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To understand why $6,843 is a fair price to pay for VAF kit speakers, read 580 words from a violinist who can’t use a screwdriver. The following is an excerpt from a review which appeared in Audio Video Lifestyle Consumer Guide ‘99 by Sian O’Neale. “Philip Vafiadis is the creative talent behind the brand and his aim with VAF Research is to market kit loudspeakers of uncompromising quality at the serious end of the hi-fi market. The VAF range is priced from $312 a pair right up to $8,863 a pair*, so we’re talking serious money here for serious equipment. We at AVL magazine have been particularly impressed with DC-X series. These kit loudspeakers are not the standard packages from consumer electronics stores. In fact, you won’t find these products in any store. The company prefers to cut out the middle-men and save buyers money, so every product is available factory-direct. The VAF Signature series includes the Signature I-66 and I-91 loudspeakers. Taking delivery of the 120kg I-66 floorstanding speakers is something of an experience; I have never seen such an imposing crate for a pair of loudspeakers before. Fortunately my brother Crispin is capable with the screwdriver and we took out the massive I-66s. You will need quite a bit of muscle and help to unpack these speakers and get them where you want them. The engineering and attention to finish that has gone into these fully assembled VAF Research I-66s is simply awesome. These elegant but powerful looking loudspeakers come with removable velcro attached grilles in a 3-way design; a 210mm hard paper bass driver with solid copper phase plugs and a 25mm double chamber sonotex dome tweeter with a pure silver wire voice coil. Turn the speakers around and you have very high quality gold plated binding posts which allow for bi-wiring and tri-wiring. The same meticulous attention to detail and build quality also goes into the smaller I-91 models, three of which are presented as left and right rear surrounds and a centre channel speaker for home theatre use (which has a customdesigned grille for a centre channel speaker). But the I-91 loudspeakers have been designed to also perform as high quality studio monitors with the same superb sound as the I-66s. The speakers were designed to be used close to a rear wall and that’s how customers use them, ideally 15cm-40cm from the nearest wall. But I think the speakers sound better when they can breathe more easily. Find the right position for the room and you will be richly rewarded. The big VAFs deliver a stunning soundstage which is wonderfully insightful and involving. Large scale orchestral works have a level of depth and accuracy that only the best loudspeakers can manage. As a violinist, I am often left unimpressed with the sound of the violin through so many loudspeakers (even high-end models), but here the presentation is accurate and engrossing. Instrument separation between different members of the orchestra is faultless. This is particularly obvious when listening to Hans Zimmer’s evocative soundtrack for The Thin Red Line in which quiet, gentle music provides so much power and atmosphere. As a system for home theatre, together with the smaller satellite I-91s, VAF has assembled an incredible system. Bass extension from the I-66s is awesome; deep and thrilling, which is ideal for action blockbusters such as Speed, Twister or Titanic (you don’t just watch the ship sink - you feel it through the floorboards). The centre channel speaker locks dialogue firmly into place and steers the sound with maximum impact; dialogue in Speed comes across as frantic as the driving. Full marks.” For the entire transcript of this review or information on our 14 models contact VAF Research and ask for your copy of “What the Critics Say”. Free call 1800 818 882. Email vaf<at>vaf.com.au or surf www.vaf.com.au VAF Research 52-54 North Terrace, Kent Town, South Australia 5067 Built by us. Sold by us. * Figures amended to reflect current pricing. kwp!VAF0003 Contents www.siliconchip.com.au Vol.15, No.1; January 2002 FEATURES 6 Segway – A Revolutionary Powered Scooter Inbuilt gyroscopes keep this amazing new scooter upright. Lean forwards and it goes forwards; lead backwards and it goes backwards – by Sammy Isreb 14 Electric Power Steering Say goodbye to hydraulic pumps and hoses in your car. Electric power steering in on the way with lots of fancy new features – by Julian Edgar PROJECTS TO BUILD 22 Touch And/Or Remote-Controlled Light Dimmer Old-fashioned light dimmers with knobs are passe! This one dims up or down at a touch or you can use an infrared remote control– by John Clarke 53 A Cheap’n’Easy Motorbike Alarm It’s simple to build, can be fitted to almost any bike and is very easy to operate. It’s armed and disarmed with the ignition key – by Mick Gergos Segway: A Revolutionary Powered Scooter – Page 6. 58 100W RMS/Channel Stereo Amplifier, Pt.3 Final article covers the assembly of the remaining modules and includes the full wiring and setting up details – by Greg Swain & Leo Simpson 77 Build A Raucous Alarm It sounds so dreadful, that you cannot ignore it. And it only uses two ICs – by Thomas Scarborough COMPUTERS 20 Computer Tips FAQs on the MP3 Jukebox player – by Peter Smith 74 Computer Troubleshooting Tracking down software problems: a step-by-step approach – by Stephen Davis Touch And/Or Remote Controlled Light Dimmer – Page 22. SPECIAL COLUMNS 34 Serviceman’s Log Too much information; or not enough? – by the TV Serviceman 86 Vintage Radio Philips Philetta vs the Titan Tiny – by Rodney Champness DEPARTMENTS 2 3 38 42 82 Publisher’s Letter Mailbag Subscriptions Form Circuit Notebook Products Showcase www.siliconchip.com.au 91 93 94 96 Ask Silicon Chip Notes & Errata Market Centre Advertising Index Cheap’n’Easy Motorbike Alarm – Page 53. On the cover: a larger-than-life view of our new motorbike alarm, pictured against a modified Suzuki GSX-R750WS. Thanks to Motorcycle Weaponry, Mona Vale, for the use of the bike. January 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.) Peter Smith Ross Tester Jim Rowe, B.A., B.Sc, VK2ZLO Rick Walters Reader Services Ann Jenkinson Advertising Enquiries David Polkinghorne 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, Alexandria, NSW. 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 Electronics Australia copyright will not be lost A number of readers have expressed their sadness at the passing of “Electronics Australia” magazine, which was briefly mentioned in last month’s editorial. In truth, I had very mixed feelings about it myself. On the one hand, it has been a tough competitor for SILICON CHIP, ever since we started in 1987 and now that it has gone, we have the field to ourselves. On the other hand, I and four other people on the SILICON CHIP staff, (Greg Swain, John Clarke, Ross Tester and Jim Rowe) all spent a great many years happily working for Electronics Australia and we read it for many more years, so a major part of our working lives has gone. Still, it is not all bad. Following the demise of EA, quite a few people suggested that we should make an attempt to ensure that all the archive material and the EA website (www.electronic­saustralia.com.au) was preserved. And over the last few months we have had increasing numbers of enquiries about EA projects, photostat copies, etc. So in fact, before last month’s issue went to press, we approached the publishers of EA to purchase all the copyright pertaining to EA, ETI and related titles and the above-mentioned website and domain name. This has now been accom­ plished, although at the time of writing, the material had not yet been transferred to us. What this means for the immediate future is that the mate­rial on the EA website will be preserved and will be ultimately linked to the SILICON CHIP website. And since we now own the copyright, we will be able to provide photostats of articles in Electronics Australia. The charge for this service will be $8.80, including postage. Unfortunately, we will not be in a position to offer tech­nical assistance with EA projects – we simply do not have the time or any familiarity with the designs of past EA projects. Nor will we initially be able to suggest EA projects when readers enquire about particular circuit applications – again, we simply do not have a detailed familiarity with what has been published over the past 15 years in EA. That will come. Importantly though, all the material that has been pub­lished over the life of Electronics Australia, going right back to the 1920s and the days of Wireless Weekly, and all the materi­al associated with Electronics Today International (ETI), will be preserved. Ultimately, some of it may be republished. Thanks to all those readers who have emailed, phoned and written in with messages of support and requests that we do not change our format. We greatly appreciate your comments and we will continue to strive to be the world’s best electronics maga­zine. Leo Simpson ISSN 1030-2662 * Recommended and maximum price only. 2  Silicon Chip www.siliconchip.com.au MAILBAG VideoScope improved with rack and pinion I loved the VideoScope project in the October 2001 issue of SILICON CHIP. I just could not wait to get it up and going. However, I changed a few things for my own convenience. I used a rack and pinion from an unused camera tripod and turned a small wooden stand to fit a glass dish. This makes focusing far easier. I study and collect ants and only need low magnification, 80-120. Other improvements would be a bellows between lens and CCD camera. I only used a B&W camera but was amazed at the picture quality. Top