April 2007 and there were members and visitors from all states (except the Northern Territory) and from New Zealand. The display, held at the Holmesglen TAFE conference centre, gave HRSA members a chance to get to know one another and to enhance their skills in restoring our important radio and television heritage. It was put together by a dedicated band of enthusiasts and there was even an auction for those who had surplus items to sell. By the way, HRSA members come from a diverse range of backgrounds. While many are retired and many come from non-radio/electronics backgrounds, others are currently involved in the industry at the cutting edge of technology. Even then, many have no professional connection with radio, although they may come from electronics backgrounds. The auction The auction took place on Saturday afternoon, with around 300 items presented for sale. Some items sold for as little as $1, with the top price of $750 paid for a Fisk Radiolette (brown empire state) receiver. However, around 20% of the items were passed in, having failed to meet their reserve prices. One interesting item passed in was a 1934 Kriesler grandfather clock radio, a bid of $2750 falling short of the mark. The spark era The history of radio began with “spark” equipment but not much of this original equipment has survived. Instead, replicas of spark equipment have been built by some enthusiasts to maintain a link to this important first step in our radio history. One such exhibitor was Ian Johnston, who displayed both original and replica spark-era equipment. This gear included coherers and other various types of detectors, spark transmitter induction coils, Morse code paper tape perforating machines, sounders, Morse keys and headphones, etc. Naturally it is all Morse code equipment and is quite different in many respects to the valve equipment developed later on. The 1920s Sales and service 1950s style – this is what a typical radio shop looked like back in the post WW2 valve era. 90  Silicon Chip By the 1920s, spark transmissions were still used for marine, land and amateur communications, although valve equipment was being introduced siliconchip.com.au This display shows a collection of speakers from the 1920s. Note the stands and the ornate patterns used to cover the speaker cones. This 1934 Kriesler grandfather clock radio was for sale but was passed in at $2750. into these services. However, for voice and music entertainment, valve-type transmitters were a necessity and any receiver with reasonable performance also had to have some valves, although crystal sets were still quite popular with the less well-heeled – including school boys. The typical receiver of the era was built either as a “breadboard” or “coffin” box style construction. This was arguably the peak time for radio experimenters who built all sorts of weird and wonderful radios. The experiments were often very haphazard with little real documentation in most cases. There were several displays of 1920s radios and the ancillary devices that made up a typical radio receiving installation of the day. In those days, radios rapidly became the focus point in the lounge room, much like the home theatre installations of today. Included in the displays were many varieties of ornamental cone type speakers, as well as the earlier horn types. Several “coffin” style sets were also on display, along with one “breadboard” 5-valve receiver. Loop antennas were also common during the 1920s and were more efficient (but much larger) than the loopstick antennas of today. A relatively siliconchip.com.au A collection of the dry batteries used to power vintage radio receivers. They came in all shapes and sizes. This stand showed both pre-war and post-war Healing receivers. September 2007  91 This collection of spark equipment dates from around 1900 through until about 1920. A lot of this gear was used for wireless telegraphy. This top-of-the-line 1935 Scott console used 23 valves and featured a chromeplated chassis that was mounted on top of the cabinet. recent replica of a 1-valve set from the era (called the “Unidyne”) was also on display. The 1930s era This era has often been described as the halcyon era of radio because so many advances were made in the 92  Silicon Chip radio field. This was the era in which consoles were the flagships of the domestic radio market. Many of the upmarket receivers had all sorts of “gizmos” included in their design, to make them more appealing to the wealthier buyers. In addition, the cabinets were carefully crafted – often using several different types of timber. The 1933 Beale (see photograph) is a good example of this craftsmanship. In fact, all the consoles on display were good examples of the woodworker’s skill when it came to cabinet design and these sets were priced accordingly. At the very top end of the console range was the 1935 Scott 23-valve receiver owned by Dick Howarth. Yes, that’s right – it employed 23 valves, which is more than most TV sets had in the B&W days. This receiver is quite different to other sets, because the radio frequency (RF) and low level audio stages are mounted on a chassis on top of the cabinet – see photo. Scott apparently believed that the works of the set should be shown for all to see and marvel at. In addition, the chassis and the components mounted on top were chrome-plated, so they really do look impressive. The chrome plated power supply and audio output stages, along with the speakers, were mounted inside the cabinet in the conventional manner. However, it really depended on what cabinet you wanted with your Scott 23-valve chassis, as conventional consoles were also available. It was a truly magnificent receiver for its era siliconchip.com.au but at 145 pounds without a cabinet, it didn’t come cheap. The top of the line unit called the “Warwick Grande Special”, complete with record changer, sold in the UK in 1935 for 612 pounds 50 pence which was several years wages for the average worker! So you needed to have been very wealthy to afford one of these. The 1940s & 1950s No displays were specifically related to this era but there were table and mantel receivers on show. The display of Healing radios featured sets from the late 1930s to the 1950s. The Americans were renowned for their novelty sets and there were two “Hopalong Cassidy” mantel radios on display, each with a decorative front panel featuring Hopalong on his horse! Full-size & miniature portables Quite a number of portable receivers were on display, starting with a 1925 superheterodyne portable complete with a swing-out loop antenna. This set has six valves, all type UV-199 triodes, and its sensitivity and selectivity are good even by today’s standards. In greater detail, it has an RF stage followed by a self-oscillating mixer