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Contents Vol.15, No.5; May 2002 www.siliconchip.com.au Shark Shield: Keeping The Man-eaters At Bay – Page 16. FEATURES 8 Fuel Cells: The Quiet Emission-Free Power Source You will be amazed at the developments that are happening with fuel cells, especially in transport. Your next car could have one as its power source – by Gerry Nolan 16 Shark Shield: Keeping The Man-eaters At Bay You strap it on for surfing, snorkelling and diving and it keeps you safe from dangerous sharks – by Ross Tester 74 Wound Up About Energy Freeplay: you wind it up to recharge your mobile phone’s battery or to power a shortwave radio – by Gerry Nolan PROJECTS TO BUILD 24 PIC-Controlled 32-LED Knightrider A PIC processor simplifies the circuit and gives 12 different lighting patterns for the 32 LEDs. You can use it as a rear window brake light or as an eye-catching display – by John Clarke 32 The Battery Guardian Don’t get caught with a flat battery; this easy-to-build circuit cuts off the power to a 12V fridge or car stereo system if the battery voltage drops below a critical level – by John Clarke 53 Build A Stereo Headphone Amplifier It’s based on a single IC and can be used with the RIAA (turntable) preamp described in our March 2002 issue (or anything else) – by Ross Tester PIC-Controlled Knightrider – Page 24. 58 Automatic Single-Channel Light Dimmer; Pt.2 Second (and final) article has all the construction and setup details – by John Clarke 76 Stepper Motor Controller Use one of those surplus stepper motors with this cheap and easy-to-build controller – by Ross Tester SPECIAL COLUMNS 40 Serviceman’s Log Stubbornness or tenacity of purpose – by the TV Serviceman 80 Vintage Radio Battery Guardian: Stops Flat Batteries – Page 32. The AWA FS6 military transceiver – by Rodney Champness DEPARTMENTS 2 4 30 57 71 Publisher’s Letter Mailbag Circuit Notebook Subscriptions Form Product Showcase www.siliconchip.com.au 90 93 94 96 Ask Silicon Chip Notes & Errata Market Centre Advertising Index Stereo Headphone Amplifier – Page 53. May 2002  1 PUBLISHER’S LETTER 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 Rick Walters Reader Services Ann Jenkinson Advertising Enquiries Leo Simpson Phone (02) 9979 5644 Fax (02) 9979 6503 Regular Contributors Brendan Akhurst Rodney Champness, VK3UG Julian Edgar, Dip.T.(Sec.), B.Ed Mike Sheriff, B.Sc, VK2YFK Philip Watson, MIREE, VK2ZPW Bob Young 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: $69.50 per year in Australia. For overseas rates, see the subscription page in this issue. Editorial & advertising offices: Unit 8, 101 Darley St, Mona Vale, NSW 2103. Postal address: PO Box 139, Collaroy Beach, NSW 2097. Phone (02) 9979 5644. Fax (02) 9979 6503. E-mail: silchip<at>siliconchip.com.au ISSN 1030-2662 * Recommended and maximum price only. 2  Silicon Chip A new reactor at Lucas Heights – it’s about time Finally, construction of a new nuclear reactor is about to commence in Sydney. The $320 million project has been the subject of a great deal of community controversy, much of it illin­formed. It will replace a reactor which is now 44 years old, highlighting just how overdue the project is. In fact, when I toured the Lucas Heights reactor in around 1985, I was struck by how old the facility seemed even then. Not only did the whole installation need a good paint and general sprucing up, but everything about it was obsolete. All the con­trol gear, instrumentation, computers and so on, was just anci­ent. I don’t imagine that much would have changed in the inter­vening 17 years or so – it would just have continued to decay (pun intended). Now, at the very least, with the installation of a new reactor, all the concerned people should be “happier”. Sure they might still be up in arms about the reactor being just near their back fences but surely a newer, safer reactor must be better than one which is very old. And besides, when Lucas Heights was first built, it was way out in the scrub, far away from any houses. Those people who have moved and built there since really should not be complaining too much. In the meantime, a great number of research people from a whole range of scientific fields, have had to make do with a second-rate installation. While they would have done their best with what was available, they would have been held back in their efforts. Just think, in the whole of Australia, for all this time, we have only had the piddly little reactor at Lucas Heights. It’s been a bad joke for a long time. Australia really does need to spend a lot more money in a whole range of fields and this nuclear reactor project is only a drop in the bucket of what should be spent to make us as competitive as possible on the world stage. Spent fuel rods do remain a problem, particularly with Greenpeace doing everything in its power to stop them being sent to France, Argentina or where ever. At present, reprocessing of fuel rods is the best method of handling the problem, but Green­peace won’t have it. In fact, I find it extremely frustrating that the so-called “greens” or environmentalists seem to oppose just about every worthwhile project ever mooted in Australia. Whether it is BassLink in Tasmania, wind farms just about anywhere, the tidal power project in Derby or any number of other projects that could have a significant benefit for the economy and the environment, the greenies are in there and against it. That their opposition appears to be supported by so many people is a sad reflection on the generally low level of scientific knowledge in the community. Let’s face it, if we had the same level of “green” opposi­tion to major infrastructure projects 50 years ago that we have now, Australia would be a much poorer place with a woeful stan­dard of living – in fact, we would be a “third world” country. Would the environment be better off? You only have to go and check the environment in a typical third world country to answer that question. Leo Simpson www.siliconchip.com.au Need more ISA slots? Now you can almost totally eliminate phone call costs to your branch office! Provides six ISA slots external to the computer. This unit is ideal for quality control testing, teaching labs, prototype development etc. Mounted in a small, quality, metal case. Cat 3053-7 $743 notebook solutions! Cat. 2857 Easy Transfer Board - Universal Front Access Bay Utilises a 3.5 in bay to provide front access for 2 x USB, 1 x Firewire, 1 x Audio in, 1 x Audio out and 1 x Serial ports. Internal cables included Cat 2857-7 Transfer board $89 Cat. 8403 Use a Notebook Computer? Don’t miss out on these problem solvers! One output-Two Monitors a very economical solution Cat 15092-7 $265 Keyboard AND Mouse into ONE PS/2 Cat 15093-7 $205 Can be used as an Internet Access Server or for remote access, or for LAN to LAN routing. It has 4 WAN (RS232) and 1 LAN (UTP) Cat 10110-7 5 LAN 2 WAN $776 Cat 10111-7 1 LAN 4 WAN $1134 Is your Terminal Terminated? 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While stocks last Satellite/Cable TV to every room This compact unit pumps your favorite Video (or audio) program to any room without wires. The quality remains excellent. Send the same signal to every room if you like (with additional receivers). Cat 11808-7 $299 or 2 sets for $500! Australia wide express courier $15 (3kg max) Dealer Enquiries Welcome! Vamtest Pty Ltd trading as MicroGram Computers ABN 60 003 062 100, Phone: (02) 4389 8444 FreeFax: 1 800 625 777 Unit 1, 14 Bon Mace Close, Berkeley Vale NSW 2261 sales<at>mgram.com.au All prices subject to change without notice. Pictures are illustrative only. info<at>mgram.com.au SHOREAD/MGRM0502 Feedback on Dr Video’s negative rail I refer to the answer to R. L., on page 92 of the February 2002 issue, regarding the Dr Video negative supply. I also had the same problem and yes, the kitset had been supplied with a 7555 in lieu of a 555. However, replacing the 7555 with two differ­ent makers’ 555 ICs did not fix the low negative supply rail. Perhaps the LED1 reference for Q4 has a higher forward voltage drop than in the prototype, causing the video output stage to put more load on the negative supply rail? Anyway, in my case, I was using a 12V regulated plugpack and I found that replacing D1 (reverse voltage protection) with a 1N5819 which has a lower forward voltage drop made a marked improvement to the pre-regulation voltage. I had on hand a Jaycar “surplus” pack of 100V Fast Recovery diodes which had better than 100mV less forward voltage drop than the 1N4004s supplied for D2 and D3 and after fitting these I had about 7.5V into the 7905 -5V regulator. Perhaps 1N5819s in all three positions would be a cheap fix. Like an earlier correspondent, I also had lower contrast at the output, compared with the input. Replacing D4 with a 1N4004 reduced the 5534’s reference voltage by about 100mV and this rectified the problem. As a matter of interest, I am using the Dr Video to remove the visible data pulses from the top of the picture, when watch­ing ABC TV from a DGTEC STB in Wide Screen mode on a conventional TV (stops the Wide 4  Silicon Chip Screen music video clips from being chopped off at the sides). This was accomplished by switching carefully selected parallel capacitors across C9 and C10. Incidentally, temporarily paralleling a suitable value capacitor at this loca­tion will readily verify the action of IC5b in a clearly visible way. On an entirely different subject, I have been using the rear end of your Dolby Pro Logic circuit (from the November & December 1995 issues) with two TDA1074a ICs, etc, in a preamp after an Onkyo Dolby Digital Decoder. Drastically reducing the value of the 180pF feedback capacitors from the inverting input to output of the inverting output buffers has noticeably improved the sound, bringing it closer to the sound of the DTS versions. However, both myself and a friend (who has recently purchased an upmarket multi-channel SACD player) have been investigating better options for multi channel preamplification. Perhaps your new 6-Channel IR Remote Volume Control will be the answer (or inspiration) to our search. I hope you don’t continue the practice of quickly rolling off the frequency response of your top audio creations. SACD and DVD-A deserve better than conventional top-end tailoring. Good quality modern equipment shouldn’t output as much “digital rub­bish” as earlier equipment. I may have ageing and damaged hearing but even 48kHz 24-bit DVD sound compared to the CD version of the same music is obviously more natural sounding when fed through your Class-A modules via the same modules modi­ fied for preamplifier use, but with less intentional HF roll-off. My friend has also found “good” commercial multi-channel gear sadly lacking on the SACD top quality setting. There is, however, no restriction on using the top setting when using his version of the “class A preamp” with an amplifier with some resemblance to your LD Amplifier (topology wise). I seem to remember reading several years ago, that even loudspeakers should go out to >50kHz to take full advantage of SACD and DVD-A. Finally, I also am wondering what happened to the plan to locate Digital TV in the UHF band? I live in a mediocre TV recep­tion area where aircraft pulsate the analog picture, there is a degree of multipath reception, and even a new upmarket antenna gives barely acceptable results much of the time. There must be hundreds of thousands of Sydney residents with even worse analog reception than me. My experience of Digital TV reception is that the picture and sound are mostly superb, but the VHF channels are very sus­ ceptible to man-made interference, even when the signal level on the bargraph is in the good signal level area. The analog picture when the lady next door is mowing her lawn with a petrol mower is of course almost unwatchable but the Digital picture and sound is completely wiped out. Even the fridge light turning on when the door is opened may cause a picture/sound disturbance. A fluores­ cent light that flickers or a neighbour www.siliconchip.com.au using a food processor is another major cause of disturbances. However, I may only get a fairly grainy picture on analog SBS in the UHF band and the STB bargraph says that the signal level is too low for reliable decoding yet most of the time I get perfect picture and sound, with a similar amount of disturbances to the VHF channels. Occasionally, in certain weather conditions, the signal level drops marginally and then the decoder has prob­lems. Why haven’t we followed the UK example and put Digital TV in the UHF band which is obviously much more resistant to impulse type interference? A. Kethel, Waitara, NSW. No-frills website is good Congratulations on a useful website. It is useful because it does not have lots of useless irrelevant whirlygig graphics that consume bandwidth and CPU. It gets straight to the point of providing information, which is the only reason I use the net. Within two mouse clicks I got directly to the information I was looking for. It did not have a convoluted path of links with their associated graphics, to get to the info I wanted. Willem Corbett, via email. Shutdown for “no keyboard” computer Here is a suggestion for a small addition to your very useful “No Keyboard” project in the February 2002 issue. In not having a keyboard on a computer you can sometimes get stuck by not being able to reset or shut down the computer cleanly. By adding a switch which shorts the necessary lines into the keyboard controller to simulate a “Crtl-Alt-Del” key press, one will be able to reboot the computer. To find the lines to short, trace the www.siliconchip.com.au tracks on the key matrix membrane or PC board. “Crtl-Alt-Del” is especially useful for Linux since this performs a clean shutdown and reboot of the system. If other keys are needed (eg, F1), then these could be added as well. A useful addition would be one of the function keys as­signed as a shortcut to cleanly shut down Windows. Karl Gramp, Athelstone, SA. Check BIOS settings with IR port What a pleasant surprise to see that nifty project for the PC IR Port transceiver in the December 2001 issue. I had been wondering about such a device and there it was. I couldn’t wait for the kit so I made my own. In fact, I made two in case one ‘died’. Actually, one did die. It turned out to be because of the settings in the BIOS! The LED current limit of the IR transmitter is set to about 200mA which would quickly fry any LED unless the ‘ON’ time was only a quick burst. But what if the LED stayed on? This can happen if the BIOS IR Port output logic is wrong. My Mobo (Gigabyte 7DXC) has the option where the IR input and output can be set to “inverting” or “non-inverting”. Mine was set to “TX,RX Inverting Enable . . Yes, No”. This meant the output was inverted and the input non-inverted. So when I plugged in and powered up, the transmitting LED was turned full on, frying it! Naturally, I wasn’t aware of this until I smelt the “Dark Brown Smell” and saw the IR LED give a flash of light and a ‘pop’! I fitted the second IR transceiver with a 100Ω resistor to limit the current to about 20mA. Now I could investigate at leisure without the risk of cooking chips and that’s when I finally understood what that ‘Inverting Enable’ meant in the BIOS. The working settings now are “TX,RX Inverting Enable.. No, Yes”. Yeah, the RX was the wrong way too! The port works a treat. My laptop can sit on the coffee table no further than a metre from my PC and still connect. I left the 100Ω resistor in place in case the BIOS settings are accidentally changed back. David Vieritz, via email. Cure for LCD fault in Parallel Port PIC Programmer I recently purchased and assembled the Parallel Port PIC Programmer project described in the March 2001 issue. It works well! I did encounter a problem when constructing the Liquid Crystal Display Adapter though and I thought I’d share my experi­ ences so that other builders of this project need not tear their hair out to make it work. I purchased the display from Dick Smith Electronics (Cat Z-4170) and hooked it up using your recommended construction procedure. It did not work! So, being new to “PICs” I embarked on the learning curve and dissected the code. It worked just fine in the simulator software available from MICROCHIP.COM (free) but the hardware refused to cooperate. Some (considerable) hardware debugging and many cups of black coffee finally stimulated the old grey cells to recall that CMOS-based peripherals often exhibit out-of-spec response times. Focusing on the “LCDBUSY” subroutine in the program led to a detailed investigation of the LCD display response time to in­struction “MOVF LCD_DATA,W” in this subroutine. Sure enough, the PIC did not read this correctly. It read some arbitrary data after executing this loop many(?) times. The trick I remembered was to re-read the peripheral several times if necessary. This fixed the problem and the program and hardware are working now. To summarise, if you have problems getting the LCD display project to May 2002  5 work, find and change: MOVF LCD_DATA,W to MOVF LCD_DATA,W MOVF LCD_DATA,W in subroutine “LCDBUSY”, then ‘rebuild’ the program and write it to the PIC using the Programmer. Frank Winter VK4BLF, via email. A salve for greenhouse consciences With regard to your article on solar power in the March 2002 issue, there is a cheaper and easier way to balance out the greenhouse gases that your car makes. Just pay $30 to the Green Fleet Sustainable Energy Authority. They claim that your $30 will be used to plant two trees that will convert the CO2 gases gener­ated by the average car. This is cheaper than changing your car. Green Fleet have a web where you can go and find out where your trees have been planted. The URL is: http:// www.greenfleet.com.au/htm/who/ who.htm Roderick Wall, via email. Electric wiring regulations I have been a reader of SILICON CHIP for many years and I have noted several letters to the Editor from technicians (and possibly others) who are irritated by the restraints that they are placed under by electrical wiring regulations in Australia. I sympathise with them but it is very difficult to change such arrangements if such a move is seen by employee unions as having the potential to reduce employment opportunities. My impression from this side of the Tasman is that the Australian union movement is a very strong one and is most unlikely to support the introduction or amending of new legislation that had the potential to reduce or eliminate employment opportunities for electrical workers. 6  Silicon Chip The situation in New Zealand is covered by the 1992 Elec­tricity Act which allows householders to carry out their own wiring but this wiring cannot be connected to a source of supply until it has been inspected and tested by a registered electrical inspector. Work of this nature carried out for hire or reward must be done by a registered electrician. All wiring work done must (necessarily) comply with regula­tions made under the Act as well as any relevant Codes of Prac­tice. There are also exemptions for the repair of domestic ap­pliances by a householder where these are solely for use on domestic premises. The above are only two small extracts from an Act that covers 123 pages but it seems to work well and the electricians that I know are still earning a comfortable living. As a registered engineer I am entitled to carry out so called “prescribed” electrical work but recently when I had a new electric stove installed I found it much more convenient to use the services of an electrical contractor. In this world, there is no substitute for experience and he was self-employed, fast and effective. John C Rogers, via email. Inaccuracy in regard to tidal power Ross Tester was inaccurate when talking of tidal power generation in the article on solar power in the March 2002 issue. The tide off north-western Australia often exceeds 10 metres ‘PP’ but the peak spring tides are only a little more, I think around 13m. ‘Tens of metres’ is literally correct but mislead­ing. The plan for the Derby tidal power plant is to use hydrau­lic ‘diodes’ to pump up a ‘capacitor’ consisting of adjacent dammed inlets. One inlet would be ‘positively’ charged (thus tending toward 10m of stored water) and the other ‘negatively’ charged (tending toward 0m). The power gen- eration equipment is sited between the two inlets and can work continually. Further­more, peak generation can be matched to peak demand, not to peak tidal change. I think the newer dollar-saving cutdown plan for the plant is to have 50MW capacity, where the capability at the site is an order of magnitude more. Ross should also have talked about batteries and the eco­nomic and environmental cost of maintaining them. Another interesting issue with wind and photovoltaic gener­ ation is that there are benefits to having generation spread out as far as the grid reaches. Depending on the site, actual power generation is only 30% or so of peak generation, because of calm periods. Western Power is planning a wind farm in Geraldton, about 800km around the coast from Albany. Thus there will be some load-levelling because the weather at the two sites will not be the same. Kevin Shackleton, Cataby, WA. (Editor’s note: recent reports suggest there is some doubt about the financing of the Derby tidal power project). Locating an article from ETI I am trying to find an article published, if I remember correctly, in Electronics Today magazine, in the early 1970s. It was about the meaning of “watts” in relation to audio amplifier power output. The general thrust was that they would use “Watts RMS” because most hifi magazines did, even though it was not correct. The article stated (correctly) that it should be “Watts Average” and did some math justification for that. Can you help me? Doug Tipping, 140c Wonga Rd, North Ringwood, Vic. Comment: at this stage we are unable to help you since we do not have an index of the feature articles that appeared in ETI. However, we have published your letter in the hope that one of our readers can locate the article. www.siliconchip.com.au .. AS AS In fact, SILICON CHIP is now the ONLY truly electronics-oriented magazine published in Australia. But if you want SILICON CHIP to continue to thrive; to continue as YOUR magazine, we need YOUR support. WE NEED YOU TO JOIN US – AS A SUBSCRIBER! You’ll not only save money, you’ll get your copy earlier than the newsstands, you’ll never miss an issue because it’s sold out . . . and if you’re in the electronics industry, it could be 100% tax deductible. CALL SILICON CHIP NOW ON (02) 9979 5644 OR TURN TO P57! www.siliconchip.com.au May 2002  7 Imagine riding in a bus or driving in a car that is quiet and emission free, in a street where there are no electrical wires. At home, you have the security of knowing that you cannot be affected by power strikes or outages and that your energy source is silently working away somewhere in your home, not only supplying all your energy needs but all the pure water you can drink and you are able to use the by-product heat to keep you warm. It’s all possible – today. Fuel Cells: the quiet power source that's soon to boom! e- from air e- Electric Circuit eH2 e- O2 e- eH+ fuel Anode Catalyst H+ + H Polymer Electrolyte Membrane O2 O2 + H O2 H+ Cathode Catalyst HO 2 Exhaust In this polymer electrolyte membrane fuel cell, hydrogen fuel is fed into the anode and oxygen (or air) enters through the cathode. Encouraged by a catalyst, the hydrogen atom splits into a proton and an electron, which, because of the chemistry, are forced to take different paths to the cathode. The proton passes through the electrolyte – which will vary in different types of cells – while the electrons create a current in an external circuit as they return to the cathode, where they rejoin with the hydrogen and oxygen to form a molecule of water. This current can be used in any way that an electric current from a generator or battery can be used, for example, to power a car. Using a fuel reformer, a fuel cell system can utilise the hydrogen from any hydrocarbon fuel—from natural gas to methanol, and even petrol. Since the fuel cell relies on a controlled chemical reaction and not relatively uncontrolled combustion, emissions from fuel cells are much lower than from even the cleanest fuel combustion processes 8  Silicon ilicon Chip hip www.siliconchip.com.au www.siliconchip.com.au F uel cells are not a new idea – for more than 200 years, researchers have been working on variations of fuel, electrodes and electrolytes to produce electricity. But with over 100,000 fuel cell powered vehicles expected on the roads by 2004, this quiet power source is at last becoming quite an achiever. As early as 1802, at the age of 24, Sir Humphrey Davy (the mine safety-lamp man) created a simple fuel cell with which he was able to give himself a feeble electric shock. But he didn’t bother to document it. Then, in January 1839, Christian Friedrich Schönbein, the German/ Swiss chemist who discovered ozone, published an article about the hydrogen-oxygen fuel cell in the Philosophical Magazine but he didn’t pursue it either. At about the same time, Sir William Grove, a Welshman who was working on the series and parallel connections of his powerful platinum-zinc battery, published an article, interestingly also in the Philosophical Magazine (perhaps I should be writing about the Philosophy of Fuel Cells). Almost as an afterthought, Grove added a note to his article, based on experiments on the electrolysis of water he had carried out, of the possibility of using the hydrogen-oxygen reaction to generate electricity. Early fuel cell noxious Grove’s first cell, known as the Grove Cell, used zinc in dilute sulphuric acid and platinum in concentrated nitric acid, separated by a porous pot. Because it nearly doubled the voltage of the then-popular Daniell primary cell and could sustain strong current output, it became the favourite cell for the American telegraph for two decades in the mid 19th century. However, when it was realised that the Grove Cell discharged poisonous nitric dioxide gas (picture large telegraph offices filled with rows of hissing Grove Cells!) the telegraph companies opted for the much less noxious Daniell cells. By the way, you might be interested to know that Western Union started life as the ‘New York and Mississippi Valley Printing Telegraph Company’, which yields the initials NYMVPTC, www.siliconchip.com.au by Gerry Nolan hardly a helpful mnemonic, later becoming the ubiquitous Western Union Telegraph Company. Grove’s second attempt, which he produced in 1839 and called a ‘gas voltaic battery’, was the prototype for today’s fuel cells. Having carried out experiments to split water into its component parts of hydrogen and oxygen by passing an electric current through it, as intimated in the postscript to his earlier Philosophical Magazine article, Grove tried reversing the reaction—combining hydrogen and oxygen to produce electricity and water. This is the basis of the modern fuel Bacon and a co-worker produced a 5kW fuel cell system. Space program first practical application of fuel cells The Bacon design was chosen by NASA, over nuclear power and solar energy, as the power supply for the Apollo and Gemini missions and the space station transport system (STS) shuttle orbiters – incidentally providing water as well as electricity. NASA went on to fund 200 research contracts for fuel cell technology. Both alkaline and polymer electrolyte membrane (PEM) fuel cells have been used successfully in the space program. Serious interest in the fuel cell as an alternative generator of electricity for public use did not begin until the 1960s. Apart from the space program, until recently, major efforts with fuel cells were focused on developing stationary power units. This application was given a sharp boost in November 2001 when, as a result of the Californian energy crisis, the California State Government called for bids on stationary fuel cells. The preamble to the call document makes the case for fuel cells ‘fairly’ clear: “California’s recent energy experience [what a great PC euphemism for ‘energy crisis’!] has confirmed that the state lacks reliable electricity William Grove’s drawing of his generating capacity, and much of the experimental “Gas Battery” – image from existing capacity is over 30 years old. Proceedings of the Royal Society. The California State Government, through the newly formed Califorcell and, because of his success in nia Consumer Power and Financing doing this, Grove is now known as the Authority (the Authority), is pursu‘father of the fuel cell.’ ing expeditious means of increasing Later on, the man who is said to have capacity, and increasing the role of coined the term ‘fuel cell’, William renewable resources and cleaner, more White Jaques, substituted phosphoric efficient generation technologies. The acid (H3PO4) as the electrolyte bath. siting of clean, efficient distributed During the 1920s, further fuel cell power systems is an important element research carried out in Germany laid of this effort. the foundation for the development “State government is taking the lead of carbonate cycle and solid oxide in introducing stationary fuel cells as fuel cells. a preferred technology for distributed In 1932, Francis T. Bacon (yes, ap- power, in part through the efforts of parently he was a direct descendant the California Stationary Fuel Cell of the famous 16th century Francis Collaborative to foster fuel cell use Bacon) developed the first successful in government buildings. Fuel cell fuel cell, which he called the ‘Bacon capacity offered through the Authority Cell’. He used hydrogen, oxygen, an will facilitate these efforts.” alkaline electrolyte (potassium hydroxide—KOH) and nickel electrodes. Fuel cells take to the streets The alkaline electrolyte performed as Claimed to be the earliest use of well as acid but was not as corrosive fuel cells in a public transport system, on the electrodes. Thirty years later, a pilot program, begun in December May 2002  9 transport system based on hydrogen fuel cell technology because it was recognised as having the best potential to combine zero emission with reliability. The trial will enable the general public, fuel cell manufacturer, public transport authorities and hydrogen and filling station producers to gain everyday experience with the most new technology in a variety of climatic and topographical conditions. DaimlerChrysler considers the fuel cell to have the potential to be the drive of the future and is investing around US$1 billion in its development over the next four years. The hydrogen fuel cell White puffs of water vapour—the only emission product of fuel cells— emanating from the tail pipe attest to the truth of the banner (ZERO EMISSION FUEL CELL BUS) on this public bus, one of three in Chicago, Illinois. The hydrogen fuel tank occupies the entire roof area of the bus. 1997 by the Chicago Transit Authority, used buses powered by polymer electrolyte membrane fuel (PEM) cells provided by Ballard Power Systems, running on hydrogen gas. Liquid hydrogen, converted to gas for bus use, was supplied by Air Products & Chemicals. The successful conclusion of the trial was announced in March 2001. Perth to trial fuel cell buses From late this year, the Transperth public transport bus fleet will be augmented by three fuel cell buses for a trial period which will run for at least two years, part of a world-wide trial by DaimlerChrysler. DaimlerChrysler is conducting an extended field trial involving 33 of its fuel cell powered Mercedes-Benz Citaro city buses, known as NEFLEET (new electric fleet). Equipped with the latest fuel cell technology, the buses will be tested in 11 cities for two years, commencing late in 2002. Perth is the only city outside Europe to have been selected because, as Western Australian Minister for Transport, Murray Criddle, said, Western Australia was embarking on a long-term strategy to build a public Fuel cell energy generated from hydrogen is the easiest to produce. It eliminates all carbon dioxide emissions and produces energy at greater efficiencies than petrol, diesel or methanol. A hydrogen-powered fuel cell is the only way to achieve a true zero emission vehicle with an extended driving range. Basically, the hydrogen fuel cell works by bringing about a controlled reaction between hydrogen and oxygen. This reaction is simply electrolysis in reverse and the energy released is converted directly into electricity. The hydrogen is able to pass through the fuel cell’s electrolyte in the form of positively charged ions (protons). It then combines with the oxygen in the air to form water, leaving behind negatively charged electrons. As a DaimlerChrysler’s NEFLEET (New Electric Fleet) Citaro City Bus. These fuel-cell powered buses will be trialled in 11 cities around the world this year, including Perth. The twelve-metre long low-floor solo bus will have a range of some 200 kilometres and can accommodate more than 60 passengers, depending on the individual customer specification. The fuel cell unit with a power output of over 200 kilowatts and the compressed gas cylinders containing hydrogen compressed at 350 bar are located on the roof of the Citaro bus. Maximum speed is up to 80km/h. The electric motor, transmission, drive-shaft and mechanical rear axle are mounted in the rear section of the bus. Three doors without steps and the continuous low-floor area through to the rear ensure a smooth flow of passengers on and off the bus. 10  Silicon Chip www.siliconchip.com.au negative charge accumulates on one side of the electrolyte and a positive charge on the other, an electric voltage is generated for use in driving an electric motor. The whole system acts like a battery but delivers its electric power only when needed. Hydrogen can be used in its pure form, or can be extracted from a hydrogen-rich fuel, such as methanol, ethanol, or natural gas. Fuel cells are also capable of using hydrogen derived from trees and plants (biomass), waste gases generated at landfills and water pollution control plants, and from sunlight, wind and geothermal energy sources. Scientists are even generating hydrogen using enzymes taken from bacteria. Hydrogen can be manufactured from a variety of sources, including natural gas. As part of the fuel cell bus trial in Perth, BP is to establish a hydrogen manufacturing plant in Western Australia at its Kwinana refinery and will also establish Australia’s first hydrogen refueling facility at a suburban bus depot for the Perth’s new buses. BP will use the Perth and European trials to help develop an efficient, effective hydrogen supply network for the future. Other types of fuel cell Basically, a fuel cell is any electric cell in which the chemical energy from the oxidation of a gas fuel is converted directly to electrical energy in a continuous process without combustion or pollution. The only byproducts are water and heat. The efficiency of conversion from chemical to electrical energy in a fuel cell is between 65% and 80%, nearly twice that of the usual