project! G. Reynolds, Wynnum North, Qld. Critical transistors I recently assembled a kit for your Ultra-Low Distortion Amplifier (described in March 2000) and in bench testing the finished product discovered the following. Distortion at supersonic frequencies was chronic and the waveform was covered in spurious garbage that would do awful things to many tweeters! On further tests it was found that there was a definite 2nd pole to the frequency response that was not explainable from the circuit design. The output devices supplied were genuine Motorola so suspi­cion fell on the MOSPEC-branded MJE15030/31 driver transistors. They were removed and tested and found to bear no relationship to quoted specs. Gain was very low, Vbe was erratic and Ft was in the kHz region! Replacing them with a reliable branded type completely cleared the problems, giving clean waveforms well beyond 100kHz. As kit suppliers no doubt buy these devices in by the truckload, I imagine there could be a lot of substandard performing (if not dangerously unstable) amplifier kits in the field by now. Hope this alert is of use. Kerry Williams, RMIT University, Dept. of Applied Physics, Bundoora, Vic. Comment: this is correct – you must use genuine Motorola or On Semiconductor devices for the MJ15030/31 driver transistors in the Ultra-LD power amplifier. These same comments apply to the power amplifiers used in the Ultra-LD 2 x 100W RMS Stereo Amplifier. Concern for copyright I am responding to your editorial in the December 2001 issue. I guarantee you that I have never photocopied your maga­zine. Not so long ago my wife Pip was leaning over my shoulder to read an article and I instantly closed the magazine and said she would have to buy her own copy. By the way, how about doing some interesting investigation. 3-pin mains plugs like those we have in Australia seem to be the same as used in parts of China, New Zealand and Argentina. Where did our 3-pin plug and socket design come from and why are they the same as used in those other countries? Dick Smith, Terrey Hills, NSW. Transformer power rating for half-wave rectification In the “Ask Silicon Chip” pages of the November 2001 issue, a reader asked why the transformer power K&W HEATSINK EXTRUSION. SEE OUR WEBSITE FOR THE COMPLETE OFF THE SHELF RANGE. www.siliconchip.com.au January 2002  3 rating for a centre-tapped two-diode rectifier is 1.4 times that for an equivalent full-wave bridge rectifier, as noted in an ARRL handbook. You responded that the “VA rating” would be the same either way. Vague recollections of my undergrad days percolated up as I read the letter and your response and I do believe the handbook is correct. For a given output voltage (V) and current (I) into a resistive load, a centre-tapped two-diode rectifier must be rated at a total 1.4 times average power: each winding is conducting only half of each cycle, which means that the RMS power in each winding is halved or 0.5 x 1.4 x VI. However, the total transformer rating (ie, both windings) would be 2(0.5 x 1.4 x VI) = 1.4VI, or 1.4 times that for a bridge. So the centre-tapped configuration saves cents on the diodes but costs dollars on the transformer. I can’t imagine it ever being used outside of academic study. Ben Low, via email. Comment: in responding to the question we did not consider a resistive load since that is extremely rare. We considered it only for a capacitor-input power supply where the rectifier duty cycle, for both full wave and centre-tap configurations, is typically around 10% or less. This makes the 50% duty cycle consideration of a centre-tap transformer feeding a resistive load quite academic, as you suggest. Windows XP review leaves questions unanswered I just read your review on Windows XP in the December 2001 issue. All well and good and it was an interesting article but the review didn’t go far enough, in my opinion. I know you are not a computer magazine, therefore the review should have covered some of the things that are of more relevance to us electronics types. What should have been included was stuff like: How does it go when I want to program my AVR via BASCOM on a Dontronics DT006 board? Will the PIC programmer you published a while ago work with XP? Will Atmel’s AVR studio work? What about the Mini and Maxi ABC boards and their software, or all the other projects that need a computer to program a micro, etc? The main reason for those questions is that XP is based on the Win2000 core, which does not allow control of the parallel and serial ports by other applications; at least not without a lot of convoluted patching and loading of special programs that release the ports for general use, maybe! And XP is different to Win2000. A few mates of mine upgraded and a lot of their stuff, EPROM programmers, microcontroller programmers, etc that worked with Win2000 no longer work with XP. Sure it is supposedly up to the developers of those pro­jects and products to put out a patch for their software to run on XP but that could be many months away or never, if the redesign project is too big. In the meantime, everyone who converts to XP expect- IT'S TRUE. I T ' S H E R E . the one you've always needed. IT'S FAST the most efficient and affordable personal analyser charger from the charger specialist IQ PAC 4  Silicon Chip  Charges and analyses with capacity display at the same time.  NO overheating.  NO overcharging. IT'S VERSATILE  Three charging rates.  Three discharge rates.  Constant current or pulse charging. IT'S FLEXIBLE  Charge adaptor plate for different battery types. IT'S EASY TO USE  Charges automatically.  Press one button to analyse PREMIER BATTERIES PTY LTD ABN 12 003 149 013 Syd  (02) 9755 1845 Fax: (02) 9755 1354 Mel  (03) 9886 3432 Email: info<at>premierbatteries.com.au Internet: www.premierbatteries.com.au www.siliconchip.com.au ing everything to work will be sorely disappointed. According to my mates, the ability of XP to emulate a previous version of Windows did not work with their equipment. Yes, you can set up a dual-boot system, Win XP or Win 98. But then why bother with XP? – might as well stick with Win98 for all it’s faults. Is it worth your while to have an update to your Win XP article explaining the above or giving details of how to get everything working again? I for one won’t even consider XP until I know that all my stuff will work. There is no point to an OS that just adds a lot of “fluffy eye candy “ and otherwise is not really better than its predeces­sors. All the multimedia stuff is another thing entirely and has nothing to do with my main point. Keep up the good work. While I’m not a subscriber for no other reason than I never got around to it, I get every copy every month and have every issue since you started. And yes I agree with the editorial. Every one should go out and buy the magazine. Ralph Teichel, Ringwood North, Vic. Comment: putting out a fairly comprehensive review of XP, as we did, is one thing. To try and answer all the sorts of questions you raise would take many weeks of work and then still leave many questions unanswered. Electric vehicle article appreciated I would like to thank you for your excellent article by Ross Tester on electric cars in the December 2001 issue. I am a mechanical engineer, a refugee from that other magazine and welcome intellectual stimulation. I remember a number of electric vehicles in UK 30 years ago, trains, buses, milk and bread floats and wonder whether electric vehicles are blokey enough for Aus­tralia. Imagine going down to the pub and saying “I’ve just bought an Electric Ute with 10 Amp-Hour battery, twin overhead terminals and turbo ventilation”. How can you lay rubber with an electric car or get that satisfying roar when you drop a cog to overtake a semi. Maybe manufacturers could incorporate speakers and a means to spray paint the road black. You could www.siliconchip.com.au download a roar or rubber squeal from your favourite website. On a serious note I have a few thoughts on the subject. I wonder if we also need to change the current infrastructure. While lightening the car to reduce the inertia and regenerative braking are all heading in the right direction, the car is still carrying all those heavy batteries. One possible option is to carry one or more battery packs depending on usage, to reduce this weight. Also battery changeover rather than recharging seems a viable option, with battery changeover stations incorporated in the current petrol stations. Each battery would carry a chip encoded with information such as the last user and their credit details, the battery condition, etc. This information is download­ed to the battery supplier and credit company each time the battery comes back for recharging. The vehicle would have its batteries under the vehicle and simply drive over a rack of batteries with their terminals on the sides touching busbars for charging/discharging and as one set of battery packs went in the other was ejected. Looking at the hybrid engine, I see it is a piston engine. While rotary engines seem to have come and gone, they would seem to be the ideal choice for this application. Maybe Ralph Sarich’s rotary could incorporate this change? Tony Rossiter, via email. Lifetime support I was horrified to read that “Electronics Australia” has closed its publication after all this time. As a longterm elec­tronics technician both for business and pleasure, I rely heavily on information and ideas that appear in your magazine. I am hoping that you are not going to abandon us in the near future. Your magazine is my lifeline. I would be lost without you so keep up the good work. You have my full support forever. Kerin Sharp, Morphett Vale, SA. Comment: thanks for the support. We’re here for the long term and we have no intention of changing format. 