stage. The output is then re-applied to the RF stage (reflexed) which doubles These miniature valve portables could all easily be mistaken for the portable transistor radios that appeared much later. The valves used are the standard 1R5, 1T4, 1S5 and 3S4 line-up These vintage radio receivers were all for sale. You could pick a good radio up for less than $70.00. The 1933 Beale console was another receiver for the well-heeled. The wooden cabinet is beautifully crafted. siliconchip.com.au Some rare and usual radios from the pre-war era. The Astor Baby Grand’s cabinet (centre) was really quite stylish. September 2007  93 This collection of radio receivers and other equipment is mainly from the 1920s era. as the first IF amplifier operating on a frequency of approximately 55kHz. From there, the signal is applied to a second IF amplifier and following that is a grid detector stage. Two transformer-coupled audio stages then complete the line-up, with the speaker fed from the last UV-199 valve. It really is quite surprising that such a sophisticated design for the time was available in a commercial portable receiver. And although it’s quite “weighty”, it was far ahead of other designs of the era. At the other extreme were six miniature 4-valve portables. These are all roughly the same size as the later Australian-made “pocket” transistor receivers, at approximately 180 x 120 x 60mm. In fact, I mistook the first one of these I saw to be a transistor receiver. In these receivers, the loop-stick antenna is quite slim and the coils are miniaturised, as are the loudspeaker and the tuning capacitor. The valves are the standard 1R5, 1T4, 1S5 and 3S4 line-up. Naturally, it is not possible to fit a miniature 467 67.5V battery into one of these sets, so an even smaller battery similar in size to three 216 9V batter- ies was fitted. The filament battery is a single D cell. The life of those batteries would have been just 10-20 hours, so these little sets would have been quite expensive to run. In fact, they were the last of the small valve portables manufactured by the Japanese. We made nothing as small in Australia. Batteries An extensive range of the dry batteries used in battery-powered valve and transistor receivers was also on display. Many of the types used were quite specialised and there were many specials produced for battery-powered radio transceivers as well. Eveready, Diamond, Impex, Volta and Vidor are just some of the brands that were available over the years. Dry batteries were not the only ones used. Some radios designed for country areas used 2V valves and were powered using either a lead-acid 2V black rubber wet cell or a 6V black rubber wet cell battery. For sets using a 2V cell, the HT was supplied by three 45V batteries. Sales & service 1950s style This 1925 RCA Radiola 24 was an early portable superhet receiver. It used six valves, was battery powered and featured a swing-out loop antenna. 94  Silicon Chip One particularly interesting display showed the style of shop a small radio retailer/serviceman might have had during the 1950s. The display cases showed some of the mantel sets of the era and behind the counter was the siliconchip.com.au Airzone 588 6-Valve Receiver (1938) Silicon Chip Binders REAL VALUE AT $13.95 PLUS P & P These binders will protect your copies of S ILICON CHIP. They feature heavy-board covers & are made from a dis­ tinctive 2-tone green vinyl. They hold 12 issues & will look great on your bookshelf. H 80mm internal width H SILICON CHIP logo printed in gold-coloured lettering on spine & cover H Buy five and get them postage free! Price: $A13.95 plus $A7 p&p per order. Available only in Aust. PRODUCED IN 1938 BY AIRZONE RADIO, SYDNEY, the model 588 was housed in a tall attractive bakelite cabinet. An interesting feature of the set was its “Teletune” pre-set tuning. The individual buttons could be set to preferred stations and the whole front “ring” assembly could then be rotated to quickly select the desired station. The valve line-up was as follows: 6A8-G frequency changer; 6U7-G IF amplifier; 6B6-G audio amplifier/ detector/ AVC rectifier; 6F6-G audio output; and 5Y3-G rectifier. Photo: Historical Radio Society of Australia, Inc. Silicon Chip Publications PO Box 139 Collaroy Beach 2097 Or call (02) 9939 3295; or fax (02) 9939 2648 & quote your credit card number. Use this handy form serviceman’s workbench, with various test instruments and spare parts. Other displays Lots of other items were on display, including a Traeger 36/40 Flying Doctor radio, a 1931 American Crosley grandfather clock radio, various homemade radios, some rare sets like the WW2 German People’s Radio, vintage amateur radio gear and WW2 military and aeronautical equipment. In short, there really was something for anyone who has even the slightest interest in vintage radio equipment. These was even a question and answer session on vintage radio restoration siliconchip.com.au run by an expert panel consisting of Michael Justin, Mike Osborne (President) and Peter Lankshear (New Zealand). For further information about the HRSA or its sister organisation in New Zealand, the contact details are as follows: (1) Historical Radio Society of Australia Inc, PO Box 2283, Mt Waverley, Victoria 3149. Phone (03) 9539 1117 or point your web browser to www. hrsa.asn.au (2) New Zealand Vintage Radio Society, PO Box 13 873, Onehunga, Auckland 1643; or browse to www.nzvrs.pl.net; SC or email office<at>nxvrs.pl.net Enclosed is my cheque/money order for $________ or please debit my  Bankcard   Visa    Mastercard Card No: _________________________________ Card Expiry Date ____/____ Signature ________________________ Name ____________________________ Address__________________________ __________________ P/code_______ September 2007  95 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. by Douglas Self 2nd Edition 2006 $69.00* A collection of 35 classic magazine articles offering a dependable methodology for designing audio power amplifiers to improve performance at every point without significantly increasing cost. Includes compressors/limiters, hybrid bipolar/FET amps, electronic switching and more. 467 pages in paperback. SMALL SIGNAL AUDIO DESIGN By Douglas Self – First Edition 2010 $95.00* The latest from the Guru of audio. Explains audio concepts in easy-to-understand language with plenty of examples and reasoning. Inspiration for audio designers, superb background for audio enthusiasts and especially where it comes to component peculiarities and limitations. Expensive? Yes. Value for money? YES! Highly recommended. 