indirect method of conversion in which fuels are used to heat steam to turn a turbine connected to an electric generator. The concept of using fuel cells was revitalised with the progress of energy technology for submarines, the Gemini space programs and the Apollo moon landings. Among the advantages of the fuel cell are: its high degree of efficiency, a complete lack of any pollutant emissions, low noise levels, no moving parts and its modular design. This OVERLEAF: www.siliconchip.com.au The Necar4 (New Electric Car) is a hydrogen-powered fuel-cell car that has been developed to demonstrate the viability of fuel cell cars as an alternative drive solution. Based on a MercedesBenz A-class compact car, the Necar4 has a top speed of over 140km/h and can travel nearly 450km without refuelling. latter feature enables the output to be adjusted to the specific requirements of individual applications. There are presently five major fuel cell types: alkaline fuel cell (AFC), molten carbonate fuel cell (MCFC), phosphoric acid fuel cell (PAFC), polymer electrolyte membrane fuel cell (PEMFC), and solid oxide fuel cell (SOFC). Each of these types will be described in more detail in a future article. Fuel cells for your personal transport Back in March 1991, I wrote an article in this magazine about electric vehicles and gave five reasons for choosing an electric vehicle (EV) over an internal combustion engined (ICE) vehicle as “. . . a shopping list for improving the environment”. Of course, fuel cell vehicles are EVs and these reasons apply. The reasons: (1) reduction of noxious emissions, especially in urban environments; (2) more efficient use of available energy; (3) reduction of audible noise in urban areas; (4) reduced consumption of petroleum; (5) greater flexibility of vehicle design and reduced vehicle maintenance costs and times. DaimlerChrysler considers the fuel cell to have the potential to be the energy source for cars of the future and is investing around US$1 billion in its development over the next four years, when it expects to have 100 000 fuel cell powered cars on the road. Practically every major vehicle manufacturer has at least one prototype fuel cell powered vehicle in operation. More comprehensive details about the different options being developed and how the different types of fuel cells operate will be given in future articles. Briefly, fuel cells are more efficient than the internal combustion engine, running at greater than 60% thermal efficiency compared with the less than 25% typically achieved using a mid-sized car engine. PEM fuel cells also run cooler and produce far fewer emissions than internal combustion engines. Cars powered by fuel cell engines will be capable of travelling from 400km to over 600km before refueling and may be able to achieve 3-4 litres per 100km. Virtually every major auto manufacturer in the world is developing fuel cell vehicles. The most optimistic is probably DaimlerChrysler. Fleet testing will begin this year under the California Fuel Cell Partnership. Fuel cell vehicles are not only a cleaner way to travel, but will create an entirely new market, generating revenue and creating employment. At the average price of a car today, 160,000 fuel cell vehicles represents a US$3.2 billion market. It is predicted that, with a 10% market penetration, more than 100,000 jobs would be created in the USA alone. Progress in putting the quiet achiever on the road As I indicated earlier, only brief details of who is doing what about putting fuel cell powered vehicles on the road will be given in this introductory article. Considerable more detail about what is happening world wide and in Australia will follow in further articles. WHO'S DOING WHAT IN FUEL CELL VEHICLE DEVELOPMENT? The answers just might surprise you! May 2002  11 In the United States of America Ballard Power Systems Ballard is the world’s leading supplier of PEM fuel cells for transport and has received orders from vehicle manufacturers around the world. Late last year, Ballard introduced the Mark 902, its most advanced fuel cell platform to date. Ballard, DaimlerChrysler and Ford Motor Company have signed an agreement in which Ballard will acquire the interests of DaimlerChrysler and Ford in XCELLSIS GmbH and Ecostar Electric Drive Systems, LLC. This transaction increases DaimlerChrysler and Ford’s commitment to, and reliance on, Ballard as their exclusive fuel cell engine supplier. Chrysler (DaimlerChrysler) DaimlerChrysler has unveiled a fuel cell powered Town & Country minivan, the “Natrium”, which uses Millennium Cell’s Hydrogen on Demand system. The unique feature of the Natrium is that the hydrogen for the fuel cell is generated from sodium borohydride, which is derived from borax. Chrysler has unveiled its second fuel cell concept vehicle based on the Jeep Commander, running on hydrogen reformed on-board from methanol. This vehicle is actually a fuel cell/battery hybrid concept, with a nickel-metal-hydride battery to provide supplemental energy during acceleration, and for cold starts. It also uses regenerative braking to help recharge the battery. This combination gives the Commander 2 close-to-zero emissions, while achieving double the fuel efficiency of a conventional SUV Energy Partners Energy Partners (EP) is one of four fuel cell ‘engine’ companies participating in the US Department of Energy funded program. EP actually claims the first fuel cell passenger car, a demonstration sports car called the ‘Green Car’ and also developed a demonstration fuel cell, utility vehicle based on John Deere’s ‘Gator’ vehicles. The company has conducted interesting work on low cost fuel cell components. Ford Motor Corporation A group of Ford Motor Company personnel recently set a national endurance record with Ford’s P2000 (SUV) fuel cell vehicle, which uses a methanol reformer. During the 24hour test, they broke the US record for fuel cell endurance, maintained an average on-track speed of 104kph and an average overall speed of nearly 93kph. The vehicle travelled just over 2225 kilometres—further than any other fuel cell vehicle has travelled in a single day. Ford has also unveiled the TH!NK FC5, a family size sedan powered by a Ballard fuel cell electric power-train using methanol fuel. Ford’s P2000 Prodigy is a fuel cell powered sedan, running on stored hydrogen. It is designed to achieve the same performance as Ford’s Taurus, with a fuel cell engine that achieves the equivalent of 67 kW. Ford and Mobil are collaborating on a fuel processor to extract hydrogen from hydrocarbon fuels for use in fuel cell vehicles. General Motors In November last year, General Motors unveiled the fuel cell AUTOnomy, a platform that looks like a giant skateboard 12  S 12  Silicon ilicon C Chip hip in which the entire propulsion and electrical systems are built into a 152.5 mm-thick chassis. The chassis, long and flat, could be built in varying lengths and widths to accept a wide array of body types, from family sedan to SUV or from station wagon to hot little sports car. General Motors and Suzuki Motors Corporation are collaborating to develop small-car applications for fuel cell technology. GM and ChevronTexaco Corp. have formed a pact to speed the introduction of petrol fuel cells in cars, a technology that is claimed to cut emissions of greenhouse gas carbon dioxide in half. In 2000, General Motors unveiled its prototype HydroGen1 fuel cell, its smallest, most powerful fuel cell yet. The HydroGen1 is two-thirds smaller than previous GM models, yet provides 80kW of power, and has a thermal efficiency of 53 to 67 per cent. In addition, the HydroGen1 can start a car in temperatures as low as -40°C. General Motors also unveiled the Precept concept car in both hybrid and fuel cell powered forms. The Precept has a four-wheel drive, dual-axle setup. Electricity from the fuel cell is used to drive the electric motor on the Precept’s front axle. GM showed the Opel Zafira fuel cell minivan, powered by its seventh generation fuel cell system. The Zafira was the pace vehicle for the marathon at the 2000 Summer Olympics in Sydney. GM’s Delphi subsidiary is working with ARCO and Exxon to jointly develop on-board fuel processing technology and hardware to convert petrol to hydrogen for use in PEM fuel cell engines. H-Power H Power makes PEM fuel cells for a variety of specialty mobile applications. H Power supplied a PEM fuel cell to the Project New Jersey Venturer, a partnership between state government, private industry, and educational institutions to build and race a fuel cell powered car in the 1999 Tour de Sol Road Rally. Humboldt University/ Schatz Energy Research Center (SERC) SERC is researching and developing fuel cells for specialty vehicles and ‘neighbourhood vehicles’ which are now street-legal in the USA. IdaTech This company develops and commercializes fuel processors and fuel cell systems and tests synthetic diesel and synthetic petrol as on-board sources of reformed hydrogen www.siliconchip.com.au www.siliconchip.com.au to power fuel cells. Plug Power LLC along with Arthur D. Little Inc. and Los Alamos National Lab, has successfully demonstrated a fuel cell operating on hydrogen derived from petrol and is working on integrating the system into a vehicle. Whistler Inc. This company has successfully demonstrated the hydrogen-fueled Carbon-X fuel cell powered golf car, featuring a 48V proton exchange membrane fuel cell developed by Anuvu Incorporated. United Technologies Corp. UTC subsidiary, UTC Fuel Cells and Hyundai have worked together to produce four hydrogen-powered fuel cell vehicles based on the Santa Fe SUV. These zero-emission vehicles have a 75kW fuel cell system and use a conventional car battery for start-up. Enova Systems will supply the electric drive train and power management systems for the vehicles. UTC is also working with Toshiba to develop a prototype fuel cell system that extracts hydrogen from petrol. UTC, in partnership with the US DOE, has also developed a petrol-powered fuel cell system powerful enough to operate a car. In Europe BMW BMW plans to unveil a hydrogen-powered Mini Cooper, featuring an internal combustion engine similar to its Clean Energy cars. The Mini Cooper features an advanced hydrogen fuel storage tank that utilizes the same space as a conventional fuel storage tank. BMW and Delphi Automotive have unveiled their first development vehicle featuring a solid oxide fuel cell auxiliary power unit (APU). The APU provides sufficient energy for existing mechanically-driven sub-systems, such as the air conditioning and water pumps. The APU could also be used to run devices while the vehicle is idle. BMW AG plans to fit an unspecified number of 7 Series sedans with fuel cells from UTCl Fuel Cells. The vehicle will run on a hydrogen combustion engine; the fuel cell will power the car’s on-board electrical system. BMW is also developing 2000 hydrogen fuelled FC forklift trucks for the company’s own facilities prior to marketing them to other users. De Nora S.p.A. Having spun off its fuel cell R & D unit to form De Nora Fuel Cells, Italy’s De Nora S.p.A works with PEM fuel cells for buses and marine applications. The company is cooperating with Renault and Peugot/Citroen on fuel cell car projects and De Nora supplied the fuel cell engine demonstrated in the Coval truck. Fiat In mid-2001, Fiat presented the prototype of its first fuel cell car, Seicento Elettra H2 Fuel Cell, a two-seater car which was developed with the support of the Italian Ministry of the Environment and runs on hydrogen. Peugot/Citroen PSA Citroen is working with Renault to speed the development of a commercially viable fuel cell car by 2010. PSA Peugeot/Citroen is leading the HYDRO-GEN project, building a second generation PEMFC car powered by a De Nora stack and compressed hydrogen and Peugeot/Citroen is involved in a European joint PEM fuel cell program designed to reduce fuel cell system weight and costs. Renault Renault SA of France and Nissan Motor Co. have decided to develop cars with a fuel cell that runs on petrol and will market the fuel cell vehicles as early as 2005. Renault has also designed, built and tested a fuel cell powered Laguna Estate. The FEVER (‘Fuel cell Electric Vehicle for Efficiency and Range’) is a Renault station wagon powered by a PEM fuel cell engine fueled by stored liquid hydrogen. Volkswagen/Volvo Volkswagen introduced its first fuel cell-powered car at the opening of the California Fuel Cell Partnership headquarters. The zero emission vehicle (ZEV) is called Bora HyMotion, is based on the Jetta and has a fuel cell engine which runs on hydrogen and has a power output of 75 kW. Volkswagen is involved with CAPRI, a project that will deliver a prototype methanol FCV. Ballard will supply the fuel cell and Johnson Matthey a ‘Hot Spot’ reformer. In a joint project, Volvo and Volkswagen have announced plans for a methanol-fueled PEM fuel cell hybrid “Golf” type car. DaimlerChrysler (formerly Daimler-Benz) Daimler-Benz began road testing a fuel cell van, NECAR (New Electric Car), in 1993. Daimler has developed and operated four generations of fuel cell passenger vehicles, utilizing a variety of fuels. In November 2000, DaimlerChrysler presented the NECAR 5, the latest version, in Berlin. The NECAR 5 runs on methanol, unlike its predecessor, the NECAR 4, which ran on hydrogen. Daimler also presented a fuel cell as a compact auxiliary power unit (APU) in an internal combustion Mercedes-Benz S class model. Daimler is part owner of Ballard and partners with Ford in several ventures related to the development and sale of fuel cell vehicles. www.siliconchip.com.au www.siliconchip.com.au DaimlerChrysler’s Necar5, the methanol-powered version of the Necar4 shown overleaf. M May ay2002  13 2002  13 Xcellsis Xcellsis plans to produce 100,000 fuel cell engines a year starting in 2004. Shell Oil has teamed up with Xcellsis to develop the hydrogen infrastructure for fuel cell vehicles. At the same time, the partnership is pursuing technologies to reform petrol. ZeVco In June 2001, London’s Westminster City Council has bought a fuel cell van (pictured right), made by ZeVco, at a cost of 33,000 pounds (over $AU90,000). The vehicle, which will be used in the upkeep of London’s parks, has a top speed of just over 100kph and is 50% cheaper to run than a conventional combustion engine-powered vehicle. ZeVco is the only company pursuing terrestrial development of alkaline fuel cells—that is, as opposed to development for space exploration. Asia Daewoo Motor Daewoo intends to embark on a fuel cell research and development program with a state-run laboratory. Diahatsu Late last year, Diahatsu presented the MOVE FCV-K-II, a four-seater fuel cell mini-vehicle that uses a high-pressure hydrogen storage tank system. The MOVE FCV-K-II uses a 30kW Toyota fuel cell stack installed beneath the floor at the rear of the vehicle. Honda Late in 2000, Honda unveiled a four-seater fuel cell car, the FCX-V3, which has a motor 25% lighter than the two-seater fuel cell car it released the year before. The car also has a considerably faster start-up time – brought down to 10 seconds from 10 minutes! It uses a newly developed ultra-capacitor instead of a battery, resulting in improved acceleration. Honda plans to build 300 fuel cell powered vehicles a year starting in 2003 for sale in Japan and the USA. Hyundai The Hyundai Santa Fe, powered by a 75kW PEM fuel cell, scored best in class in two key performance tests at the Michelin Challenge Bibendum, an annual event where new vehicle technologies are evaluated by independent judges. The Santa Fe scored an “A” in noise and a “B” in energy efficiency. UTC Fuel Cells and Hyundai have worked together to produce four hydrogen-powered fuel cell vehicles based on the Santa Fe sport utility vehicle. These zero-emission vehicles have 75kW fuel cell systems and use a conventional car battery for start-up. Enova Systems will supply the electric drive train and power management systems. Hyundai will also use fuel cells in its research and development of fuel cell technology as part of a cooperative program with the Korean government. Hyundai has developed a fuel cell concept car powered by methanol with its affiliate Kia Motors Corp. The hybrid car, a result of a two-year project costing 9 billion won ($AU16,000,000), has a 10kW fuel cell. 14  Silicon Chip Mazda Mazda Motor Corp. plans to start test-runs of its ‘Premacy FC-EV’ car powered by a methanol-reformer fuel cell system and an electric motor in Japan and plans to start marketing fuel cell cars around 2005. Mitsubishi Mitsubishi plans to have a running prototype FCV with a production model ready in 2005. Nippon Mitsubishi oil is also working to produce a liquid fuel that can be used in fuel cells instead of petrol. Nissan Nissan Motor Co. and Renault SA of France have decided to develop cars with a fuel cell that runs on petrol and plan market the fuel cell vehicles as early as 2005. Nissan showcased the new fuel cell-powered electric Xterra SUV at the opening of the California Fuel Cell Partnership headquarters. In May 2000, Nissan began test drives in Japan of a direct hydrogen fuel cell vehicle equipped with a methanol reformer. The Xterra utilizes this technology as well as a neodymium magnet synchronous traction motor combined with a lithium-ion battery. Nissan and Suzuki have joined a government-sponsored project to develop direct methanol fuel cells for vehicles. Suzuki Suzuki unveiled a fuel cell-powered Covie two-seater at the 2001 Tokyo Motor Show. The vehicle features a General Motors fuel cell stack, and uses natural gas as the fuel. Toyota Toyota has demonstrated its new fuel cell hybrid vehicle, the FCHV-4, based on the new Highlander SUV. The vehicle, which Toyota says will be launched on a limited basis in 2003, will be demonstrated through their participation in the California Fuel Cell Partnership. Toyota says the vehicle, with a cruising range of more than 250km, has ‘three times the vehicle efficiency of an ordinary gasoline-powered car.’ Toyota also unveiled the FCHV-5, which runs on clean hydrocarbons, in Japan. Toyota has also unveiled methanol and hydrogen fueled versions of its FCEV, based on the RAV4 sport utility vehicle. Both use Toyota’s own PEM engines in hybrid configuration. Toyota plans to launch a commercial FCV in 2003. Exxon and Toyota are working on technology to extract hydrogen from petrol, although Toyota has said methanol is SC the preferred option in the near term. www.siliconchip.com.au www.siliconchip.com.au COMPUTER GAMING SUPER SPECIALS (LIMITED STOCK) ALL BRAND NEW IN ORIGINAL PACKAGING All come with full instructions & EIDOS demo CD and can be played across a network. EIDOS FORMULA 1 Formula 1 racing game, Rated "G" Comes with full instructions and disk: $18 EIDOS DAIKATANA Shoot em up adventure game, Rated "MATURE" Comes with full instructions and disk: $18 EIDOS DEATHTRAP Shoot em up adventure game, Rated "MATURE" Comes with full instructions and disk: $18 THRUSTMASTER STEERING WHEEL AND PEDAL SET IBM games port compatible. Features include Quick release desk clamp, 4 on wheel buttons and 2 paddles for gear change etc. Comes with installation CD: $69 SPECIAL PACKAGE DEAL 1 X STEERING WHEEL AND PEDAL SET 1 X FORMULA 1 game 1 X DAIKATANA game 1 X DEATHTRAP game ALL FOR JUST $100 NEW 2.4 Ghz A/V TRANSMITTER MODULES AND CAMERAS ASK FOR A FREE VHF MODULATOR KIT WITH EACH CAMERA PURCHASE SUPPLIED IN MODULE FORM, NO PLUGS/SOCKETS, SOME ASSEMBLY/ SOLDERING REQUIRED. GOOD PICTURE QUALITY TRANSMITTER / RECEIVER MODULES A: MINI 2.4Ghz 10 mW VIDEO TRANSMITTER (Max. legal power) 15 X 15 X 5mm (Main body). This is the smallest 2.4 Ghz 10Mw transmitter we have seen. Requires 5Vdc. Will Transmit up to 100 Mtr. with a 30mm wire as an antenna. Module "A" plus module "C" $169 C & D: 10mW 2.4Ghz STEREO AUDIO VIDEO TRANSMITTER AND RECEIVER MODULES Will Transmit up to 100 Mtr. with a 30mm wire as an antenna.:$90 G: STEREO AUDIO VIDEO TRANSMITTER / RECEIVER KIT. This kit contains modules as per C & D and includes PBCs and all on-board components. :$119 A B C D CAMERAS B: MINI HIGH QUALITY LOW LIGHT CMOS PINHOLE CAMERA... 20 X 25 X 19mm. $98 E: MINI HIGH QUALITY LOW LIGHT CMOS BUTTON HOLE CAMERA WITH AUDIO 30 X 30 X 30mm. :$82 F: MINI HIGH QUALITY LOW LIGHT CMOS BUTTON HOLE CAMERA WITH AUDIO and HOUSED IN A SECURITY DOME Dia. 86mm X 60mm. $92 USED) LOW COST PRINTER: These serial interface printers are in good condition & were made in England. Supplied with ribbon installed. This is a rugged printer useful for Point of Sale applications. It is able to be used on a wide variety of hardware platforms - not confined to a PC. Any equipment with a standard RS232 port is capable of utilising this printer. (ZB0340) $50 each (limited quantity) F E G *** BARGAIN *** ROBOT BUILDERS BARGAIN!!! RADIO CONTROL CAR / TRUCK REAR AXLE (DIFERENTIAL) ASSEMBLEY Complete assembly from a model car differential / gearbox and a 380 motor (Nom. 7.2V). The overall width is approx. 24cm. Good quality brand new unit as used in some Tandy electric cars. We have a good quantity in stock for a small fraction of their retail price - $11 for units with wheels. Extra wheels $1ea Type supplied may differ from the one shown. CAMBRIDGE SOUNDWORKS COMPUTER SPEAKERS We have a limited quantity of these Cambridge SoundWorks GCS300 Computer Speakers. These are Brand New in original packaging that includes two speakers with power supply, cables, and manual. Response: 90 - 20kHz... Amplifier Gain: 12dB <at> 1KHz volume max... Output Power: 92 dB SPL at . 5m listening position... Power (each satellite): 2 Watt... Input Impedance: 10K ohms... Controls: On/off/master volume on right speaker... Weight: 1.5Kg per speaker set including adapter... Dimension:153X101X114mm..(GCS300): $22 limited quantity. (NEW) COLOUR CHRISTMAS LIGHTS (140LIGHTS) Plug-pack not supplied, requires 24VAC. In original packaging (may be shop soiled) $8 635nM LEDS Bright (60mCd) 3mm red LEDS, type HLMP1340, data at fairchildsemi.com, large but limited quantity: 10 for $1.50, 50 for $6 or a sealed pack of 250 for $22 POWER TRANSISTORS 2N3055 New TO3 package metal cased power transistors, large but limited stock: $1.20Ea. or 10 for $8 REMOTE CONTROL TRANSMITTERS Brand new Radio Shack two channel crystal controlled 27MHz transmitters with 2 3 position joystick, need 9V battery, style can differ from the pictured unit: $7 Ea. Or 2 for $10 MORE NEW STOCK We have more used test equipment coming all the time and we need to clear stock to make way for the next lot. The only way to make sure you don’t miss out is to subscribe to our bargain corner & receive advanced notice by E-Mail Just send us a blank E-Mail to.... bargaincorner-subscribe <at>oatleyelectronics.com CK O ST !!! W W NE N NO I $8 (NEW) SOUND BLASTER LIVE! 5.1 SE AND BOSTON ACOUSTICS DIGITAL ENTERTAINMENT This special edition is supplied with the PCI card, Software on CD and leads to connect the card to a CD-ROM. Visit the creative website for further information. These are brand new in their retail packaging. A manual is not supplied but can be downloaded The card has a digital output suitable for driving the Boston Acoustics sound system: (SBDE51) $100 These cards can only be purchased with a Boston Acoustics sound system. Previous purchasers of the Boston Acoustics sound system may also Purchase these cards. 9 6 1 $ LAST FEW VERY LIMITED STOCK www.oatleyelectronics.com Orders: Ph ( 02 ) 9584 3563, Fax (02) 9584 3561, sales<at>oatleyelectronics.com, PO Box 89 Oatley NSW 2223 major cards with ph. & fax orders, Post & Pack typically $7 Prices subject to change without notice ACN 068 740 081 ABN18068 740 081 SC_MAY_02 Sea Change Technology’s Shark Shield: how one Australian company could make your visits to the beach a little safer . . . Shark! by Ross Tester 16  Silicon Chip www.siliconchip.com.au T he very mention of the word “shark” engenders dread in the vast majority of humans. After all, we’ve all seen Jaws, Jaws 2, Jaws 3 (how many is it now?) and we know what those nasty creatures can do. And how clever they are. And every year, just about the time you are starting to think that it’s safe to go back in the water, one or more of our more sensationalist papers trots out some expert or other to warn that “this year will be one of the most dangerous on record for shark attacks . . .” Yet most of our fear of sharks is completely without foundation. As regular readers of SILICON CHIP may know, on my days off for good behaviour I am involved in Surf Lifesaving on Sydney’s Northern Beaches. This includes training and examining new recruits. One of the first and most-raised topics is about sharks. It’s not just the kids – all ages are petrified! When they see images on TV of the recent 2002 National Surf Lifesaving Championships at Kurrawa (on Queensland’s Gold Coast) with literally dozens of sharks close inshore in a feeding frenzy, that fear is perhaps understandable. To try to reassure them, I ask all new squad members to tell me when the last fatal shark attack occurred around Sydney. The answers usually vary anywhere from “last year” to “about 10 years ago.” The truth is that the last fatal attack occurred not off a surfing beach but in Middle Harbour almost 40 years ago (1963 to be precise), when actress Marcia Hathaway was mauled by a shark in less than two feet of water. (She died from shock/blood loss when the ambulance sent to retrieve her burned between May and November. In fact, you’re much more likely to be killed by a wayward bee on your way to the beach than you are being taken by a shark. Worldwide, there are perhaps 50-75 shark attacks per year, with an average of 8-12 fatalities. Allergic reaction to bee stings takes many, many times this number each year! There were 76 documented attacks in 2001, 5 of them fatal. This compares with 85 reported attacks in 2000, (12 of them fatal) and 58 attacks in 1999. Remember, this is world-wide! And compare that tiny number of fatalities with the 100-200 million sharks caught each year through fishing – they might be excused for wanting to get even! Of course, there have been attacks – some of them fatal – in other areas of Australia. Two attacks in quick succession on Perth’s Cottesloe Beach a couple of years back certainly got the tabloids into a feeding frenzy! Shark netting its clutch out trying to get back up the steep track from the beach). And as far as attacks off an ocean beach are concerned, we go back even further – much further. The last occurred in 1937 – incidentally the same year in which shark netting was introduced in Sydney. And there have never been any reported attacks We mentioned shark netting a moment ago. This has been the preferred method of protecting humans for more than half a century. The idea of the nets (which are generally only 200m long and 6m deep) is not so much to “catch” sharks – though they do that – but to discourage sharks from establishing their “territory” near a Fitting the Sea Change Technology “Shark Shield” before snorkelling or even catching waves – it’s as simple as strapping the unit to your leg, and it could save your life . . . www.siliconchip.com.au May 2002  17 The “figure 8” field produced around a diver, using the scuba tank as one of the electrodes. A board rider has two trailing electrodes, resulting in a polar pattern under the surfboard. The field for a swimmer or snorkeller with one trailing electrode is similar to that from the board rider. beach. The nets, with 50cm mesh, are not permanent – they are moved from beach to beach by contractors. That they are successful is not questioned (no attacks off any Sydney beach since installation). However, in recent years conservationists have started to question the number of other marine creatures accidentally caught by the nets (dolphins, turtles, etc). Fortunately for swimmers, governments have decided to keep the nets in place. Witness the history of Durban (South Africa) where a mesh barrier was put into place as far back as 1907. It was in place for 21 years before it was allowed to fall apart. During those 21 years there was never an attack off Durban. Records for the years between 1943 and 1951 show that Durban had 21 shark attacks. very commonly found in Sydney and southern Australia – might lick you to death (or perhaps scare you to death!). There are three sharks which dominate reports of attacks: the great white, the tiger and the bull shark. All three can grow to very large sizes and all three are common in Australia. There are areas along Australia’s southern coast where large numbers of Great Whites congregate; needless to say, swimming and surfing are not high on the sporting agenda. . . Having said that, the majority of attacks occur in the warmer waters of the tropics. the shark can detect their presence, via the Ampullae of Lorenzini, even under the sand. Not all sharks are dangerous There are around 350 shark species, of which 32 have been proved to attack humans. Another 35 or so are considered potentially dangerous. The rest – such as the Port Jackson shark 18  Silicon Chip Why do sharks attack? Many experts believe that attacks (particularly those NOT of the “big three”) are often a case of mistaken identity – to a shark, a swimmer or surfer in a wet suit does not look all that different to a seal (yum!). There have been many cases of sharks “tasting and spitting” which tends to reinforce that theory. Some sharks, though, have been known to stalk victims. Others stage “hit and run” attacks where the victim has no idea of the shark’s presence until the last moment. It is believed that sharks sense their prey at least partially by electrical means. On the nose of all predatory sharks are small sensory organs called the “Ampullae of Lorenzini”. These organs can detect the tiniest of electrical currents (which are generated by all animals, humans included) and can guide a shark to its prey from some distance away, even to completely hidden prey. You might have seen film of sharks “digging” out stingrays which had buried themselves under a layer of sand to try to escape: Turning the tables It is those same Ampullae of Lorenzini that researchers in South Africa discovered, several years ago, could be used to repel sharks. By setting up an electric field around a swimmer/diver/surfer/etc, any predatory shark entering the field finds it impossible to stay. The same field does not affect humans or other marine creatures because they do not have the sensory organs. The exact mechanism – why it works – is not yet completely understood. But it could be that the generated electric field is not only detected by the Ampullae of Lorenzini – it massively overloads this ultra-sensitive organ. The result is extreme discomfort and muscular spasms in the shark which cause it to veer away whenever it enters the field. There is also evidence that the shark loses muscle control around the mouth and gill, meaning it may not be able to take a bite even if it wanted to. But noone is quite willing to test that theory! First developed in Natal, South Africa, for professional divers, Adelaide-based SeaChange Technology has refined and miniaturised the original “Shark Pod” into its recently released “Shark Shield.”