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. 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 January 2002  5 Revolutionary Invention... or Expensive Toy? Following months of media hype and speculation, inventor Dean Kamen’s Segway Corporation have finally unveiled their unique machine – a scooter with an uncanny ability to replicate the balance and motion mechanisms of the human brain. While some analysts have touted that the creation will ‘change the shape of cities’, others remain unimpressed. In this article we take a closer look at the ‘Segway’ and its brilliant technical design (well, at least as close as we’re allowed!). By Sammy Isreb 6  Silicon Chip www.siliconchip.com.au I t sounds as though it has the elements of immense success. With over $100 million in funding from America’s top venture capital firms and designed by some of the top engineering minds available, Segway developed a product which gained some phenomenal media hype leading up to its release. Adding to the hype, some amazing quotes from big names – “As big a deal as the PC”: Steve Jobs – “Maybe bigger than the Internet”: John Doerr, a venture capitalist who backed Netscape and Amazon.com. So what exactly is the Segway HT (Human Transporter)? A very fancy powered scooter would be the simplest answer. Based on a footprint of only 48cm by 63.5cm, the Segway is designed to take up as little space as possible. Touted as a solution to inner city transportation woes, the Segway is meant to transport people quickly and efficiently, taking up no more room than a pedestrian. It was never designed to replace cars, simply to provide an alternative for short distance commuting and to www.siliconchip.com.au clean up densely crowded and polluted city areas. It seems as though this admirable desire to simplify short distance commuting puts the Segway in the same market category as a myriad of other devices – bicycles, rollerblades, scooters and skateboards, to name just a few. What sets the Segway apart from the rest is its safety, simplicity of use, and highly ergonomic design. The Segway was designed from the outset to mimic the body’s natural sense of balance and motion. It uses some incredible sensory and computing technology simply to stay upright, providing unmatched ease of use. To start moving forwards or backwards the user simply leans slightly forward or backward. Leaning further will increase speed, while moving towards centre will slow down. It is a natural human response to try and upright one’s body under panic. Segway uses this phenomenen to dispense with the need for mechanical brakes – as the user assumes an upright position it slows then stops completely. Steering is as simple as twisting the handlebar, with the amount of twist determining the turning speed. Amazingly, the unit can turn on its own footprint, rotating on the spot. Intelligent key The amazing technology begins as soon as you start the Segway using the electronic “Intelligent Key”. A 128-bit encrypted key word is stored on the key, which is required to start the particular unit it was shipped with. In addition to the security feature, the Intelligent Key also stores the user’s profile, with all units supplied with “beginners” and “advanced” keys. The beginner’s key limits the Segway’s top speed, among other things. It is envisaged that in the future users will be able to customise their operating parameters via programmable keys. User display Next to the key slot on the ‘handlebar’ is an LCD display which provides the user with all relevant information such as battery charge level and current operating conditions. This display is designed for ease of January 2002  7 gravitational field. The design philosophy of the Segway has been to incorporate a very high level of redundancy into the device, which has been reflected though the use of five rather than the required three gyroscopes. Each of the Segway’s gyroscopes consists of a solid-state angular rate sensor, a device of silicon construction used to measure rotation. This uses a tiny silicon wafer attached to a supporting structure. An AC voltage is applied to the wafer, causing it to vibrate in a predictable manner. When the device is moved, the vibration is altered and thus measured and used to determine the degree of rotation. Electronics Controller Boards The Segway uses dual, fully redundant controller boards to accept inputs from the Inertial Sensor Assembly, along with other sensors, in order to process the data and appropriately drive the motors. While Segway is very secretive regarding the architecture of these processor boards, they have reportedly claimed 10 onboard processors distributed amongst the two boards, with around three times the processing power of an average consumer PC. If either of the boards experiences a failure, the other board assumes control, and will bring the Segway to a safe stop. Riding is said to be as easy as falling off a log! Lean forward and it goes forward. Lean back and it stops, then goes backward. Twist the handlebar one way and it turns that way. And vice versa. visibility in high levels of sunlight. Chassis Design The chassis is constructed from aluminum, sealed from the atmosphere to protect the electronics inside. Aside from obviously providing somewhere to stand on and a case for the internals of the unit, the chassis has been designed to act as a heatsink for the complex assembly of gyroscopes, processor boards, motors and batteries. According to the manufacturer’s testing, the chassis can withstand an amazing seven tonnes of load. Inertial Sensor Assembly This subsystem is probably one of 8  Silicon Chip Batteries the most amazing of the entire device. Incorporated into the top rim of the chassis are hidden injection-moulded rubber diaphragms. When the user gets onto the unit the diaphragms deform towards the electronics below, engaging the self-balancing systems. At this stage the unit is aware of the operator’s presence and begins balancing the unit and the user upright. In fact, anything but the hardest shove to a Segway rider will not tip them. The Inertial Sensor Assembly resides within the chassis, sandwiched by the motors to one side and the batteries to the other. The assembly consists of five aviation-grade gyroscopes, used to determine the location of the machine in relation to the Earth’s Probably the most conventional technology aboard the Segway are the rechargeable batteries, which are supplied in either Nickel Cadmium or Nickel Metal Hydride varieties. According to early testing, fully charged Ni-MH batteries will be able to propel the Segway anywhere from 17km to 28km depending on the terrain, weight of the user, and method of riding. Each Segway uses two batteries, which are sealed and incorporate charge and temperature monitoring electronics. The unit is charged from mains power and will take around six hours to fully charge. Motors and Transmission Each wheel is driven by two (redundant) high speed brushless electric motors. For each wheel, the motor consists of two windings, functioning as separate electric circuits, with full www.siliconchip.com.au redundancy, providing a single mechanical unit. In order to allow the motors to run at a high speed, which optimises efficiency, a 24:1 two stage helical sealed transmission unit is used in each wheel. In addition to maximising efficiency, the beauty of the drive train design is the fact that by running the motors in opposite directions the unit is able to turn on the spot. This is a major selling feature of the Segway. In addition to this, the motors can propel the unit to a top speed of 20km/h, even with operators weighing up to 110kg. The unit has no brakes as such, using the motors for accelerating, turning and braking. When the user signals his intent to slow or stop by leaning back, the control boards cause the motors to decelerate. Wheels and Tyres Each wheel is made from a forged steel hub surrounded by a glass-reinforced thermoplastic rim. Each rim has a cutaway hole for threading a bicycle-style lock through. The wheels attach to the main unit via a single nut mechanism. In order to maximise the range of the unit, the wheels have special low-rolling-resistance silica tyres, which are air inflated and puncture resistant. Synopsis As the amazing array of technological features will surely attest, the Segway is indeed a machine which could go a long way towards being a personal transportation medium. It does, however, come with a US$3000 price tag (AU$6000) for the yet-to-be-released consumer version Specifications: Top speed: 20km/h Weight: 36kg Dimensions: 48 x 63.5cm Weight capacity: 110kg person with 34 kg of cargo Range: About 28km on even ground, or 17km on undulating terrain Motors: Each wheel is driven by a two horsepower brushless DC electric motor Transmission: Two-stage transmission with 24:1 gear ratio Computer: Two redundant processing boards with 10 processors distributed amongst them Power: Two rechargeable batteries. Either Ni-MH or Nicad Sensors: Five solid state gyroscopes plus sensors to detect presence of user Brakes: No mechanical braking system. Regenerative engine braking. Turning radius: On the spot Security: Intelligent Electronic Key system, using 128-bit encrypted key code. Also determines operational profile Driver interface: High visibility LCD display which indicates battery charge and operational status Price: Approx. US$3,000 (consumer version) and an astounding US$8,000 (AU $16,000) for the commercial model recently released. But this has not deterred several US corporations, including the US Postal Service, The National Park Service and General Electric, amongst others, from signing on to field test the units over the next few years. While all those involved with the Segway believe – or hope – it will become the next craze to sweep the world, one can not help but wonder why the average individual consumer would wish to spend almost half the price of a new small car on a device which is intended to replace one of life’s most healthy activities – walking. Depending on the success of the corporate trials, mass production for the consumer market could quite easily see the price fall to attainable levels. Until then the Segway will remain SC a very expensive toy! 