558 pages in paperback. AUDIO POWER AMPLIFIER DESIGN HANDBOOK by Douglas Self – 5th Edition 2009 $85.00* "The Bible" on audio power amplifiers. Many revisions and updates to the previous edition and now has an extra three chapters covering Class XD, Power Amp Input Systems and Input Processing and Auxiliarly Subsystems. Not cheap and not a book for the beginner but if you want the best reference on Audio Power Amps, you want this one! 463 pages in paperback. DVD PLAYERS AND DRIVES by K.F. Ibrahim. Published 2003. $71.00* OP AMPS FOR EVERYONE By Bruce Carter – 4th Edition 2013 $83.00* This is the bible for anyone designing op amp circuits and you don't have to be an engineer to get the most out of it. It is written in simple language but gives lots of in-depth info, bridging the gap between the theoretical and the practical. 281 pages, A guide to DVD technology and applications, with particular focus on design issues and pitfalls, maintenance and repair. Ideal for engineers, technicians, students of consumer electronics and sales and installation staff. 319 pages in paperback. by Sanjaya Maniktala, Published April 2012. $83.00 Thoroughly revised! The most comprehensive study available of theoretical and practical aspects of controlling and measuring EMI in switching power supplies. Subtitled Exploring the PIC32, a Microchip insider tells all on this powerful PIC! Focuses on examples and exercises that show how to solve common, real-world design problems quickly. Includes handy checklists. FREE CD-ROM includes source code in C, the Microchip C30 compiler, and MPLAB SIM. 400 pages paperback. By Garry Cratt – Latest (7th) Edition 2008 $49.00 Written in Australia, for Australian conditions by one of Australia's foremost satellite TV experts. If there is anything you wanted to know about setting up a satellite TV system, (including what you can't do!) it's sure to be covered in this 176-page paperback book. See Review Feb 2004 SWITCHING POWER SUPPLIES A-Z PROGRAMMING 32-bit MICROCONTROLLERS IN C By Luci di Jasio (2008) $79.00* PRACTICAL GUIDE TO SATELLITE TV See Review March 2010 ELECTRIC MOTORS AND DRIVES By Austin Hughes & Bill Drury - 4th edition 2013 $59.00* This is a very easy to read book with very little mathematics or formulas. It covers the basics of all the main motor types, DC permanent magnet and wound field, AC induction and steppers and gives a very good description of how speed control circuits work with these motors. Soft covers, 444 pages. NEWNES GUIDE TO TV & VIDEO TECHNOLOGY By KF Ibrahim 4th Edition (Published 2007) $49.00 It's back! Provides a full and comprehensive coverage of video and television technology including HDTV and DVD. Starts with fundamentals so is ideal for students but covers in-depth technologies such as Blu-ray, DLP, Digital TV, etc so is also perfect for engineers. 600+ pages in paperback. RF CIRCUIT DESIGN by Chris Bowick, Second Edition, 2008. $63.00* The classic RF circuit design book. RF circuit design is now more important that ever in the wireless world. In most of the wireless devices that we use there is an RF component – this book tells how to design and integrate in a very practical fashion. 244 pages in paperback. PRACTICAL RF HANDBOOK 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 by Carl Vogel. Published 2009. $40.00* by Ian Hickman. 4th edition 2007 $61.00* Alternative fuel expert Carl Vogel gives you a hands-on guide with A guide to RF design for engineers, technicians, students and enthusiasts. the latest technical information and easy-to-follow instructions Covers key topics in RF: analog design principles, transmission lines, for building a two-wheeled electric vehicle – from a streamlined couplers, transformers, amplifiers, oscillators, modulation, transmitters and scooter to a full-sized motorcycle. 384 pages in soft cover. receivers, propagation and antennas. 279 pages in paperback. *NOTE: ALL PRICES ARE PLUS P&P – AUSTRALIA ONLY: $10.00 per order; NZ – $AU12.00 PER BOOK; REST OF WORLD $AU18.00 PER BOOK To Place Your Order: INTERNET (24/7) PAYPAL (24/7) eMAIL (24/7) www.siliconchip. com.au/Shop/Books Use your PayPal account silicon<at>siliconchip.com.au silicon<at>siliconchip.com.au with order & credit card details FAX (24/7) MAIL (24/7) Your order and card details to Your order to PO Box 139 Collaroy NSW 2097 (02) 9939 2648 with all details PHONE – (9-5, Mon-Fri) Call (02) 9939 3295 with with order & credit card details You can also order and pay for books by cheque/money order (Mail Only). Make cheques payable to Silicon Chip Publications. ALL TITLES SUBJECT TO AVAILABILITY. PRICES VALID FOR MONTH OF MAGAZINE ISSUE ONLY. ALL PRICES INCLUDE GST ALL S ILICON C HIP SUBSCRIBERS – PRINT, OR BOTH – AUTOMATICALLY QUALIFY FOR A REFERENCE $ave 10%ONLINE DISCOUNT ON ALL BOOK OR PARTSHOP PURCHASES. CHIP BOOKSHOP 10% (Does not apply to subscriptions) SILICON For the latest titles and information, please refer to our website books page: www.siliconchip.com.au/Shop/Books PIC MICROCONTROLLERS: know it all SELF ON AUDIO Multiple authors $85.00 The best of subjects Newnes authors have written over the past few years, combined in a one-stop maxi reference. Covers introduction to PICs and their programming in Assembly, PICBASIC, MBASIC & C. 900+ pages. PROGRAMMING and CUSTOMIZING THE PICAXE By David Lincoln (2nd Ed, 2011) $65.00* A great aid when wrestling with applications for the PICAXE See series of microcontrollers, at beginner, intermediate and Review April advanced levels. Every electronics class, school and library should have a copy, along with anyone who works with PICAXEs. 300 pages in paperback. 2011 PIC IN PRACTICE by D W Smith. 2nd Edition - published 2006 $60.00* 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. by Douglas Self 2nd Edition 2006 $69.00* A collection of 35 classic magazine articles offering a dependable methodology for designing audio power amplifiers to improve performance at every point without significantly increasing cost. Includes compressors/limiters, hybrid bipolar/FET amps, electronic switching and more. 467 pages in paperback. SMALL SIGNAL AUDIO DESIGN By Douglas Self – First Edition 2010 $95.00* The latest from the Guru of audio. Explains audio concepts in easy-to-understand language with plenty of examples and reasoning. Inspiration for audio designers, superb background for audio enthusiasts and especially where it comes to component peculiarities and limitations. Expensive? Yes. Value for money? YES! Highly recommended. 558 pages in paperback. AUDIO POWER AMPLIFIER DESIGN HANDBOOK by Douglas Self – 5th Edition 2009 $85.00* "The Bible" on audio power amplifiers. Many revisions and updates to the previous edition and now has an extra three chapters covering Class XD, Power Amp Input Systems and Input Processing and Auxiliarly Subsystems. Not cheap and not a book for the beginner but if you want the best reference on Audio Power Amps, you want this one! 463 pages in paperback. DVD PLAYERS AND DRIVES by K.F. Ibrahim. Published 2003. $71.00* OP AMPS FOR EVERYONE By Bruce Carter – 4th Edition 2013 $83.00* This is the bible for anyone designing op amp circuits and you don't have to be an engineer to get the most out of it. It is written in simple language but gives lots of in-depth info, bridging the gap between the theoretical and the practical. 