. Both use the same technology but the Shark Shield is very much smaller and lighter, a “personal” version. SeaChange Technology’s Technical Director, Mike Wescombe-Down, said that the Shark Shield was the result of many years of development, refinement and above all testing and retesting. And those tests have been 100% effective agains a variety of sharks. He was not at all reticent about www.siliconchip.com.au sharing some of the technical features of the Shark Shield with SILICON CHIP. However, we must warn readers not to think this information is an invitation to try to build your own version. As we mentioned before, sharks can sense the tiniest electrical stimulii – and during their early testing, the Natal Board of Sharks even found that a very slight variation in the waveform actually attracted sharks! We’d hate to think that readers would try to build their own version, because if it doesn’t work as intended, you won’t get a second chance to fix it! “You can’t argue with a Great White bearing down on you at speed,” said Mike. How does it work? The heart of the Shark Shield is an intelligent microprocessor-controlled high-voltage pulse generator. The patented, very complex waveform includes a very fast-rising pulse every 500ms. This is fed into the trailing electrodes or “antennas” which in turn produce the electric field in the water. The microprocessor not only controls the waveform generation but also detects whether the antennas are under water (it throttles back the output if they are not) or whether they have become short circuited. If so, it switches over to a test mode and restores the output when the short is removed. The pulsing field (which can be felt on bare skin in salt water but does not cause discomfort at reasonable distance) decays quite dramatically from the antennas but is effective up to a range of about 2-3 metres and even up to five metres. Several factors affect the output and hence distance: Water temperature (the warmer the water the more output) – fortunate, because shark attacks do increase with warmer water! Battery life – also affected by temperature. Water salinity – requires salt water (does not work in fresh, is very limited in brackish). Size of electrodes (antennas) and spacing – the Shark Shield antenna is designed to be have the most effect possible without compromising the user’s mobility. The dive model has larger electrodes, more widely spaced, and has a range of three to www.siliconchip.com.au five metres or so. There are two models of Shark Shield: the more powerful (4-5m range) DIVE01 unit is 21cm x 7cm x 3cm and weighs 590 grams (excluding electrodes and pouch). The combined total weight is about 1kg; and the GPSS01 (personal) unit is 17cm x 7cm x 3cm and weighs 450 grams (excluding antenna and pouch) The combined total weight is about 960 grams. Testing the Shark Shield SeaChange Technologies’ Technical Director, Mike Wescombe-Down. Thanks to Mike for his assistance with this feature. As we said before, a huge amount of laboratory and field testing has taken place before the Shark Shield was released to the market. Scientists know that sharks are much more intelligent than most people give them credit for (hence the success of shark netting). But that intelligence could just as easily have turned a “normal” shark into a dangerous predator. Much of the testing involved the use of shark bait and bloodied water. SeaChange Technologies used a variety of test floats and scenarios to ensure that the sharks would not associate a particular float (such as a surfboard) with a food source, even if much of the time they were repelled. The types of sharks tested included the “big three” mentioned above – great whites, bull sharks and tigers, but also included makos (known to become very aggressive and a threat to man) and, interestingly, the ocean white-tip shark. This particular shark is thought responsible for a huge number of attacks on sailors off sinking ships during World War II, attacking in packs and creating carnage. Testing will never stop Mike Wecombe-Down says that his company will continue to develop the Shark Shield and related products. “We have an ongoing program of testing and refining, at the same time looking at ways of adapting the technology for other uses.” “We’re already working on an electronic beach barrier, something that in time may replace beach netting. But the biggest problem to date has been not only getting sufficient energy to where it is required but making the package strong enough to withstand the forces of nature,” he said. Research and Development has commenced on variants of the Shark Shield, suitable for sailboarding, jet skiing, kayaking, boat protection and even a model for life jackets. A commercial range is also planned, which will include protection for aquaculture stocks and electronic beach barriers. Where, how much? Retail price of both units is about $700.00. The Australian and New Zealand distributors of the product are Aquanaut Pty Ltd (www.aquanaut .com.au); more information about the Shark Shield can be found on www. SC seachangetechnology.com.au The Shark Shield is a development of the earlier POD, originally used by divers in South Africa. May 2002  19 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 More LEDs, more patterns, more exciting than ever 32-led Flashing LED displays are always intriguing, particularly if they emulate the KnightRider car from the old TV series. This KnightRider light chaser includes 12 different lighting patterns using 32 LEDs for a big and impressive display. Not restricted to KnightRider use, the display can be used as a rear window brake light or as an eye-catching conversation piece at parties or even on retail displays. By JOHN CLARKE 24  Silicon Chip www.siliconchip.com.au I the other in May 1996. Both of these Our latest version of KnightRider n the early 1980s there was a TV used 16 LEDs and had a single fixed has twice as many LEDs, 32, and a series called KnightRider. Its “star” scanning display pattern. number of different display patterns was a rather clever car going by the are available which are selectfetching name ‘Kit’. ed using a pushbutton switch. Mind you, Kit was no There are four scanning seordinary car. It had powers quences, a chaser and a strobe. and abilities far beyond those Ds LE 32 of mortal cars. Kit could talk, If you mounted the display * including medleys s, rn tte pa y pla drive itself and supposedly on your car’s parcel shelf, you dis D LE * 12 d see using a row of lights on could also use it as a brake ee sp rn tte pa * Adjustable the front which ‘scanned’ from light. ss tne igh br side to side to simulate moni* Adjustable LED The patterns toring what was ahead. * 12V operation While the KnightRider TV The four scanning patterns series has long since ceased, include the traditional moveBut both of these were in the days such scanning lights have ment of LEDs from left to right and before microcontrollers – or at least becontinued appeal and we have pubfrom right to left which is repeated fore microcontrollers were commonly lished two different KnightRider light to simulate scanning across a field used in projects. displays, one in November 1988 and in front of the LEDs. Pattern 2 begins Features Fig.1: in this circuit, the 32 LEDs are arranged in an array, driven in their various patterns by the PIC microcontroller. www.siliconchip.com.au May 2002  25 with two LEDs in the centre LEDs which then spread (light up) to the left and right and contract back to the centre. Patterns 3 and 4 are similar, with pattern 3 moving from the centre to the outside and then back to centre again. Pattern 4 starts from the outside LEDs and moves to the centre and then back the outside again. Chaser sequences include a right to left movement and a left to right movement. The strobe patterns can be at a regular or random flashing rate. For brake light use, there are two patterns. The first lights all LEDs initially for a minimum of about 18 seconds (depending on the speed setting) and then the LEDs randomly switch off until they are all out. Alternatively, you can just have all LEDs lit while ever the brake is applied. The KnightRider PC board measures 210 x 72mm. All 32 LEDs mount horizontally along one edge of the PC board. There are two trimpots, one to adjust the LED scanning rate and the other to adjust display brightness. A pushbutton selects the display pattern while a LED next to the switch flashes once or more to indicate the pattern that has been selected. Circuit description Apart from the 33 LEDs, the KnightRider uses relatively few components and is based around IC1, a PIC16F84 microcontroller. This provides all the LED patterns. The PIC16F84 has 18 pins, 13 of which can be used as inputs or outputs. For our circuit we are using 12 as outputs to drive the LEDs and one as an input and an output to monitor the pattern select switch and drive the pattern LED. Fig.1 shows the circuit details. Multiplexed rows and columns While the 32 LEDs are physically arrayed along one side of the PC board, they are actually connected as a matrix of four columns and eight rows, as shown in Fig.1. The eight rows are driven directly from IC1 (RB0-RB7) while the four columns are driven by four transistors, Q1-Q4. These transistors are switched by the RA0, RA1, RA2 and RA3 outputs of IC1. When the RA0 output (pin 17) is pulled low by IC1, transistor Q1 is switched on and applies power to the anodes of LEDs 1-8. A low output on any of the RB outputs will drive the LED connected to it via its series 150Ω resistor. For example, if RB0 goes low, LED1 will light. The RA0 line is kept low for a short time before this goes high to switch off Q1. Thus LEDs1-8 are switched off. The RA3 line (pin 2) is then brought low to drive Q2 and the anodes of LEDs 9-16. Now any low RB outputs will then light up LEDs 9-16. Similarly, RA2 (pin 1) is brought low to drive Q3 and LEDs 17 to 24 and then RA1 (pin 18) is pulled low to drive Q4 and Scope 1: The upper trace is the oscillator waveform at pin 16 (OSC IN). This is a classic sawtooth expected from a relaxation oscillator. The lower trace is the waveform at pin 15 (OSC OUT) which in this RC mode is a square wave at one quarter the oscillation frequency. 26  Silicon Chip LEDs 25-32. This cycle repeats endlessly with each column of eight LEDs being lit at a very fast rate so that the LEDs appear to be continuously lit rather than only being on for some of the time. This system of driving the LEDs is called “multiplexing”. Its big advantage is that it saves power and drastically reduces the number of connections required. If the LEDs were not multi-plexed we would need 33 separate lines (32 actives and one common) whereas with multiplexing we can drive the 32 LEDs using only 12 lines connected in the matrix. Brightness control Overall LED brightness is controlled with trimpot VR2. This varies the voltage at pin 3 of IC2 from 5V down to about 2.4V when the wiper is at its lowest point. Op amp IC2 operates as a unity gain buffer amplifier, with transistor Q5 providing extra current drive capability. If the emitter of Q5 is at 5V, the LEDs will be driven at maximum brightness. Typical LED current will be (5V - 1.8V)/150Ω, or 21mA. This is the pulse current, not average current. The pattern select switch S1 connects to RA4 of IC1. This pin is normally held at 5V via the 10kΩ pullup resistor. When S1 is pressed, LED33 lights and RA4 is pulled low. This is recognised by IC1 as a switch closure and the next pattern in the sequence of 12 is selected. When the Scope 2: These traces show the time duration between when power is applied to the circuit and when the LEDs light for the brake light pattern selections. Top waveform is the applied voltage and when this goes high, there is some 67ms before the LEDs light. This is fast enough to display almost instantly the brakes are applied. www.siliconchip.com.au 15pF DEEPS VR1 50k 0.1F K K 4.7k 150 LED31 150 LED30 150 IC1 PIC16F84 LED29 150 LED28 1 10F 1k A 22k 68k 150 10k 150 NRETTAP Q6 BC328 150 150 LED27 LED26 LED25 LED24 LED23 S1 LED22 LED33 10k LED21 10F Q5 BC338 10F + LED18 LED17 LED16 LED15 THGIRB Q3 BC328 VR2 50k LED14 LED13 Q2 BC328 680 680 LED12 LED11 Q1 BC328 680 LED10 LED9 12050180 Q4 BC328 680 2002 C LED19 10F 1 LED20 47k IC2 LM358 1k LED32 LED8 LED7 REG1 10F LED6 LM7805 +12V +12V LED4 16V ZD1 LED3 10 1N4004 KNIGHT RIDER LED2 D1 LED1 A 0V GND LED5 100F A Fig. 2: here’s the full-size PC board component overlay, with a matching photo to make assembly a breeze! switch is released, IC1 flashes LED33 to indicate the pattern selected. For example, pattern 2 is indicated by two flashes. Note that the RA4 pin is an open drain output when configured as an www.siliconchip.com.au output. This allows RA4 to drive LED33 when pin 3 is low. When RA4 is set high, the open drain connection means that it becomes a high impedance output which is pulled high via the 10kΩ resistor. In this condition, IC1 can monitor RA4; if it is pulled low, that indicates that the switch is closed. No crystal required Most PIC circuits use a crystal for May 2002  27 Parts List – KnightRider 1 PC board coded 08105021, 210 x 72mm 1 heatsink, 19 x 19 x 10mm 1 2-way PC-mount screw terminal 1 snap-action PC pushbutton switch (S1) 1 M3 x 6mm screw and nut 4 adhesive rubber feet 1 350mm length of 0.8mm tinned copper wire Semiconductors 1 PIC16F84P (IC1) programmed with Knight.hex 1 LM358 dual op amp (IC2) 1 7805 regulator (REG1) 5 BC328 PNP transistors (Q1-Q4, Q6) 1 BC338 NPN transistor (Q5) 1 16V 1W zener diode (ZD1) 1 1N4002 diode (D1) 33 5mm red high-brightness LEDs (LED1-LED33) Capacitors 1 100µF 16VW PC electrolytic 5 10µF 16VW PC electrolytic 1 0.1µF MKT polyester (code 100n or 104) 1 15pF NP0 ceramic (code 15p or 15) Resistors (0.25W, 1%) 1 68kΩ 1 47kΩ 1 22kΩ 2 10kΩ 1 4.7kΩ 2 1kΩ 4 680Ω 8 150Ω 1 10Ω 2 50kΩ horizontal trimpots (code 503) (VR1,VR2) the internal oscillator but this circuit does not require precision timing. For these situations, the PIC can be set up as a relaxation oscillator (similar to the 555) whereby a capacitor connected to pin 16 is charged from the positive supply (+5V) via a resistance and then discharged via an internal transistor. In this case we connected a 15pF capacitor to pin 16, charged from +5V via trimpot VR1 and a 4.7kΩ resistor. The classic sawtooth waveform of the oscillator can be seen in the top trace of Scope 1. 28  Silicon Chip Interestingly, the waveform at pin 15, OSC OUT, is not the same as at pin 16. Instead it is a square wave at one quarter the frequency. Frequency of operation can be varied from about 4MHz when VR1 is set to minimum resistance, down to about 500kHz when VR1 is at maximum resistance. Transistor Q6 and its associated resistors provide a reset for IC1 when the supply is below a certain voltage. This ensures correct start up for IC1 when power is applied. The circuit can be powered from a 12V battery, DC power supply or DC plugpack. Diode D1 gives reverse polarity protection while the 10Ω resistor and zener diode ZD1 provide transient protection. The 12V supply is filtered with a 100µF capacitor before being applied to REG1, a 5V regulator. Its output is decoupled with a 10µF capacitor to ensure stability. Software The software required to provide the various LED display patterns was written to minimise the number of instruction codes. This is because there are only 1024 bytes of memory and we would quickly run out of space if we were to list each individual LED and its state during a pattern sequence. This normal approach involves using a lookup table. Instead of using a lookup table, the software makes note of the fact that much of the sequence is repetitive and only a short list of LED switching operations is required. This list is used in various ways to generate the required pattern. The efficiency of this approach is evident by the fact that we managed to include some 12 distinct patterns into the software with some space left over. In contrast, if we had used a lookup table it would have only allowed one or maybe two patterns at the most. The full software listing for the KnightRider is called knight.asm; it (and the .hex file) is available from our website – www.siliconchip.com.au Construction The KnightRider is constructed on a PC board coded 08105021 and measuring 210 x 72mm. Begin construction by checking the PC board for shorted tracks or any breaks in the copper pattern. Check the pattern against the published artwork to verify that it is correct. Repair any defects on the PC board before starting assembly. Fig.2 shows the component overlay for the PC board. First, install all the links on the PC board. Then install the resistors, using the colour codes shown in the parts list as a guide to selecting the values. You can also check each value with a digital multimeter to be sure that you have the correct resistor for each position. The diodes can be installed next, taking care not to confuse zener diode ZD1 with standard diode D1. IC1 is mounted using a socket while IC2 can be soldered directly into the PC board. The 3-terminal regulator is mounted horizontally, so carefully bend the regulator leads before inserting them into the relevant holes on the PC board. It is mounted onto a small heatsink and secured with an M3 screw and nut. When installing the five transistors, make sure that the BC338 is placed in the Q5 position. Next, install the capacitors. The codes of low value types are listed in the parts list. The electrolytic capacitors will have their values marked in µF; be sure to orient them correctly. Switch S1 should be installed with the ‘flat’ side oriented as shown Fig.2. Insert LED 33 with the anode (longer lead) placed toward the VR1 side of the PC board. Trimpots VR1 and VR2 and the PC-mount terminal block can then be soldered into place. Finally, the 32 LEDs can be installed along the edge of the board. They are placed with the anode leads (longer lead) to the left. You can preform all the LED leads by cutting a length of cardboard 10mm wide. Place the LED across this with the anode to the left and bend the leads downward. This will allow the LEDs to be inserted into the PC board with sufficient clearance for the LED body to just protrude over the front edge of the PC board. Check your work carefully for correct orientation of the capacitors, for the correct transistors in each place and the correct orientation of IC2 and the socket for IC1. Do not install IC1 yet. Testing Now apply power to the +12V and www.siliconchip.com.au TABLE 1: PATTERNS AVAILABLE K Type 1 Scan LEDs move from left to right and then right to left yes 2 Scan LEDs move symmetrically from centre to outside and from outside to centre yes 3 Scan LEDs move symetrically from centre to outside yes 4 Scan LEDs move symetrically from outside to centre yes Patterns 1, 2, 3 & 4 selected in sequence with change every power up yes# 1 6 Medley 8 cycles of pattern 1 16 cycles of pattern 2 16 cycles of pattern 3 16 cycles of pattern 4 7 Chaser LEDs chase from right to left yes ## 8 LEDs chase from left to right yes 9 Strobe All LEDs on then off at regular rate 10 Strobe All LEDs on then off at random rate yes 11 Random LEDs lit at random until all on, then off at random until all off yes 12 Medley 100 cycles of pattern 7 100 cycles of pattern 8 20 cycles of pattern 9 20 cycles of pattern 10 2 cycles of pattern 11 yes+ 13 Brake All LEDs on at power-up for 18s minimum then off at random until all off no 14 Brake All LEDs on at power up and remain on until power off no++ yes 1 BRIGHT 08105021 C 2002 # ## + ++ Chaser PATTERN 5 Scan Pattern Description     Repeat SPEED No. (of selected pattern) (Medley repeats of patterns 1, 2, 3 & 4) (Medley repeats of patterns 7, 8, 9 & 10) (only lights again after power off and on again) GND +12V 0V supply terminals and measure the voltage between the metal tab of REG1 and pin 14 of the IC1 socket. This should be +5V. If this is correct, disconnect power and insert IC1, making sure it is oriented correctly. Apply power again and check that the LEDs start to light up and produce a chasing pattern. The initial pattern is the KnightRider chaser (Pattern 1) with the LEDs moving from left to right and from right to left. www.siliconchip.com.au Check that you can adjust the speed with trimpot VR1 A KNIGHT RIDER and vary brightness with VR2. You can test for the other Full-size PC board artwork. Use this to check patterns by pressing the commercial boards or to make your own board. pattern switch. Each time you press the pattern switch, LED33 trimpot (VR1) so that you can easily count the number of flashes from will flash the required number of times and then the selected pattern sequence LED33. will start to run. Table 1 shows the 14 patterns You may need to adjust the speed available. SC May 2002  29 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. Protection for white LED in torch The article on the LED Torch published in the December 2000 issue warns against powering up the circuit without the LED and then subsequently connecting the LED. This can destroy the white LED from over-current due to the over-charged tantalum capacitor. While this should be a “remote possibility” because the LED is hard-wired into the circuit, in fact that LED-destroying condi­tion can occur fairly easily. The problem arises when the screw-type torch is used and the wire twists off, as it inevitably will, from screwing and un­screwing to change the battery (or what is more likely, to show other interested parties what is inside!). Then, when investigat­ing why the LED will not light, the LED can make momentary con­tact again and will immediately blow from over-current. The suggested fix limits the voltage across the tantalum capacitor with a 4.7V zener diode (which normally does nothing because the LED holds the zener below its operating voltage) and uses a 15Ω limiting resistor in series with the LED to ensure that it can be safely connected or disconnected and at no time exceed the 200mA rated absolute maximum peak LED current. The 15Ω resistor does waste some power but this amounts to less than 10% and is well worth sacrificing to help provide a fail-safe circuit for the expensive LED. The zener also protects the tantalum capacitor from over-voltage breakdown that can otherwise occur when the LED is not in circuit. The total cost of the modification is less than 50 cents and the additional components can be mounted on the existing PC board. Rick Matthews, Adelaide, SA. ($30) Relative field strength meter for a DMM it works with the high-impedance load of a digital multimeter, typically switched to the 200mV range. The sensitivity is adequate for low power equipment like CB radios, cordless phones and model R/C sets (cars, model airplanes, etc). For best results, use OA81 or similar germanium diodes. Modern Schott­ky Many passive field strength meters have appeared in the past, typically using a 50µA analog meter movement if reasonable sensitivity was to be obtained. This circuit is similar but has the advantage that 30  Silicon Chip www.siliconchip.com.au Constant current LED drive Most LED driver circuits use a series resistor to control the current through the LED. For applications needing a few LEDs, this is optimal. However, for applications needing many LEDs, this becomes extravagantly inefficient and it is tempting to keep the voltage drop across the resistor as small as possible. That leads to poor control of the current. ICs such as the MM5450 and its relatives and the A6275 and its relatives provide constant current outputs so that the current through the LEDs is well controlled even though the voltage drop across the circuit doing the control is accept- ably small. Howev­er, the difficulty with these circuits is that because they contain many constant current drivers crowded into a relatively small package, unless the supply voltage is small, they become too hot and can destroy themselves. This problem is not easy to solve. The solution is to maintain a small voltage across each constant current source. In this circuit, this is accomplished by REG1, the LM317L, which provides a bias of about 1.5V ±5%. Each transistor works as an emitter-follower, presenting the A6275 inputs with about 0.9V. Vled, the LED supply voltage, needs to be high enough to ensure that there will be at least 0.5V across each transistor but it is safe to allow significantly more than this and the supply need not be well regulated. The transistors can be general Keith Anderson p u r p o s e N P N is this month’s wintypes such as ner of the Wavetek Meterman 85XT BC548 and a sintrue RMS digita l gle LM317L will multimeter. easily supply a total LED current of at least 1A. A6275s are made by Allegro and are available from Farnell, catalog numbers 300-5306, 300-5318. Keith Anderson, Kingston, Tas. signal diodes could also be used but the results are not as good. The circuit can be wired directly into a small plastic box with protruding banana posts to match the terminals on your DMM. A banana jack can also be used for the antenna which could be just a 500mm length of wire as a starting point. Gerard La Rooy, Christchurch, New Zealand. ($30) www.siliconchip.com.au May 2002  31 Don’t get caught with a flat battery BUILD THE By JOHN CLARKE BATTERY GUARDIAN Got a big stereo system in your car? Got a fridge in your van or 4WD? Ever had the battery discharged to the point where you couldn’t start the motor? Not a good feeling, is it? You need our Battery Guardian. It monitors the battery voltage and will switch off the current to your fridge or stereo (or whatever) when the battery voltage falls below a preset level to allow you to still start your engine. 32  Silicon Chip www.siliconchip.com.au E LECTRIC FRIDGES IN VANS and 4WDs are a great idea but if you are not careful, they can severely discharge the battery and leave you stranded. Maybe the battery will end up with severe damage as well. The same problem applies if you have a big stereo system and you like to play it without the motor running. Operation on 12V is fine when the motor is running and battery charge is maintained but if the fridge is allowed to run for too long when the motor is stopped, it can flatten the bat­tery in a relatively short time. This is where the Battery Guard­ian comes into play. It monitors the battery voltage and discon­nects power to the fridge before the battery becomes too flat to allow the engine to be started again. Note that some fridges already have a low battery cut-out that prevents operation if the battery voltage goes below 10.5V. The cut-out is included for two reasons. One is to prevent the battery from being discharged to the point beyond which the battery life is reduced. The second is to prevent the fridge motor from stalling since it would not be able to drive the fridge pump at such a low voltage. However, at 10.5V, no vehicle battery could start the motor and therefore you could easily be stranded way out in Woop Woop. By contrast, the SILICON CHIP Battery Guardian disconnects the power when the battery voltage drops to about 11.5V. At this voltage, the battery should still have sufficient reserves to start the engine but you can set the cut-out voltage higher or lower to suit your vehicle. The SILICON CHIP Battery Guardian has to operate without causing any significant additional current drain from the bat­tery. If it did have a significant current drain, it would become part of the problem rather than being the solution. This fact means we cannot use a relay to control the power switching. A suitable automotive relay would draw some 120mA continuously when activated so clear­ly we had to rule this option out. Instead of a relay, the Battery Guardian uses a power Mosfet and this cuts power consumption dramatically. In fact, the whole circuit draws an average current of less than 2.5mA. Fig.1 shows the circuit. It uses three www.siliconchip.com.au MAIN FEATURES • • • • • • Cuts power to load (eg, fridge) when battery voltage drops below a preset level. 10A rating. Low power drain. Chirping sound during cut-out. Flashing LED indication during cut-out. Automatically reconnects power when battery recharged. low-cost ICs, the power Mosfet and not much else. Mosfet Q1 provides the switching for the 12V rail (ie, between the 12V IN and the 12V OUT). This rail is fused using fuse F1 (10A), to protect against short circuits on the 12V output. High side switching One of the problems with using a Mosfet to switch +12V rail is that its Source and Gate electrodes cannot be connected to the 0V side of the supply. Instead, we are using the Mosfet as a “high side switch” (ie, switching the positive supply rail). This means that the gate voltage must be referenced to the source electrode of the Mosfet which rises to almost the full positive supply when the Mosfet is switched on. Hence, we need to generate a gate voltage for the Mosfet which is tied to its source electrode and isolated from the 0V line. And Q1 needs a gate voltage which is at least 10V above its source in order to switch fully on. This voltage is provided using an oscillator circuit (IC1) which drives transistor Q2 and a small step-up transformer, T1, wound on a ferrite toroid. The output of T1 is rectified using D1 and a 0.1µF capacitor (for filtering) to derive a signal which is fed to Q1’s gate. IC1 is a CMOS 7555 timer which is connected to operate in astable (continuous) mode. Its frequency of oscillation is set by the .0015µF timing capacitor on pins 6 & 2 and by the associated series 1MΩ and 1kΩ resistors on pin 7. Using the timing components shown, IC1 runs at about 1kHz, with the charging time (.0015µF x (1MΩ + 1kΩ) x 0.693 = 1.04ms. By comparison, the discharge time is very short, around 1µs, since the 1MΩ resistor is not involved. The pin 3 output of IC1 is high while the timing capacitor is charging and low when discharging (ie, the output is a pulse waveform with a high duty cycle). This pulse signal is inverted using NAND gate IC3a and inverted All the parts fit on a single PC board, so the circuit is easy to build. Note that the corners of the PC board must be removed to clear the corner mounting pillars inside the case. May 2002  33 Fig.1: the circuit uses IC1 to provide a 1kHz signal which pulses Q2 on and off. Q2 in turn drives transformer T1, the output of which is rectified and filtered to provide a DC voltage to turn on Mosfet Q1. REF1, VR1 & IC2a set the cutoff voltage and provide the gating signal to IC3b. again using IC3b (assuming that pin 6 of IC3b is high). IC3b drives the base of transistor Q2 via a 1kΩ resis­tor. As a result, Q2 switches on for about 1µs every 1ms and pulses the primary of transformer T1. The secondary of transform­er T1 drives diode D1 and its associated 0.1µF filter capacitor and the resulting DC voltage turns on Mosfet Q1. Zener diode ZD1 limits the gate voltage applied to Q1 to a safe value – ie, to no more than 15V between gate and source (or 27V above ground). Q1’s “on resistance” is typically .02Ω and this means that it will dissipate about 0.5W when supplying 5A to the load (eg, fridge or whatever). In addition, as the Mosfet turns off, it dissipates power as its gate voltage 34  Silicon Chip falls. In fact, the dissipa­tion will be higher during this turn-off period (about 50ms), as its “on resistance” increases. For this reason, a heatsink has been used to ensure that the device runs cool. Mosfet Q1 is switched off (to cut the power to the load) when pin 6 of IC3b is pulled low. This sets pin 4 of IC3b high and so transistor Q2 turns off (and remains off). As a result, the 470kΩ resistor between Q1’s gate and source terminals dis­charges the 0.1µF capacitor over a 47ms period and the Mosfet switches off. Voltage sensing Pin 6 of IC3b is controlled by a voltage sensing circuit consisting of REF1 and comparator IC2a. REF1 is a 2.5V voltage reference and is supplied with cur­rent via a 10kΩ resistor from the 12V rail. Its 2.5V output is attenuated by trimpot VR1 (which sets the cut-out voltage) and applied to the inverting input (pin 2) of IC2a. At the same time, the non-inverting input (pin 3) monitors the supply voltage via a voltage divider consisting of 47kΩ and 10kΩ resistors. Normally, with a fully charged battery, the voltage on pin 3 is greater than that on pin 2 and so pin 1 is high. As a re­sult, pin 6 of IC3b is also high and so IC3b gates through the pulses from IC1 to Q2, as described previously. The 220kΩ feed­back resistor between pins 1 & 3 of IC2a provides a small amount of hysteresis, so that IC2a switches cleanly at the cut-out set­ting. The resistors connected to pin 3 set the voltage at this pin to about www.siliconchip.com.au 1/5Vcc (ie, one fifth of the supply voltage). This means that if we want Q1 to switch off at 11V, we have to set VR1 so that pin 2 is at 2.2V. When pin 3 falls below this voltage (ie, as the battery voltages falls below 11V), pin 1 of IC2a goes low and so IC3b blocks any further pulses from IC1 and IC3a. As a result, Q2 remains off and so Q1 also turns off and disconnects power to the load (ie, the fridge). At the same time, the low output at pin 1 of IC2a pulls pin 3 down to 1.86V, since the 220kΩ feedback resistor and 10kΩ resistor are now effectively in parallel. The voltage on pin 3 is now effectively 0.169 x Vcc, which means that the battery voltage must now go above 13V before the voltage at pin 3 equals the 2.2V at pin 2 and pin 1 switches high again. Without the hysteresis provided by the 2.2MΩ feedback resistor, pin 1 would simply cycle rapidly between high and low as the battery voltage recovered each time the fridge load was removed. Note that REF1 has a 10µF capacitor across it. That’s there to ensure that REF1’s output is initially low when power is first applied, so that pin 1 of IC2a is high. Pin 1 of IC2a will then go low again if the supply voltage is below the cut-out value set by VR1 but only when REF1’s output has settled to its correct value – ie, after the capacitor has charged via the 10kΩ resis­tor. Indicator circuitry As well as controlling pin 6 of IC3b, IC2a also drives the inverting input (pin 6) of comparator IC2b. As shown, IC2b’s non-inverting input is connected to VR1’s wiper, which means that it is nominally at 2.2V. When pin 1 of IC2a is high (ie, Q1 on), IC2b’s output at pin 7 is low and so NAND gate IC3d and any following circuitry is disabled. However, when pin 1 of IC2a goes low (ie, to turn Q1 off), pin 7 of IC2b goes high and allows NAND gate oscillator IC3d to operate. The feedback components between pins 11 & 12 and the asso­ciated 10µF timing capacitor set the frequency of the NAND gate oscillator. To understand how this works, just remember that the output of a NAND gate only goes low when both inputs are high. Assume initially that Mosfet Q1 is on. This means that pin 7 of IC2b and www.siliconchip.com.au thus pin 13 of IC3d are low and so pin 11 of IC3d will be held high. Pin 12 of IC3d will also be high during this time, since the 10µF timing capacitor will charge via the 1MΩ feedback resis­tor. At the same time, PNP transistor Q1 will be off (since its base is held high by pin 11) and so both LED1 and the piezo siren will also be off. OK, now let’s see what happens when the Mosfet (Q1) switches off. When that happens, pin 7 of IC2b goes high and pin 11 of IC3d switches low. The 10µF timing capacitor now discharges into this low output via D2 and a series 4.7kΩ resistor until it reaches the logic low threshold of pin 12. When that point is reached, pin 11 of IC2b switches high again and recharges the 10µF capacitor via the 1MΩ feedback resistor, whereupon pin 11 switches low again. This cycle continues while ever pin 13 of IC3d is high, with the 10µF timing capacitor charging via the 1MΩ resistor and discharging via D2 and the 4.7kΩ resistor (ie the capacitor discharges far more quickly than it charges). As a result, pin 11 of IC3d is high for about 10s and low for about 10ms during each complete cycle. Each time pin 11 pulses low, Q3 turns on and briefly flash­es LED1. It also briefly enables NAND oscillator IC3c (by pulling pin 9 high). This oscillator runs at around 1-2kHz (depending on the setting of VR2) and briefly drives the piezo siren. As a result the piezo siren briefly “chirps” and the LED flashes once every 10 seconds to let you know that the power to the load (fridge) is “off”. Unlike NAND gate oscillator IC3d, IC3c runs with an even duty cycle, since its .01µF timing capacitor both charges and discharges via VR2 and its series 10kΩ resistor. In practice, VR2 is adjusted so that the frequency is the optimum for the piezo to produce its loudest output. Power for IC1, IC2 and IC3 is derived from the incoming 12V supply rail via fuse F1 and a 10Ω resistor. Further supply decou­pling is provided by several 10µF and 0.1µF capacitors, while zener diode ZD1 protects the circuit from voltage transients by clamping any spike voltages to 16V. Construction All the parts for the Battery Guardian are mounted on a single PC board, Parts List 1 PC board, code 05105021, 122 x 60mm 1 plastic case, 130 x 67 x 44mm 1 front panel label, 129 x 67mm 1 piezo transducer (Jaycar AB3440 or equivalent.) 1 4-way PC mount terminal strip (Altronics P-2103) 1 mini-U heatsink, 19 x 19 x 10mm 1 ferrite toroid, 17m OD x 10mm ID x 6mm (Jaycar LO-1230 or equivalent.) 