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 EACH INC GST www.siliconchip.com.au January 2002  9 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 Swapping hoses and pumps for electric motors and electronic control . . . Electric Power Steering By Julian Edgar T he conventional hydraulicallyassisted power steering used in most cars is soon to be replaced with electric power steering. Already, many manufacturers are using electronically controlled hydraulic systems, while some car manufacturers have recently introduced purely electric systems to their mass production vehicles. In addition to reducing parasitic loads, full electric power steering allows steering responsiveness to be automatically varied depending on speed, road conditions – and even the driver’s ability! Hydraulic Power-Assisted Steering Hydraulic Power Assisted Steering (HYPAS) has been used in automotive applications for about 50 years. The systems use an engine-driven hydraulic pump, a control valve, steering cylinder and connecting hydraulic hoses. The pump is usually of a vane design with an integrated internal bypass. It is sized so that, even at idle rpm, it delivers enough oil flow to provide a suitable degree of power assistance. The control valve uses a flexible torque-measuring device (such as a torsion bar, spiral spring or leaf spring) to convert the steering torque into a small control movement. This movement is transferred to a valve that regulates fluid flow to the power assistance mechanism. In rack and pinion steering, a double-ended hydraulic ram mounted parallel to the rack (within the rack as14  Silicon Chip sembly) is used, while recirculating ball systems incorporate the mechanism into the steering box. Fig. 1 shows an example of a traditional HYPAS recirculating ball steering system. Note that in this particular system, the fluid reservoir is incorporated into the pump. A major problem with simple HYPAS systems is that the assistance level is not reduced at high speeds, resulting in a lack of steering feel. American cars of the 1950s and 1960s were particularly noteworthy for their feather-light steering effort during parking, a trait which resulted in extreme vagueness at high speeds. To overcome this problem, most HYPAS systems of the last few decades have incorporated mechanisms that reduce steering assistance, either as engine speed increases or (less frequently) as road speed increases. The reason that engine speed was more commonly used as the control parameter to reduce steering effort is that such a system can remain purely hydraulic, whereas using road speed as the control variable requires the use of an electronic system. Electronically-Controlled HYPAS The introduction of electronic speedometers – and subsequently, full engine management – meant that an electronic road speed signal became available, allowing the widespread use of electronically-controlled HYPAS systems. These vary steering effort depending on road speed and also, in some cases, other parameters. A number of different hydraulic approaches to regulating steering assistance are used. These are: 1.Flow Control A solenoid valve is located on the discharge port of the hydraulic pump. Electronic control is used to control the solenoid valve opening, thus regulating the fluid flow. The flow is reduced at high road speeds, decreasing the degree of assistance provided. 2.Cylinder Bypass A solenoid valve and associated bypass line is located between the two Fig.1: traditional Hydraulic Power Assisted Steering (HYPAS) systems use an engine-driven hydraulic pump, fluid reservoir, connecting hoses and a hydraulic steering box or rack. [Nissan] www.siliconchip.com.au chambers of the hydraulic cylinder, allowing a reduction of the pressure differential. The solenoid valve opening is controlled electronically, its opening greater at high road speeds. This reduces the degree of assistance that is provided. 3.Hydraulic Reaction Force A hydraulic force is enabled that works against the power assistance. As speed increases, the reaction force is increased. Since fluid flow to the power cylinder is not affected, the steering response rate can remain high without reductions occurring in feel. In their electronically-controlled H Y PA S s y s t e m , Hyundai use an ECU equipped with an 8-bit microprocessor. Two major inputs – vehicle speed and steering angular velocity – are used. From these inputs the ECU determines the driving conditions and via a 3-dimensional look-up map, provides the appropriate current flow to a hydraulic solenoid valve. Three different driving conditions are recognised: Parking – maximum current is supplied to the solenoid valve, resulting in maximum steering assistance. High Speed – minimum current is supplied to the solenoid valve, resulting in minimum steering assistance. Evasive Steering – a large and sudden steering input causes the ECU to supply a current to the solenoid proportional to the angular veloc- · · · Fig.2: electronically-controlled HYPAS uses the inputs from both a road speed sensor and steering angle sensor. [Mazda] ity of the steering input. The control algorithm used in the system is as follows: IS = IV + IAW + IA + IT; where IS = Solenoid actuating current IV = Current according to vehicle  speed IAW = Current according to steering   angle velocity IA = Current according to steering  angle IT = Current according to time The purpose of IA is to prevent the driver from experiencing an excessive steering holding force on banked roads. This current is increased in proportion to steering input angle. IT provides additional assistance in situations where the vehicle enters a corner that follows a long straight driven at high speed. ECU ANGULAR VELOCITY SENSOR CALCULATION OF ANGULAR VELOCITY CPU VEHICLE SPEED SENSOR (FROM SPEEDOMETER) CALCULATION OF VEHICLE SPEED ENGINE SPEED CALCULATION OF ENGINE SPEED BASIC CONTROL MAP POWER CIRCUIT CONTROL VOLTAGE PUMP MOTOR GENERATION OF HYDRAULIC PRESSURE MONITORING OF MOTOR CURRENT Fig.3: a schematic diagram of a Honda hybrid HYPAS control system. The hydraulic pump speed is controlled on the basis of inputs from steering wheel movement and engine and road speed. [Automotive Electronics Handbook] www.siliconchip.com.au January 2002  15 Fig.4: this General Motors hybrid HYPAS system senses motor current to determine the actual steering loads and so the degree of assistance that needs to be provided. The 3-phase brushless DC motor (12) is supplied power by the Motor Power Circuit. The EHPS control provides a duty cycle control to the Motor Power Circuit in response to input signals from the motor angle sensor, motor current sensor and battery current sensor, as well as operating system voltage. The temperature of the hydraulic fluid is also measured. The scaler is used on the motor current input to allow high resolution at low values without requiring a more costly A/D converter. [General Motors Corporation] TF TEMP IMH SCALER IML EHPS CONTROL ANGLE DUTY MOTOR POWER CIRCUIT BATTERY 12 CURRENT CURRENT IB IM Fig.2 shows the layout of a Mazda HYPAS system where the degree of assistance is based on road speed and steering angle. Hybrid Hydraulic/Electric Power Steering Systems Hybrid HYPAS systems use an electric motor to drive the hydraulic pump, rather than having the pump driven directly by the engine. This approach allows the steering effort to be easily controlled by varying the pump speed. While the efficiency of such an approach is actually lower than a conventional belt-driven pump, because flow can be better matched to actual requirements, the overall parasitic power loss is reduced. Fuel economy savings of up to 0.2 litres/100 km are claimed to be possible by taking this approach. The control approach that is taken can be of three types: Driving Mode – where driving conditions (such as city, country, highway, etc) are automatically judged with appropriate levels of assistance then provided; Steering Wheel Input Mode – where · · Features Benefits Engine independence Reduced engine power drain Improved fuel economy and acceleration Instant-on power steering Assistance available even should the engine stall Elimination of pump, hoses, Simplified packaging fluid, drivebelt and pulley Environmental compatibility Reduced mass Modular design and integrated controller Reduced assembly time Design and packaging flexibility Multi vehicle use Design and packaging flexibility Software tuning Wide assistance range In-vehicle laptop PC tuning Tuning process reduced from months to hours Cost-effective advanced features Variable effort steering Assisted return to centre Steering damping capability Fig.5: some of the possible benefits of using Electric Power-Assisted Steering (EPAS) systems in place of traditional hydraulic power steering. [Delphi] 16  Silicon Chip the angular velocity of the steering wheel movement is used to determine the degree of assistance required. Steering Load Mode – where demand for power assistance is indicated by