281 pages, A guide to DVD technology and applications, with particular focus on design issues and pitfalls, maintenance and repair. Ideal for engineers, technicians, students of consumer electronics and sales and installation staff. 319 pages in paperback. by Sanjaya Maniktala, Published April 2012. $83.00 Thoroughly revised! The most comprehensive study available of theoretical and practical aspects of controlling and measuring EMI in switching power supplies. Subtitled Exploring the PIC32, a Microchip insider tells all on this powerful PIC! Focuses on examples and exercises that show how to solve common, real-world design problems quickly. Includes handy checklists. FREE CD-ROM includes source code in C, the Microchip C30 compiler, and MPLAB SIM. 400 pages paperback. By Garry Cratt – Latest (7th) Edition 2008 $49.00 Written in Australia, for Australian conditions by one of Australia's foremost satellite TV experts. If there is anything you wanted to know about setting up a satellite TV system, (including what you can't do!) it's sure to be covered in this 176-page paperback book. See Review Feb 2004 SWITCHING POWER SUPPLIES A-Z PROGRAMMING 32-bit MICROCONTROLLERS IN C By Luci di Jasio (2008) $79.00* PRACTICAL GUIDE TO SATELLITE TV See Review March 2010 ELECTRIC MOTORS AND DRIVES By Austin Hughes & Bill Drury - 4th edition 2013 $59.00* This is a very easy to read book with very little mathematics or formulas. It covers the basics of all the main motor types, DC permanent magnet and wound field, AC induction and steppers and gives a very good description of how speed control circuits work with these motors. Soft covers, 444 pages. NEWNES GUIDE TO TV & VIDEO TECHNOLOGY By KF Ibrahim 4th Edition (Published 2007) $49.00 It's back! Provides a full and comprehensive coverage of video and television technology including HDTV and DVD. Starts with fundamentals so is ideal for students but covers in-depth technologies such as Blu-ray, DLP, Digital TV, etc so is also perfect for engineers. 600+ pages in paperback. RF CIRCUIT DESIGN by Chris Bowick, Second Edition, 2008. $63.00* The classic RF circuit design book. RF circuit design is now more important that ever in the wireless world. In most of the wireless devices that we use there is an RF component – this book tells how to design and integrate in a very practical fashion. 244 pages in paperback. PRACTICAL RF HANDBOOK 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 by Carl Vogel. Published 2009. $40.00* by Ian Hickman. 4th edition 2007 $61.00* Alternative fuel expert Carl Vogel gives you a hands-on guide with A guide to RF design for engineers, technicians, students and enthusiasts. the latest technical information and easy-to-follow instructions Covers key topics in RF: analog design principles, transmission lines, for building a two-wheeled electric vehicle – from a streamlined couplers, transformers, amplifiers, oscillators, modulation, transmitters and scooter to a full-sized motorcycle. 384 pages in soft cover. receivers, propagation and antennas. 279 pages in paperback. *NOTE: ALL PRICES ARE PLUS P&P – AUSTRALIA ONLY: $10.00 per order; NZ – $AU12.00 PER BOOK; REST OF WORLD $AU18.00 PER BOOK To Place Your Order: INTERNET (24/7) PAYPAL (24/7) eMAIL (24/7) www.siliconchip. com.au/Shop/Books Use your PayPal account silicon<at>siliconchip.com.au silicon<at>siliconchip.com.au with order & credit card details FAX (24/7) MAIL (24/7) Your order and card details to Your order to PO Box 139 Collaroy NSW 2097 (02) 9939 2648 with all details PHONE – (9-5, Mon-Fri) Call (02) 9939 3295 with with order & credit card details You can also order and pay for books by cheque/money order (Mail Only). Make cheques payable to Silicon Chip Publications. ALL TITLES SUBJECT TO AVAILABILITY. PRICES VALID FOR MONTH OF MAGAZINE ISSUE ONLY. ALL PRICES INCLUDE GST 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 Ignition retard at boost wanted The new programmable electronic ignition system from the March, April & May 2007 issues is very interesting but I am trying to figure out if this will suit my car. I am after something to retard timing by 3° per PSI of boost on my 650HP supercharged Chevrolet engine (max boost 6 PSI) in order to be able to run advanced timing for better fuel economy when not in boost. Can this be done? (J. A., Silverdale, NSW). • There are several ways of switching in retard on turbo boost. The first is to just include this in the mapping of timing against RPM and pressure (load). So at high boost, the retard is increased. This can be done because the MAP sensor will measure the boost pressure and this will be in the high load map sites. Another way is to include extra retard in the second ignition timing map and then switch this map when required. So map alpha would have your normal timing and map beta would have the boost retard. You could map the entire RPM/load sites for the boost. Note that the boost retard can be altered for the boost pressure using the MAP sensor signal. Alternatively, you can use the knock sensor input. This would be a little harder to do as the input needs to see a voltage from 1.25V to 5V in order to change the retard value. So a voltage that varies with boost pressure could be applied to the knock input when the retard is required. The actual retard value will depend on the 0.5° or 1° resolution setting and the voltage applied. The retard amount can be seen on the display. See the April 2007 issue for the knock sensor article for more detail on this input. Workout timer for gym circuit I am after a timer that will activate a buzzer sound every 30 seconds to be used in a circuit gym. Can you help? (A. D., Hobart, Tas). • We published a workout timer in the March 1990 issue of SILICON CHIP. This can be set to sound a buzzer every 30 seconds. The circuit is powered from the 240VAC mains, although there is no reason why it could not be run from a 12V DC plugpack, dispensing with the relay, transformer and mains power section. Remote control for Teac TV I am trying to replace a lost/stolen remote control for a Teac TV. It is not available from Teac. After checking many universal remotes, none have the code for Teacs. There are learning remotes but these have to be fed the codes to learn, for which of course, the original is needed. Perhaps a PC interface and flexible software for creating continuously increasing code may solve the conundrum? (D. H., via email). • Most likely a universal remote control