1 10A 3AG fuse 2 PC-mount 3AG fuse clips 1 1m length of 0.25mm enamelled copper wire 1 200mm length of 0.8mm tinned copper wire 1 M3 x 6mm screw 1 M3 nut 2 M2.5 x 9mm screws 2 PC stakes 2 100kΩ horizontal mount trimpots (code 104) (VR1,VR2) Semiconductors 1 7555 CMOS timer (IC1) 1 LM393 dual comparator (IC2) 1 4093 quad Schmitt NAND gate (IC3) 1 STP60NE06 60A 60V N channel Mosfet (Q1) 1 BC640 NPN transistor (Q2) 1 BC327 PNP transistor (Q3) 1 LM336-2.5 reference (REF1) 1 15V 1W zener diode (ZD1) 1 16V 1W zener diode (ZD2) 2 1N914, 1N4148 switching diodes (D1,D2) 1 5mm high-brightness red LED (LED1) Capacitors 3 10µF 16VW PC electrolytic 7 0.1µF MKT polyester 1 .01µF MKT polyester 1 .0015µF MKT polyester Resistors (0.25W, 1%) 2 1MΩ 5 10kΩ 1 470kΩ 1 4.7kΩ 1 220kΩ 1 2.2kΩ 1 100kΩ 3 1kΩ 2 47kΩ 1 10Ω so it’s a snack to build. This board is coded 05105021 and measures just 122 x 60mm. The completed assembly May 2002  35 Fig.2: follow this diagram when installing the parts on the PC board. Take care to ensure that transformer T1 is correctly oriented – it is secured to the PC board using a couple of wire loops. then fits neatly inside a standard plastic case measuring 130 x 67 x 44mm (see photo). Start by inspecting the PC board for shorted tracks or breaks in the copper by comparing it with the published pattern. While you’re at it, check that the holes are large enough for the component leads, particularly for the screw terminals. Note also that the corners of the PC board must be shaped as shown on the PC layout diagram (Fig.2), so that it can be fitted into the box – ie, the corners have to be removed to clear the integral mounting pillars. You can remove the corners by first cutting out a rectangular piece using a small hacksaw and then carefully filing to shape using a round file. Alternatively, you can use a mini-drill fitted with a small grinding disk (eg, a Dremel tool, or similar). Fig.2 shows how the parts are fitted to the PC board. Begin by installing the three wire links plus two PC stakes to termi­nate the wiring from the piezo transducer. This done, install the resistors in the positions shown. Table 1 shows the resistor colour codes but we recommend that you also check each value using a digital multimeter as some of the colours can be difficult to decipher. Diodes D1 & D2 can go in next, followed by zener diodes ZD1 and ZD1. Take care to ensure that these are all installed the right way around and don’t get ZD1 & ZD2 mixed up (their voltages are different). Now for the three ICs. These are all soldered directly to the PC board, again making sure that they are oriented correctly. It’s easy to identify pin 1 on each IC – it will be adjacent to a notch or dot at one end of the body. Next, install the capacitors, taking care to ensure that the electrolytics are oriented as shown. That done, the transis­tors can go in but don’t get Q2 and Q3 mixed up – Q2 must be a BC640, while Q3 is the BC327. The Mosfet transistor (Q1) is mount­ ed horizontally on a small heatsink and is secured using a 10mm M3 screw and nut. This means that you have to bend Q1’s leads down by 90° before installing it on the board. This is best done by first slipping an M3 screw through the device tab, positioning it on the board and then gripping one of the leads with a pair of needle-nose pliers just before it reach­ es its mounting hole. The device is then lifted clear of the board, the lead bent at right-angles and the procedure then repeated for the remaining two leads. Once all the leads have been bent, Table 2: Capacitor Codes     Value IEC Code EIA Code 0.1µF   104   100n .01µF  103   10n .0015  152   1n5 Table 1: Resistor Colour Codes  No.   2   1   1   1   2   5   1   1   3   1 36  Silicon Chip Value 1MΩ 470kΩ 220kΩ 100kΩ 47kΩ 10kΩ 4.7kΩ 2.2kΩ 1kΩ 10Ω 4-Band Code (1%) brown black green brown yellow violet yellow brown red red yellow brown brown black yellow brown yellow violet orange brown brown black orange brown yellow violet red brown red red red brown brown black red brown brown black black brown 5-Band Code (1%) brown black black yellow brown yellow violet black orange brown red red black orange brown brown black black orange brown yellow violet black red brown brown black black red brown yellow violet black brown brown red red black brown brown brown black black brown brown brown black black gold brown www.siliconchip.com.au The Tiger comes to Australia The BASIC, Tiny and Economy Tigers are sold in Australia by JED, with W98/NT software and local single board systems. The piezo transducer is secured to the lid of the case using two M2.5 x 10mm screws. Before mounting it, drill a small hole directly in front of the element, to let the sound escape. the device can be se­cured to the PC board with its heatsink and the leads soldered. Note that it’s not necessary to isolate the tab from the heat­sink, since the heatsink doesn’t touch any other parts. However, because Q1’s tab is connected to its drain terminal (which is connected to the +12V rail), this means that the heatsink will be at +12V when the circuit is operating. The PC board assembly can now be completed (except for transformer T1) by installing the 4-way screw terminal block, the fuse clips (make sure these go in with the retaining flanges towards the outside), pots VR1 & VR2 and the LED. The latter should be mounted so that the top of its plastic body is 30mm above the PC board. By the way, we’ve provided two sets of mounting holes for the right­hand fuse clip, so that you can use either a 3AG fuse or the shorter M205 type (the position shown on Fig.2 is for a 3AG fuse). Unless you have a good reason to do otherwise, stick with a 3AG fuse as these are more commonly available from service stations (note: M205 fuse clips are smaller). We’ve also designed the board to accept the two commonly available trim­pot sizes for VR1 and VR2. It’s up to you which type you use. Winding the transformer The primary and secondary of transformer T1 are wound on a ferrite toroid as shown in Fig.3. Wind on 14 turns of 0.25mm enamelled copper wire for the primary, in the direction shown. Similarly, wind on 19 turns for the secondary, in the direction shown. Once the coils have been wound, scrape away the enamel from the ends of the leads and install the unit on the PC board. Make sure that you get the Fig.3: here are the winding details for transformer T1. Be sure to wind the turns on in the directions shown. Tigers are modules running true compiled multitasking BASIC in a 16/32 bit core, with typically 512K bytes of FLASH (program and data) memory and 32/128/512 K bytes of RAM. The Tiny Tiger has four, 10 bit analog ins, lots of 2 digital I/O, two UARTs, SPI, I C, 1-wire, RTC and has low cost W98/NT compile, debug and download software. JED makes four Australian boards with up to 64 screw-terminal I/O, more UARTs & LCD/keyboard support. See JED's www site for data. TIG505 Single Board Computer The TIG505 is an Australian SBC using the TCN1/4 or TCN4/4 Tiger processor with 512K FLASH and 128/512K RAM. It has 50 I/O lines, 2 RS232/485 ports, SPI, RTC, LCD, 4 ADC, 4 (opt.) DAC, and DataFLASH memory expansion. Various Xilinx FPGAs can add 3x 32bit quad shaft encoder, X10 or counter/timer functions. See www site for data. $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 www.siliconchip.com.au May 2002  37 positions, then removing the board and drilling the four holes to accept the power cables. Once all the holes have been drilled, clip the board back into the case and mount the piezo transducer on the lid using two M2.5 x 10mm screws. The transducer’s leads can then be soldered to the two PC stakes on the PC board. Finally, install the fuse and you’re ready for the smoke test. Testing Fig.4: this full-size artwork can be used as a drilling template for the front panel. Fig5: this is the full-size etching pattern for the PC board. Check your board carefully before installing any of the parts. windings the right way around, with the primary towards IC1 and the secondary towards Q1. The toroid is then secured using short lengths of tinned copper wire which loop over either side of the core and solder to the PC board (see Fig.2). Final assembly There’s not much to the final assembly, apart from drilling a few holes in the case and clipping the PC board into position. The first step is to affix the front panel label to the lid. The label can then be used as a template for drilling the mounting holes for the LED (3mm) and the piezo transducer (2.5mm). You will also have to drill a small hole in front of the piezo transducer to let the sound out. You also have to drill four holes in one end of the case, in line with the screw terminal block. This is best done by clipping the board into the integral slots in the case, marking out the hole TABLE 3: SETTING THE CUTOUT VOLTAGE Remaining Battery Capacity 0% Battery Cutout Voltage (Typical) 10.5V 10% 11.0V 13.0V 2.2V 15% 11.2V 13.25V 2.24V 20% 11.5V 13.6V 2.3V 25% 11.6V 13.7V 2.32V 30% 11.7V 13.8V 2.34V 38  Silicon Chip Voltage Required To Reapply Power 12.4V VR1 Setting (Voltage At Pin 2 of IC2) 2.1V Before applying power, check the assembly carefully to make sure that all parts are installed correctly. That done, apply power from the battery and use your multimeter to check for +12V on pin 8 of IC1, pin 8 of IC2 and pin 14 of IC3. Assuming these are correct, check the voltage between Q1’s gate and the “+12V IN+” terminal (positive lead to Q1’s gate). You should get a reading of either 15V or 0V, depending on VR1’s setting. If you get a reading of 0V, rotate VR1 anticlockwise until the reading jumps to 15V. If the voltage only reaches a volt or two when you rotate VR1, check that you have wound T1 correctly. If you wind one of the windings in the wrong direction, the windings will operate in anti-phase. Now adjust VR1 clockwise until you get a reading of 0V. LED1 should now flash once every 10 seconds or so and the piezo transducer should chirp when the LED flashes. Adjust VR2 for the best sound from the transducer. Setting the cut-out voltage Assuming it’s all working correctly, VR1 can now be used to set the cut-out voltage (ie, the battery voltage at which the fridge is disconnected). Table 3 shows how to set VR1 for various cut-out voltages from 10.5V to 11.7V. It also indicates the remaining battery capacity for each of these voltages but note that these are typical figures only and are not precise. Basically, it’s just a matter of selecting the desired cut-out voltage and adjusting VR1 to get the correct reading on the wiper. So, if you want to set the cut-out voltage to 11.5V, for example, adjust VR1 for 2.3V on its wiper (ie, 2.3V between the wiper and ground). Generally, a cut-out voltage of about 11.5V or 11.6V is the way to go, since www.siliconchip.com.au Scope 1: the top trace shows the low-going output from pin 4 of IC3b (it is low for 1.47µs), while the middle trace shows the collector of Q2 which is pulled to the 12V supply when switched on via a low-going signal from IC3b. When IC3b goes high, the collector goes below ground due to the back EMF pro­duced by the primary of T1. The lower trace is the voltage on Q1’s gate which is about 26V above ground (14V above the 12V supply rail). Scope 2: this scope shot shows Q1’s gate rise time following the first low-going signal from NAND gate IC3b. The top trace shows IC3b’s output at pin 4, while the lower trace shows Q1’s gate voltage. Notice how the gate voltage reaches 20V (8V above 12V) the instant IC3b’s output goes low and high again. The full gate voltage is reached after about four pulses from IC3b – a period of around 4ms. Scope 3: this shot shows how the gate voltage (bottom trace) falls when pin 1 of IC2a switches low (middle trace). As shown, the gate voltage on Q1 falls slowly (via the associated 470kΩ resistor) over a period of about 100ms. Scope 4: this expanded scope shot shows the outputs from IC3d (top trace) and NAND oscillator IC3c (bottom trace). The output from IC3d is 30ms wide and drives LED1, while IC3c drives the piezo transducer. Its frequency here is 746Hz (as set by VR2). this leaves about 20% battery capacity in reserve for starting the car’s engine. However, you can set the cut-out voltage higher or lower than this to suit your own par­ticular requirements. Installation The Battery Guardian simply connects in-line between your car’s cigarette lighter socket and the fridge (or load). Your fridge will already be fitted with a cigarette lighter plug and this can be removed and transferred across to the Fridge Cutout’s input power leads. The fridge itself is then www.siliconchip.com.au connected to the top two termi­nals of the screw terminal block. Be sure to use automotive power cable for all supply con­nections to and from the Battery Guardian. Do not connect the Battery Guardian directly to the battery. If you don’t wish to use the cigarette light socket, the +12V supply should be taken from a fused (but unswitched) terminal on the fusebox. Note that if you wish to use the Battery Guardian with a large car stereo system, you cannot power all the amplifiers via the circuit because they are likely to draw more than 10A, which would exceed the fuse rating. Instead, the Battery Guardian would be connected in line with the supply to the head-end unit; ie, the CD/tape/ tuner unit. That way, if the battery drops below the threshold, the headend unit will be cut off and so the current drain from the amplifiers in the system will drop to a low value. Finally, the Battery Guardian could also be used to protect the batteries in a 12V lighting system, with the overall current limit again set by the 10A fuse. SC May 2002  39 SERVICEMAN'S LOG Stubbornness or tenacity of purpose? Regardless of the motive, there is much to be said for the habit of “sticking with it”, when not all the symptoms match. Taking the easy way out can have adverse consequences. My first story this month is about a Teac EU-68St which employs an 11AK19 chassis. This is a 68cm silver-coloured stereo TV set, manufactured in Turkey around January 2000. I was sur­prised to see it come into the workshop, as it looked brand spanking new. I could tell from the owner’s face that he was extremely upset; it was no longer under warranty and it had failed so soon. However, when I took down the details of his address, an absolute water frontage on the beach, I wasn’t so surprised. The set was dead and it didn’t take long to diagnose a shorted horizontal output transistor (Q605, BU2508D). This was due to an overheating horizontal output transformer (TR602), no doubt hastened to its demise by the layer of salt deposited by the onshore winds. In fact, most of the metal screening cans were already rusty. An order was placed for the parts and a service manual and they arrived some time later. When the parts were installed and the set switched on, I was faced with a new symptom – no vertical deflection. As a result, a new vertical output IC (IC701, TDA8351) was ordered. This duly arrived and was fitted only to produce symptom number three: no picture, just a raster with 40  Silicon Chip retrace lines. This time, I knew I would be faced with a difficult problem and that I would have to consult the service manual. Unfortunate­ly, this document is somewhat disappointing and mainly consists of 29 pages of a detailed “Bill of Material List”. The circuit and PC board layout diagrams were also difficult to follow, being rather poor photocopies. Because the problems with this set had all started with the horizontal output transformer, I was looking for components that might have been destroyed by the breakdown. With that in mind, I started by checking the beam current and ABL (Automatic Bright­ ness Limiter) circuit. This is easier said than done because the main PC board is small and carries unmarked surface mount compon­ents on the copper side and normal-size parts on the other. As can be imagined, the assembly is quite compact, which makes it difficult to trace the circuit. Anyway, that circuit eventually checked out OK. One of the vital symptoms I noticed was that there was no OSD (On Screen Display). This suggested that the problem was likely to be affecting the video output rather than the small signal circuits from the tuner/ IF onwards. In an effort to isolate the problem area, I connected a monitor to the AV output socket and found, with some mucking about, that I could get a clear full-colour picture on it from the tuner. Next, I connected a colour bar generator into the video output sockets but could not display that on either the TV set or the monitor, regardless of what I did with the remote control. I then measured horizontal pulses and the sandcastle on pin 41 of the jungle IC (IC401, TDA8844/N2) and checked all seven of the voltage rails from the power supply with the CRO, looking for excessive ripple. I also checked the five voltage rails sourced from the horizontal output transformer and these were all OK. My next step was to check for the blanking pulses from IC501 (SDA545XOTP) but I couldn’t detect them. But when I unsol­dered pins 23, 24 and 25 of IC401, they reappeared. This was enough proof for me that the jungle IC was crook, so I ordered a new one. However, when it arrived, I was disappointed to find it made absolutely no difference. It was only then that I found that these pulses were there only when the OSD was on (although I couldn’t see this on the screen) – pressing the menu button would produce the pulses. From here on in, things just became worse. I was following one blind alley after another and pursuing all sorts of strange and wonderful theories. There are a lot of circuits in this set. And it’s not obvious what all of them do. For example, I couldn’t work out the function of Q425 and Q426; a possible spot suppres­sor – who knows? I phoned Teac for technical support and they suggested that I replace C604 (.047µF) on the beam limiting line from the hori­zontal output transformer. I did this but it made no difference. Back off mate! To be honest, I was close to quitting and returning the set to the customer. This elusive fault was eating into my time and the repair was becoming uneconomic, even for a fairly new TV set. In the meantime, the customer was pressuring me to fix the prob­lem quickly but it doesn’t work like that www.siliconchip.com.au Kits without compromise with this type of problem. You need space and time and the pressure tactics don’t work. Knowing that it’s probably an insignificant little part that’s causing the problem doesn’t help either. And neither does the customer’s implication that I don’t know what I’m doing –even if I don’t! And then, suddenly, there was a clue. I was running my finger across IC401’s pins (the jungle IC) and, somewhere around pin 22 & D701, the picture nearly appeared. Encouraged, I renewed my investigation into this area, even though I previously could not find anything wrong with it. And I now noticed that although the DC voltage and amplitude waveform didn’t change much, the width of the vertical pulse changed. I traced the circuit back via Q701 and ended up back at the vertical IC (IC701). At this point, I also noticed that the blank raster wasn’t perfectly linear in the vertical deflection and neither were the retrace lines, especially at the top. So was the new vertical IC faulty? Well, before I replaced it again, I measured the DC voltage and checked the waveform on each of its nine pins. When I reached pin 6, I noticed that this was at 20V or so, despite being fed via a 100Ω resistor (R704) from a 45V rail. This meant that another 20V was www.siliconchip.com.au being developed across R704, which struck me as a much too high a voltage across a 100Ω resistor, considering the likely current level in this part of the circuit. I removed R704, a 1% metal film type, and measured it. It was nearly 5kΩ. I fitted a new 100Ω resistor in its place and the rest, as they say, is history. The picture was fully restored, although it required ad­justments to the screen voltage and focus settings. The OSD appeared as expected and when I investigated the menu system, I found I could switch the ‘AV-OUT’ from ‘TV’ and the other ‘AV-IN’ sockets. I think, in retrospect, I should have been more observ­ ant and followed the likely path of the sparking horizontal output transformer and the vertical output IC failure – but it’s easy to be smart after the event. Blaupunkt MS-70-109 VTM I have had a few Blaupunkt sets in Items Covered This Month • Teac EU-68ST TV set. • Blaupunkt MS-70-109.VTM TV set. • Mitsubishi HS-E11(A) VCR. • IBM Thinkpad T20 computer. • Troubleshooting an Internet connection. “Sound quality to die for” Rolling Stone Magazine “..A new benchmark in every criteria” Best Buys Home Theatre Speaker Kits without compromise from $312 pr to $8,863 pr FreeCall 1800 818882 www.vaf.com.au vaf<at>vaf.com.au May 2002  41 Serviceman’s Log – continued recently, all about 10 years old. The fact that I rarely see them younger than that indicates how reliable they are. I am pretty sure, too, that they are now all made by Grundig. The Blaupunkt in this case was an MS 70-109 VTM, using an FM 500-70 (7 669 840) chassis (probably equivalent to a Grundig 29701-057). Like most German sets it is somewhat upmarket, with a remote controlled motorised swivel base, sub-woofer, Toptext and menu system, etc. And, of course, it was as dead as a dodo. In our hot humid climate, most faults start at the set’s high voltage end and create further damage from there. Its owner had lost track of how old it was and as this was the first time it had broken down, he just told me fix it as soon as possible. I initially diagnosed a faulty tripler (yes, there are still a few about), a faulty horizontal output transformer, and a crook horizontal output transistor (BU508AG, T541). The avalanche of faulty parts then continued with the horizontal oscillator driver IC (IC500, TDA8140), electrolytic cap­ acitors C541 and C507, the east/ west modulator diode (D546), C573 (0.36µF), plus collateral damage in the small signal circuits – eg, IC7010 and D7012 on the east/west deflection correction module. All in all, this set was very sick but this bloke was determined – he wanted it fixed. I replaced all the above parts plus IC500 and a few extra horizontal out42  Silicon Chip put transistors. I used a BU508A for the horizontal output transistor and the extra ones were due to a few mishaps which I won’t go into here. I also found some electrolytic ca­pacitors on the deflection correction module that were in dire need of replacement and there were poor joints everywhere – not surprising given the age of the set. Anyway, after a lot of kerfuffle, up came a first class picture. I soak tested the set for a few days and then told the customer to come and pick it up. I then thought that I had better check the Teletext – there was nothing and neither was there any menu system. And so, after a hasty rearrangement of the pick-up schedule, the set landed back on the bench. From what I can make out from the circuit, all the menu and text action comes (naturally enough) from the Teletext module. However, I noticed that after the set had been running for a while, I could just see a faint image in the background. I also noticed that vertical hold was rolling slowly in the text and menu modes. Without extension leads, it is hard to work close to these modules. Nevertheless, with the hairdryer switched to high (I nearly melted the set), I found that I could almost recover a fully working Teletext (actually Blau­punkt Toptext) and menu system. Unfortunately, I couldn’t quite pinpoint the culprits by then applying freezer. I next measured the voltages applied to the text module and replaced all the electrolytic capacitors on this board but this made no difference. However, I did find one thing – while check­ing the voltages, I decided to make more space for the probes by removing the AV module (socket board), which I thought was re­dundant for the time being. Amazingly, removing this module restored both the text and the menu but the colours weren’t right because there was a red caste all over the text picture. There isn’t a lot on the AV module – mostly analog switching ICs and transistors. The RGB lines go to SCART socket 1 and are terminated with 75Ω resistors. And I found that hanging an extra 75Ω resistor across R233 re­stored everything. It would have been easy to stop there – one resistor fixes the problem; go home. But this would smack of the stripped apron approach. There had to be a real reason for all this and I was curious. The original resistor measured perfectly OK, so I removed and cleaned the SCART socket itself, as well as the plug that fits into the main chassis. However, these proved to be OK. The only other thing in common with this socket was the U DATA line which feeds the AV module, the chroma module, transistor T364 and socket P15. I decided to check this out more carefully and my patience was quickly rewarded when I found that T364 (BC548B) was open circuit. Unfortunately, a new one made no difference, much to my dismay. Next, I checked the other transistors (T361, T366 & T363) on the motherboard and followed the line all the way to the control unit module and to IC830 (UAA2022). I found that unplug­ging BP1 also “fixed” the problem but that left a blue caste this time (this line is called U screen B). Plug BP1 connects pin 3 of IC830 with the rest of the circuit and replacing IC830 made no difference. I also checked T2817 and IC2860 on the text module by substitution but this achieved nothing. By now, I was really quite tetchy over all this – I had come so far and fixed so much but this elusive fault remained. There wasn’t much left to test on the U DATA line – only the chroma module and I felt it was highly unlikely to be that as the picture and colour were perfect. Nevertheless, I persevered and rewww.siliconchip.com.au placed IC5200 (TDA3505), as pin 11 is directly connected to U DATA. That was it! Apparently, pin 11 is the pole for the analog switch that switches between TV and text, and it wasn’t toggling properly. It had probably been damaged by spikes from the tri­pler, along with all the other parts. All the other temporary fixes were just red herrings. This really was a beast of a fault but it was worth “sticking with it”. Mitsubishi VCR I had an interesting problem with a Mitsubishi HSE11(A) VCR, employing an Fo deck. The tracking was out because a white plastic roller on the exit guide had seized on its shaft. I found that by freezing the stainless steel shaft, I could free it so that it would rotate even if I just blew on it. But once it returned to room temperature I had to use a lot of strength to rotate it at all. I asked a knowledgeable friend who does a lot of VCRs what he did in these circumstances. His answer was to wick in some 3-in-1 oil at the top and bottom of the roller. So I duly tried that but all I succeeded in doing was make a mess with oil every­where. The guide was still seized. I even froze it and then applied the oil but it always seized again. Finally, I tried heating it with a hairdryer for a long time until I couldn’t touch the metal any more. The roller was seized hard but back at room temperature, it was beginning to feel a little freer. I then cleaned it with “metho” to remove all the excess oil and lo and behold, it freed up completely. Well, this poses more questions than it answers. Had the roller seized because the plastic had contracted with time, or had the lubricant (if it used a lubricant) dried up inside? By cooling it, the shaft diameter shrank enough to free it. So, when it was heated, did the shaft expand enough to stretch the plastic? Or was it just that the “metho” dissolved any dried out lubricant? Sorry, I don’t have the answers but perhaps someone else does. Anyway, it fixed the problem. PS: a new roller assembly would require a lot more effort and money to install and align than the machine is worth. Computer problems I had two interesting computer problems this month, the first involving an IBM Thinkpad T20, Type 2647 (Pentium III-700) belonging to a student. Its operating system was Windows XP Pro v2002. The problem was that it wouldn’t boot at all, either from a floppy, a CD or the 9.3GB hard drive. Neither could I get into the BIOS setup. The only thing I could see was the opening Think­pad flash screen with an F1 option to go into the BIOS or F2 to select a bootable device. Selecting either would cause the com­puter to go to a blank screen and hang. My approach to fix it was to remove the power supply, the main battery and the memory battery and switch on. Obviously, nothing happened! But when I then replaced them all and switched on again, everything now worked. XP took some time to boot up but running CHKDSK/F on the next boot automatically fixed things. www.siliconchip.com.au May 2002  43 Serviceman’s Log – continued How it had happened I could only guess. No viruses were de­tected later and a few files were found to be corrupted; eg, dsprov.dll, esscli.dll and framedyn.dll. There were also four bad clusters but nothing that couldn’t fixed. Internet access problem The second problem actually happened to my own machine. It’s pretty ancient (to match its impecunious owner) but it can just handle Windows Me. The problem I had was being unable to access the Comsec (Commonwealth Securities) website in order to flog some shares to pay the overdraft. Unfortunately, each time I attempted to go to this website, IE5.5 asked if I wanted to go to a secure site before timing out and displaying a “Page Unavailable” message. But much to my frustration, I could browse other websites. I then tried accessing http:// www. comsec.com.au by following links from other sites (such as Netbank) but got nowhere. Eventually, after trying lots of other things, I swallowed my pride and sought help from both Comsec and from my ISP (Internet Service Provider), Zip Australia (now Pacific Internet). At their prompting, I upgraded my browser to IE6 (plus up­dates), deleted all my temporary files and history, reset my defaults and set the security level to medium. But it made no difference. We then tried a few fancy tricks like running a trace test at DOS level: c:/>tracert www.comsec.com.au> c:\ trace.txt. This produced a route to this website over a maximum of 30 hops which I then emailed to Comsec and Pacific Internet. I tried entering http://203.202.9.126 (Comsec’s IP number) directly into my web browser but that didn’t work either. I was then advised to try http:// www.commsec.com.au/Public/Content/CMD-ServiceDifficul­t ies.asp. This failed the “Secure Connection” test and indicated either an SSL (Secure Socket Layer) or proxy setting fault. I messed about with various proxy settings but it made no difference. Comsec were very helpful and came up with a 5-page screed on how to set up your browser for secure commercial sites. I tried everything on the list but nothing worked. Finally, David Luger, Network Development Manager of Pacif­i c Internet, was the one to crack it. He noticed that I had an incorrect DNS (Domain Name Server) entry (a DNS server links domain names to IP addresses). When you do a “ping” or a “tracert” for a domain name, the system shows the IP address it is trying to access. And mine was selecting the wrong one. In fact, he noticed that mine was always looking up an obsolete address. Anyway, David Luger suggested that this might be due to some “Internet acceleration software” that I may have previously installed, with the system now storing an old lookup address. This was beginning to ring some bells with me. To track down the problem, he told me to try this at the DOS prompt from the root directory: dir/s hosts.*. This came up with three “hosts” files: hosts. tpx, hosts.sam and hosts. The first two are sample Seagate and Microsoft files but the last one – c:\ windows\hosts – was created by Modem Wizard (the Internet acceleration software I had installed). A “hosts” file, by the way, is nothing more than a simple text file that stores domain names and their corresponding IP addresses. It allows the system to bypass a DNS server for any domain names that are listed, thereby providing faster lookup (in effect, the hosts file acts as a local DNS). Unfortunately, this list was now out of date – at least as far as the Comsec website was concerned. So, on David’s advice, I simply renamed this file and tried Comsec again. This time there was no problem and I had full access to the secure site. So, SC thank you, David. Nice one. PARALLAX BS2-IC BASIC STAMP $112.00 INC GST WE STOCK THE COMPLETE DEVELOPMENT SYSTEM 44  Silicon Chip www.siliconchip.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.jaycar.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.jaycar.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.jaycar.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.jaycar.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.jaycar.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.jaycar.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.jaycar.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.jaycar.com.au In March, we told you how we rescued an old turntable and fitted it with a self-powered RIAA preamplifier so it could be used with modern hifi amplifiers. Here’s the promised second part of the story: a matching headphone amplifier so you can enjoy the fantastic black plastic in perfect peace and privacy! A Simple Headphone Amp For Your RIAA Turntable (or anything else!) By Ross Tester T we always had this little project in the back of our minds. o briefly recap, the RIAA preamplifier was presented for those who have a modern sound system. About the only change we’d make from the project More often than not these days, modern systems published in March would be the use of larger U-shaped don’t include a “phono” input, which precludes the use heatsinks to cope with increased current (there’s tonnes of of a turntable to listen to records (as distinct from CDs!). room on the PC board for them) and the use of PC-board The preamp not only provides the necessary gain for mounting screw-in terminal blocks on at least the power a magnetic cartridge, it also “tailors” the signal to the supply board (where there is plenty of room) and possibly RIAA standard, allowing you to plug into any “aux” or the RIAA board – where space might be a tad tight. line-level input. Of course, there’s nothing to stop you using this project The idea of our preamplifier was to make it fully as a general-purpose headphone amplifier, as long as it is self-contained, with its own 240V to ±15V DC supply built fed with “line level” signals – such as the output of a CD/ on the PC board. To be honest, this didn’t work out quite DVD player, tuner, etc. as well as we had hoped due to noise being induced into The amplifier circuit the preamp from the mains supply. But we were one step ahead on this one (just in case!), making the two sections This design is a tried-and-true circuit we have used of the PC board separable. before. It’s rather similar (or at least one channel of it is!) The 240V to to the one John power the whole Clarke used in the Performance of Prototype shebang is, of mono headphone course, already monitor amplifier Output level.................................. 90mW (max) into 8Ω headphones available from the Frequency response..................... 0.5dB down at 30Hz and 20kHz (see Fig.2) in the 8-channel turntable supply. Mixer (described in Input sensitivity............................ 0.83V RMS for full power The ±15V, 10VA November and DecDC supply was in ember 1996). We’ve Harmonic distortion..................... see Fig.3 & Fig.4 fact a bit of overmade just a few Signal-to-noise ratio.................... -95dB unweighted (20Hz to 20kHz)     changes which we kill, being capable ..................................................... with respect to 500mV input signal of much more than will go into shortly. demanded by the All components Separation between channels..... -50dB between 20Hz and 10kHz preamp. But then, except a stereo www.siliconchip.com.au May 2002  53 the result of DC flowing in them and to the contact point of the wiper. 5pF RIGHT CHANNEL ONLY SHOWN IC PIN NOS IN BRACKETS ARE FOR LEFT CHANNEL 330k +15V How it works Signal from the RIAA preamp (or other “line level” audio source) is applied to the ganged RIGHT C pots, VR1a and VR1b. AUDIO B Q1(Q3) INPUT BC338 The pot simply forms a voltage divider A 10F 50k E across the preamp output, presenting the 35V LOG (VR1) op amp input with a level of signal de33 2 D1(D3) K 8 pendent on the pot setting. At minimum (6) 68 1N914 0.27F 1 56k IC1a setting, very little (if any) signal gets TL072 (7) A 3 4 through; at maximum most gets through. (5) 33 Presto: a level or volume control. 