the counter-pressure of the hydraulic fluid, sensed through variations in the motor current load. Fig.3 shows the processes followed in one Steering Wheel Input Mode system to calculate the appropriate degree of assistance, while Fig.4 shows a schematic diagram of a control system that uses the Steering Load Mode. · Electric Power-Assisted Steering Electric Power-Assisted Steering (EPAS) completely replaces the hydraulic system that hitherto has always been associated with power steering. EPAS systems assist driver effort by the use of an electric motor which acts through a reversible gearbox and also, in some cases, an electromagnetic clutch. An electronic control unit determines the degree of assistance that is rendered. EPAS has some significant advantages over any form of HYPAS, both for the owner of the car and its manufacturer. The reduction in engine load of an EPAS system (it can be as low as 4W when the car is being driven in a straight line) means that the fuel economy of a car equipped with EPAS is very similar to that of a car with no form of power steering. Analyses provided by manufacturers of EPAS systems indicate potential www.siliconchip.com.au Fig.6: the electronic control system for a Honda EPAS system. [Automotive Electronics Handbook] fuel savings of 4-8 per cent over cars equipped with conventional HYPAS, with the lighter mass of an EPAS also having an impact. The independence of the system from engine operation also means that should the engine stall, steering assistance does not vary. (In a conventional HYPAS system, a stalled engine immediately reduces steering assistance to zero – a problem if this occurs part way around a tightening corner!) From a manufacturer’s perspective, it has cost benefits. Using EPAS reduces assembly line time, allows easy software tuning of the steering assistance characteristics to suit a variety of cars (eg, a sports car or a limousine) and has the potential to improve reliability – 53% of all power steering warranty claims are from pump and hose problems. Environmental gains are also possible from the decreased production and disposal of hydraulic fluid (world- wide, an estimated 40 million litres of power steering fluid was in use in 1995) and from the decreased requirement for the non-recyclable polymers used in hydraulic hoses. Fig.5 shows the range of benefits potentially realisable from EPAS. A number of EPAS systems are currently in production or in the final stages of prototyping. The LucasVarity system uses a brushless DC servo motor and gearbox to develop a torque that varies from GPS SYSTEM RAM SPEED SENSOR STEERING SENSOR BRAKE PEDAL SENSOR INPUT UNIT CPU OUTPUT UNIT SKILL RATING THROTTLE PEDAL SENSOR YAW RATE SENSOR RAM  ESTIMATING DEVICE Fig.7: a recently patented Honda EPAS system actively calculates the driver’s ability and provides steering feel and weight to match. Inputs to this system can include GPS navigation and yaw rate information, with the system comparing the actual path taken by the vehicle with its computed target trajectory. [Honda] www.siliconchip.com.au January 2002  17 Fig.8: calculation of the available road friction is carried out in the the Honda active EPAS system by spectrumanalysing the noise generated by the tyres on the road! [Honda] START SPEED INPUT transformer) techniques, with the twist of a torsion bar converted to a slider displacement. Other system inputs include vehicle speed and battery voltage. Fig.6 shows the schematic diagram of a Honda EPAS system. Driver Skill Estimation! SOUND PRESSURE INPUT FREQUENCY ANALYSIS EVALUATE ROAD CONDITION DRY, WET, SNOWY, POWDERY SNOWY, AND ICY One of the most interesting aspects of EPAS is the ability that the manufacturer has to ‘tune’ the system’s responsiveness. As indicated earlier, this allows the easy software matching of a single EPAS to applications as diverse as a two-seater sports car or luxury sedan but it also means that system responsiveness can be made to vary in different driving situations in the one car. When this approach is taken, the input by the driver of a certain amount of steering lock does not always result in the same degree of assistance – should the ECU determine that such a steering movement is not appropriate for the conditions that the vehicle is undergoing, the steering assistance may be reduced or the steering input even actively resisted! As an indication of the far-reaching implications of this, Honda has very recently developed an EPAS system that estimates the skill of the driver and provides steering assistance to match. In the Honda system, a ‘driver skill estimation device’ is used, as shown in Fig.7. This device has inputs from: a GPS system(!); a vehicle speed sensor; a steering sensor that provides information on steering angular speed, angular acceleration and torque input; a brake pedal sensor that detects braking stroke, speed and force; a throttle pedal sensor that detects accelerator stroke and speed; a yaw rate sensor; a road friction estimate input. The road friction estimate is deter- mined by yet another system, with the approach taken shown in Fig.8. Vehicle speed and a sound pressure signal are gained from appropriate sensors, with an audio frequency analysis of this data then undertaken to determine whether the road is dry, wet, snowy, powdery snow or icy. (Note that while the GPS and yaw rate inputs are included in the Honda patent of the system, Honda state that the system can still work effectively without them.) The ‘driver skill estimation device’ analyses the actual path taken by the vehicle and compares this with a computed target trajectory. Using this and data on the vehicle wheelbase, the distance that the front and rear wheels are from the vehicle centre of gravity and other factors, the system awards the driver an ability that varies on five levels from “very poor” to “very good”. A very good driver is rewarded with very little steering force resistance (the driver gets what he or she asks for), while a poor driver will encounter steering that actively does not allow major steering inputs to be made at high speed. According to Honda, this allows the skilled driver to “positively control the turning behaviour of the vehicle so as to briskly manoeuvre the vehicle. Conversely, if the vehicle operator is not skilled, the control system produces a reaction which prevents the vehicle operator from over-reacting to the vehicle response, and [so] stabilises the vehicle.” One wonders what happens when a ‘very poor’ driver suddenly needs to swerve around a child that runs out onto the road. . . That they are a poor driver becomes a self-fulfilling prophecy, perhaps? However, the Honda system does provide a very strong indication of the direction that EPAS systems can be expected to follow in the future. SC about 15Nm in a small car to 75Nm in a large sedan. Other manufacturers, such as TRW, use variable reluctance motor designs. The electric motor that is used requires low levels or ripple and “cogging”. LucasVarity achieve this by using a three-phase inverter to vary motor phase currents and so torque. Power mosfets are used to control the switching and pulse width modulation techniques are used. Depending on the location of the electric assist unit, drive can be transmitted to the steering mechanism by a number of means. These are shown in the table of Fig.9. In the LucasVarity system, a dual-channel optical device is used to sense steering input torque. Two optical discs are mounted 50mm apart at either end of a torsion bar, which is incorporated into the steering shaft. Torque applied to the steering wheel Method Electric Assist Unit Location Power Transmission causes a relative movement of the two Pinion assist Under the dashboard on Motor > worm gear > column discs, with the angular offset optically the steering column shaft > pinion shaft sensed. On the steering rack input pinion Motor > gear train > pinion shaft Comparison of the two output sigRack assist On the steering rack Motor > ball screw > rack shaft nals allows the calculation of steering On a second pinion on Motor > planetary geartrain > torque, steering wheel angular velocthe steering rack another shaft pinion > rack shaft ity, and steering angle. Anther torque sensor that can be used incorporates Fig.9: electric assist units can transmit drive in a variety of ways, depending on LVDT (linear variable differential their physical location in the vehicle. ·· · · · ·· 18  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: info<at>amn.org.au COMPUTER TIPS Compiled by Peter Smith FAQs On The MP3 Jukebox Player The MP3 Jukebox player featured in the September & October 2001 issues has been very successful and already several hundred have been built and are operating. However, as with any project, questions frequently arise. Here are some of the ques­tions, together with their answers. Saving Playlist Files Q I have just purchased and built the MP3 Jukebox kit from Altronics. I found it worked better than I expected but the only problem is that I am only able to load one playlist and play from that. Can you please tell me what I am doing wrong? I have about 1000 MP3s on their own hard drive (F), broken up into about 25 different categories. I have created some Winamp playlists and put them in each directory (ie, F:\80s\80s.m3u). Also, I have tried putting all the playlists in F drive (ie, F:\80s.m3u). I cannot load another playlist using the remote control. I have set up the remote control as you suggested on page 31 of the October 2001 issue. What am I doing wrong or is it the software? Playlist (.M3U) files must be saved in the same directory as the MP3 files that they list. Each