will work on your Teac TV. The remote units generally have a search feature where you have the appliance off and the remote will go through all its codes to turn an appliance on. When the appliance switches on, you press a button and the codes required for that unit are found. Electronic fuel gauge for old Morris I have adapted the Vehicle Voltage Monitor (SILICON CHIP, May 2006) to behave as an electronic fuel gauge in my wife’s Morris Minor. The LEDs are lined up across the bottom of an XD Falcon electronic speedo (where I also use the Speedo Corrector kit). I removed the original gauge and replaced it with a suitable resistance to reduce the voltage, when the tank is full, to just below 5V. I use the 0-5V link to monitor the fuel level. It works fine but is very sensitive to voltage fluctuations from the fuel tank sender Modifying The 240VAC 10A Speed Controller For 32V Operation I wonder if you could advise me as to the feasibility of converting John Clarke’s excellent 240VAC 10A Universal Motor Speed Controller (SILICON CHIP, November 1997) for operation on 36V AC? My plan is to substitute a 600W 32V universal motor for the current 240V 4-pole induction motor on my pedestal drill, in order to facilitate speed control without undergoing the usual tedious belt changing procedure. Clearly, the circuit98  Silicon Chip powering 4.7kW 5W resistors (and perhaps the BUP213) would have to be changed but I’m uncertain about what else may need altering. I would prefer to use this particular controller (instead of Triac or PWM controllers) because of its excellent torque maintaining feedback capabilities. I have used one for many years and I am more than satisfied with its excellent qualities. (J. B., Burragate, NSW). • The two series-connected 4.7kW 1W resistors for the 15V supply can be replaced with a single 680W 1W resistor. Use a link for the second 4.7kW resistor position. Use a higher-rated IGBT such as the FGH50N3, rated at 300V and 75A (available from www.farnellinone. com.au cat number 109-5032). You should also thicken the tracks for the motor drive section (IGBT, power diode and connecting leads) on the PC board using a thick layer of solder. siliconchip.com.au UHF TV Reception Quandary I recently helped to improve the television reception at a friend’s house by replacing the old antenna, and in particular to improve the SBS reception on channel 28-29 (digital). My friend’s house is only about 6km from the transmitter which is to the east of Perth in the hills and has strong VHF TV reception. A TV antenna was selected which was designed for good signal. However, the SBS reception was marginal and in particular, the digital reception was coming and going. Being a radio amateur I have some knowledge of antennas, so I started investigating the new antenna and why its performance was poor on UHF. It turned out the UHF part of the antenna was designed for UHF low band (CH28) and UHF high band (CH69). The CH28 part consisted of a dipole and a reflector with several other directors in front of this for the higher UHF frequencies. Just how all this comes together and provides gain across the UHF band I fail to and the voltage of the car’s electrical circuit, depending on regulation. I notice at night that the low end LED glows slightly (not visible in daylight) regardless of the 0-5V reading. Does this indicate a fault in my construction or can this be explained? It certainly makes an interesting fuel gauge. (G. D., Bathurst. NSW). • The supply voltage for the fuel gauge sender should be taken from a regulated voltage (eg, the original fuel sender supply) rather than the 12V vehicle supply which can vary from around 11V to 14.4V. The lower LED does glow dimly and this is due to residual current flow included within the LM3914 to allow easy cascading of more than one LM3914. The LED can be prevented from glowing by connecting a 10kW resistor across its terminals. Increasing the output of the DC-DC converter I am interested in modifying the circuit for the DC-DC converter project published in SILICON CHIP, June 2003 to siliconchip.com.au fully understand. Yagi antennas have a fairly limited bandwidth. However, what really surprised me was how many other TV antennas installed on houses locally had the high-band elements. These are pointless in Perth, as UHF TV is only on channels 28, 29 & 31. Sure, there is the odd UHF high-band translator in the metro area but not for the vast majority of the Perth metropolitan area. So we have the silly situation of various local retail outlets selling TV antennas that give limited performance on UHF low band. If the front UHF high-band elements were replaced with longer ones, UHF TV reception would be much better. Do I have the conclusion correct or have I become lost in the complexities of TV antenna design? (W. M., Lesmurdie, WA). • Your conclusions about UHF hi-band yagis are correct. We think that a 4-band bow-tie array is a much better proposition where you mainly want the UHF low band. obtain a significantly increased output current capacity of 4A at a voltage of 16.5V. Is this a practical proposition? I am considering replacing the fuse, upgrading the heatsinks on the semiconductor devices and replacing D1 and D3 with MBR20100CT devices. Assuming this is a practical proposition, what circuit changes, in addition to or other than the above, would you suggest? (L. W., via email). • In addition to your proposed chang­ es, the DC-DC Converter would require the 0.1W 5W resistor to be reduced to 0.05W by connecting another 0.1W 5W resistor across it. Each 1000mF and 470mF low-ESR capacitor would also need to be paralleled with the same value capacitor to increase ripple rating. If power supply reversal is not going to be a problem because of polarised inputs, then D3 can be omitted; ie, shorted out. Inductor L1 would need to be wound with two strands of the 1mm wire, while the PC tracks for the power supply would need to be thickened with a solder run over each. Also make sure the switch you use Want a real speed controller kit? If you need to control 12 or 24 volt DC motors and want a speed controller that will easily handle 30 amps, then this is the kit for you. This controller allows you to vary the speed of DC motors from 0 to 100%. It is also ideal for controlling loads such as incandescent/halogen lamps and heating elements. This kit makes a great controller for use on small electric vehicle projects, such as electrically assisted bikes and go-carts. We have tested it to over 30 amps without problems—it barely gets warm! Item code: SPEEDCON. We also have solar maximiser kits, Luxeon LEDs, and lots of interesting products and publications. Go to shop.ata.org.au or call us on (03)9639 1500. for S1 can handle the current as there will be more than 4A through it when