22k E D2(D4) K As both stereo channels are identical Q2(Q4) 1N914 TO we’ll just look at one (the left) channel. BC328 B LEFT C CHANNEL After passing through a 56kΩ resistor A 10k (which basically sets the input impedance), K 8 E BC -15V the signal is applied to the inverting input of 1 one of the TL072s twin op amps. SC Normally, the feedback loop for the op amp 2002 would go from the output back to the input – Fig.1: each channel of the headphone amplifier uses an op amp driving a but in this circuit, transistors Q1 and Q2 are complementary pair of transistors which are within the overall negative included in the loop. This helps minimise feedback loop. harmonic distortion. (dual ganged) volume control pot mount on a single PC The transistors themselves boost the output current caboard measuring 65 x 65mm. pability of the op amp. To minimise crossover distortion, The biggest change from the earlier circuit was to duplithe transistors are slightly forward-biased by D1 and D2 cate it for stereo. Rather than use two TL071 op amps (one between their bases. for each channel) we used a TL072, which is effectively two The 33Ω emitter resistors on each transistor maintain the TL071s in the one 8-pin DIL package. The other changes bias stability. They, along with the 68Ω resistor between involve the components in the input and feedback circuits their junction and the headphones, limit the output current – these have been adjusted to make them optimum for the to less than 150mA under catastrophic failure conditions, RIAA preamp output. That’s not to say it won’t work with protecting the headphones from damage. other audio sources – it should be pretty-well “universal.” The feedback loop previously mentioned consists of A DC blocking capacitor has also been included in series a 5pF capacitor in parallel with a 330kΩ resistor. This with both inputs. This is not to prevent any DC present in limits the response to about 50kHz and sets the overall the preamplifier output from reaching the op amp inputs; gain of the amplifier (op amp plus output pair) to about rather it is to prevent any DC offset voltage at the op amp six (330kΩ/56kΩ). inputs (albeit tiny) from being impressed back on the Construction potentiometer. DC on pots is a no-no: most “noisy pots” that you come Start by checking your PC board for any defects, then across are not the result of mechanical wear and tear but mount and solder components in the usual way: lowest 10k HEADPHONE AMPLIFIER Fig.2: the frequency response of both channels with an input signal of 250mV RMS. The minor differences between channels is probably due to transistor tolerances. 54  Silicon Chip Fig.3: total harmonic distortion (THD) versus frequency with both channels driven with an input signal of 250mV RMS. www.siliconchip.com.au 12050110 PMA ENOHPDAEH PIHC NOCILIS 5pF 10k D1 D2 10F 56k 0.27 TL072 L IN TO SOURCE (RIAA PREAMP) TO AMP INPUT ( ) VO -15V V51- +15V V51+ 22k 22k 0.27 56k 0V STEREO HEADPHONES 8 1 D3 D4 B C 10k Q4 10k 5pF E 33 L EARTH C B 10k R IN Q1 E 68 R EARTH E Q2 33 C 33 LOOKING AT REAR OF POT 330k B 33 POT WIRING (ONE HALF OF DUAL-GANG POT SHOWN) E 330k Q3 C B 68 Compare the same-size photo and the component overlay (Fig.5) when assembling the PC board. We used 1A diodes in our prototype but ordinary silicon signal diodes are cheaper! profile (resistors) first, the link (using an offcut from a resistor), then the four small capacitors, the electrolytic (watch the polarity) and finally the semiconductors: diodes, transistors and the IC. Again, watch both the placement and the polarity of the semiconductors. The headphone socket mounts on the board – provision is made for sockets with pins either side. The power supply is connected via an on-board screw terminal block while signal is connected via four PC stakes. Checking it out Check your component placement, polarity and soldering before proceeding. If you’re happy with it after a thorough examination, connect the +15V, 0V and –15V from the RIAA preamp supply to this board. Note that the order of the terminals are not the same on both boards: you have been warned! With no headphones nor any inputs connected, turn the power on. Absolutely nothing should happen (at least as far as visual observation is concerned!). Check that you have +15V and –15V on the board and (respectively) on pin 8 and pin 4 of IC1 and (again respectively) on the collectors of Q1 and Q2. All of these voltages, by the way, are measured with respect to 0V. Check that you have 0V (or within a couple of millivolts of 0V) on pins 2, 3, 5 and 6 of the IC. You should also have 0V (or very close to it) on pins 1 and 7 (the outputs). Now check the voltages across the diodes and between base and emitter of the four transistors. In every case it should be around 0.6V, give or take. Obviously, in half the cases the polarity should be reversed compared to the other half. Parts List – Headphone Amp 1 PC board, 65 x 65mm, coded 01105021 1 PC mount stereo headphone socket 1 PC mount 3-way terminal block 4 PC stakes 4 mounting screws (as required) Suitable lengths red, black and white hookup wire Semiconductors 1 TL072 dual op amp (IC1) 2 BC338 NPN transistors (Q1, Q3) 2 BC328 PNP transistors (Q2, Q4) 4 1N914 or similar silicon signal diodes (D1-D4) Capacitors 1 10µF 35VW PC electrolytic 2 0.27µF MKT polyester (code 274 or 270n) 2 5pF ceramic (code 5 or 5p) Fig.4: total harmonic distortion (THD) versus output level; measured at the junction of 33Ω emitter resistors when driving 8Ω headphones. www.siliconchip.com.au Resistors (0.25W, 5%) 2 330kΩ 2 56kΩ    2 22kΩ 4 10kΩ 2 68Ω 4 33Ω 1 50kΩ dual-gang logarithmic pot (VR1) May 2002  55 Finally, check the voltage bescrape off some of the passivation SILICON CHIP HEADPHONE AMPLIFIER 010502011 tween the outputs and 0V – again, to bare metal) to the earth braids. it should be pretty close to zero. The pot should be a “logarithIf all this passes muster, it’s time mic” type to match the sensitivity to plug in a pair of headphones. characteristics of the human ear. This done, apply the “blurt” test: But if all you have (or can get) RIGHT touch your finger on the input pins is a linear pot, you could use it (not the earth pins!). You should – it won’t do any harm but there + hear a healthy “blurt” out of each won’t be much control: you’ll of the headphones in turn. find that minimum to maximum is squeezed into a tiny section of If you do, you can reasonably LEFT the pot’s travel. assume the system is working (what you’re doing is simply If you are fitting the amplifier connecting a big source of hum board underneath your turntable OV and noise – you!) If you don’t as with the power supply and -15V get any sound, check that (a) the preamp, you’re going to have to headphones are turned on or up, mount the board so the headphone +15V if they have any controls; (b) they socket emerges from an appropriare plugged into the socket; and ately-drilled hole in the plinth. c 2002 (c) you still have power to the And the volume control will board. also need a mounting hole drilled Fig.6: actual size artwork for the PC board. There’s not much that can be – make sure that neither the board that the inputs to the amplifier go to wrong given the tests you have already nor the pot foul any under-deck methe wipers of the pots and that both the chanical operations. undertaken but if you have sound in earths (preamp and amplifier) connect one channel only, it’s nice to know Just remember to keep the input there is a “reference” right alongside together at the bottom end. side of the PC board as far away as If when using your amplifier later possible from the mains transformer with which to compare voltages. you find that a lot of hum is generated and the motor. The pot when you touch the volume control, Being a line level input, it’s not as it might pay you to solder a wire from critical as the RIAA preamp input – but Wire the 50kΩ dual-ganged pothe pot body (you’ll probably need to tent-iometer as shown. It’s important it’s better to play safe. 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Australia: $A8.80 ea (including p&p by return mail). Overseas: $A10 ea (inc. p&p by air). *BINDERS: BUY 5 or more and get them postage free.   (Available in Aust. only): $A12.95 ea plus $5.50 p&p.  Cheque/Money Order  Bankcard  Visa Card  Master Card Card No. *SOFTWARE: $7.70 per item (project) plus $3.30 p&p per order within Australia, $5.50 p&p per order elsewhere.       (Most software is available free on www.siliconchip.com.au) *COMPUTER OMNIBUS: $A12.50 inc p&p Australia; NZ/Asia/ Pacific $A15.95 inc. p&p (air); elsewhere $18.95 inc. p&p (air). *ELECTRONICS TESTBENCH: Aust. $A13.20; NZ/Asia/Pacific $A15.95 inc. p&p (air); Elsewhere $18.95. (All prices inc. p&p). Card expiry date    Signature_____________________________ *BOOKSHOP TITLES: Please refer to current issue of SILICON CHIP for currently available titles and prices as these may vary from month to month. SUBSCRIBERS QUALIFY FOR 10% DISCOUNT ON ALL SILICON CHIP PRODUCTS AND SERVICES# #except subscriptions/renewals and Internet access Item Price Qty Item Description P&P if extra Total Price Total $A TO PLACE YOUR ORDER Phone (02) 9979 5644 9am-5pm Mon-Fri Please have your credit card details ready OR Fax this form to (02) 9979 6503 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, Australia 2097 * Special offer applies while stocks last. 03-01 . . . dimming with the power of a PIC Last month we covered the features and design details of this completely new high power automatic dimmer. It is controlled by a PIC16F84 microcontroller. This month, we conclude with the construction and setting up details and the parts list. Pt.2: By JOHN CLARKE 58  Silicon Chip The Automatic Light Dimmer is constructed on three PC boards: a Display board coded 10104021 and measuring 89 x 102mm; a Controller board coded 10104022 and measuring 84 x 96mm; and a filter PC board coded 10104023 and measuring 52 x 59mm. These are housed in a diecast box measuring 171 x 121 x 55mm. You can begin by checking each PC board for any possible problems before they are assembled. In particular, check the pattern against the published artwork for any shorts or breaks in the tracks. Also check the hole sizes drilled to ensure they are suitable for each component. Note that switches S2-S4 and S6-S8 need slotted holes to suit their terminals. The component overlays for all three boards are shown in Fig.4. Start assembly of the Display PC board by installing the links and diodes. Place the four DIP20 IC sockets in the LED1-40 positions on the PC board. The 10-LED bargraphs need to be in­serted with the correct polarity. One of the corners of the LED bargraph package has a small chamfer down one edge. This is the cathode (K) side of bargraph and should be installed in the sockets as indicated on the overlay diagram in Fig.4. Now install the 8-way right angle pin headers for connec­tors CONA, B, C and D. Switch S5 can be installed with the “flat” side oriented as shown. www.siliconchip.com.au Fig.4: install the parts on the three PC boards as shown here but don’t initially mount any of the switches except for S5 (all the other switches are installed on the case lid first – see photo). Note that the two LED bargraph displays on the Display board mount in opposite directions. Do not install the remaining switches. LED41 is mounted so that the top of its convex lens is 10mm above the top of the LED bargraphs. Work can now begin on the Controller PC board by installing the links and IC2, IC3 and IC4. IC1 uses a socket. Take care with orienting the ICs and socket and note that IC3 is oriented dif­ferently to IC2 and IC1. When installing the resistors, use the resistor code table as a check when selecting each value. You can also use www.siliconchip.com.au a multi­ meter to check each value. The eight 4.7kΩ resistors near IC3 are mounted vertically, ie, end-on. Diodes D13 and D14 can be installed as well as Q1-Q5, taking care with their orientation. Install the 20MHz crystal and the capacitors, taking care to orient the electrolytic capacitors with the correct polarity, as shown. Note that the 1µF bipolar electrolytic can be installed either way. Install the PC stakes near D13 and D14. Triac1 and REG1 are mounted WARNING! Part of the circuitry used in this Automatic Light Dimmer operates at 240VAC (see Figs.1 & 6) and is potentially lethal. Do not touch any part of this circuit while the unit is plugged into the mains and do not operate the circuit outside its earthed metal case. This project is for experienced constructors only. Do not build it unless you are entirely familiar with mains wiring practices and construction techniques. May 2002  59 Table 2: Capacitor Codes     Value IEC Code EIA Code 0.1µF   100n   104 .047µF   47n  473 22pF   22p   22 the PC board, the inductor is secured with two cable ties, each wrapping around the toroid and through holes in the PC board. Install the four 8-way vertical pin headers as shown. Making the filter board The filter PC board is assembled with the 0.1µF 250VAC capacitor soldered in place next to the 4.7MΩ resistor as shown. Inductor L2 has two windings on the one Philips 4330 0303 4220 toroid, using 1mm diameter enamelled copper wire. Wind on 11 turns evenly spaced on one side of the toroid. The second winding needs to be wound as a mirror image of the first, so be careful with the winding direction. In other words, if the turns on the first winding go clockwise around the core, the turns on the second winding MUST go anticlockwise. Make sure you get this RIGHT! Wind on 11 turns as before. Terminate the windings after scraping and tinning the wire ends. We secured the toroid using two 100mm long cable ties around it and the bottom of the PC board. This holds the toroid in position but also allows some movement, preventing it from shattering if the assembled Automatic Light Dimmer is dropped. Note that this ferrite toroid is rather brittle compared to This view shows the fully assembled Display board. It’s best to attach the four 8-way cables before soldering it to the matching switch hardware mounted on the lid of the case. under the PC board as shown in Fig.5. The leads are bent at right angles and soldered to the PC board so that the device tabs are 6mm below the bottom of the PC board. Bend the leads over on the top of the PC board to secure them in position before soldering. Inductor L1 is wound on a Neosid 17-730-22 or Jaycar LO-1244 powdered-iron core using 1mm enamelled copper wire. Wind on 16 turns evenly spaced around the toroid and terminate the leads in the PC boards holes. You will need to scrape away the enamel insulation at each end of the wires and tin them with solder. After soldering the leads to the underside of Table 1: Resistor Colour Codes  No.   1   1   2   8   2   5   2   1   2   5 60  Silicon Chip Value 4.7MΩ (VR37) 100kΩ 10kΩ 4.7kΩ 2.2kΩ 680Ω 470Ω 360Ω 220Ω 47Ω 4-Band Code (1%) yellow violet green yellow brown black yellow brown brown black orange brown yellow violet red brown red red red brown blue grey brown brown yellow violet brown brown orange blue brown brown red red brown brown yellow violet black brown 5-Band Code (1%) brown black black orange brown brown black black red brown yellow violet black brown brown red red black brown brown blue grey black black brown yellow violet black black brown orange blue black black brown red red black black brown yellow violet black gold brown www.siliconchip.com.au Here’s how to wire the four cables: on each of the “A” and “B” cables, connect pin 1 on one header plug to pin 8 on the header plug at the other end, pin 2 to pin 7 and so on. Conversely, for the “C” and “D” cables, connect pin 1 of one header plug to pin 1 of the header plug at the other end, pin 2 to pin 2 and so on. Mark the ends of each cable with a felt-tipped pen as it is completed, so that you don’t get them mixed up later on. That way, when the header sockets are plugged into the pin headers on the Controller PC board, all the connections will be correct, since the headers will only fit one way. Once the cables have been completed, plug them into the Display PC board, so that it is ready for mounting onto the lid of the case. Take care not to transpose cables “B” and “D” – remember that Fig.4 shows the Display board from the component side. Drilling the case Take care when installing the switches on the lid – they must all be oriented correctly (see text) and some of the switch styles differ (see photo). The two red Perspex windows should be a force fit and can be further secured using a few drops of superglue. the more robust powdered iron toroid used for L1. Making the header cables There are four cables to be made up using polarised 8-way pin header plugs and 8-way rainbow cable. The “A” and “B” cables are 90mm long, the “C” cable is 180mm long and the “D” cable is 135mm long. The header cables are made up by first crimping the stripped wire ends into the pins. You may also wish to apply a small amount of solder to each crimp connection to ensure a good contact. The pins then clip into the header plug. Note, however, that the wiring connections to the polarised header plugs are quite critical. For this reason, be sure to follow the wiring details set out in the next paragraph exactly. The lid of the case will require drilling for the switches, LED bargraph displays and the 10mm LED. Use the front panel artwork as a guide to the hole locations and use the display PC board to measure the exact positions. The rectangular holes for the switches and LED bargraphs can be made by drilling out a series of holes within the cutout area and then filing to shape. Of course, if you buy a kit, all the drilling will have been done for you. We fitted clear red Perspex windows into the LED bargraph cutouts. When the drilling and filing of the lid is complete, attach the front panel label and cut out the holes with a sharp hobby knife. Insert the switches into the holes allocated, making note of these important points: (1) Switches S1 and S4 need to be oriented so that UM66 SERIES TO-92 SOUND GENERATOR. THESE LOW COST IC’S ARE USED IN MANY TOYS, DOORBELLS AND NOVELTY APPLICATIONS 1-9 $1.10 10-24 $0.99 25+ $0.88 www.siliconchip.com.au May 2002  61 Fig.5: both REG1 (7805) and the BTA41 insulated tab Triac are bolted to the bottom of the case as shown here. Note that the device tabs must be 6mm below the bottom of the PC board. the switch contacts are closed when set to the Flash and Rate B positions; (2) Switch S2 is oriented so that its contacts are closed when set to the Manual dimming position; and (3) Switch­ es S3, S6, S7 & S8 can be mount­ed either way but it is best to orient them all with the same switch legend positions. We elected to place these four switch­es with the double bar toward the top. The display PC board is mounted by soldering it directly onto the switch terminals. Now that the lid is finished, the case itself requires a fair amount of drilling. Mounting holes are required for the controller and filter PC boards, the regulator, Triac, earthing lug and the transformer. As well, one end of the case requires holes for the power switch S9, fuse F1, cord-grip grommet and the surface mount General Purpose Outlet (GPO) mains socket. Two Fig.6: this diagram shows the mounting details for the two earth lugs. The second nut locks the first nut, so that there is no possibility of the earth lug later working its way loose. holes are required to mount the socket and three holes are for the grommets that allow the wires to pass through the panel into the GPO terminals. Transformer T1 is mounted on the side of the case at an angle so that it does not foul the display PC board when the lid is placed on the box. One of the mounting feet needs to be bent up so that it fits against the integral pillar in the case. Use countersunk screws to mount the transformer so This is the view inside the prototype with most of the wiring completed. The headers from the Display PC board plug into matching header pins on the Controller PC board. 62  Silicon Chip www.siliconchip.com.au Fig.7: the mains wiring details. Use cable ties to bind the leads and note that inductor L2 (top) is secured with two cable ties that loop under the PC board (see photo). Be sure to use nylon screws, nuts and spacers where specified. that they are flush with the outside of the box. Installing the hardware We are now in the final assembly stage where everything is wired together, as shown in Fig.7. Install the mains cord first. Strip back about 200mm of the outer www.siliconchip.com.au sheath of the mains cord so that there is sufficient lead length for all the mains wiring. Cut off 50mm and 100mm lengths of the brown Active wire from the mains cord and solder the 50mm length to provide the connection between the filter board and the controller PC board. The 100mm length provides the connection from the fuseholder to the controller board (shown as “X” on Fig.7). Apply a smear of heatsink compound to the underside of the Triac tab and regulator tab before bolting them down. Note that the specified Triac has an isolated tab which means that the metal flange on the device is not connected to any of the pins. You can May 2002  63 to the case with 8mm long screws and nuts. Fit the mains cord into the hole in the case with a cordgrip grommet. Make sure that this cord cannot be pulled out from the case once secured in place. The green-yellow earth wires are attached to the case using crimp eyelets and a screw, two star washers and two nuts – see Fig.6. Fit switch S9, fuseholder F1, the GPO socket and its grom­mets and wire switch S9 and fuseholder F1 as shown. Be sure to sheath the fuseholder terminals, with 10mm diameter heatshrink tubing and the switch terminals with 5mm heatshrink tubing. Mount the transformer now. Note that the switch terminals will need to be bent over slightly to allow clearance for the transformer. Connect the wiring to the filter PC board and to the GPO before mounting the filter PC board on 25mm screws and 15mm Nylon spacers. Note that a Nylon screw and nut is used for the corner mounting position on the filter PC board. Do not use a metal screw in this position otherwise there is a risk of flashover. This applies to any position where we have specified Nylon screws – see Fig.7. Connect the transformer secondaries to the Controller PC board as shown. The mains wiring needs to be tied so that if one wire should come adrift it will still be secured in place with another wire connection. Use cable ties to strap the wires in place on the switch, the back of fuseholder F1 and the wires on the filter PC board. Finally, attach four rubber feet to the base of the case. Here's how to fit the folded Presspahn insulation into the case. Note that many of the parts underneath the Presspahn insulation operate at 240VAC. Presspahn insulation This view shows how the mains socket, on/off switch and safety fuseholder are mounted on one end of the case. Make sure that the mains cord is properly secured using a cordgrip grommet. check this by meas­uring the resistance between the tab and the pins with a multi­meter. If the resistance shows a short circuit then the Triac is not an isolated tab type and should not be used. An open circuit measurement will show 64  Silicon Chip if the Triac is the correct isolated tab device. Mount the controller PC board on 6mm Nylon spacers using 15mm long screws. Note that the screw near Triac1 must be a Nylon screw (see Fig.7). Secure the regulator and Triac As shown in the accompanying photo, a folded piece of Presspahn or Elephantide insulation is used to cover the high-voltage section of the circuitry (apart from the mains switch). This serves to isolate the low-voltage cable wiring from those components operating at mains potential when the lid is attached and is important for long-term reliability. Fig.8 shows the cutout and folding details for the insulation material. Testing Check your wiring very carefully, making sure all the wires are connected to the correct positions. Also check that the mains Earth lead is connected www.siliconchip.com.au Scope 4: this shows the lamp voltage when the Triac is fired at the peak of the mains waveform. The resulting RMS vol­tage is about half the 250V or 126V as measured by the oscillo­scope. Scope 5: this is the gate drive pulse as seen at pins 2 and 3 of IC1. This pulse drives the optocoupled Triac driver IC4 via a 220Ω resistor. The gate pulse width is 82µs. Fig.8: you can use this diagram as a template for marking out and cutting the Presspahn insulation material. Fold the cutout along the dotted lines in the direction indicated. to chassis and that the Earth terminal on the GPO is also connected to chassis. You can check that there is continuity from the Earth pin on the mains plug to chassis and to the Earth connection on the GPO using a multimeter. The Automatic Dimmer is best initially tested with the lid secured in place with its mounting screws. Apply power and check that the display LEDs light. If the LEDs do not light, switch off power immediately and disconnect the power plug. Check that the fuse is intact and that the switch was turned on. PLEASE NOTE! The scope waveforms in this article are shown to explain the operation of the circuit. DO NOT try to reproduce these waveforms yourself – it is much too dangerous. www.siliconchip.com.au Scope 6: the yellow trace is the mains waveform at 50Hz and 250VAC. The blue trace is the signal applied to pin 6 of IC1 to detect the zero voltage crossing point of the mains wave­form. This voltage is clipped at +5.6V and 0.6V below ground via the internal clamping diodes of IC1. May 2002  65 Parts List 1 display PC board, code 10104021, 89 x 102mm 1 controller PC board, code 10104022, 84 x 96mm 1 filter PC board, code 10104023, 52 x 59mm 1 front panel label, 116 x 168mm 1 diecast aluminium box, 171 x 121 x 55mm 2 10mm x 51.5 x 2mm clear red Perspex or Acrylic 1 sheet of Elephantide or Press­ pahn insulation, 100 x 160mm 1 30V centre-tapped 5VA mains transformer with internal thermal fuse (T1) (Jaycar MM2007 or equivalent) 1 iron powdered toroid, 25 x 13 x 10mm approx, AL 77 (L1) (Neosid 17-730-22 or Jaycar LO-1244) 1 Ferrite toroid, 37 x 22 x 16mm approx, AL 7390 (L2) (Philips 4330 0303 4220 or Jaycar LO1238) 2 SPST ultra-mini rocker switch (S1,S4) (Jaycar SK-0975, Altron­ics S-3202 or equiv.) 4 SPDT centre off spring return rocker switch (S3,S6,S7,S8) (Jaycar SK-0987 or equiv.) 2 SPST mini rocker switch (S2, S9) (Jaycar SK-0984 or equiv.) 1 snap action keyboard switch (S5) (Jaycar SP-0721, Altronics S-1096 or equiv.) 1 20MHz parallel resonant crystal (X1) 1 10A surface mount mains outlet (HPM Cat. NO.35) 1 2AG panel-mount safety fuse holder 1 10A 2AG fuse 1 10A mains plug and lead 1 cord grip grommet to suit mains lead 4 DIP20 IC sockets (for LEDs1-40) 1 DIP18 IC socket (for IC1) 3 9mm rubber grommets 8 8-way 0.1-inch polarised header plugs (Jaycar Cat. HM-3408 or equivalent) 4 8-way 0.1-inch polarised pin headers (Jaycar Cat. HM-3418 or equivalent) 4 8-way 0.1-inch polarised right-angle pin headers (Jaycar Cat. HM-3428 or equivalent) 1 550mm length of 8-way rainbow cable 2 M3 x 10mm countersunk screws 2 M3 x 8mm pan head screws 1 M3 x 12mm pan head screw 2 M3 x 20mm pan head screws 1 M3 x 15mm Nylon screw 3 M3 x 15mm metal screws 1 M3 x 25mm Nylon screw 1 M3 x 25mm metal screw 2 15mm M3 tapped plastic standoffs 4 6mm M3 tapped plastic standoffs 12 M3 nuts 2 M3 Nylon nuts 2 M3 star washers 2 crimp eyelets 4 rubber feet 1 45mm length of 10mm diameter heatshrink tubing 1 20mm length of 4mm diameter heatshrink tubing 10 100mm long cable ties 1 2.3m length of 1mm diameter enamelled copper wire Check that the LED bargraphs have been installed correctly. Also you may need to check the supply voltages on IC1 and IC2 for 5V. There should be 5V between pins 5 and 14 on IC1 and between pins 8 and 16 on IC2. Be careful when checking voltages since the righthand side of the PC board has mains voltages on it. This includes the MOC3021 (IC4), L1 and the adjacent 360Ω and 470Ω resistors and the Triac leads. If the displays are operating, you should be able to set the dim and flash levels and the rates using the up and down set level switches. Also the LED lamp indicator should light accord­ ing to the dimming level. Check operation of the autodim function and the flash. You can set the filament preheat by connecting up an in­candescent lamp via the GPO socket. Note that you must use a lamp that is at least 60W. A smaller bulb rating may flicker since the Triac holding current is too high for these. Press all three lefthand switches (Store Settings, Set UP and Dim Up switches) and wait as the slow in- 66  Silicon Chip 1 150mm length of 0.8mm tinned copper wire 3 PC stakes Semiconductors 1 PIC16F84A-20P microcontroller programmed with autodim.hex (IC1) 1 4017 decade counter (IC2) 1 ULN2803 8-way Darlington driver (IC3) 1 MOC3021 Triac driver (IC4) 1 7805 3-terminal regulator (REG1) 1 BTA41.600B 40A 600V insulated tab Triac (TRIAC1) 5 BC328 PNP transistors (Q1-Q5) 12 1N914, 1N4148 diodes (D1D12) 2 1N4004 diodes (D13,D14) 4 10-red LED bargraph displays (LED1-LED40) 1 10mm red LED (LED41) Capacitors 1 470µF 25VW PC electrolytic 2 10µF 25VW PC electrolytic 1 1µF bipolar electrolytic 2 0.1µF 250VAC X2 class 2 0.1µF MKT polyester 1 .047µF 250VAC X2 class 2 22pF NP0 ceramic Resistors (0.25W 1%) 1 4.7MΩ Philips VR37 high-voltage type (DO NOT substitute) 1 100kΩ 2 470Ω 2 10kΩ 1 360Ω 8 4.7kΩ 2 220Ω 2 2.2kΩ 5 47Ω 5 680Ω Fig.9: the is the full-size etching pattern for the filter PC board. www.siliconchip.com.au Fig.10: this is the full-size front panel artwork. Fig.11: the full-size etching patterns for the Display PC board (left) and Controller PC board. crease in voltage applied to the lamp is sufficient to provide a soft glow in the filament. Release the switches and press the Store Settings switch to www.siliconchip.com.au retain this value of preheat. Note that the dim up and set up switches may have altered settings at the time the filament preheat adjust- ment was made. You can store the dim and flash levels and A and B rates that you set on the display at any time using the store settings switch. SC May 2002  67 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 5MHz Personal LCD Handheld Oscilloscope The 5MHz Velleman Personal Oscilloscope has high sensitivity and extended scope functions, making it suitable for measuring audio equipment, digital signals, mains voltage applications and car hifi just to name a few. It gives users a high contrast LCD with a wide viewing angle, full automatic setup for volt/div & time/div, true RMS and dB measurements, screen hold function, low battery detection and auto power off. The scope is housed in a durable ABS plastic case which includes a tilting bail and tactile-style rubber switches. A handy neoprene/nylon zip-up carry case and a standard test lead are also included. The scope also has a handy optional feature that allows you to select different display aids such as a Grid that divides the screen into reference points. With a recommended retail price of $319.00, the Velleman Personal Oscilloscope (Cat no. QC1906) is available through all Jaycar Electronics stores. More information is also available on the company’s website. Contact: Jaycar Electronics PO Box 6424, Silverwater NSW 1811 Ph: (02) 9741 8555 Fax: (02) 9741 8500 Website: www.jaycar.com.au Reach for the stars – or at least look at ’em! Here’s a great gift for the budding astronomer at your place: a 60mm refracting telescope, complete with a 60mm objective lens and 1.5x erecting lens. A variety of eyepieces are included including F10mm, F15mm H and F25mm K, along with a right-angle adaptor, a 5x24 “finderscope” and a 3x Barlow lens. It has a standard mount and includes the wooden tripod (shown). Recommended retail price of the telescope is $148. It is available through all Dick Smith Electronics stores and DSE PowerHouse stores, most dealers and via mail orders. Anyone really into computer games? If you (or anyone else in the family!) like really getting into PC games, Oatley Electronics has a bargain for you. These brand new “Thrustmaster” steering wheel/pedal sets can be used with any PC (full instructions and drivers on CD are included) and the wheel clamps on to any table. It has four on-wheel buttons and two paddles for gear changes, etc. Price is just $69.00 each. Oatley also have some great game bargains to go with them: Eidos Formula 1, Eidos Daikatana and Eidos Deathtrap for $18 each, or all three games and the Thrustmaster for $100 (a saving of $23). Note stock is limited! Contact: Contact: Dick Smith Electronics Ph: (02) 9642 9100 Fax: (02) 9642 9153 Website: www.dse.com.au Oatley Electronics PO Box 89, Oatley NSW 2223 Ph: (02) 9584 3563 Fax: (02) 9584 3561 Website: www.oatleyelectronics.com New Wiltronics and Rockby catalogs released It’s catalog season. Recently the Altronics and Jaycar Catalogs have appeared (SILICON CHIP readers received a complimentary copy) and now the Wiltronics Research and Rockby Electronics 2002 catalogs are available. The Wiltronics catalog is a conventional (paper) A4size with 100 pages, while the Rockby catalog is on CD-ROM. More information from their respective websites. Psst! Your Dick Smith Electronics 2002 catalog will be in June SC! Contact: Contact: Ph: (03) 5334 2513 Fax: (03) 5334 1845 Ph: (03) 9562 8559 Fax: (03) 9562 8772 Wiltronics Research Pty Ltd Website: www.wiltronics.com.au www.siliconchip.com.au Rockby Electronics Pty Ltd Website: www.rockby.com.au May 2002  71 Jaycar’s new Chipkartenleser Huh? OK, just in case you don’t speak German (we think!) Jaycar has just released a new product: a handy Sim Card Reader. The Reader allows you to download Sim Card data to your computer. It can then be stored, managed, shared, or simply used to print the data stored in the Sim Card of any mobile phone. Once the information is down-loaded it is then possible to update it and write it back to the card. The reader can change the phone’s PIN and will even create backups of SMS data and phonebook. This is especially useful if one is changing phone companies or sharing a common phone book on several broadcast quality phones. The reader attaches to the computer via the serial port and will accept both full-sized and miniature SIM Cards. Recommended retail price is $39.95. Contact: Jaycar Electronics PO Box 6424, Silverwater NSW 1811 Ph: (02) 9741 8555 Fax: (02) 9741 8500 Website: www.jaycar.com.au 16MB “Go Anywhere” storage drive It’s about the size of a highlighter pen and clips onto a shirt pocket or key ring – and can store up to 16MB of information to take wherever you go. The Targus “Go Anywhere” StorageDrive is fully plug-and-play in operation, with no driver, power supply or battery required. It plugs into any USB port on Windows (98/2000/ ME/XP), Mac (OS9 +) or Linux-based (2.4.0) system. The host computer immediately detects it, recognising it as a supplementary removable disk and assigning it a drive letter. The KeySafe security application ensures confidentiality of data by 9/40 Leighton Pl. HORNSBY 2077 Ph (02) 9476-5854 Fx (02) 9476-3231 Register your business with Austrade Contact: Targus Australia Pty Ltd 117-119 Bowden St, Meadowbank, NSW 2001 Ph: (02) 9807 1222 Fax: (02) 9807 3555 Website: www.targus.com.au than 0.07%THD at all levels, the Descent is unquestionably one of the lowest distortion subwoofers on the market. It is equally at home in both 2-channel and multi-channel Home Theatre systems. Frequency response is from 200-150Hz ±3dB with switchable crossover points at 40 and 70Hz. Inputs are RCA line levels and XLR LFE. Contact: Denon GPO Box 2301, Sydney NSW 2001 Ph: (02) 9560 6266 email: sales<at>kedcorp.com.au 72  Silicon Chip Manufactured in Australia Harbuch Electronics Pty Ltd means of user-defined password and           internally-secured access verification. The Targus “Go Anywhere” drive is available wherever computers are sold for around $129. New receiver, active sub from Denon New from Denon are the 50 watt/ channel DRA-295 receiver (rrp $599) and Martin Logan Descent, an active 400 watt subwoofer system with an rrp of $7,950.00 In the remote-controlled amplifier, the power supply, power amp, tuner and preamp stages are all kept separate. The Martin Logan Descent is an active 400 watt subwoofer system that employs three 10-inch drivers in parallel utilising an advanced servo monitor and control. With less AUDIO MODULES Businesses wanting international exposure are being invited to register on Austrade’s Australian Suppliers Database. The Australian Suppliers Database is a comprehensive, searchable directory of Australian companies accessible by potential buyers anywhere in the world. Run by the Australian Trade Commission (Austrade), the database already lists around 7000 Australian suppliers. It allows companies to touch base with buyers overseas. The database is widely promoted through Austrade’s 90 offices located throughout Australia and the world. Listing on the database is a free service that will include your products and services, your company message and your contact details. Contact: Austrade GPO Box 2301, Sydney NSW 2001 Ph: (02) 9390 2077 Fax: (02) 9390 2341 Website: www.austrade.gov.au www.siliconchip.com.au SILICON CHIP WebLINK How many times have you wanted to access a company’s website but cannot remember their site name? Here's an exciting new concept from SILICON CHIP: you can access any of these organisations instantly by going to the SILICON CHIP website (www.siliconchip.com.au), clicking on WebLINK and then on the website graphic of the company you’re looking for. It’s that simple. No longer do you have to wade through search engines or look through pages of indexes – just point’n’click and the site you want will open! Your company or business can be a part of SILICON CHIP’s WebLINK. For one low rate you receive a printed entry each month on the SILICON CHIP WebLINK page with your home page graphic, company name, phone, fax and site details plus up to 50 words of description– and this is repeated on the WebLINK page on the SILICON CHIP website with the link of your choice active. Get those extra hits on your site from the right people in the electronics industry – the people who make decisions to buy your products. Call SILICON CHIP today on (02) 9979 5644 NEW! HC-5 hi-res Vid eo Distribution Amplifier DVS5 Video & Audio Distribution Amplifier Five identical Video and Stereo outputs plus h/phone & monitor out. S-Video & Composite versions available. Professional quality. For broadcast, audiovisual and film industries. Wide bandwidth, high output and unconditional stability with hum-cancelling circuitry, front-panel video gain and cable eq adjustments. 