entry in a .M3U file must A What Are The Hardware Requirements? Q Before beginning to build the MP3 Jukebox I am wondering about some modifications. I have a Gigabyte GA-6WMMC7 board, 10 months old, with an Intel 810 chipset, capable of up to 512MB of RAM and up to PIII processors. As I understand it, the player would not be multi-tasking, merely running a modified version of Winamp. As such, what is the minimum memory I should use and minimum processor speed to have a reliable player? Also, I am sure that this board is capable of “soft-power”. Is this the mode that the player goes into after shutdown or is the system halted? As the 810 chipset has integrated sound and video, would it be advisable to put a cable from the player to a switchbox and then to my desktop PC to be able to make modifications to the player? Could I then use my keyboard, mouse and monitor to change settings on the player via a switchbox? Finally, I have at my disposal a 20GB Seagate drive that I was planning on using for the drive in the player. As I Doing Without The LCD Screen Q The MP3 Jukebox seems great. I’ve having a great time playing around with it. Just a quick question though – could you release the source code for your IR program that controls Winamp? And second, will the module work without the LCD screen? Yes, you can use the IR Remote Receiver & LCD module without the LCD screen (no changes are needed) – just don’t plug it in. The VB code is probably not a great example if you’re look­ing for inspiration but this is a link to it anyway: http://www.siliconchip.com.au/Shop/6/2102 A 20  Silicon Chip contain only the filename, not the full pathname. For example, the full pathname to a track might be “F:\80s\ MySong.MP3” but the entry for this track in the .M3U file should be only “MySong.MP3”. You don’t mention anything about having created a metalist. Following the instructions in the article, create a metalist that contains the full path­ name to each of your .M3U files. You can save the metalist file anywhere. Remember to define the path to the metalist in IR Remote Setup, selecting the “metalist” option. have only 4-5GB of MP3s so far, I was planning on installing a network card so as I could rip MP3s and transfer them to the player, and also use the player’s drive as a secondary storage device; ie, storing little-used data files. Also, using the player to store all my MP3s would free up space on my existing drive. Is this possible? We talked about PC requirements in the second article. Brief­ly, we think the minimum requirements would be a P133 (or equiv­alent) processor with about 32MB of memory. Currently, the software performs a “hard” rather than “soft” power down. Yes, you could use a switchbox. This is quite a good way to do it but your networked idea is even better. Once set up, you will rarely need to modify the software configuration. Note that we use a completely standard (unmodified) version of Winamp. Although our Jukebox software is standalone, it con­ trols Winamp in the same way that plug-ins do – via Windows IPCs. If you’d like to know more about Winamp’s programming interface, check out the Developer pages at www.winamp.com A www.siliconchip.com.au Q Doing Without The Remote I just made up the MP3 Jukeboox and the unit powers up and works fine with Hyperterminal. However, are there any manual entries I can make in the IRRemote/keycode registry keys to get the program to perform without the IR section as I have not yet got a remote and do not wish to buy one just now. Could you tell me the format for these keys? I tried default settings of 53 for play and 54 for stop but I always get a loading registry settings (run setup) error. The following file contains all the key codes for a BC3000 remote (as featured in the article). Type it into Notepad as a text file and then rename it BC3000.reg. Then just double-click on it to load the codes into the registry. A REGEDIT4 [HKEY_CURRENT_USER\Software\VB and VBA Program Settings\IRRemote] [HKEY_CURRENT_USER\Software\VB and VBA Program Settings\IRRemote\Key Codes] “Play”=”53" “Pause”=”48" “Stop”=”54" “Fade Out”=”55" “Prev”=”33" “Next”=”32" “Back 5 Secs”=”50" “Fwd 5 Secs”=”52" “Volume Up”=”16" “Volume Down”=”17" “Repeat”=”10" “Shuffle”=”35" “Shift”=”39" [HKEY_CURRENT_USER\Software\VB and VBA Program Settings\IRRemote\Shift Codes] “Load Playlist”=”53" “Reload Playlist”=”54" “Prev Playlist”=”33" “Next Playlist”=”32" “Close Winamp”=”55" “Shut Down PC”=”12" “Toggle Equaliser”=”35" “Set Equaliser”=”10" [HKEY_CURRENT_USER\Software\VB and VBA Program Settings\IRRemote\System] “Address”=”5" What About The Windows Media Player? Q I’m intrigued by the MP3 Jukebox. I was wondering wheth­er it is possible to use the same system/program with other media playing programs? Is it only limited to Winamp? Is it at all possible to use this setup with Windows Media Player, mainly taking control of the volume, play and pause? I’d be using the standard media player with Windows 2000. The IR Remote software is designed to work with Winamp only. However, if you have some VB6 or C++ programming experience, you could write a program using the hardware part of the project (the IR Remote Receiver & LCD Display) to control Windows Media Play­er. Microsoft provide an ActiveX control for Media Player – check out what’s available at: www.microsoft.com/windows/windowsmedia/default.asp For an example of how to use the Media Player ActiveX con­trol, see www.elementkjournals.com/ivb/0011/ivb00b1.htm The IR Remote Receiver & Display (hardware) part of the project is entirely suitable for use with Windows Media Player in conjunction with suitable software. Windows Media Player updates are available from: www.microsoft.com/windows/windowsmedia/download/default.asp A www.siliconchip.com.au Using Playlists Q I’ve built the MP3 Jukebox kit (and everything works fine), programmed the Altronics A-1007 Universal Remote and catalogued over 160 music CDs! Finally, I found time to try the system together and everything seems OK. However, I found that if you are playing a song and you want to listen either to another song or playlist, the music currently playing stops immediately and it starts to play the next selection; even if the song has only just started. Is this how the system is supposed to operate? I would have thought that like a proper jukebox (like the ones you can hire), this one would also continue to play the current selection before proceeding to the next track/playlist. Winamp by default works in this way but through this kit and using the remote control, Winamp doesn’t seem to “buffer” the tracks. This is how it is designed to work. Your only option really is to sort the tracks in the playlists in the order you would like to hear them. It probably wouldn’t be too difficult for an experienced VB6 programmer to alter the IR Remote program to do what you want. The source code can be downloaded from: http://www.siliconchip.com.au/ Shop/6/2102 A Substituting A Slower Crystal Q Could you please advise if there are any implications with using the 10MHz version of the Atmel AVR Microcontroller in the IR & LCD MP3 Jukebox project? There are no problems using the 10MHz part with a 4MHz crystal as used in the project. We used a 10MHz micro in the prototype because although 4MHz parts are cheaper, they’re harder to obtain. A January 2002  21 (( TOUCH and/or REMOTECONTROLLED LIGHT DIMMER (( (( (( (( (( (( (( (( (( (( (( (( (( (( down – by simply touching an attractive plate which takes the place of the light switch and knob. And you can add one or more extensions for two, three or more-way dimming. The dimmer itself is very sleek. The only part that you see when mounted onto a wall is a modern aluminium wallplate (we used a commercially-available Clipsal Classic 2000 blank plate – so it looks very professional and as modern as tomorrow. A bezel is added to allow for reception of the remote control infrared transmission from the hand-held unit. www.siliconchip.com.au ( 22  Silicon Chip dimmers are installed in living rooms, lounge rooms, bedrooms – in fact, just about anywhere. But the traditional wall-mounted, knob-controlled light dimmer has a major drawback. You decide you want to dim the lights and you have to get up out of your comfy chair and go and do it. Wouldn’t it be nice if you could do it by remote control? You can with the all-new SILICON C HIP light dimmer. What’s more, there’s no ugly knob. There’s not even a light switch! As well as using a remote control, you can actuate the dimmer – up or (( E very now and then we get a letter or email criticising our use of a microcontroller when (perhaps) a similar job could have been done with (lots of!) discrete components. Well, look at our latest light dimmer – and what it does. We make no apologies for using a PIC because it does so much, so simply. A project such as this demonstrates perfectly why we use microcontrollers. There would be very few homes that don’t have a light dimmer or three. So-called “mood lighting” became the big thing in the eighties; today light (( Old-fashioned light dimmers with their knobs on the architrave are so passé! Here’s one that you simply touch to dim up or down, or touch again to turn full on or full off. Not decadent enough? How about full remote control from the comfort of your armchair? Now that’s a dimmer! (( By John Clarke (( (( (( (( You don’t even have to build the started” to reduce stress on the lamp one control – a touch – which must infrared controller yourself: it is a filament. What this means is that powperform several functions but the low-cost, commercially available unit er is applied to the lamp gradually to remote hand-held unit has