stepping up the voltage for the output. Speedo controller wanted I am doing an engine/gearbox conversion in a car that came with a cable-drive speedo. The new gearbox has a Hall effect sensor that generates four pulses per revolution. I want to drive the original speedo head, for a variety of reasons, with a 12V DC motor. Can you recommend a simple circuit (LM2917?) that can take the pulses and use them to control the motor? (M. P., via email). • While you could convert the frequency to a voltage with an LM2917 and then use this voltage to provide a pulse width modulated signal to drive the DC motor, the results will be poor. This is because you need to set the gain of the pulse width modulation variation versus the voltage and so the LM2917 output will need to be amplified or attenuated to get the correct motor speed. Secondly, the motor will not turn at a constant speed with the applied September 2007  99 Notes & Errata Programmable Ignition System for Cars, March, April and May 2007: for some motorcycles, go-carts and other engines, the ignition can be operated without using a MAP sensor. In this case, the MAP sensor input on the PC board would be connected to the 0V (ground) supply pin provided for the external MAP sensor. This will set the programmable ignition at a single fixed load setting. In the settings, set the minimum load to about 20 and the maximum load to around 200. The ignition will then be programmed for RPM load sites only and at the fixed load setting. RPM mapping would voltage unless it has feedback (similar to our train speed controllers). There are gearbox converters available that can do this conversion for you. It involves a gear set that can be altered in ratio. Kick-start not a problem for ignition system I purchased your Universal High Energy Ignition System Mk.2 (SILICON CHIP, December 2005, January 2006) with the intention to install it into a single-cylinder motorcycle with a manual kick-start system. I was disappointed to read that the system has been designed to turn off the power to the ignition coil after just one second. This is clever design but this feature is not usable on my motorbike. be over 11 RPM sites (or 15 RPM sites if the single 15 x 15 map is selected). 20W Class-A Amplifier Module, May 2007: the parts list on page 37 specifies a transformer with both 16V+16V and 15V+15V secondary windings. The latter are no longer required and the transformer will be supplied with 16V+16V windings only. Loudspeaker Protection & Muting Module, July 2007: on page 75, the testing procedure is wrong, as 1.5V is not enough to bias on transistors Q5 or Q7 Use a 6V or 9V battery or two 1.5V cells in series for the test. Due to the time it actually takes to manually kick-start or rotate the engine using the kick-start lever (usually about 10 seconds), the unit will have switched off the power to the coil. So the engine is never going to fire. I was wondering if the auto switchoff feature can be disabled or perhaps the time lengthened to, say, about 30 seconds, with the substitution of a different value resistor or capacitor. Could you please advise a simple fix for this problem? (J. K., via email). • No fix is required. The coil is switched off after one second but this is only if there is no points trigger signal. So the engine will fire even if there is interruption of the points signal during kick-start. The switch-off feature is to prevent coil burnout if no points signal is present. Super Ear is motor-boating I built the Super Ear project from Electronics Australia magazine of May 1998. On the whole, the kit seems to work, ie, the electret microphone is picking up sound which is being fed via the BC548 and LM386 op amp to the loudspeaker, with plenty of volume. The unit seems to be working to spec, ie, higher frequencies are being selected, etc via the switchable filter. The problem is that at around 5070% of volume, the unit goes into oscillations which sound like a Harley Davidson motorbike in first and second gears, then it gets very noisy, like idling, towards maximum volume. Initially, I assumed damage to the unit (battery is good at around 9V), possibly due to a momentarily reversed supply when connecting the battery. I swapped in another LM386 to check this and got the same result. Could it be the BC548 or the Mosfet? (M. E., via email). • Your circuit would appear to be “motor-boating”. This is a spurious low-frequency oscillation which can happen if there is insufficient supply bypassing in the circuit. Try increasing the 1mF (C12) capacitor to 10mF or more. Headset connection for cordless phone I wondered if you have an article or information on how to connect a headset to a cordless phone, in order to have hands-free operation. Can you help? (B. A., via email). • Have a look at the Telephone Headset Adaptor in the July 2002 issue. SC WARNING! SILICON CHIP magazine regularly describes projects which employ a mains power supply or produce high voltage. All such projects should be considered dangerous or even lethal if not used safely. Readers are warned that high voltage wiring should be carried out according to the instructions in the articles. When working on these projects use extreme care to ensure that you do not accidentally come into contact with mains AC voltages or high voltage DC. If you are not confident about working with projects employing mains voltages or other high voltages, you are advised not to attempt work on them. Silicon Chip Publications Pty Ltd disclaims any liability for damages should anyone be killed or injured while working on a project or circuit described in any issue of SILICON CHIP magazine. Devices or circuits described in SILICON CHIP may be covered by patents. SILICON CHIP disclaims any liability for the infringement of such patents by the manufacturing or selling of any such equipment. SILICON CHIP also disclaims any liability for projects which are used in such a way as to infringe relevant government regulations and by-laws. Advertisers are warned that they are responsible for the content of all advertisements and that they must conform to the Trade Practices Act 1974 or as subsequently amended and to any governmental regulations which are applicable. 