240V AC, 120V AC or 24V DC. VGS2 Graphics Splitter High resolution 1in/2out VGA splitter. Comes with 1.5m HQ cable and 12V supply. Custom-length HQ VGA cables also available. Check our NEW website for latest prices and MONTHLY SPECIALS www.questronix.com.au Email: questav<at>questronix.com.au Video Processors, Colour Correctors, Stabilisers, TBC’s, Converters, etc. QUESTRONIX VAF Research offers Speakers for the Audiophile Purist or Home Theatre Extremist. Home Entertainment Equipment and Accessories. They have ready-to-assemble loudspeaker kits along with quality drivers from the world's leading suppliers. VAF Research Pty Ltd Tel: 1800 818 882 Fax: (08) 8363 9997 WebLINK: www.vaf.com.au A 100% Australian owned company supplying frequency control products to the highest international standards: filters, DIL’s, voltage, temperature compensated and oven controlled oscillators, monolithic and discrete filters and ceramic filters and resonators. Hy-Q International Pty Ltd Tel:(03) 9562-8222 Fax: (03) 9562 9009 WebLINK: www.hy-q.com.au www.siliconchip.com.au www.siliconchip.com.au JED designs and manufactures a range of single board computers (based on Wilke Tiger and Atmel AVR), as well as LCD displays and analog and digital I/O for PCs and controllers. JED also makes a PC PROM programmer and RS232/RS485 converters. Jed Microprocessors Pty Ltd Tel: (03) 9762 3588 Fax: (03) 9762 5499 WebLINK: www.jedmicro.com.au Looking for GENUINE Stamp products from Parallax . . . or Scott Edwards Electronics, microEngineering Labs & others? Easy to learn, easy to use, sophisticated CPU based controllers & peripherals. See our website for new range of ATOM products! MicroZed Computers Tel: (02) 6772 2777 Fax: (02) 6772 8987 WebLINK: www.microzed.com.au All mail: PO Box 348, Woy Woy NSW 2256 Ph (02) 4343 1970 Fax (02) 4341 2795 Visitors by appointment only When it comes to purchasing quality products over the Web, you can count on the Wiltronics team to provide you with the best value for money. For over 25 years, Wiltronics has supplied the needs of the Electronics Industry, and look forward to continuing this service. Wiltronics Pty Ltd For everything in radio control for aircraft, model boats and planes, etc. We also carry an extensive range of model flight control modules including GPS, altitude and speed, interfaces, autopilot and groundstation controllers. More info on our website! Silvertone Electronics Tel: (03) 9762 3588 Fax: (03) 9762 5499 Tel:(07) 4639 1100 WebLINK: www.wiltronics.com.au WebLINK: www.silvertone.com.au 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°. SPECIALISTS in AUDIO, VIDEO, CD, DATA Media and Multimedia manufacturing & wholesale. We also specialise in DVD Prod-uction & editing. We can produce Short Run or Bulk CD Audio, CD Rom & DVD projects. Distributor of Emtec (by Basf) TDK, HHB and Quantegy Professional Products. Av-COMM Pty Ltd Tel:(02) 9939 4377 Fax: (02) 9939 4376 WebLINK: www.avcomm.com.au Fax: (07)4639 1275 PRO-COPY Tel: (08) 9375 3902 Fax: (08) 9375 3903 WebLINK: www.procopy.com.au May 2002  73 May 2002  73 Wind-up energy is about to make a resurgence Wound up ab by Gerry Nolan­ W ind-the-handle, magneto telephones were com mon in rural areas until the late 60s (I used one myself as late as 1965) and now the handle is back. Wind-up mobile telephone chargers are just about to be released in Australia. Since, as someone said recently, ‘A mobile phone with a flat battery is as useless as a hip pocket in a singlet,’ a lightweight charger that depends on nothing but human energy will be a boon to those people who find themselves with a flat mobile battery and no power source in the vicinity. Wind-up radios have been around for several years and wind-up torches have been a more recent development. Also known as self-powered energy, the technology has evolved from the fairly clunky Mark 1 wind-up radio to the sleek Freeplay Ranger with the choice of wind-up, solar and rechargeable power. Of course, a long time before any of these developments, wind-up energy storage was commonly used in gramophones, toys and rubber-powered model aeroplanes. Since the production of the first “Freeplay” radio in 1996, over 150,000 have been brought to communities in at least 40 developing countries. It is estimated that these radios have already directly benefited over three million people and up to 30 million indirectly. While this seems to be a large ratio, the radios are used for example in schools where there is no electricity, for entertainment as well as education. A major use of the radios is in emergency situations around the world, a striking case being the unprecedented floods in Mozambique in the Spring of 2000. The Freeplay Foundation donated thousands of radios to people who had lost their homes and possessions to enable them to access vital health and safety information. So successful were the communications that additional FM transmitters were imported to improve reception in remote areas. Back to mobile phones… A technical collaboration between Freeplay and Motoro- The Freeplay wind-up mobile phone charger, shown about life-size (at right) and in use (above). A 30-second wind will give enough power for a few minutes talk time. 74  Silicon Chip www.siliconchip.com.au bout energy la puts an end to the mobile phone with the flat battery. Known as the FreeCharge, the unit incorporates a winder handle, gearbox, alternator, rectification, power conditioning, intermediate battery storage cells, energy input charge indicator and power output socket. The internal battery can be charged by either the human-powered alternator or an AC/DC adapter and energy supplied to the mobile phone as required. Winding the charger for 30 seconds will supply energy for about 4-5 minutes talk time (depending on the type of mobile phone) and several hours standby. Winding for an accumulated 35 minutes fully charges the internal battery of the charger. This is a non-removable, Ni-MH battery pack, with a capacity of 3.5V and 1,000mA hours, or about the same as the handset battery. A LED charge level indicator illuminates when the optimal charge rate (winding effort) is reached, but the more vigorously you wind the more energy is supplied to the mobile phone, extending the talk time proportionately. A 24 hour charge via the AC/DC adapter will also fully charge the battery. At 52x145x60mm and weighing 230g, the FreeCharge units are about twice as large as the average mobile phone and weigh considerably more but the size and weight are expected to decrease as the technology develops. At present the adapter module range covers about 80% of the current model mobiles and will expand as new models are introduced. With wind-up technology improving the way it is, perhaps it won’t be too long before larger equipment, such as motor vehicles will use spring storage instead of fuel or batteries. After all, you could drive into a service station for a quick wind-up using an electric motor. We’ve come a long way from the wind-up SC gramophone but it’s a circular path. www.siliconchip.com.au Above is the Global Shortware wind-up radio, distributed in hundreds of thousands to third-world coutries. Below is the AM/FM Freeplay S360, partially disassembled to show some of the wind-up mechanism. It also runs from solar energy or rechargeable batteries.. May 2002  75 Stepper Motor Controller By Ross Tester With so many stepper motors in use (and disposed of) these days, one of our most-asked questions is “how do I use one?” Here’s how . . . S tepper motors are everywhere. For example, every computer contains several (in the floppy and hard disk drives – one popular hobbyist source). They’re used because it is easy to achieve very precise positional control – far better than you can achieve with a “normal” motor (if you can control it at all). Unlike a conventional motor, where you simply connect an appropriate voltage and “away she spins”, stepper motors require considerably more effort to get them to work. So what is a stepper motor? First of all, think of a conventional motor. It has two main components – a stator, which sets up the magnetic field, and a rotor, which by magnetic attraction or repulsion turns toward or away from the magnetic field. But there’s also a commutator (actually part of the rotor) which keeps switching power from one coil to the next, moving the magnetic field as well, so the rotor has to keep moving, or rotating. Yes, that’s a pretty simplistic explanation – but will suffice for our purposes. Stepper motors are similar in many respects – they have stators and they have rotors – but they don’t have commutators. The magnetic fields which cause attraction/repulsion, and therefore turning, are set up externally by the motor controller. 76  Silicon Chip A stepper motor operates a little like a chaser: one stator coil is energised, repelling the rotor. Then that coil is de-energised and the next one energised, again repelling the rotor. Keep this up and the rotor turns continuously. The rotor may be either a permanent magnet, a variable reluctance or a combination of both. By controlling which field coils are energised and when, the rotation and stopping position of the rotor can be extremely closely controlled. You will hear stepper motors referred to as 0.9° degrees, 1.8°, 3.6° and so on. This refers to the rotation of one “step” in the motor – a 0.9° motor will have 400 individual steps to make one full rotation of 360°. As you can see, 400 steps in one rotation is a lot of steps, especially as each one can be individually accessed. And many stepper motors operate through a gearbox, multiplying that yet again. The speed of rotation is obviously directly related to how fast you can switch current between the coils. At low speeds, there is no problem – but as the switching frequency increases, we can start to get into difficulties. Loss of power At low speeds, most stepper motors are generally quite powerful devices – ie, lots of torque – especially when driven by an appropriate supply. However, most hobbyists tend to drive a stepper motor from a fixed voltage supply. This is fine at low speeds (low frequency) but as the speed increases, the torque drops off, often dramatically, due to the impedance of the coils. There are three main methods used The stepper motor controller is shown here with a typical 6-wire disposals stepper motor. www.siliconchip.com.au Fig.1: three ICs, four Mosfets and a handful of other components make up the controller. It can be use in “stand alone” or computer-controlled modes. to overcome this reduction in torque: 1 – The use of a higher voltage switched-mode power supply that increases the duty cycle at higher motor speeds. 2 – The use of a higher voltage power supply along with a power (ballast) resistor in series with the motor. The resistor limits the current to that of the nominal motor current. 3 – The use of a constant current source that maintains constant current to the motor at all speeds. As the speed increases, the voltage also increases. There are disadvantages in the first two methods. Switched-mode (some times called "chopper") power supplies need to be carefully tailored to suit the specific motor being used and its torque curve. So it’s hard to make a “universal” supply. The ballast-resistor method results in less current being applied at higher speeds and is therefore less efficient. However, the use of a constant current source ensures the motor current remains constant throughout its speed range. Although this method is perhaps wasteful compared to the "chopper" due to the heat generated in the driver it requires little or no setup. In practice this type of circuit is already proven and is in common use in industrial drivers. How it works This circuit can be used in either free-standing or computer-controlled K&W HEATSINK EXTRUSION. SEE OUR WEBSITE FOR THE COMPLETE OFF THE SHELF RANGE. www.siliconchip.com.au May 2002  77 Parts List - Stepper Motor Controller 1 PC board, 72 x 42mm, coded K179 (Oatley Electronics) 2 3-way PC-mount terminal blocks 1 2-way PC-mount terminal block 1 4-way PC-mount header pin set (or 4 PC stakes) Semiconductors 1 4093 IC(IC1) 1 4030 (IC2) 1 4013 (IC3) 1 7805 5V regulator (REG1) 4 IRFZ44N Mosfets (Q1-Q4) Capacitors 1 100µF 35VW 1 100µF 10VW 1 1µF 20VW 2 0.1µF polyester Resistors (0.25W, 5%) 1 10kΩ 1 1MΩ PC-mounting preset pot modes. In the free-standing mode, an internal square-wave oscillator based on IC1b supplies timing pulses to the “OSC” output. The frequency of these pulses (and therefore stepper motor speed) is controlled by preset pot, VR1. (A standard 1M linear pot could be substituted to allow external speed control at any time). Either the oscillator pulses or control pulses from a computer are fed into the “STEP” input which in turn are buffered and inverted by IC1d, a 4093 Schmitt trigger. This helps prevent false triggering. Similarly, IC1c buffers and inverts the “DIR” (direction) input which once again can be either manually set or taken from a PC. Taking the DIR input to +5V causes the stepper to turn in one direction; taking it to GND will reverse the rotation. IC2c and IC2d (4030 exclusive OR gates) invert the outputs available at the Q and Q-bar outputs of each of the flip-flops, IC3a and IC3b. The incoming step pulses clock the flip-flops thus toggling the Q and Q-bar outputs, this turns the MOSFETs on or off in sequence. The IRFZ44 MOSFETs have a very low on resistance and can deliver 5 or 6A each without heat sinking. For higher current use, small clipon heatsinks could be used or the 78  Silicon Chip Fig.2: be careful when soldering in the ICs: the tracks are closely spaced! MOSFETs could be removed from the PC board and placed on a larger heatsink. The power supply is a conventional circuit using a 7805 3-terminal regulator, producing 5V output. A minimum of about 8 volts DC is required at the input and the maximum (limited by the 7805 rating) is 35V. Construction All components mount on a single PC board measuring 72 x 42mm, coded K179. This board is only available as part of a complete kit from Oatley Electronics. It is perhaps easier with this board to depart from normal practice and solder in the three ICs first. The reason for this is that there are tracks going between the IC pin pads and these will require very careful soldering and checking. Make sure you get the three ICs in their right places and the orientation is correct (all three face the same way). Next, solder in the resistors and capacitors and use some of the lead cut-offs for the three links. Solder in the header pins, the on-board terminal blocks and finally the regulator and the four Mosfets. Note that the Mosfets are NOT oriented all the same way – and it’s important to keep their drains (the metal tabs) separated from each other, especially if you fit heatsinks. (If you decide to mount the Mosfets on a larger heatsink for more power capability, as mentioned above, you will need to fit insulating washers and bushes to each Mosfet to ensure they are electrically isolated from each other). Before use, check and double check your component placement and soldering – especially the ICs as noted above. In use It’s outside the scope of this article to go into much detail. It’s sort-of like “if we need to explain then you shouldn’t be doing it!” However, a quick note on using surplus steppers: as you can see from the circuit diagram, the windings on most of the steppers you will come across are centre-tapped. This means you can usually identify the pairs with a multimeter, as well as working out which is the centre tap. Having got that far, connect up the circuit with the “OSC” and “STEP” pins shorted to each other, plus the “DIR” and “GND” pins to each other. Connect the centre-taps of your stepper motor windings to the V+ terminals and their pairs to the M1B and M1A, M2A and M2B terminals as appropriate. Set VR1 to half-way. Apply power and see if your stepper is continuously turning. If not (eg, if it is “hunting”), swap the M1B and M1A windings only (leave the M2A and M2B) and check again. Now it should be turning. Varying VR1 should vary the speed up and down. If it doesn’t work, check to see if IC1b is oscillating (an analog meter on a low voltage [<10V] setting connected between OSC and GND should show up and down deflection, especially with VR1 set to its maximum). If so, check the voltage between each of the motor terminals and ground with your meter set to a bit higher (say <50V) and see if the meter deflects. At the oscillator’s higher speed range, you probably won’t see any movement – the meter will read the average voltage. If this test proves OK, you probably have a dud stepper motor! Computer control There is quite a range of stepper motor controller freeware available on the ’net. Google “Stepper Motor Software” or words to that effect and see what you come up with. We have given a few sources in this article but www.siliconchip.com.au Software Here are just a few of the demoware or shareware downloads available from the net. Name: Download from: Runs under: Number of axes: Features: Imports: Name: Download from: Runs under: Number of axes: Features: Loads: Imports: Exports: DANCAD www.metalworking.com DOS up to 4 Extensive printable manual with printer port connection diaggrams etc. Able to be configured to suit most applications, (lathe and mill etc.) including angular and linear axis set up. Dancad is able to be set up with a tangential knife for sign cutting. HPGL KCAM www.kellyware.com/index.shtml WIN9X. 3 It gives a 2D or 3D view of the Item to be machined, manual jogging, controller and table setup to suit most machine tables including backlash compensation. Tool paths can be programmed in its Gcode editor, or imported as DXF, NC, and PLT files. Ideal for engraving signs and plates, drill printed circuit boards, mill parts, plasma cuts, PCB Isolation. Conversion from Gerber (RS274X) files or plot pictures. G&M code files, Excellon ASCII drill files, DXF files DXF, HPGL files PLT, Gerber files GB0 G&M code files Name: Download from: Runs under: Number of axes: Features: STEPSTER www.thegallos.com/stepster.htm DOS up to 6 Simple to use and set up, Able to be configured to suit most applications, (lathe and mill etc.), including angular and linear axis set up. Name: Download from: Runs under: Number of axes: Features: EMC www.isd.mel.nist.gov/projects/emc/ LINUX up to 6 Hard to set up. Able to be configured to suit most applications (lathe and mill etc.), including angular and linear axis set up. there are lots (and lots!) more. Most of the software available uses the same connections to your PC’s printer port: Pin Function 2 X axis step 3 X axis direction 4 Y axis step 5 Y axis direction 6 Z axis step 7 Z axis direction 8 C axis step 9 C axis direction 18-25 GND The other printer port pins vary according to the particular software – www.siliconchip.com.au they are often used for limit and home switches. Depending on the software used up to 6 motors (with 6 controller boards) can be controlled just by connecting the stepper drivers to the printer port of your computer. In other words, complete three-directional control is possible (we hope to have more on this in a future issue). Where do you get it? This project is available as a complete kit of parts from Oatley Electronics. Contact details can be found on SC page 15 of this issue. May 2002  79 VINTAGE RADIO By RODNEY CHAMPNESS, VK3UG The AWA FS6 army transceiver A significant number of vintage radio buffs collect and restore amateur, military and commercial radio equipment. Along with the more familiar domestic radio gear, this equipment is also a part of our radio heritage and an interesting part of it at that. The front panel layouts of military radios are purely utilitarian and they don’t look a million dollars in matt khaki or some other unexciting colour. Aesthetics was not one of the design principles and there are no elegant timber consoles here. However, it is interesting to compare them in many ways with the domestic radios of the same era. During WWII and on the military surplus market in the late 1940s and early 1950s, the FS6 high frequency (HF) portable army transceiver was common. Many amateur radio operators modified them for use on amateur radio bands and they were also used by bushfire brigades, the Flying Doctor Service (WA), fishermen and other organisations. However, the FS6 is not the sort of gear that the majority of vintage radio buffs collect. There are various reasons for this, the most common being that there are now very few such units around. General description The 1943 provisional training man­ ual on the FS6 gives us a few pertinent facts about the equipment, which I have para­phrased. It is quoted as a medium range, portable combination sender-receiver, suitable for pointto-point communication. It has a frequency range of 4.2-6.8MHz and will operate on both W/T (CW telegraphy, Morse) or R/T (radio telephony). For transporting over short distances, the set can be classed as a 2-man pack. The weight of the station is listed at 157lb, or about 71.4kg (I’m glad they said “short distances”) and it can be used as a ground station or as a mobile truck station. The receiver has two headphone outlets so that two opera­ tors can operate the set at the same time. The receiver is a 5-valve superheterodyne with AVC, while the sender (transmitter) has three valves consisting of a master oscillator, a modulator and an RF power amplifier. The power source is a 6V, 75Ah battery. A 6V vibrator power supply provides all of the HT and bias voltages and the set draws 3.2A on receive and 6.0A on transmit W/T. If a pedal generator is used, only a 25Ah battery is needed to power the set. Background to the FS6 This view shows the FS6 transceiver with the valve access panel open. Military equipment was designed so that all valves were accessible via a single panel. 80  Silicon Chip Prior to WWII, the military had a variety of specifications that had to be met when supplying equipment for their particular needs. One particular specification for radio equipment specified that the valves should all be www.siliconchip.com.au This is the complete FS6 station, with the power supply unit at right. accessible through a hatch in the front of the case. This is clearly shown in one of the photo­graphs of the transceiver – here, the hatch (or cover) has been left open and all the valves are clearly visible. This made valve replacement an easy task. However, there was a real disadvantage in that the valves could not be placed in their optimum positions for stable operation, maximum gain or highest frequency operation. I suspect that this requirement came into being around the end of WWI when valves were very unreliable and hadn’t been rescinded by the outbreak of WWII. In the late 1930s, AWA produced a predecessor for the FS6 designated the 101. I don’t know exactly when it was produced but I suspect that, at the time, it was the most modern set of its type, using the recently produced octal battery valves. It was a very low-powered set, mounted in the same cabinet as the FS6 and supplied with power from a slightly smaller power supply. The 101 struggled to provide an RF output of 0.4W on voice and 0.8W on CW, whereas its successor, the FS6, put out 4W and 8W respectively – a big improvement. However, to the untrained eye, the 101 looks the same as the FS6. I suspect that AWA was asked to provide an updated, more powerful version of the 101, that looked virtuwww.siliconchip.com.au ally the same and could be used in the same way as the 101 (although I have no firm evidence for this). For example, the microphone, headphones, connectors and the like would have to be interchangeable between the two types. The receiver remained the same in each set (101 or FS6) as it had proved to be quite satisfactory. The transmitter though was a complete redesign but was still be capable of fitting into the original space allocated for it in the 101. the equipment assembled and almost ready to operate, needing only a battery and an anten­na and earth to complete the installation. The microphone rubber mouth piece had perished, so it is no longer fitted. Normally the power Looking for an old valve? or a new valve? Valve lineup The 101 used all battery valves. A 1K5G acted as a master oscillator with two parallel 1K5Gs in the RF output stage. Voice modulation of the 1K5G output stage was achieved by impressing the voice signal onto its grid. Carbon microphones are high output units and there was sufficient audio energy put out to modulate the transmitter output stage when fed through a micro­phone transformer. The transmitter was redesigned to use a 1L5G as the master oscillator and the ubiquitous 807 small transmitting valve as the output stage. However, it was more difficult to modulate the grid of the 807. As a result, another 1L5G was added after the micro­phone transformer to boost the audio to a sufficient level to modulate the transmitter effectively. Another of the photographs shows BUYING - SELLING - TRADING Australasia's biggest selection Also valve audio & guitar amp. books SSAE DL size for CATALOGUE ELECTRONIC VALVE & TUBE COMPANY PO Box 487 Drysdale, Victoria 3222. Tel: (03) 5257 2297; Fax: (03) 5257 1773 Mob: 0417 143 167; email: evatco<at>mira.net Premises at: 76 Bluff Road, St Leonards, Vic 3223 May 2002  81 This view shows the FS6 power supply with the access cover removed. The vibrator is at bottom left. supply is stood to the left of the set and the headphones should be low impedance. The cabling between the power supply and the transceiver is made in such a way that it is impossible to interconnect them incorrectly. The receiver is located in the righthand section of the cabinet while the transmitter is on the left. The receiver has relatively few controls and they don’t follow the general layout used on domestic receivers. Starting at the top left, the control here is the aerial tuning control, which is used to peak the performance of the receiver on different aerials. Once set, it can be locked in position by its central knob. At the far right is the volume control, with the earth terminal nearby. The tuning control is in the centre, with the vernier tuning control just to the right of it. On the far right are the parallel headphone sockets. At the Photo Gallery: Tasma Model 22 TASMA MODEL 22: manufactur­ed by Thom & Smith, Sydney in 1931, the Tasma Model 22 is a 3-valve TRF receiver with the following valves: 224 detector, 247 output and a 280 rectifier. (Photo and information courtesy of Historical Radio Society of Australia). 