several conwhich is preprogrammed for hundreds bring it up to brightness. trols. So we can use different buttons of different types of TVs, VCRs, satelto perform various dimming functions. When you turn on a normal light, lite receivers, etc. a very high surge current flows for a We have selected five buttons to do The light dimmer can be set to brief period (until the cold filament the job. The ‘CH +’ and ‘CH –‘ buttons operate on one of four programming heats up). This causes a thermal shock provide fast up and down dimming codes so you can select one which can cause the filament to respectively. The ‘volume +’ and which does not operate any ‘volume –’ buttons provide for slow of your other devices. (You’d up and down dimming. Features hardly want the telly to change The ‘mute’ button turns • Attractive slimline appe volume whenever you dimmed off the lights. arance - no knobs! • Touch Plate dimming the lights!). Incidentally, fast dimWe have tested two different ming takes two seconds • Soft start for lamp when switched on hand-held remote controls. from one lamp brightness • Last dimming setting sto red and returned at switc One is a simple TV-only unit extreme to the other, while h on • Full brightness restored on second touch with minimal controls while slow up and down dim• Remote control operatio the second is more elaborate ming takes 11.6 seconds. n • Full control features with and can control several difYou can use the fast conTouch Plate extension • RFI suppression ferent devices. This could trols to set the approximate also be used to control your brightness required and the • Reset for brownout and blackout TV set and VCR as well as slow dimming buttons to the light dimmer. more accurately set the level. Hey, we’ve just helped you get rid There are 102 brightness of a couple of remote controls! levels available from minibreak – especially when the lamp is mum brightness to full brightness and Dimming and “soft starting” reaching the end of its life. You have the brightness is varied so that its level probably noticed that the vast majority appears to change in approximately As mentioned, dimming of the of lamps “blow” at the instant they equal steps. lights can be achieved in two ways: are turned on. When the light dimmer is first using the touch plate or using the reAllowing the lamp to warm up installed or if power is restored after mote control. We’ll look at the touch slowly, with soft starting, prevents the a blackout or brownout, the lamp is plate first. filament from changing from cold to initially set as off. Full brightness is Dimming is initiated by simply hot too quickly, reducing the thermal returned with a quick touch of the holding your hand on the touch plate shock. Even though it happens slowly dimmer plate. Also the last dimmed and the light will be dimmed either up as far as the filament is concerned, as level is not remembered when the or down. It takes just on three seconds far as you (the user) are concerned power is lost. for the light to be dimmed over its full it all happens pretty quickly. The T he dimmer is powered from ­ range. Dimming stops when either soft start brings the brightness of the the mains via a dropping capacitor minimum brightness or full brightness lamp up automatically from minimum (0.47µF) which does not itself conis reached. brightness to full brightness in just sume power in order to deliver the Dimming the light in the opposite 340ms. Therefore it takes 17 mains current required by the circuit. direction simply requires the hand cycles (50Hz) for the lamp to be at full Power drawn by the dimmer circuit to be momentarily removed from the brightness. from the mains is a miniscule 0.42W touch plate and then reapplied. Soft starting occurs whether the which equates to about 3.7 kilowattWant instant light? A quick tap of lamp is only brought up to a low hours per year. This will make its cost the touch plate will switch the light brightness setting or to full brightof running (ignoring the power used by on and another quick tap will turn it ness. Normal up/ off. When switching on, the lamp is down dimming returned to the brightness that it was also effectively last dimmed to. provides a soft If you want the lamp at full brightstart because ness, you can give the touch plate of its slowanother quick touch and the lamp will er change in be brought up to full brightness. This brightness over second touch must be done within 2.5 time. seconds or the lamp will be switched off instead. Alternatively, you can Remote control hold your hand on the plate so that it Remote control features is dimmed up to the required brightare different to those availaness. ble with the touch plate. The Even when apparently switching touch plate has effectively only on instantly, the lamp is always “soft (( (( (( (( (( (( (( (( (( (( (( (( (( (( (( (( (( (( (( (( (( (( (( (( (( (( (( (( (( (( (( (( (( (( (( (( (( (( (( (( ( www.siliconchip.com.au January 2002  23 15 CRYSTAL TIMEBASE MAINS IN 6 10MHz 16 START ZERO VOLTAGE NEGATIVE EDGE DETECTOR LOCK TIMER (250) CLOCK RESET BRIGHTNESS COUNTER VALUE 0-250 MONITOR TOUCH PLATE 17 EXTENSION BRIGHTNESS LEVEL REGISTER TOUCH PROCESSOR & EXTENSION PROCESSOR EXCLUSIVE COMPARATOR 10,11 12,13 TRIAC GATE DRIVE VALUE 48-211 18 1 START/STOP 7 2 CODE SELECT INPUTS TRACER DECODING 8 DECODE 3 SHIFT REGISTER IC2 IR SIGNAL  9 IR MONITOR TIMER AMPLIFIER DEMODULATOR Fig.1: there appears to be a lot in the dimmer but most of the work is under-taken by the PIC microcontroller, IC1, which comprises the yellow blocks. the lamp) less than 40 cents per year. Phase controlled dimming The dimming circuitry is based on phase control to set the lamp brightness. As you know, our electricity supply (nominally 240V AC) is a 50Hz sinewave which goes positive for 10ms, back through zero and negative for 10ms, back through zero and positive for 10ms, and so on. Normally, of course, the lamp filament is connected to the supply when ever it is switched on. But what if it could be switched on and off very rapidly, so that only a percentage of the mains voltage could get through? If it was connected 50% of the time, you would expect the lamp to be significantly dimmer than when connected 100% of the time. Now what if this on/off switching was so accurately timed that the “on” point occurred at the same point in each half cycle (say half way through, or 50%) and the “off” point occurred at the end of that half cycle? The effect would be exactly the same. That is effectively what a phase controlled Triac dimmer does. It allows power to get to the lamp only for 24  Silicon Chip certain portions of the mains cycle. If power is connected early in the cycle, the lamp will glow brighter. But if it is connected much later in the cycle, the lamp will glow much dimmer, simply because there isn’t the power to heat the filament as much. Switching is performed by a device known as a Triac which can be triggered on by a voltage at its gate. The Triac will only turn off when current through it drops below a certain threshold value. In practice, when driving a resistive load, this means that the Triac switches off when the mains voltage is near 0V. The accom- panying oscilloscope traces show how it works. The first oscilloscope waveform (Scope 1) is the 50Hz mains sinusuoidal voltage measured on the active output of a power point. This has an effective or RMS voltage of 240V (±5%) while the peak voltage is about 339V. Note that the mains voltage shown here is higher – 250VAC and 355V peak (half the peak-to-peak voltage). The second oscilloscope waveform shows (Scope 2) shows the waveform applied to the lamp when it is required to have a low brightness. In this case, the lamp is powered about 150° from the start of each mains half cycle and is switched off at 0V. The lamp voltage is applied for both positive and negative excursions of the mains and the RMS voltage is around 39V. The next oscilloscope waveform (Scope 3) show the lamp voltage when it is bright. Now the voltage is applied early in each mains half cycle so that almost the full mains waveform is applied. Again the lamp is switched off at 0V. The RMS voltage is now a lot higher at 242V. Circuitry for the lamp dimmer utilises this phase control by dividing up each half of the mains waveform into 250 discrete sections. There are 250 sections starting from the 0° and finishing at 180° for the positive half cycle and another 250 discrete sections from 180° through to 360° for the negative half cycle. Thus each discrete section of the mains is about 0.72° (180/250). This is shown in Fig.2. A count of 48 is therefore 34° and a count of 211 is 152°. These are the two extremes over which the circuit will dim the lights. Block diagram Fig.1 shows the general arrangement TOUCH PLATE DETECTION TOUCH PLATE DETECTION BRIGHTNESS COUNTER RESET ZERO VOLTAGE DETECTION TIME 0 10ms 20ms 30ms 0 34 90 152 180 214 332 360 90 180 BRIGHTNESS 0 COUNTER 48 125 250 211 0 48 211 250 0 125 250 DEGREES Fig.2: this diagram represents 1.5 cycles (30ms) of mains voltage. The degrees and brightness counter scales are explained in the text. www.siliconchip.com.au These three oscillograms show how phase control delivers various amounts of power to a load. On the left (Scope1) is a somewhat distorted sine wave, straight out of a power point. While nominally 240V AC, 50Hz, in this case it’s actually 250V AC and the frequency is just a tad low (neither of which is unusual). The second shot (Scope 2, above right) shows power being made available to the load very late in the half cycle so it effectively receives just under 40V. In this case, the lamp would be barely glowing. Scope 3, the waveform at