100  Silicon Chip siliconchip.com.au MARKET CENTRE Cash in your surplus gear. Advertise it here in Silicon Chip. CLASSIFIED ADVERTISING RATES Advertising rates for these pages: Classified ads: $27.00 (incl. GST) for up to 20 words plus 80 cents for each additional word. Display ads: $49.50 (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:___________________ siliconchip.com.au FOR SALE SURPLUS SALE:  LAMINA  BL2000, BL3000, BL4000, White, Red, Green, Amber, RGB, HIGH POWER LEDs, also heatsinks, optical lenses and wiring harnesses for sale. LEDS range from  4 watts to 104 watts. Contact: Gee-Tek P/L, Phone (03) 5223 3555 or http:// led.gee-tek.com.au/ for prices and information. AMPLIFIER BUILDERS: ezChassis® pre-punched cabinets make all your DIY amplifier projects easier and professional looking. Matching heatsinks and hardware. www.designbuildlisten. com LEDs! New Osram surface mount range, easy to handle and can even be used through-hole! NOS standard and superbright brand name LEDs from just a few cents each. 20 x 2 OLED displays $35. Also LED drivers, kits and all sorts of other stuff. www.ledsales.com.au September 2007  101 Silicon Chip Binders REAL VALUE AT $13.95 PLUS P & P ELNEC IC PROGRAMMERS High quality Realistic prices Free software updates Large range of adaptors Windows 95/98/Me/NT/2k/XP CLEVERSCOPE USB OSCILLOSCOPES 2 x 100MSa/s 10bit inputs + trigger 100MHz bandwidth 8 x digital inputs 4M samples/input Sig-gen + spectrum analyser Windows 98/Me/NT/2k/XP IMAGECRAFT C COMPILERS H 80mm internal width H SILICON CHIP logo printed in gold-coloured lettering on spine & cover H Buy five and get them postage free! Price: $A13.95 plus $A7 p&p per order. Available only in Aust. Silicon Chip Publications PO Box 139 Collaroy Beach 2097 Or call (02) 9939 3295; or fax (02) 9939 2648 & quote your credit card number. Use this handy form GRANTRONICS PTY LTD www.grantronics.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 Telelink Communications www.telelink.com.au e-mail Jack Chomley – jack<at>telelink.com.au or call (07) 4934 0413 or 0428 199 551 SPK360 3/5/06 1:10 PM Page 1 20 years experience! HI-FISPEAKER REPAIRS YOUR EXPERT SPEAKER REPAIR SPECIALISTS 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 These binders will protect your copies of S ILICON CHIP. They feature heavy-board covers & are made from a dis­ tinctive 2-tone green vinyl. They hold 12 issues & will look great on your bookshelf. ANSI C compilers, Windows IDE AVR, TMS430, ARM7/ARM9 68HC08, 68HC11, 68HC12 tel: 03 9647 7000 www.speakerbits.com Enclosed is my cheque/money order for $________ or please debit my  Bankcard   Visa    Mastercard Card No: _________________________________ Card Expiry Date ____/____ Signature ________________________ Name ____________________________ Address__________________________ __________________ P/code_______ 102  Silicon Chip More control solutions for you: NEW Radio Modules: Zigbee Radio Modem 1km, Bluetooth Serial Modem 100m. NEW Ethernet Modules: Ethernet to RS232/RS422/RS485 1, 2, 4 & 8-port Modules. NEW Protocol Gateways: Lonworks to Modbus, Profibus to Modbus, Can (J1939) to Modbus, AB-DF1 to Modbus, Hart to Modbus and more. NEW M325 Microstepping Bipolar Stepper Driver only $99. NEW 500oz-in plus Stepper Motor: may not be the fastest motor on the block but it has real grunt. NEW USB 8 Relay and 4 isolated input card. NEW 20A DC Motor Speed Con­troller. Low Cost Dual DC Amplifier Kit: per­ fect for Data Acquisition. Amplify signals from 1.5 to 10 or reduce signals by a factor of 0.7 to 0.1. Electronic Thermostats with digital temperature display, 2 control relays. Can be used in heating and cooling. NTC thermistor or J T/C or Pt100 sensors. Isolated and Non Isolated RS232 to RS485 converters. siliconchip.com.au Satellite TV Reception VIDEO - AUDIO - PC 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°. distribution amps - splitters digital standards converters - tbc's switchers - cables - adaptors genlockers - scan converters bulk vga cable - wallplates DVS5c & DVS5s High Performance Video / S-Video and Audio Splitters AV-COMM P/L, 24/9 Powells Rd, Brookvale, NSW 2100. Tel: 02 9939 4377 or 9939 4378. Fax: 9939 4376; www.avcomm.com.au MD12 Media Distribution Amplifier QUEST ® C O N T R O L S Quest AV® MS120 HQ VGA Cables The world’s lowest cost controller with inbuilt operator interface  12 digital I/O  2 line LCD  5 push buttons  Expandable  Easy to program VGA Splitter VGS2 AWP1 A-V Wallplate Come to the specialists... QUESTRONIX ® 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 $164 Developer’s Kit $197 includes programming cable & software Made in Australia - used world-wide splat-sc.com www.dontronics.com has 300 selected USB to RS422/RS485 converter with 1500V isolation, RTS or Auto Data Flow control. Signal Conditioners – non isolated and isolated: Convert thermocouples, RTDs to 4-20mA or 0-10V. Fully programmable. Stepper Motors: we have a selection of Stepper motors for hobby and high torque CNC applications. DC Motors for both hobby and high torque applications. DC, Stepper and Servo Motor controller kits. Serial and Parallel Port relay controller cards. PIC MicroProgrammers: serial and USB port operated. Switch Mode, Battery Chargers and DC-DC converters. Full details and credit card ordering available at www.oceancontrols.com.au Helping to put you in control. MicroByte Electronics: PIC Micros – Development Board – Development tools & Components. Phone: (03) 9378 4288. info<at>microbyte.com.au; www. microbyte.com.au Sales Engineers Wanted – NSW, QLD, SA Sales experience not essential TRIO Smartcal is one of Australia’s foremost Test & Measurement companies. We represent major manufacturers such as Agilent, Yokogawa, Ideal and others. We sell products ranging from handheld multimeters to GHz spectrum analysers, to protocol analysers. We are growing the company and have opportunities for Sales Engineers in NSW, Qld and SA working with our established customer base. We offer an attractive salary package consisting of base, commission and profit share, and a generous car allowance. Visit www.triosmartcal.com.au to learn more about us. If you have a strong background in electronics and wish to move into test & measurement sales or further your sales career, then please send your resume to employment<at>triosmartcal.com.au siliconchip.com.au 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 September 2007  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. RFMA 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. Advertising Index AJ Distributors.............................. 57 Alternative Technology Assoc...... 99 Altronics.................................. 82-85 Av-Comm................................... 103 Dick Smith Electronics............ 16-19 Dontronics.................................. 103 Ecowatch.................................... 103 Emona.......................................... 33 Energy Australia............................. 5 FreeNet Antennas...................... 101 RF Modules Australia Low Power Wireless Connectivity Specialists Grantronics................................. 102 Harbuch Electronics..................... 87 Hills Industries.............................. 88 Applications: UHF: SMX2-433-5 Rural Multichannel Transceiver Multichannel Transceiver Utilities Narrowband. 5kbps Narrowband. 