82  Silicon Chip bottom left is a toggle switch which changes the operation of the receiver from voice (radio-telephone) to Morse code (wireless-telegraphy) – ie, this is the mode switch. Above the mode switch is a “mystery” circular black bakel­ ite holder of some sort. These devices were a mystery to me for some time and are mounted on many military radio transceivers. They are a holder for a fob watch. It was necessary to have a watch in a secure spot so that radio schedule (skeds) times could be kept. The transmitter front panel is a little more crowded than the receiver. At the top left is the earth terminal, with the mode switch (speech-key) alongside it. In the centre top is the aerial current meter which is used when tuning the transmitter for maximum output power. Alongside it to the right is the aerial terminal and just below that is the “send/off/ receive/net” switch which controls the switching between the transmitter and the receiver. On the bottom left are the variable frequency oscillator controls. There is a locking knob in the centre of the frequency control knob and a rubber drive vernier onto the edge of the main control knob. The two controls at bottom right are used together to tune and match the transmitter to the aerial. Alongside these controls is the microphone jack. The Morse key is set into the valve access cover and is slid out when it is to be used. Alongside it is a jack which is used for remote control of the set. However, remote control of sets like these is rather limited in scope compared with what is expected from modern remote controls. The power supply is in the separate case at left and has only one control which is the on-off switch. It also has three plug/socket connections to go to the transceiver and the battery. The receiver The receiver has a conventional superhet circuit typical of the era. The converter uses a 1C7G, followed by a 1K5G first IF amplifier on 460kHz, then a 1K7G as a second IF amplifier, detec­ tor, AGC detector and reflexed first audio. Following the 1K7G, audio is applied to another 1K7G which feeds a pair of low-im­pedance headphones via a transformer. The basic circuit is similar in many www.siliconchip.com.au FS6: RECEIVER UNIT Fig.1: the FS6 receiver unit employed a conventional superheterodyne circuit with five valves. ways to sets such as the Fisk Radiola 184 of 1939. This set had a different job to do compared to the domestic receivers of the era and so there are noticeable differences in some areas of design. Portable military radios very rarely had loudspeaker output, for several reasons: (1) it was much easier to hear clearly what was being sent to you if headphones were used and this avoided mistakes; (2) quite a bit of radio traffic was for the officer in command only and no-one else (operator excluded); and (3) when the sets were used on the front line, you didn’t want the enemy hearing what was going on or being able to pinpoint where you were. The other major difference is in the use of a beat frequen­cy oscillator, which is V5 (1C7G) in the circuit. When receiving Morse code messages, this oscillator – which operates at around 460 kHz in the FS6 – beats with the incoming Morse signal to give an audio tone. AGC systems of the era didn’t work well with Morse code signals, so the AGC system is disabled and a variable bias is applied to the AGC line via a ganged volume control (R12 and R16 are ganged via a belt). www.siliconchip.com.au Inside the FS6 receiver (rear of chassis view). May 2002  83 un­ soldered and then the mounting screws are removed. The transformer is then withdrawn through the underside of the chassis (plate) – nifty. It is not possible to operate the receiver out of its case unless jumper leads are attached to the 4-pin plug shown in the top left of the circuit (see Fig.1). The connections are: (1) HT +175V <at> 27mA (maximum); (2) filaments +6V <at> 240mA; (3) bias -6V <at> < 1mA; and (4) aerial/antenna. The chassis is the common return circuit for the HT and filament negative, the bias and the anten­na system earth. The sender (transmitter) Inside the FS6 transmitter (rear of chassis view). By increasing the volume control, the volume setting is increased and the bias applied to the AGC line (via R16) is de­creased, thus increasing the gain of the RF section of the set. In operation, the receiver works quite well and is reason­ably sensitive. The dual-speed tuning is easy to operate and, using the vernier dial drive, shortwave stations are tuned as easily as broadcast band stations on typical domestic radios. This particular receiver needed no replacement components when it was refurbished back in 1973, although that situation may have changed by now of course. The receiver circuitry is removed by undoing four screws at the front of the set and pulling it out of the case. Most military sets aren’t particularly easy to service and the FS6 receiver appears to be no different. That said, a close inspection of the chassis reveals 84  Silicon Chip that much thought has gone into making the components relatively easy to access, despite the compact nature of the radio. For example, the bottom adjustments for the IF transformers are easily accessed at the back of the set. On the other hand, the top adjustments are close to the front panel and at first sight, appear to be inaccessible. However, although not obvious in the photographs, there is a small panel on the front of the set that is removed to gain access to the IF transformer adjust­ments. Should an IF transformer become defective, it is surpris­ ingly easy to remove. Conventional wisdom has it that IF trans­formers are removed through the top of the chassis (plate) but this clearly impossible with the FS6, as the transformer top is hard up against the front panel. In this case, the transformer connections are In this section I’ve gone into more detail than usual, as many vintage radio buffs are unfamiliar with the operation of transmitters. Generally an AM or CW transmitter has a simpler circuit than a superhet receiver but they are noticeably differ­ent from each other. As with the receiver, the transmitter is removed from the case by undoing four screws and pulling it out. A rear view of the chassis is shown in one of the photos. This is a reasonably simple transmitter, having just two stages in the RF section and one in the audio section. A 1L5G (V2) acts as the variable frequency oscillator (master oscillator or VFO) and determines the actual transmission frequency. It has temperature compensating capacitors (top left in circuit) to ensure that the transmitter’s output frequency does not drift unduly when operating. The VFO is similar to the local oscillator in a superhet receiver but works at a higher power level. The signal from the VFO is applied to the 807 where it is amplified. The output signal is then applied to the tuning and matching circuits con­sisting of C14, L2 and S3 which ensure efficient transfer of power to the antenna system. The output circuit of the transmitter is not unlike the circuitry of crystal sets, where the antenna and diode detector are matched to the tuned circuit for best performance. It is necessary to have a transmitter working at optimum efficiency for several reasons: (1) to provide the maximum output power transfer possible (for maximum efficiency); (2) to keep the valve dissipa­ tion down; and (3) to economise on the use of electrical power (important www.siliconchip.com.au when using batteries). In the Morse code mode (CW), the transmitter has grid block keying. This involves placing a bias of -20V onto the grids of the 1L5G (V2) and the 807 (V3), which effectively prevents the 1L5G from conducting and in the case of the 807, reduces the current drain to a safe level when the key is up. When the key is down, the bias is removed and the transmitter operates. When the transmitter is switched to voice operation, the VFO (V2) runs continuously with no blocking bias. The 807 power amplifier operates using both fixed bias (-20V) and self-bias, the latter derived from half-wave rectifying the signal from the VFO at its grid. The voice signal from the carbon microphone is amplified by V1 (1L5G) and fed to the grid of the 807 via T2, the modulation transformer. The voice signal is impressed onto the grid of the 807 in series with the -20V bias. The resulting variation in the bias causes the 807 circuit to act as a high-power mixer. Mixers have several signals in their outputs and, in this case, we have the VFO frequency, the audio frequency and the products VFO + audio frequency and VFO - audio frequency. The circuit only passes the RF signals. The VFO signal is the carrier and the + and - audio signals form the upper and lower sidebands. These three components form the composite AM signal we are all familiar with. The power supply The power supply is quite large for the amount of power it provides to the transmitter and receiver. As shown in one of the photos, there isn’t a lot of spare space inside the case. The front cover is just clipped on by two catches, one on each end. But despite this being an imperfect fit around the edges, there is very little interference to reception from the supply. This is also quite a reliable power supply. The vibrator had a long life and rarely required replacement. This was prob­ably due to the design of the vibrator transformer (T1) and the buffer arrangement (C6, C7, R7 & R8). In addition, the vibrator was sealed and filled with nitrogen gas. Summary Commercially made HF radio transwww.siliconchip.com.au FS6: SENDER UNIT Fig.2: the sender (or transmitter) circuit sender used three valves: a modulator (V1), a VFO (V2) and an RF power amplifier (V3). ceivers were rare and expensive after WWII. However, many of these WWII transceivers came onto the surplus market at a relatively low price. They were often extensively modified to provide crystal control of the transmitter and to provide different and extended frequency ranges. Loudspeaker output was also sometimes added. For example, amateur radio operators modified them extensively to operate on the 3.5MHz and 7.0MHz bands. Unfortunately, the FS6 wasn’t very suitable for use where mud, water, humidity and dust were common – and that included many areas where the set was expected to be used. The set had no sealing gaskets around the cabinet edges, along control shafts or over sockets to prevent the ingress of water, mud and the like. Additionally, it did not have “tropic proofing” or desiccator crystals to keep the moisture out of the set. It also drew more current from the battery than later sets and its tuning range was quite restrictive – 4.26.8MHz, whereas later sets intended for the same job tuned 2-8MHz. However, despite its many faults I believe that in the right environment, it would have proved an easy set to operate and keep in working order. As an aside, the later 122 portable transceiver cost around 1000 pounds during WWII – about the same as a Holden car soon after the war. Military equipment wasn’t cheap to produce! SC May 2002  85 REFERENCE GREAT BOOKS FOR ALL PRICES INCLUDE GST AND ARE AUDIO POWER AMP DESIGN HANDBOOK PIC Your Personal Introductory Course From one of the world’s most respected audio authorities. The new 2nd edition is even more comprehensive, includes sections on load-invariant power amps, distortion residuals and diagnosis of amplifier problems. 368 pages in paperback. Concise and practical guide to getting up and running with the PIC Microcontroller. Assumes no prior knowledge of microcontrollers, introduces the PIC’s capabilities through simple projects. Ideal introduction for students, teachers, technicians and electronics enthusiasts – perfect for use in schools and colleges. 270 pages in soft cover. By Douglas Self. 2nd Edition Published 2000 by John Morton – 2nd edition 2001 89 $ $ VIDEO SCRAMBLING AND DESCRAMBLING FOR SATELLITE AND CABLE TV by Graf & Sheets 2nd Edition 1998 If you've ever wondered how they scramble video on cable and satellite TV, this book tells you! Encoding/decoding systems (analog and digital systems), encryption, even schematics and details of several encoder and decoder circuits for experimentation. Intended for both the hobbyist and the professional. 290 pages in paperback. $ AUDIO ELECTRONICS By John Linsley Hood. First published 1995. Second edition 1999. 79 $ UNDERSTANDING TELEPHONE ELECTRONICS By Stephen J. Bigelow. Fourth edition published 2001 4th EDITION Based mainly on the American telephone system, this book covers conventional telephone fundamentals, including analog and digital communication techniques. Provides basic information on the functions of each telephone component, how dial tones are generated and how digital transmission techniques work. 402 pages, soft cover. 65 GUIDE TO TV & VIDEO TECHNOLOGY 3rd EDITION By Eugene Trundle. 3rd Edition 2001 Eugene Trundle has written for many years in Television magazine and his latest book is right up to date on TV and video technology. The book includes both theory and practical servicing information and is ideal for both students and technicians. 382 pages, in paperback. This book is for anyone involved in designing, adapting and using analog and digital audio equipment. It covers tape recording, tuners and radio receivers, preamplifiers, voltage amplifiers, audio power amplifiers, compact disc technology and digital audio, test and measurement, loudspeaker crossover systems, power supplies and noise reduction systems. 375 pages in soft cover. 3rd EDITION $ By Tim Williams. First pub­­lished 1992. 3rd edition 2001. By Ian Hickman. 2nd edition1999. 63 $ Based mainly on British practice and first published in 1997, this book has much that is relevant to Australian systems as a guide to home and small business installations. A practical guide to installation of telephone wiring, ranging from single extension sockets to PABX, with the necessary tools, test equipment and materials needed by installers... 178 pages in soft cover. 86  Silicon Chip EMC FOR PRODUCT DESIGNERS ANALOG ELECTRONICS Essential reading for electronics designers and students alike. It will answer nagging questions about core analog theory and design principles as well as offering practical design ideas. With concise design implementations, with many of the circuits taken from Ian Hickman’s magazine articles. 294 pages in soft cover. VIDEO & CAMCORDER SERVICING AND TECHNOLOGY by Steve Roberts. 2nd edition 2001. 67 85 $ Widely regarded as the standard text on EMC, provides all the key information needed to meet the requirements of the EMC Directive. Most importantly, it shows how to incorporate EMC principles into the product design process, avoiding cost and performance penalties, meeting the needs of specific standards and resulting in a better overall product. 360 pages in paperback. 99 TELEPHONE INSTALLATION HANDBOOK $ 43 85 $ by Steve Beeching (Published 2001) Provides fully up-to-date coverage of the whole range of current home video equipment, analog and digital. Information for repair and troubleshooting, with explanations of the technology of video equipment. 318 pages in soft cover. 67 $$ www.siliconchip.com.au www.siliconchip.com.au BOOKSHOP WANT TO SAVE 10%? 10% OFF! SILICON CHIP SUBSCRIBERS AUTOMATICALLY QUALIFY FOR A 10% DISCOUNT ON ALL BOOK PURCHASES! ENQUIRING MINDS! LOWER THAN RECOMMENDED RETAIL PRICE Power Supply Cookbook Analog Circuit Techniques With Digital Interfacing by Marty Brown. 2nd edition 2001. An easy-to-follow, step-by-step design framework for a wide variety of power supplies. Anyone with a basic knowledge of electronics can create a very complicated power supply design . Magnetics, feedback loop, EMI/RFI control and compensation design are all described in simple language. 265 pages in paperback. by T H Wilmshurst. Published 2001. 93 $ Microcontroller Projects in C for the 8051 by Dogan Ibrahim. Published 2000. 69 $$ Through graded projects the author introduces the fundamentals of microelectronics, the 8051 family, programming in C and the use of a C compiler. The AT89C2051 is an economical chip with re-writable memory. Provides an interesting, enjoyable and easily mastered alternative to more theoretical textbooks. 178 pages in paperback. 69 $ Antenna Toolkit by Joe Carr. 2nd edition 2001. Together with the CD software included with this book, the reader will have a complete solution for constructing or using an antenna - bar the actual hardware. The software is based on the author’s own Antler program, which provides a simple Windowsbased aid to carrying out the design calculations at the heart of successful antenna design. Free software CD included. 253 pages in paperback. Electric Motors And Drives O R D E R H E R E ❏ ❏ ❏ ❏ ❏ ❏ ❏ ❏ ❏ ❏ ❏ ❏ ❏ ❏ ❏ ❏ by Howard Hutchings. Revised by Mike James. 2nd edition 2001. 59 $ ANALOG ELECTRONICS..................................................$85.00 AUDIO POWER AMPLIFIER DESIGN...............................$89.00 AUDIO ELECTRONICS.....................................................$85.00 EMC FOR PRODUCT DESIGNERS...................................$99.00 GUIDE TO TV & VIDEO TECHNOLOGY............................$63.00 PIC - YOUR PERSONAL INTRODUCTORY COURSE........$43.00 TELEPHONE INSTALLATION HANDBOOK.......................$67.00 UNDERSTANDING TELEPHONE ELECTRONICS.................$65.00 VIDEO & CAMCORDER SERVICING/TECHNOLOGY........$67.00 VIDEO SCRAMBLING/DESCRAMBLING..........................$79.00 POWER SUPPLY COOKBOOK..........................................$93.00 M'CONTROLLER PROJECTS IN C FOR 8051..................$69.00 ANALOG CIRCUIT TECHNIQUES WITH DIGITAL INT......$69.00 ANTENNA TOOLKIT.........................................................$83.00 INTERFACING WITH C.....................................................$63.00 ELECTRIC MOTORS AND DRIVES..................................$59.00               ORDER TOTAL: $...................... P&P Orders over $100 P&P free in Australia. AUST: Add $A5.50 per book NZ: Add $A10 per book, $A15 elsewhere www.siliconchip.com.au 83 $ Interfacing With C by Austin Hughes. 2nd edition 1993. Reprinted 2001. VERY POPULAR BOOK NOW BACK IN STOCK WITH A NEW LOWER PRICE! For non-specialist users – explores most of the widely-used modern types of motor and drive, including conventional and brushless DC, induction, stepping, synchronous and reluctance motors. 339 pages, in paperback. Covers all the analog electronics needed in a wide range of higher education programs: first degrees in electronic engineering, experimental science course, MSc electronics and electronics units for HNDs. Text is supported by numerous worked examples and experimental exercises. 312 pages in paperback. $ 63 Anyone interested in ports, transducer interfacing, analog to digital conversion, convolution, filters or digital/analog conversion will benefit from reading this book. The principals precede the applications to provide genuine understanding and encourage further development. 302 pages in paperback. TAX INVOICE Your Name_________________________________________________ PLEASE PRINT Address ___________________________________________________ ___________________________________ Postcode_______________ Daytime Phone No. (______) __________________________________ STD Email___________________<at>_________________________________ ❏ Cheque/Money Order enclosed OR ❏ Charge my credit card – ❏ Bankcard ❏ Visa Card ❏ MasterCard No: Signature______________________Card expiry date PLUS P&P (if applic): $........................... TOTAL$ AU.............................. POST TO: SILICON CHIP Publications, PO Box 139, Collaroy NSW, Australia 2097. OR CALL (02) 9979 5644 & quote your credit card details; or FAX TO (02) 9979 6503 2002  87 ALL TITLES SUBJECT TO AVAILABILITY. PRICES VALID FOR MONTH OF MAGAZINE ISSUE ONLY. M ALLay PRICES INCLUDE GST Silicon Chip Back Issues April 1989: Auxiliary Brake Light Flasher; What You Need to Know About Capacitors; 32-Band Graphic Equaliser, Pt.2. May 1989: Build A Synthesised Tom-Tom; Biofeedback Monitor For Your PC; Simple Stub Filter For Suppressing TV Interference. July 1989: Exhaust Gas Monitor; Experimental Mains Hum Sniffers; Compact Ultrasonic Car Alarm; The NSW 86 Class Electrics. September 1989: 2-Chip Portable AM Stereo Radio Pt.1; High Or Low Fluid Level Detector; Studio Series 20-Band Stereo Equaliser, Pt.2. October 1989: FM Radio Intercom For Motorbikes Pt.1; GaAsFet Preamplifier For Amateur TV; 2-Chip Portable AM Stereo Radio, Pt.2. November 1989: Radfax Decoder For Your PC (Displays Fax, RTTY & Morse); FM Radio Intercom For Motorbikes, Pt.2; 2-Chip Portable AM Stereo Radio, Pt.3; Floppy Disk Drive Formats & Options. January 1990: High Quality Sine/Square Oscillator; Service Tips For Your VCR; Phone Patch For Radio Amateurs; Active Antenna Kit; Designing UHF Transmitter Stages. February 1990: A 16-Channel Mixing Desk; Build A High Quality Audio Oscillator, Pt.2; The Incredible Hot Canaries; Random Wire Antenna Tuner For 6 Metres; Phone Patch For Radio Amateurs, Pt.2. January 1994: 3A 40V Variable Power Supply; Solar Panel Switching Regulator; Printer Status Indicator; Mini Drill Speed Controller; Stepper Motor Controller; Active Filter Design; Engine Management, Pt.4. February 1994: Build A 90-Second Message Recorder; 12-240VAC 200W Inverter; 0.5W Audio Amplifier; 3A 40V Adjustable Power Supply; Engine Management, Pt.5; Airbags In Cars – How They Work. In To Satellite TV, Pt.2. September 1991: Digital Altimeter For Gliders & Ultralights; Ultrasonic Switch For Mains Appliances; The Basics Of A/D & D/A Conversion; Plotting The Course Of Thunderstorms. October 1991: Build A Talking Voltmeter For Your PC, Pt.1; SteamSound Simulator For Model Railways Mk.II; Magnetic Field Strength Meter; Digital Altimeter For Gliders, Pt.2; Military Applications Of R/C Aircraft. November 1991: Colour TV Pattern Generator, Pt.1; A Junkbox 2-Valve Receiver; Flashing Alarm Light For Cars; Digital Altimeter For Gliders, Pt.3; Build A Talking Voltmeter For Your PC, Pt.2. December 1991: TV Transmitter For VCRs With UHF Modulators; Infrared Light Beam Relay; Colour TV Pattern Generator, Pt.2; Index To Volume 4. March 1992: TV Transmitter For VHF VCRs; Thermostatic Switch For Car Radiator Fans; Coping With Damaged Computer Directories; Valve Substitution In Vintage Radios. April 1992: IR Remote Control For Model Railroads; Differential Input Buffer For CROs; Understanding Computer Memory; Aligning Vintage Radio Receivers, Pt.1. March 1994: Intelligent IR Remote Controller; 50W (LM3876) Audio Amplifier Module; Level Crossing Detector For Model Railways; Voice Activated Switch For FM Microphones; Engine Management, Pt.6. April 1994: Sound & Lights For Model Railway Level Crossings; Discrete Dual Supply Voltage Regulator; Universal Stereo Preamplifier; Digital Water Tank Gauge; Engine Management, Pt.7. May 1994: Fast Charger For Nicad Batteries; Induction Balance Metal Locator; Multi-Channel Infrared Remote Control; Dual Electronic Dice; Simple Servo Driver Circuits; Engine Management, Pt.8. June 1994: 200W/350W Mosfet Amplifier Module; A Coolant Level Alarm For Your Car; 80-Metre AM/CW Transmitter For Amateurs; Converting Phono Inputs To Line Inputs; PC-Based Nicad Battery Monitor; Engine Management, Pt.9. July 1994: Build A 4-Bay Bow-Tie UHF TV Antenna; PreChamp 2-Transistor Preamplifier; Steam Train Whistle & Diesel Horn Simulator; 6V SLA Battery Charger; Electronic Engine Management, Pt.10. August 1994: High-Power Dimmer For Incandescent Lights; Microprocessor-Controlled Morse Keyer; Dual Diversity Tuner For FM Microphones, Pt.1; Nicad Zapper (For Resurrecting Nicad Batteries); Electronic Engine Management, Pt.11. June 1992: Multi-Station Headset Intercom, Pt.1; Video Switcher For Camcorders & VCRs; IR Remote Control For Model Railroads, Pt.3; 15-Watt 12-240V Inverter; A Look At Hard Disk Drives. September 1994: Automatic Discharger For Nicad Battery Packs; MiniVox Voice Operated Relay; Image Intensified Night Viewer; AM Radio For Weather Beacons; Dual Diversity Tuner For FM Microphones, Pt.2; Electronic Engine Management, Pt.12. October 1992: 2kW 24VDC - 240VAC Sinewave Inverter; Multi-Sector Home Burglar Alarm, Pt.2; Mini Amplifier For Personal Stereos; A Regulated Lead-Acid Battery Charger. October 1994: How Dolby Surround Sound Works; Dual Rail Variable Power Supply; Build A Talking Headlight Reminder; Electronic Ballast For Fluorescent Lights; Electronic Engine Management, Pt.13. June 1990: Multi-Sector Home Burglar Alarm; Build A Low-Noise Universal Stereo Preamplifier; Load Protector For Power Supplies. February 1993: Three Projects For Model Railroads; Low Fuel Indicator For Cars; Audio Level/VU Meter (LED Readout); An Electronic Cockroach; 2kW 24VDC To 240VAC Sinewave Inverter, Pt.5. November 1994: Dry Cell Battery Rejuvenator; Novel Alphanumeric Clock; 80-Metre DSB Amateur Transmitter; Twin-Cell Nicad Discharger (See May 1993); How To Plot Patterns Direct to PC Boards. July 1990: Digital Sine/Square Generator, Pt.1 (covers 0-500kHz); Burglar Alarm Keypad & Combination Lock; Build A Simple Electronic Die; A Low-Cost Dual Power Supply. March 1993: Solar Charger For 12V Batteries; Alarm-Triggered Security Camera; Reaction Trainer; Audio Mixer for Camcorders; A 24-Hour Sidereal Clock For Astronomers. December 1994: Easy-To-Build Car Burglar Alarm; Three-Spot Low Distortion Sinewave Oscillator; Clifford – A Pesky Electronic Cricket; Remote Control System for Models, Pt.1; Index to Vol.7. August 1990: High Stability UHF Remote Transmitter; Universal Safety Timer For Mains Appliances (9 Minutes); Horace The Electronic Cricket; Digital Sine/Square Generator, Pt.2. April 1993: Solar-Powered Electric Fence; Audio Power Meter; Three-Function Home Weather Station; 12VDC To 70VDC Converter; Digital Clock With Battery Back-Up. January 1995: Sun Tracker For Solar Panels; Battery Saver For Torches; Dolby Pro-Logic Surround Sound Decoder, Pt.2; Dual Channel UHF Remote Control; Stereo Microphone Pre­amp­lifier. September 1990: A Low-Cost 3-Digit Counter Module; Build A Simple Shortwave Converter For The 2-Metre Band; The Care & Feeding Of Nicad Battery Packs (Getting The Most From Nicad Batteries). June 1993: AM Radio Trainer, Pt.1; Remote Control For The Woofer Stopper; Digital Voltmeter For Cars; Windows-Based Logic Analyser. February 1995: 2 x 50W Stereo Amplifier Module; Digital Effects Unit For Musicians; 6-Channel Thermometer With LCD Readout; Wide Range Electrostatic Loudspeakers, Pt.1; Oil Change Timer For Cars; Remote Control System For Models, Pt.2. March 1990: Delay Unit For Automatic Antennas; Workout Timer For Aerobics Classes; 16-Channel Mixing Desk, Pt.2; Using The UC3906 SLA Battery Charger IC. April 1990: Dual Tracking ±50V Power Supply; Voice-Operated Switch With Delayed Audio; 16-Channel Mixing Desk, Pt.3; Active CW Filter. October 1990: The Dangers of PCBs; Low-Cost Siren For Burglar Alarms; Dimming Controls For The Discolight; Surfsound Simulator; DC Offset For DMMs; NE602 Converter Circuits. November 1990: Connecting Two TV Sets To One VCR; Build An Egg Timer; Low-Cost Model Train Controller; 1.5V To 9V DC Converter; Introduction To Digital Electronics; A 6-Metre Amateur Transmitter. January 1991: Fast Charger For Nicad Batteries, Pt.1; Have Fun With The Fruit Machine (Simple Poker Machine); Build A Two-Tone Alarm Module; The Dangers of Servicing Microwave Ovens. March 1991: Transistor Beta Tester Mk.2; A Synthesised AM Stereo Tuner, Pt.2; Multi-Purpose I/O Board For PC-Compatibles; Universal Wideband RF Preamplifier For Amateur Radio & TV. May 1991: 13.5V 25A Power Supply For Transceivers; Stereo Audio Expander; Fluorescent Light Simulator For Model Railways; How To Install Multiple TV Outlets, Pt.1. July 1991: Loudspeaker Protector For Stereo Amplifiers; 4-Channel Lighting Desk, Pt.2; How To Install Multiple TV Outlets, Pt.2; Tuning July 1993: Single Chip Message Recorder; Light Beam Relay Extender; AM Radio Trainer, Pt.2; Quiz Game Adjudicator; Windows-Based Logic Analyser, Pt.2; Antenna Tuners – Why They Are Useful. August 1993: Low-Cost Colour Video Fader; 60-LED Brake Light Array; Microprocessor-Based Sidereal Clock; Satellites & Their Orbits. September 1993: Automatic Nicad Battery Charger/Discharger; Stereo Preamplifier With IR Remote Control, Pt.1; In-Circuit Transistor Tester; +5V to ±15V DC Converter; Remote-Controlled Cockroach. October 1993: Courtesy Light Switch-Off Timer For Cars; Wireless Microphone For Musicians; Stereo Preamplifier With IR Remote Control, Pt.2; Electronic Engine Management, Pt.1. November 1993: High Efficiency Inverter For Fluorescent Tubes; Stereo Preamplifier With IR Remote Control, Pt.3; Siren Sound Generator; Engine Management, Pt.2; Experiments For Games Cards. December 1993: Remote Controller For Garage Doors; Build A LED Stroboscope; Build A 25W Audio Amplifier Module; A 1-Chip Melody Generator; Engine Management, Pt.3; Index To Volume 6. March 1995: 2 x 50W Stereo Amplifier, Pt.1; Subcarrier Decoder For FM Receivers; Wide Range Electrostatic Loudspeakers, Pt.2; IR Illuminator For CCD Cameras; Remote Control System For Models, Pt.3. April 1995: FM Radio Trainer, Pt.1; Photographic Timer For Dark­ rooms; Balanced Microphone Preamp. & Line Filter; 50W/Channel Stereo Amplifier, Pt.2; Wide Range Electrostatic Loudspeakers, Pt.3; 8-Channel Decoder For Radio Remote Control. May 1995: Build A Guitar Headphone Amplifier; FM Radio Trainer, Pt.2; Transistor/Mosfet Tester For DMMs; A 16-Channel Decoder For Radio Remote Control; Introduction to Satellite TV. June 1995: Build A Satellite TV Receiver; Train Detector For Model Railways; 1W Audio Amplifier Trainer; Low-Cost Video Security System; Multi-Channel Radio Control Transmitter For Models, Pt.1. July 1995: Electric Fence Controller; How To Run Two Trains On A Single Track (Incl. Lights & Sound); Setting Up A Satellite TV Ground 10% OF F SUBSCR TO IB OR IF Y ERS Please send the following back issues:      ____________________________________________________________ 10 O OU BUY R MORE Please send the following back issues: ORDER FORM Enclosed is my cheque/money order for $­______or please debit my: ❏ Bankcard ❏ Visa Card ❏ Master Card Card No. Signature ___________________________ Card expiry date_____ /______ Name ______________________________ Phone No (___) ____________ PLEASE PRINT Street ______________________________________________________ Suburb/town _______________________________ Postcode ___________ 88  Silicon Chip Note: prices include postage & packing Australia ....................... $A7.70 (incl. GST) Overseas (airmail) ............................ $A10 Detach and mail to: Silicon Chip Publications, PO Box 139, Collaroy, NSW, Australia 2097. Or call (02) 9979 5644 & quote your credit card details or fax the details to (02) 9979 6503. Email: silchip<at>siliconchip.com.au www.siliconchip.com.au Station; Build A Reliable Door Minder. Motor Cards; Understanding Electric Lighting Pt.2; Index To Vol.10. to 40V) Pt.1; CD Compressor For Cars Or The Home. August 1995: Fuel Injector Monitor For Cars; Gain Controlled Microphone Preamp; Audio Lab PC-Controlled Test Instrument, Pt.1; How To Identify IDE Hard Disk Drive Parameters. January 1998: Build Your Own 4-Channel Lightshow, Pt.1 (runs off 12VDC or 12VAC); Command Control System For Model Railways, Pt.1; Pan Controller For CCD Cameras. February 1998: Multi-Purpose Fast Battery Charger, Pt.1; Telephone Exchange Simulator For Testing; Command Control System For Model Railways, Pt.2; Build Your Own 4-Channel Lightshow, Pt.2. July 2000: A Moving Message Display; Compact Fluorescent Lamp Driver; El-Cheapo Musicians’ Lead Tester; Li’l Powerhouse Switchmode Power Supply (1.23V to 40V) Pt.2. September 1995: Railpower Mk.2 Walkaround Throttle For Model Railways, Pt.1; Keypad Combination Lock; The Vader Voice; Jacob’s Ladder Display; Audio Lab PC-Controlled Test Instrument, Pt.2. October 1995: 3-Way Loudspeaker System; Railpower Mk.2 Walkaround Throttle For Model Railways, Pt.2; Build A Fast Charger For Nicad Batteries. April 1998: Automatic Garage Door Opener, Pt.1; 40V 8A Adjustable Power Supply, Pt.1; PC-Controlled 0-30kHz Sinewave Generator; Build A Laser Light Show; Understanding Electric Lighting; Pt.6. November 1995: Mixture Display For Fuel Injected Cars; CB Trans­verter For The 80M Amateur Band, Pt.1; PIR Movement Detector. May 1998: Troubleshooting Your PC, Pt.1; Build A 3-LED Logic Probe; Automatic Garage Door Opener, Pt.2; Command Control For Model Railways, Pt.4; 40V 8A Adjustable Power Supply, Pt.2. December 1995: Engine Immobiliser; 5-Band Equaliser; CB Transverter For The 80M Amateur Band, Pt.2; Subwoofer Controller; Knock Sensing In Cars; Index To Volume 8. June 1998: Troubleshooting Your PC, Pt.2; Universal High Energy Ignition System; The Roadies’ Friend Cable Tester; Universal Stepper Motor Controller; Command Control For Model Railways, Pt.5. January 1996: Surround Sound Mixer & Decoder, Pt.1; Magnetic Card Reader; Build An Automatic Sprinkler Controller; IR Remote Control For The Railpower Mk.2; Recharging Nicad Batteries For Long Life. July 1998: Troubleshooting Your PC, Pt.3; 15-W/Ch Class-A Audio Amplifier, Pt.1; Simple Charger For 6V & 12V SLA Batteries; Auto­ matic Semiconductor Analyser; Understanding Electric Lighting, Pt.8. April 1996: Cheap Battery Refills For Mobile Phones; 125W Audio Amplifier Module; Knock Indicator For Leaded Petrol Engines; Multi-Channel Radio Control Transmitter; Pt.3. August 1998: Troubleshooting Your PC, Pt.4 (Adding Extra Memory); Simple I/O Card With Automatic Data Logging; Build A Beat Triggered Strobe; 15-W/Ch Class-A Stereo Amplifier, Pt.2. May 1996: Upgrading The CPU In Your PC; High Voltage Insulation Tester; Knightrider Bi-Directional LED Chaser; Simple Duplex Intercom Using Fibre Optic Cable; Cathode Ray Oscilloscopes, Pt.3. September 1998: Troubleshooting Your PC, Pt.5; A Blocked Air-Filter Alarm; Waa-Waa Pedal For Guitars; Jacob’s Ladder; Gear Change Indicator For Cars; Capacity Indicator For Rechargeable Batteries. June 1996: BassBox CAD Loudspeaker Software Reviewed; Stereo Simulator (uses delay chip); Rope Light Chaser; Low Ohms Tester For Your DMM; Automatic 10A Battery Charger. October 1998: Lab Quality AC Millivoltmeter, Pt.1; PC-Controlled Stress-O-Meter; Versatile Electronic Guitar Limiter; 12V Trickle Charger For Float Conditions; Adding An External Battery Pack To Your Flashgun. July 1996: Build A VGA Digital Oscilloscope, Pt.1; Remote Control Extender For VCRs; 2A SLA Battery Charger; 3-Band Parametric Equaliser; Single Channel 8-Bit Data Logger. August 1996: Introduction to IGBTs; Electronic Starter For Fluores­cent Lamps; VGA Oscilloscope, Pt.2; 350W Amplifier Module; Masthead Amplifier For TV & FM; Cathode Ray Oscilloscopes, Pt.4. September 1996: VGA Oscilloscope, Pt.3; IR Stereo Headphone Link, Pt.1; High Quality PA Loudspeaker; 3-Band HF Amateur Radio Receiver; Cathode Ray Oscilloscopes, Pt.5. October 1996: Send Video Signals Over Twisted Pair Cable; Power Control With A Light Dimmer; 600W DC-DC Converter For Car Hifi Systems, Pt.1; IR Stereo Headphone Link, Pt.2; Build A Multi-Media Sound System, Pt.1; Multi-Channel Radio Control Transmitter, Pt.8. November 1998: The Christmas Star; A Turbo Timer For Cars; Build A Poker Machine, Pt.1; FM Transmitter For Musicians; Lab Quality AC Millivoltmeter, Pt.2; Improving AM Radio Reception, Pt.1. December 1998: Engine Immobiliser Mk.2; Thermocouple Adaptor For DMMs; Regulated 12V DC Plugpack; Build A Poker Machine, Pt.2; Improving AM Radio Reception, Pt.2; Mixer Module For F3B Gliders. January 1999: High-Voltage Megohm Tester; Getting Started With BASIC Stamp; LED Bargraph Ammeter For Cars; Keypad Engine Immobiliser; Improving AM Radio Reception, Pt.3. August 2000: Build A Theremin For Really Eeerie Sounds; Come In Spinner (writes messages in “thin-air”); Proximity Switch For 240VAC Lamps; Structured Cabling For Computer Networks. September 2000: Build A Swimming Pool Alarm; An 8-Channel PC Relay Board; Fuel Mixture Display For Cars, Pt.1; Protoboards – The Easy Way Into Electronics, Pt.1; Cybug The Solar Fly. October 2000: Guitar Jammer For Practice & Jam Sessions; Booze Buster Breath Tester; A Wand-Mounted Inspection Camera; Installing A Free-Air Subwoofer In Your Car; Fuel Mixture Display For Cars, Pt.2. November 2000: Santa & Rudolf Chrissie Display; 2-Channel Guitar Preamplifier, Pt.1; Message Bank & Missed Call Alert; Electronic Thermostat; Protoboards – The Easy Way Into Electronics, Pt.3. December 2000: Home Networking For Shared Internet Access; Build A Bright-White LED Torch; 2-Channel Guitar Preamplifier, Pt.2 (Digital Reverb); Driving An LCD From The Parallel Port; Build A Morse Clock; Protoboards – The Easy Way Into Electronics, Pt.4; Index To Vol.13. January 2001: How To Transfer LPs & Tapes To CD; The LP Doctor – Clean Up Clicks & Pops, Pt.1; Arbitrary Waveform Generator; 2-Channel Guitar Preamplifier, Pt.3; PIC Programmer & TestBed. February 2001: How To Observe Meteors Using Junked Gear; An Easy Way To Make PC Boards; L’il Pulser Train Controller; Midi-Mate – A MIDI Interface For PCs; Build The Bass Blazer; 2-Metre Elevated Groundplane Antenna; The LP Doctor – Clean Up Clicks & Pops, Pt.2. March 2001: Making Photo Resist PC Boards; Big-Digit 12/24 Hour Clock; Parallel Port PIC Programmer & Checkerboard; Protoboards – The Easy Way Into Electronics, Pt.5; A Simple MIDI Expansion Box. April 2001: A GPS Module For Your PC; Dr Video – An Easy-To-Build Video Stabiliser; Tremolo Unit For Musicians; Minimitter FM Stereo Transmitter; Intelligent Nicad Battery Charger. May 2001: Powerful 12V Mini Stereo Amplifier; Two White-LED Torches To Build; PowerPak – A Multi-Voltage Power Supply; Using Linux To Share An Internet Connection, Pt.1; Tweaking Windows With TweakUI. March 1999: Getting Started With Linux; Pt.1; Build A Digital Anemometer; Simple DIY PIC Programmer; Easy-To-Build Audio Compressor; Low Distortion Audio Signal Generator, Pt.2. June 2001: Fast Universal Battery Charger, Pt.1; Phonome – Call, Listen In & Switch Devices On & Off; L’il Snooper – A Low-Cost Automatic Camera Switcher; Using Linux To Share An Internet Connection, Pt.2; A PC To Die For, Pt.1 (Building Your Own PC). November 1996: 8-Channel Stereo Mixer, Pt.1; Low-Cost Fluorescent Light Inverter; Repairing Domestic Light Dimmers; Multi-Media Sound System, Pt.2; 600W DC-DC Converter For Car Hifi Systems, Pt.2. April 1999: Getting Started With Linux; Pt.2; High-Power Electric Fence Controller; Bass Cube Subwoofer; Programmable Thermostat/ Thermometer; Build An Infrared Sentry; Rev Limiter For Cars. July 2001: The HeartMate Heart Rate Monitor; Do Not Disturb Tele­phone Timer; Pic-Toc – A Simple Alarm Clock; Fast Universal Battery Charger, Pt.2; A PC To Die For, Pt.2; Backing Up Your Email. December 1996: Active Filter Cleans Up Your CW Reception; A Fast Clock For Railway Modellers; Laser Pistol & Electronic Target; Build A Sound Level Meter; 8-Channel Stereo Mixer, Pt.2; Index To Vol.9. May 1999: The Line Dancer Robot; An X-Y Table With Stepper Motor Control, Pt.1; Three Electric Fence Testers; Heart Of LEDs; Build A Carbon Monoxide Alarm; Getting Started With Linux; Pt.3. January 1997: How To Network Your PC; Control Panel For Multiple Smoke Alarms, Pt.1; Build A Pink Noise Source; Computer Controlled Dual Power Supply, Pt.1; Digi-Temp Monitors Eight Temperatures. June 1999: FM Radio Tuner Card For PCs; X-Y Table With Stepper Motor Control, Pt.2; Programmable Ignition Timing Module For Cars, Pt.1; Hard Disk Drive Upgrades Without Reinstalling Software? August 2001: Direct Injection Box For Musicians; Build A 200W Mosfet Amplifier Module; Headlight Reminder For Cars; 40MHz 6-Digit Frequency Counter Module; A PC To Die For, Pt.3; Using Linux To Share An Internet Connection, Pt.3. February 1997: PC-Con­trolled Moving Message Display; Computer Controlled Dual Power Supply, Pt.2; Alert-A-Phone Loud Sounding Telephone Alarm; Control Panel For Multiple Smoke Alarms, Pt.2. July 1999: Build A Dog Silencer; 10µH to 19.99mH Inductance Meter; Build An Audio-Video Transmitter; Programmable Ignition Timing Module For Cars, Pt.2; XYZ Table With Stepper Motor Control, Pt.3. March 1997: Driving A Computer By Remote Control; Plastic Power PA Amplifier (175W); Signalling & Lighting For Model Railways; Build A Jumbo LED Clock; Cathode Ray Oscilloscopes, Pt.7. August 1999: Remote Modem Controller; Daytime Running Lights For Cars; Build A PC Monitor Checker; Switching Temperature Controller; XYZ Table With Stepper Motor Control, Pt.4; Electric Lighting, Pt.14. April 1997: Simple Timer With No ICs; Digital Voltmeter For Cars; Loudspeaker Protector For Stereo Amplifiers; Model Train Controller; A Look At Signal Tracing; Pt.1; Cathode Ray Oscilloscopes, Pt.8. September 1999: Autonomouse The Robot, Pt.1; Voice Direct Speech Recognition Module; Digital Electrolytic Capacitance Meter; XYZ Table With Stepper Motor Control, Pt.5; Peltier-Powered Can Cooler. May 1997: Neon Tube Modulator For Light Systems; Traffic Lights For A Model Intersection; The Spacewriter – It Writes Messages In Thin Air; A Look At Signal Tracing; Pt.2; Cathode Ray Oscilloscopes, Pt.9. October 1999: Build The Railpower Model Train Controller, Pt.1; Semiconductor Curve Tracer; Autonomouse The Robot, Pt.2; XYZ Table With Stepper Motor Control, Pt.6; Introducing Home Theatre. June 1997: PC-Controlled Thermometer/Thermostat; TV Pattern Generator, Pt.1; Audio/RF Signal Tracer; High-Current Speed Controller For 12V/24V Motors; Manual Control Circuit For Stepper Motors. November 1999: Setting Up An Email Server; Speed Alarm For Cars, Pt.1; LED Christmas Tree; Intercom Station Expander; Foldback Loudspeaker System; Railpower Model Train Controller, Pt.2. July 1997: Infrared Remote Volume Control; A Flexible Interface Card For PCs; Points Controller For Model Railways; Colour TV Pattern Generator, Pt.2; An In-Line Mixer For Radio Control Receivers. December 1999: Solar Panel Regulator; PC Powerhouse (gives +12V, +9V, +6V & +5V rails); Fortune Finder Metal Locator; Speed Alarm For Cars, Pt.2; Railpower Model Train Controller, Pt.3; Index To Vol.12. August 1997: The Bass Barrel Subwoofer; 500 Watt Audio Power Amplifier Module; A TENs Unit For Pain Relief; Addressable PC Card For Stepper Motor Control; Remote Controlled Gates For Your Home. January 2000: Spring Reverberation Module; An Audio-Video Test Generator; Build The Picman Programmable Robot; A Parallel Port Interface Card; Off-Hook Indicator For Telephone Lines. September 1997: Multi-Spark Capacitor Discharge Ignition; 500W Audio Power Amplifier, Pt.2; A Video Security System For Your Home; PC Card For Controlling Two Stepper Motors; HiFi On A Budget. February 2000: Multi-Sector Sprinkler Controller; A Digital Voltmeter For Your Car; An Ultrasonic Parking Radar; Build A Safety Switch Checker; Build A Sine/Square Wave Oscillator. October 1997: Build A 5-Digit Tachometer; Add Central Locking To Your Car; PC-Controlled 6-Channel Voltmeter; 500W Audio Power Amplifier, Pt.3; Customising The Windows 95 Start Menu. March 2000: Resurrecting An Old Computer; Low Distortion 100W Amplifier Module, Pt.1; Electronic Wind Vane With 16-LED Display; Glowplug Driver For Powered Models; The OzTrip Car Computer, Pt.1. November 1997: Heavy Duty 10A 240VAC Motor Speed Controller; Easy-To-Use Cable & Wiring Tester; Build A Musical Doorbell; Replacing Foam Speaker Surrounds; Understanding Electric Lighting Pt.1. May 2000: Ultra-LD Stereo Amplifier, Pt.2; Build A LED Dice (With PIC Microcontroller); Low-Cost AT Keyboard Translator (Converts IBM Scan-Codes To ASCII); 50A Motor Speed Controller For Models. December 1997: Speed Alarm For Cars; 2-Axis Robot With Gripper; Stepper Motor Driver With Onboard Buffer; Power Supply For Stepper June 2000: Automatic Rain Gauge With Digital Readout; Parallel Port VHF FM Receiver; Li’l Powerhouse Switchmode Power Supply (1.23V www.siliconchip.com.au September 2001: Making MP3s – Rippers & Encoders; Build Your Own MP3 Jukebox, Pt.1; PC-Controlled Mains Switch; Personal Noise Source For Tinnitus Sufferers; The Sooper Snooper Directional Microphone; Using Linux To Share An Internet Connection, Pt.4. October 2001: A Video Microscope From Scrounged Parts; Build Your Own MP3 Jukebox, Pt.2; Super-Sensitive Body Detector; An Automotive Thermometer; Programming Adapter For Atmel Microcomputers. November 2001: Ultra-LD 100W RMS/Channel Stereo Amplifier, Pt.1; Neon Tube Modulator For Cars; Low-Cost Audio/Video Distribution Amplifier; Short Message Recorder Player; Computer Tips. December 2001: A Look At Windows XP; Build A PC Infrared Transceiver; Ultra-LD 100W RMS/Ch Stereo Amplifier, Pt.2; Pardy Lights – An Intriguing Colour Display; PIC Fun – Learning About Micros. January 2002: Touch And/Or Remote-Controlled Light Dimmer, Pt.1; A Cheap ’n’Easy Motorbike Alarm; 100W RMS/Channel Stereo Amplifier, Pt.3; Build A Raucous Alarm; Tracking Down Computer Software Problems; Electric Power Steering; FAQs On The MP3 Jukebox. February 2002: 10-Channel IR Remote Control Receiver; 2.4GHz High-Power Audio-Video Link; Assemble Your Own 2-Way Tower Speakers; Touch And/Or Remote-Controlled Light Dimmer, Pt.2; Booting A PC Without A Keyboard; 4-Way Event Timer. March 2002: Mighty Midget Audio Amplifier Module; The Itsy-Bitsy USB Lamp; 6-Channel IR Remote Volume Control, Pt.1; RIAA Prea­ mplifier For Magnetic Cartridges; 12/24V Intelligent Solar Power Battery Charger; Generate Audio Tones Using Your PC’s Soundcard. PLEASE NOTE: November 1987 to March 1989, June 1989, August 1989, December 1989, May 1990, February 1991, June 1991, August 1991, January 1992, November 1992, December 1992, January 1993, May 1993, February 1996, March 1998 and February 1999 are now sold out. All other issues are presently in stock. For readers wanting articles from sold-out issues, we can supply photostat copes (or tear sheets) at $7.70 per article (includes p&p). When supplying photostat articles or back copes, we automatically supply any relevant notes & errata at no extra charge. A complete index to all articles published to date is available on floppy disk for $11 including p&p, or can be downloaded free from our web site: www.siliconchip.com.au May 2002  89 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 Substituting a 3-spring reverb unit Could you please advise if I could use a “Belton” 3-spring reverb unit in your module described in the January 2000 issue? If so, where would I be able to buy the PC board (014002000) from? (H. P., via email). • Whether or not you can use your 3-spring unit largely de­pends on its input and output impedances. As presented, our circuit drives an 8Ω input coil and the output impedance is 800Ω. If your unit broadly matches these figures or has higher impe­ dances, then you can probably make the circuit work. You can purchase the PC board from RCS Radio: www.cia.com.au/rcsradio LEDs flashing on mixture meter I have constructed the Fuel Mixture Display kit described in the “EFI Tech Special”. The kit is not functioning as it should, with lights buzzing left and right on idle at normal temperature. The red light stays on all the time. If I adjust the trimpot, the yellow light shows. What could be the fault in this situation? (E. B., via email). • There isn’t too much that can go 18V setting for Nicad discharger Looking at your Automatic Discharger for nicad battery packs in the September 1994 issue, is it possible to include an 18V range? I have an 18V cordless drill battery pack. What would I need to change or add? (H. P., via email). • Yes, you can use the Nicad Discharger to discharge an 18V battery pack. This pack comprises 15 cells and the 1.1V per cell voltage would be 16.5V. To add the necessary 18V switch position, you need to replace the 1.8kΩ resistor at the bottom of the 90  Silicon Chip wrong with this circuit. It seems that the IC is driving the LEDs from one extreme to the other as the yellow (rich) and red (lean) ones light with varia­tion of VR1. Check that there are no shorts between tracks on the PC board, by scraping between tracks with a sharp knife. Also check that there are no solder bridges between pins on IC1 by comparing the published pattern with the underside of your board. It is possible that the input at pin 5 has been damaged. It can be protected by connecting a .01µF capacitor between pin 5 and pin 4 and using a 100kΩ resistor in series with the input from the oxygen sensor. Altec Lansing re-cone kits available All those owners of Altec Lansing professional drivers (515s, 421/921, 418/918, 411, etc) who may have been told that genuine re-cone kits were no longer available, now that the Altec Lansing name has been sold to that computer speaker company, might be interested to know that there is a source of GENUINE parts in the USA at what are reasonable prices. I’ve recently imported 22 cone and coil sets for various types of Altec Lanvoltage divider with a 600Ω (560Ω plus 39Ω) resistor and a 1.2kΩ resistor, with the 1.2kΩ value going to ground. The junc­tion of the 1.2kΩ resistor and 600Ω resistor would be the new 18V battery position. Note that the LM358 is rated for a supply voltage of 32V and so it can be used here without change. Other components should also cope. The exception is the 27Ω 5W resistor which will glow red hot under reverse polarity connection with 18V applied. It would be best to replace this with a parallel combination of two 56Ω 5W resistors, one on top of the PC board and the other in parallel, on the underside of the board. sing drivers and they are as genuine as you could get; they even smell like the originals! The coils are wound on the original machinery that Altec used by a guy who used to work for them, while the cones are sourced from outside, to the original specifications. (Brad Sheagold, Collaroy, NSW. bwscdm<at> tech2U.com.au) Transistor-assisted ignition query I have a 1973 Mercedes 280S with carburettor and standard points/coil ignition. Did you ever publish an article on building a transistor-assisted ignition system, where the transistor carried the coil primary current and the points fed only a small current for the base circuit? I have already emailed your office for the two High Energy Ignition System articles described in 1998 and 1999 but the simple system mentioned above is suggested in the Bosch automotive book. (D. J., via email). • The High Energy Ignition System is a transistor-assisted system. A high voltage transistor does the switching while a current of about 250mA is switched by the points. The points current cannot be too small otherwise they tend to oil up and stop working. Hum on FM transmitter I recently bought the MiniMitter FM transmitter from Jay­car and after assembling and tuning it in, I’m getting a hum on the radio. I don’t notice it too much with music playing but I am using it as a baby monitor sometimes and was hoping for better results. I’ve tried it on two different radios and find the same problem. I’ve also tried moving the antennas around but that doesn’t help either. Do you suppose I’m transmitting too close (7-8m)? (J. R., Brisbane, Qld). • There should not be any evidence of hum when used with a signal source such as a CD player. The hum could www.siliconchip.com.au Tachometer for a Go-Kart I’ve recently purchased your tacho kit from Jaycar (Cat KC-5290) and would like some advice on modifying it for use on a Go-Kart. First, as a kart has no power supply, I would like to use a 9V battery and on/off switch rather than a 12V auto supply. Next is the connection to the kart’s ignition system, which has three wires to the motor and a fourth brown wire for a cut-out switch. They are as follows: Red – high voltage exciter input; Black – earth; Yellow – trigger. Could you please advise the correct connection from these to the tacho unit and the necessary component modifications to adapt it to a 9V battery. (S. B., via email). • You can operate the tachometer on 9V without changes to the circuit. Your Go-Kart appears to have a magneto ignition and would probably not drive the tachometer directly without some changes. You could try connecting the red wire from the magneto to the “ignition coil -ve” input on the tacho­meter. If this doesn’t work try the yellow trigger wire at the “low input” on the tachometer instead. Note that the 2.2µF capacitor at the anode of D1 may need to be removed from circuit for successful operation. ELAN Audio The Leading Australian Manufacturer of Professional Broadcast Audio Equipment Featured Product of the Month PC-BAL PCI Format Balancing Board Interface PC Sound Cards to Professional Systems Not only do we make the best range of Specialised Broadcast "On-Air" Mixers in Australia. . . We also make a range of General Audio Products for use by Radio Broadcasters, Recording Studios, Institutions etc. And we sell AKG and Denon Professional Audio Products be caused by expecting the transmitter to operate from very low signal level or from a high impedance. You do not say how the baby monitor circuitry is connected or how the microphone is amplified, but using a micro­phone could be the problem. Hum can also be evident if the FM tuner or radio is set to receive a subharmonic rather than the main fundamental frequency. Try tuning the receiver to another frequency for best signal. Also you may be getting interference from another off-air sta­tion which could cause the hum problem. In this case, retune both transmitter and receiver to a quieter part of the FM band. Control circuit for thermatic fans I have a Falcon EBII XR6. These models came with a belt-driven fan. I purchased the twin thermatic fans with shroud from an EF Falcon as the radiator is the same. I need to set up a switch somehow. I’m not wanting to use the Davies-Craig unit as I’m trying to get a factory look. I thought I could get something to work off the output of the temperature gauge in the dash but I can’t find something that will work. Any help would be gratefully appreciated. (R. W., via email). • Have a look at our article entitled “Thermostatic Switch For Car Radiator Fans” in the March 1992 issue. We can supply the issue for $7.70 including postage. Fuel mixture display for a hotrod I’ve built the Fuel Mixture Display kit (September & Octob­er 2000) which I brought from Dick Smith Electronics in New Zealand. The kit is going to For Technical Details and Professional Pricing Contact Elan Audio 2 Steel Crt South Guildford WA 6055 Phone 08 9277 3500 08 9478 2266 Fax email sales<at>elan.com.au WWW elan.com.au be used on my hotrod. However, I’m having problems locating the Bosch EGO probe you listed in the kit as being matched to the unit. The local Bosch agent said the part number is incorrect (LSM11 , 0258104002). Is the number correct or was there a mistake? Even if you can tell me what type of car the above probe is from it would be helpful. (J. B., Stratford, NZ). • The Bosch type number is correct. It is a sensor generally used for sensing exhaust smoke stacks, not necessarily MINI SUPER DRILL KIT IN HANDY CARRY CASE. SUPPLIED WITH DRILLBITS AND GRINDING ACCESSORIES $61.60 GST INC. www.siliconchip.com.au May 2002  91 Electric fence controller I have purchased the High Power Electric Fence Controller de­scribed in the April 1999 issue of SILICON CHIP. I put the kit together and ran it through both the tests. I got 340V on the first test and everything ran perfectly for about a minute on the second test, then everything went dead. I had a good spark in the test. I can now only get a maximum of 12-13V across D2 and earth on the voltmeter when adjusting VR1. I have replaced both ICs and the zener diode, but to no avail. What in the automotive industry. The sensor can be purchased from Farnell (NZ 649 357 0646) but it is cheaper to get an EGO sensor (eg, as used in Ford and Holden 6-cylinder cars) from a wrecker’s yard. The Fuel Mixture Display operates successfully with most automotive sen­sors. Balance control for the Ultra-LD amplifier I note with interest that you have not provided for a balance control in the design of the Ultra-LD Amplifier de­scribed in the November 2001 to January 2002 issues. This a disappointing omission for me as I suffer from a slight hearing loss in one ear and the balance control, to some degree, com­ pen­sates for this. I wonder what would have been behind the decision not to include the control? (L. S., via email). • Most audiophile stereo amplifiers eliminate the balance control and the tone controls because they do degrade other component is likely to have failed? Is it likely to be in the DC-DC converter or the error amplifier? (C. R., via email). • Take out Triac1 and then check if you can get the correct voltage at diode D2. If so, the Triac has failed. If the voltage is still low, remove the 7µF 250V capacitor connection and again check for voltage. Having the correct voltage with the capacitor out is a sign that transformer T2 has a short and will need rewinding. If the voltage is still not correct, perhaps Q1 is shorted. Test this with a multimeter between Drain and Source. the perfor­mance. Balance controls also tend to be hard to obtain. If you wanted to put in a balance control you could do so using the same scheme as we employed in the 50W stereo amplifier published in the March & April 1995 issues. This used a single pole 12-position rotary switch and resistors. We can supply these back issues for $7.70 each including postage. Using the Sparkrite Hall Effect pickup I just purchased a high energy ignition kit (June 1998) from Dick Smith Electronics. I am using this kit with a Sparkrite Hall Effect pickup which I purchased secondhand. This Hall Effect pickup is over 10 years old and I know it was used with one of the first versions of the High Energy Ignition over 10 years ago. I would just like to ask if you know how to connect this Hall Effect sensor to the current High Energy Ignition? The Hall Effect pickup only has two connections, which is a problem as the High Energy Ignition requires three connections to the Hall Effect sensor. I also didn’t get the instructions with the Hall Effect sensor so I don’t know what’s going on. Also I found out that the Sparkrite sensor can’t be used with V8s. This is a problem as I bought it to put on my Holden V8. Would it be possible to modify the sensor to fit a Bosch V8 distributor? I can make up my own mounting plates/brackets and was thinking about setting it up like the Siemens HKZ101 Hall Effect sensor, with a stationary magnet and using a Bosch Vane. Will this work? I would get a Siemens sensor but they are no longer available. Would you know of any other Hall Effect sensors suit­able for my application which are currently available? (S. N., via email). • The Sparkrite Hall sensor is only a one-wire unit with the case connection for earth. The wire output is actually connected directly to the supply for the Hall Effect sensor, with a 330Ω resistor between the supply and output. Connection to the 12V supply requires a resistor in series so that the output terminal will pull the Hall supply lower than normal. The output voltage does not swing fully from 12V to ground and is not suitable for the High Energy Ignition circuit. You could experiment with the resistors at transistor Q2 so that the Sparkrite sensor will operate the circuit. Using a 330Ω pullup resistor from the Hall Effect sensor terminal to the 12V supply will give an output swing from about 5V down to 3V with magnets passing the sensor. Use a 1kΩ resistor at Q2’s base to emitter. This value may need to be determined experimentally using a trimpot. As you state, the Sparkrite sensor is not suitable for 8-cylinder engines as 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. 92  Silicon Chip www.siliconchip.com.au Questions on guitar preamp I have a few questions regarding the guitar preamp featured in the November 2000 issue of SILICON CHIP, sold in kit form by Jaycar Electronics, Cat KC-5303. Can you please tell me: (1) To connect the second channel’s PC board to the main board, do I need to connect the points marked ‘TP1’? If not, what are they for? (2) All of the connection points on the back (FX send/rtn, balanced out & unbalanced out) have a ground point, except for the ‘line input’ point. Should this line be grounded somewhere? (3) On the schematic for the power supply, where the leads are earthed to the chassis, a 0.47µF capacitor is shown going from the chassis earth point to a regular earth point. Where should this capacitor go to earth? (P. M., via email). • Do not interconnect the TP1 points on the first and second channels. These are test points to adjust the offset in each amplifier (IC2) using trimpot VR7. The line input shares the unbalanced output ground point. The 0.47µF capacitor connects from signal ground to chassis as shown in Fig.1 of the January 2001 issue of SILICON CHIP. they did not make a rotating magnet assembly for these distributors. The HKZ101 Hall sensor is still available from Jaycar (Cat ZD-1900) but the Bosch rotating vane is not available. This would need to be manufactured using a steel cup-shaped vane with eight slots spaced 45° apart. This vane can be glued to the existing rotor button using high temperature (120°C or more ) epoxy or similar. models available but they are in the “cost you an arm and a leg” price range and I am sure such a design would be greatly appreciated by all of us dads who spend half of our lives repairing our son’s R/C cars. R. H., Yatala Vale, SA). • We described a 50A speed control for R/C cars in the May 2000 issue. We can supply this issue for $7.70 including postage. Matching amplifiers to speakers Converting a UPS to use as inverter I am concerned about possible damage to an amplifier when more ‘powerful’ speakers are connected. For example, if 150W speakers are connected to a 100W amplifier, is there the pos­sibility of the amplifier being damaged? Thinking along the lines of source/ load matching as in antennas it seems to me that, provided the amp/speaker matching is correct, there should be no problem. (N. D., Carine, WA) • There is no chance of damage by connecting 150W speakers to a 100W amplifier. Speakers are passive transducers. Provided their impedance is within normal limits, no damage will result. I have a Chloride 12V computer UPS I want to utilise as an inverter but it needs 240V to be on at the moment of a blackout before the 12V inverter will work. This is of no value to me in the fieldwhen trying to operate a drill or grinder. How can I fix it? (R. M., via email). • Without knowing anything about the circuit, we cannot sug­gest a modification. However, it probably has a stepdown trans­former and rectifier to produce a DC voltage from the mains. When that disappears, the inverter kicks in. You need to measure that voltage and then alter the monitoring circuit to disable it. Speed controller for R/C cars I would like to suggest a project for an electronic speed controller for radio controlled cars. There are commercial www.siliconchip.com.au Notes & Errata Mighty Midget 50W Module, March 2002: the list of parts for the capacitors should be as follows: 2 4700µF 16VW, 1 2200µF 16VW, 2 0.22µF MKT, SC 4 0.1µF MKT. SMART FASTCHARGERS® 2 NEW MODELS WITH OPTIONS TO SUIT YOUR NEEDS & BUDGET Now with 240V AC + 12V DC operation PLUS fully automatic voltage detection Use these REFLEX® chargers for all your Nicads and NIMH batteries: Power tools  Torches  Radio equip.  Mobile phones  Video cameras  Field test instruments  RC models incl. indoor flight  Laptops  Photographic equip.  Toys  Others  Rugged, compact and very portable. Designed for maximum battery capacity and longest battery life. AVOIDS THE WELL KNOWN MEMORY EFFECT. SAVES MONEY & TIME: Restore most Nicads with memory effect to capacity. Recover batteries with very low remaining voltage. CHARGES VERY FAST plus ELIMINATES THE NEED TO DISCHARGE: charge standard batteries in minimum 3 min., max. 1 to 4 hrs, depending on mA/h rating. Partially empty batteries are just topped up. Batteries always remain cool; this increases the total battery life and also the battery’s reliability. DESIGNED AND MADE IN AUSTRALIA For a FREE, detailed technical description please Ph (03) 6492 1368; Fax (03) 6492 1329; or email: smartfastchargers<at>bigpond.com 2567 Wilmot Rd., Devonport, TAS 7310 P.C.B. Makers ! • • • • • • • • If you need: P.C.B. High Speed Drill 3M Scotchmark Laser Labels P.C.B. Material – Negative or Positive acting Light Box – Single or Double Sided – Large or Small Etch Tank – Bubble Electronic Components and Equipment for TAFEs, Colleges and Schools Prompt and Economical DeliverySC FREE ADVICE ON ANY OF OUR PRODUCTS FROM DEDICATED PEOPLE WITH HANDS-ON EXPERIENCE We now stock Hawera Carbide Tool Bits KALEX 40 Wallis Ave E. Ivanhoe 3079 Ph (03) 9497 3422 FAX (03) 9499 2381 ALL MAJOR CREDIT CARDS ACCEPTED May 2002  93 MARKET CENTRE Cash in your surplus gear. Advertise it here in Silicon Chip. CLASSIFIED ADVERTISING RATES Advertising rates for this page: Classified ads: $20.00 (incl. GST) for up to 20 words plus 66 cents for each additional word. Display ads: $33.00 (incl. GST) per column centimetre (max. 10cm). Closing date: five weeks prior to month of sale. To run your classified ad, print it clearly in the space below or on a separate sheet of paper, fill out the form & send it with your cheque or credit card details to: Silicon Chip Classifieds, PO Box 139, Collaroy, NSW 2097. Or fax the details to (02) 9979 6503. Taxation Invoice ABN 49 003 205 490 _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ Enclosed is my cheque/money order for $­__________ or please debit my ❏ Bankcard   ❏ Visa Card   ❏ Master Card Card No. Signature­­­­­­­­­­­­__________________________ Card expiry date______/______ Name ______________________________________________________ Street ______________________________________________________ Suburb/town ___________________________ Postcode______________ 94  Silicon Chip FOR SALE TELEPHONE EXCHANGE SIMULATOR: test equipment without the cost of telephone lines. Melb 9806 0110. http://www.alphalink.com.au/~zenere KITS KITS AND MORE KITS! Check ‘em out at www.ozitronics.com UNIVERSAL DEVICE PROGRAMMER: Low cost, high performance, 48-pin, works in DOS or Windows inc NT/2000. $1320. Universal EPROM programmer $429. Also adaptors, (E) EPROM, PIC, 8051 programmers, EPROM simulator and eraser. Dunfield C Compilers: Everything you need to develop C and ASM software for 68HC08, 6809, 68HC11, 68HC12, 68HC16, 8051/52, 8080/85, 8086, 8096 or AVR: $198 each. Demo disk available. ImageCraft C Compilers: 32-bit Windows IDE and compiler. For AVR, 68HC11, 68HC12. $396. Atmel Flash CPU Programmer: Handles the 89Cx051, 89C5x, 89Sxx in both DIP and PLCC44 and some AVR’s, most 8-pin EEPROMS. Includes socket for serial ISP cable. $220, $11 p&p. SOIC adaptors: 20 pin $99, 14 pin $93.50, 8 pin $88. Full details on web site. Credit cards accepted. GRANTRONICS PTY LTD, PO Box 275, Wentworthville 2145. (02) 9896 7150 or http://www.grantronics.com.au A NEW RANGE of European kits made by SMART KIT now available in Australia at www.q-mex.com.au RCS HAS MOVED to 41 Arlewis St, Chester Hill 2162 and is now open, with full production. Tel (02) 9738 0330; Fax 9738 0334. rcsradio<at>cia.com.au; www.cia.com.au/rcsradio PCBs MADE, ONE OR MANY. Low prices, hobbyists welcome. Sesame Elec­tronics (02) 9586 4771. sesame<at>internetezy.com.au; http:// members.tripod.com/~sesame_elec www.siliconchip.com.au Circuit Ideas Wanted Do you have a good circuit idea? If so, sketch it out, write a brief description of its operation & send it to us. Provided your idea is workable & original, we’ll publish it in Circuit Notebook & you’ll make some money. We pay up to $60 for a good circuit so send your idea to: Silicon Chip Publications, PO Box 139, Collaroy, NSW 2097. WEATHER STATIONS: Windspeed & direction, inside temperature, outside temperature & windchill. Records highs & lows with time and date as they occur. Optional rainfall and PC interface. Used by Government Departments, farmers, pilots, and weather enthusiasts. Other models with barometric pressure, humidity, dew point, solar radiation, UV, leaf wetness, etc. Just phone, fax or write for our FREE catalogue and price list. Solar Flair/Ecowatch phone: (03) 9761 7040; fax: (03) 9761 7050; Unit 5, 17 Southfork Drive, Kilsyth, Vic. 3137. ABN 63 006 399 480. Audio, Video, S-Video and VGA cables distribution amps, switchers, adaptors, price lists at: www.questronix.com.au CCTV EQUIPMENT: Best prices best-tange Cameras from $34. Digital PC Video Recording Dial In/Out Software & much more. www.allthings.com.au CONTROL ANYTHING BY REMOTE CONTROL. We supply a 14 button remote control unit and a decoder IC for all 14 buttons. You use these active low outputs in your own project. Kit 92 at www.ozitronics.com. Contact Frank Crivelli at (03) 9434 3806. $22.00 plus postage and GST. VALVE RADIOS, valves, testing equipment and speakers. Syd 9771 6116. SATELLITE DISH ACTUATOR $150 incl GST. Inf. Rem. Positioner $145 incl GST. Plus freight. Electrophase Ph/Fax 02 4274 9222 ephase<at>ihug.com.au MOTORBIKE ALARM KITS $49.50 + $5.00 P&H. Includes programmed microprocessor, quality sensor, PCB, heatshrink, miscellaneous and tilt switch. Details at: www.users.tpg.com. au/micwen www.siliconchip.com.au Professional A/V Accessories • Variety of A/V selectors • Hard-to-find A/V cables • • • • Video-editing New New New Mark22-SM Slimline Mini FM R/C Receiver VHS/Photos to DVD Notebook computers Computer peripherals • Best value on Home Theatre Alltac International P/L, Suite 230, 813 Pacific Hwy, Chatswood, NSW 2067. Phone: 9411 3088 Fax: 9412 1855 www.alltac.com.au • • • • • 6 Channels 10kHz frequency separation Size: 55 x 23 x 20mm Weight: 25gm Modular Construction Price: $A129.50 with crystal Electronics Satellite TV Reception International satellite TV reception in your home is now affordable. Send for your free info pack containing equipment catalog, satellite lists, etc or call for appointment to view. We can display all satellites from 76.5° to 180°. AV-COMM P/L, 24/9 Powells Rd, Brookvale, NSW 2100. Tel: 02 9939 4377 or 9939 4378. Fax: 9939 4376; www.avcomm.com.au PO Box 580, Riverwood, NSW 2210. Ph/Fax (02) 9533 3517 email: youngbob<at>silvertone.com.au Website: www.silvertone.com.au Need prototype PC boards? We have the solutions – we print electronics! Four-day turnaround, less if urgent; Artwork from your own positive or file; Through hole plating; Prompt postal service; 29 years technical experience; Inexpensive; Superb quality. Printed Electronics, 12A Aristoc Rd, Glen Waverley, Vic 3150. Phone: (03) 9545 3722; Fax: (03) 9545 3561 Call Mike Lynch and check us out! We are the best for low cost, small runs. Positions At Jaycar We are often looking for enthusiastic staff for positions in our retail stores and head office at Silverwater in Sydney. A genuine interest in electronics is a necessity. Phone 02 9741 8555 for current vacancies. SOLUTIONS IN A BOX For price list, write Acetronics 5/32 Seton Rd, Moorebank 2170 or email acetronics<at>acetronics.com.au Phone (02) 9600 6832 www.acetronics.com.au HEWLETT PACKARD STORAGE OSCILLOSCOPE Model 1744A (100MHz) (with manual) $400.00. Hi-Tec Electronics, PO Box 10, Coniston, NSW 2500. (02) 4868 2099 (all hours). USB KITS: DDS-HF Generator, 4-channel Voltmeter, I/O Relay Card. Also Digital Oscilloscope and Temperature Loggers. www.ar.com.au/~softmark Affordable Web Hosting From $11/Month, includes POP/WEB email. Other plans available. Servers In A Box. sales<at>siab.com.au  www.siab.com.au Phone (02) 4341 6555 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 May 2002  95 Silicon Chip Binders Keep your copies safe, secure and always available with SILICON CHIP binders: they’re cheap insurance!  Heavy board covers with 2-tone green vinyl covering REAL VALUE AT $12.95 PLUS P &P Advertising Index Acetronics....................................95 Alltac International.......................95 Altronics................................. 68-70 Allthings Sales & Services...........95 Av-Comm Pty Ltd.........................95 Dick Smith Electronics........... 20-23  Each binder holds up to 14 issues so that you can include catalogs eLabtronics..................................72 Elan Audio....................................91 Evatco..........................................81  SILICON CHIP logo printed in gold-coloured lettering on spine & cover Grantronics..................................94 Harbuch Electronics.....................71 Price: $12.95 (includes GST) plus $5.50 p&p each (available Aust. only). Price includes GST. Hy-Q International........................83 Instant PCBs................................95 Order by phoning (02) 9979 5644 & quoting your credit card number; or fax the details to (02) 9979 6503; or mail your order with cheque or credit card details to Silicon Chip Publications, PO Box 139, Collaroy, NSW 2097. Jaycar ................................... 45-52 JED Microprocessors..............37,73 Kalex............................................93 Microgram Computers...................3 MicroZed Computers...................73 Oatley Electronics........................15 Subscribe & Get this FREE!* Ozitronics.....................................95 Printed Electronics...................... 95 Procopy........................................73 Polykom................................ 4-6,43 Quest Electronics.........................73 *Australia only. Offer valid only while stocks last. RCS Radio...................................94 THAT’S RIGHT – buy a 1- or 2-year subscription to SILICON CHIP magazine and we’ll mail you a free copy of “Computer Omnibus”. RF Probes....................................73 RTN..............................................79 Silicon Chip Binders.....................96 Subscribe now by using the handy order form in this issue or call (02) 9979 5644, 8.30-5.30 Mon-Fri with your credit card details. Silicon Chip Bookshop........... 86-87 SC Computer Omnibus................96 SC EFI Tech Special..................IBC SC Electronics Testbench..........IFC NOW AVAILABLE FROM Silicon Chip Subscriptions.............7 Silicon Chip Order Form..............57 Silvertone Electronics..................95 www.siliconchip.com.au Project Reprints Limited Back Issues Limited One-Shots If you’re looking for a project from ELECTRONICS AUSTRALIA, you’ll find it at SILICON CHIP! We can now offer reprints of all projects which have appeared in Electronics Australia, EAT, Electronics Today, ETI or Radio, TV & Hobbies. First search the EA website indexes for the project you want and then call, fax or email us with the details and your credit card details. Reprint cost is $8.80 per article (ie, 2-part projects cost $17.60). SILICON CHIP subscribers receive a 10% discount. We also have limited numbers of EA back issues and special publications. Call for details! visit www.siliconchip.com.au or www.electronicsaustralia.com.au 96  Silicon Chip Smart Fastchargers.....................93 Solar Flair/Ecowatch....................95 Solutions In A Box........................95 Telelink Communications.........OBC VAF Research.........................41,73 Wiltronics................42,61,73, 77,91 _________________________________ PC Boards Printed circuit boards for SILICON CHIP projects are made by: RCS Radio Pty Ltd. Phone (02) 9738 0330. Fax (02) 9738 0334. www.siliconchip.com.au   Own an EFI car? Want to get the best from it? You’ll find all you need to know in this publication       
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