5kbps Industrial Range: 500m+ Range: 5km+ Commercial Tx Pwr: 25mW Tx Pwr: 50mW 128 Channels Government 128 Channels 1200 baud serial modem 1200 baud serial modem Meter Reading RADIOMETRIX: Low Power, Licence Exempt Radio Modules Instant PCBs.............................. 103 RF Modules Australia. P.O. Box 1957 Launceston, TAS., 7250. Ozzie Sim..................................... 89 VHF: SMX1-151-5 Ph: 03-6331-6789. Email: sales<at>rfmodules.com.au. Web: rfmodules.com.au Jaycar........................ IFC,49-56,104 JED Microprocessors..................... 4 eLabtronics................................. 102 LEDsales.................................... 101 Modtronix Engineering................. 41 Oatley Electronics...................... IBC Ocean Controls................... 102-103 Prime Electronics........................... 6 Quest Electronics....................... 103 FOR THE COLLECTOR: 17-inch Healing Model 400 TV and two JR service books. All excellent condition. Info and offers to (08) 8087 4574. 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 PCBs MADE, ONE OR MANY. Any format, hobbyists welcome. Sesame Electronics Phone (02) 9593 1025. sesame<at>sesame.com.au www.sesame.com.au PCB CARBIDE DRILLS $3.50ea (new). Riston coated Laminate. PCBs made, great prices. acetronics<at>acetronics. com.au Phone (02) 9600 6832. WANTED WANTED: EARLY HIFIs, AMPLIFIERS, Speakers, Turntables, Valves, Books, Quad, Leak, Pye, Lowther, Ortofon, SME, Western Electric, Altec, Marantz, McIntosh, Tannoy, Goodmans, Wharf104  Silicon Chip DOWNLOAD OUR CATALOG at www.iinet.net.au/~worcom WORLDWIDE ELECTRONIC COMPONENTS PO Box 631, Hillarys, WA 6923 Ph: (08) 9307 7305 Fax: (08) 9307 7309 Email: worcom<at>iinet.net.au edale, radio and wireless. Collector/ Hobbyist will pay cash. (07) 5471 1062. johnmurt<at>highprofile.com.au CUSTOMERS: Truscotts Electronic World – large range of semiconductors and passive components for industry, hobbyist and amateur projects including Drew Diamond. 27 The Mall, South Croydon, Melbourne. (03) 9723 3860. electronicworld<at>optusnet.com.au KIT ASSEMBLY NEVILLE WALKER KIT ASSEMBLY & REPAIR: • Australia wide service • Small production runs • Specialist “one-off” applications Phone Neville Walker (07) 3857 2752 Email: flashdog<at>optusnet.com.au RCS Radio................................. 104 Richard Foot Pty Ltd.................... 47 RF Modules................................ 104 RS Components....................... OBC Rockby Electronics....................... 24 Sesame Electronics................... 104 Silicon Chip Binders.............. 77,102 Silicon Chip Bookshop............ 96-97 Silicon Chip Subscriptions........... 57 Siomar.......................................... 23 Speakerbits................................ 102 Splat Controls............................. 103 Tekmark....................................... 29 Telelink....................................... 102 Trio Smartcal......................... 81,103 Trusys......................................... 102 Wagner Electronics...................... 45 Worldwide Elect. Components... 104 Yokogawa....................................... 7 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. siliconchip.com.au 100W SOLAR PANEL ARRAY WITH FREE REGULATOR KIT L A E ED L A I PEC G A K PAC S This 100W solar array includes five 20W – 12V polycrystalline solar panels, a 12V/24V regulator kit + weatherproof kit box. Why 5 X 12V/20W panels and not 1 X 100W panel?...Loss of output due to damage or obstruction of a panel will result in a 20% loss in output, not 100% loss. Air gaps between panels increase cooling and thus increases panel efficiency. Much cheaper and less fragile to post. The wiring configuration can be changed for different voltages. Does not include the 2 lengths of aluminium angle, rivets or connecting wire, all worth around $15. Specifications For Individual Panel:Peak Power: 20W, Open Circuit Voltage: 21V, Short Circuit Current: 1.3A, Voltage At Max. Power: 17.5V, Current At Max. Power: 1.1A, Dim: 610 x 290 x 25mm. 5 X 12V/20W panels +regulator kit + weatherproof box (ARRAY) $690.00 We have a new shipment of our BRAND NEW HIGH QUALITY POLYCRYSTALLINE SOLAR PANELS hugely popular high power These panels are waterproof and have tempered DC Motors that has just arrived. glass with a strong aluminium frame. These units all have screw terminals inside a small box Also wheels, chains and sprockets. See our Website for more details attached to the rear of the panel. We believe that NEW T EN M P I SH these ratings are very conservative as we have NEW MOTOR tested and found similar START RELAY figures in late afternoon 600V 24A autumn sunlight. BRAND NEW 4W-12V HIGH CURRENT Peak Power: 4W Sprecher + Schuh Open Circuit: 21V CA3-9=CT3(K) Short Circuit: 0.258A DIN rail or screw "V" At Max. Power: 16.8V mount. 240V coil. 200W WIND GENERATOR "C" At Max. Power: 0.24A Approx 68 X 45 X WITH SLIP RINGS AND FREE Dim: 395 x 161 x 18mm 80mm. BATTERY CHARGE CONTROLLER KIT Weight: 0.9kgs LIMITED STOCK This serious 3ph 200W wind generator has [SP4W12] $36.00 DON'T MISS OUT. fibreglass blades spanning 2.1m. It is designed to At just a fraction of NEW 4W-6V start operating at wind speeds around 9kph while the new price. Peak Power: 4W being robust enough to withstand high winds. It (MSR)$22 Open Circuit: 10.6V automatically furls in extreme winds and back Short Circuit: 0.5A NEW CONTROLLER PCB again as the wind drops to protect it's self. V At Max. Power: 8.5V Rated Power: 200W Maximum Power: 250W This PCB was built to control an industrial C At Max. Power: 0.47A Nominal Rotor Diameter: 2.1m process. With logic level inputs via optoDim.: 395 x 161 x 18mm For more information and instructions see our couplers on the board you can control 4 high Weight: 0.9kgs Website. [WGEN1] $399.00 [SP4W6] $36.00 current outputs using TPDV1240 40A/1200V Triacs. There are a further 3 X NEW KIT K251 INVERTER KIT NEW KIT 12V WINDSCREEN WIPER MOTOR 10A relay outputs. CCT. for SSR section of We have a limited quantity of these powerful This kit is designed to PCB on our Website .( VPCB) $15 wiper motors. Ideal for lots of projects including efficiently charge12V batteries and provide robotics etc. Only $28 isolation. Ideal for use with our [SP4W6] solar panels. [K251] $15 CK O T S IN NOW PACKAGE DEAL Only $9 when purchased with our 4W-6V Solar Panel [K251P] $45 EXPERIMENTERS DELIGHT www.oatleyelectronics.com Suppliers of kits and surplus electronics to hobbyists, experimenters, industry & professionals. Orders: Ph ( 02 ) 9584 3563, Fax 9584 3561, sales<at>oatleyelectronics.com,SPO Box 89 Oatley NSW 2223 OR www.oatleye.com siliconchip.com.au eptember 2007  105 major credit cards accepted, Post & Pack typically $7 Prices subject to change without notice ACN 068 740 081 ABN18068 740 081 SC_SEP_07