right, shows triggering very much earlier in the cycle, so the lamp receives almost all the available power. Here the lamp would be at virtually full brilliance. WARNING: These scope waveforms are shown to explain the operation of the circuit. DO NOT try to reproduce these waveforms yourself – it is too dangerous. We used a special low-voltage test jig to obtain some of these waveforms. of the dimmer circuit. Most of the operation, with the exception of the infrared amplifier demodulator (IC2), is performed by IC1, a single chip microcontroller. We used a PIC16F84-10/P (or PIC16F84A-20/P), programmed to perform phase control. It accepts inputs from the mains, from the touch plate and external terminal and also from the remote control amplifier demodulator (IC2). It then provides an output to drive a Triac. The mains input at pin 6 of IC1 provides information about the phase of the waveform. Each time the voltage passes through zero (see Fig.2) the zero crossing detector resets the brightness counter. This counts from 0 through to 250 for both the 10ms positive and the 10ms negative half cycles of the mains voltage. It counts up every 40µs provided by a signal from an internal timer which is clocked using a 10MHz crystal timebase. An important part of this circuit is the feedback from the brightness counter back to the internal timer. This is required to lock the internal timer to the brightness counter. Any deviation from this locked arrangement will produce flickering in the phase controlled lamp. Without locking, the counter could be any value between 225 to 275 depending on the mains frequency and crystal frequency drift. We therefore lock the counter to the mains by adjusting the internal timer in increments of 800ns either faster or www.siliconchip.com.au slower over the 10ms period between each zero crossing. Adjustments are carried out every 20ms. Inputs from the touch plate (and extension, if fitted) are monitored by the touch processing block. Touch plate detection is checked at around 90° which is the peak positive excursion of the mains waveform. The actual power supply for the dimmer follows the mains voltage and so if we want to pull pin 17 towards ground, the best sensitivity for this is when the dimmer circuit is sitting at the peak positive excursion of the mains waveform. The touch processing determines how long the touch plate has been touched or how long the extension input is connected by counting the number of mains cycles. It processes this to control the brightness level register. Similarly, the brightness level register is altered using the remote control. IC2 detects the infrared remote control code and amplifies the signal. Its output provides a demodulated signal of the transmitted code. Oscilloscope traces show the signal from the infrared hand held unit which is a modulated signal on a 36kHz carrier (Scope 4). The second set of traces (Scope 5) show this modulated signal in channel 1. Channel 2 shows the demodulated signal at the output of IC2 where the carrier is removed. Note that IC2 inverts the remote control signal. The remote control signal at the output of IC2 is applied to pin 9 of the infrared decode select block. A shift register January 2002  25 Scope 4, on the left, shows the signal from the infrared hand-held unit which is a modulated signal on a 36kHz carrier. Scope 5, top right, shows this modulated signal in channel 1 (the yellow waveform). Channel 2 (blue waveform) shows the demodulated signal at the output of IC2 where the carrier is removed. Channel 3 (magenta) is the tracer waveform, while the green waveform (Channel 4) shows the decoded output. Scope 6 (right) is similar to Scope 5 except that channel 1 (yellow) shows the stop start waveform. This signal can be used to sync the oscilloscope. converts the remote control serial code into a parallel form suitable for comparing with the known control codes in the decoder. Remote control operation codes are shown at pins 1, 7 & 8 which give the start and stop signal for the remote control signal, the tracer output which shows the position where the level of the remote control signal is read and the final decoded signal as applied to the decoder. Channels control decoding will not operate correctly and will result in loss of remote control operation. Fortunately, the mains 2, 3 and 4 show this. frequency is usually well within 5% of the nominal 50Hz The remote control signal applied to pin 9 is a bi-phase code where a low level is represented by a high level go- and with this variation (47.5Hz to 52.5Hz) the remote control will still operate. ing to a low level and a high is represented by a low level In fact, the mains frequency will be very, very close to going to a high level. Note how the tracer signal in channel 3 (short positive 50Hz most of the time. This is because it must remain acpulse) is essentially in the middle of the high or low square curate for power stations to keep in lock with each other and also to maintain load waveform of the remote conconditions over time. trol signal found at the pin 9 And if it varied too much, input at channel 2. Incorrect every mains-locked clock decoding will occur if the This circuit operates on the 240 volt mains and radio and alarm clock in tracer rate is too fast or too most parts of the circuit are at mains potential the country would show slow, which will shift the and therefore DANGEROUS. Furthermore, the wrong time – and then tracer too far to the left or installation into fixed wiring can only be wouldn’t people get upset! to the right respectively. The waveform resulting Once the remote control undertaken by licensed electricians under from the detection at the signal is decoded it is comcurrent legislation in most states. tracer points is the lower pared with stored codes. channel 4 output and is the Inputs at pins 2 and 3 select decoded signal. the particular code that is used with four possible different codes available. When the selected stored code is the same The Scope 6 waveforms are similar to those above except as the received remote control signal the brightness level that we have included the stop start waveform for channel register is altered in response to the particular function 1. This signal can be used to sync the oscilloscope. delivered by the remote control. So, for example, if fast Decoding periods are set by the internal timer which as previously mentioned is locked to the mains frequency. If up dimming is selected, the brightness level register is the mains frequency drifts too far off 50Hz, then the remote decreased to increase lamp brightness. PLEASE NOTE! 26  Silicon Chip www.siliconchip.com.au The PC board is secured to the plastic face plate with nylon screws. The hole in the bottom of the PC board actually has a nut soldered to the track on the other side, ready to accept the touchplate contacting metal screw. The following comparator monitors both the brightness level register and the brightness counter. When they are equal, the comparator output provides a pulse to drive the Triac gate. If the brightness level register is a low value, this value will be equal to the brightness counter early in the mains cycle to provide a bright lamp. If the brightness level register is a larger value, the value will be equal to the brightness counter later in the mains cycle and so the lamp will be dimmer. the infrared decoder (IC2), a Triac, several diodes, a transistor, a crystal and an inductor plus a few resistors and capacitors . The Triac is connected between the mains active and the lamp via an inductor (L1). This inductor, in conjunction with the 0.1uF 250VAC capacitor, provides suppression of The circuit Considering the complexity of the dimmer operation, there is not too much in the actual circuit itself. This is because most of the work is done in the PIC16F84-10P microcontroller (IC1). Apart from this IC there is only electromagnetic radiation caused by the Triac switching. The inductor core is made from an iron powdered material which is very lossy in the high frequencies, particularly above 1MHz. Power for the circuit is derived directly from the mains supply, using a 0.47µF 250VAC mains capacitor as a dropping impedance for the following A TOUCH PLATE Q1 BC327 B 68k 22k EXTN 4.7M VR37 47k 14 18 MCLR RB4 RB5 RB6 RB7 RA1 17 10 11 12 13 470F 16VW IC2 RB0 0.1F 2 WARNING: MOST PARTS OF THIS CIRCUIT OPERATE AT MAINS POTENTIAL A1 IC2 TRIAC1 SC141D A2 1 .01F 680k 6 RB2 9 RB3 RA3 RA4 2 0V +5V 3 5 1 8 7 3 2 680k Q1 L1 60H +5V RB1 1 +5V IC1 PIC16F84-10/P RA2 REMOTE SIGNAL +5V G A2 16 3 l G 1M X1 10MHz 22pF 39 A1 RA0 15 +5V 0.1F 250VAC D1 FR102 4 10k 22pF TRIAC1 +5V C A 4.7M VR37 10k E 47F TANT 1M E START/STOP B C DECODE TRACER ZD1 5.6V 5% 1W D2 1N4004 LAMP 250W MAX 1k 5W N 0.47F 250VAC LAMP (NOT CONNECTED TO CIRCUIT) E 0V CODE SETTING LINKS SC 2002 LIGHT DIMMER Fig.3: the circuit is based on a suitably programmed PIC 16F84. It can handle input from either a touch plate or from a selection of infrared remote controllers. The code setting links depend on the specific controller. www.siliconchip.com.au January 2002  27 UNDERSIDE DIMMER BOARD off, then the 0.47µF capacitor can charge and discharge smoothly with the sine wave voltage and the current CABLE TIE D1 through the 1kΩ resistor is SECURING FR102 SOLDER L1 ABOVE about 35mA RMS. This gives 680k CAPACITOR TO TRIAC1 SENSOR CASE a power dissipation in the AND PCB TRACK 1kΩ resistor of 1.23W. 0.1F Things are different when INSULATE PC L1 TRACK WITH the Triac is fired. This is TAPE UNDER IC2 SOLDER because of the energy stored SHIELD CAN M3 TAPPED IC2 0.47F 250VAC 6mm SPACER in the capacitor – 27mJ (1/2 IC2 CV2). To convert this to watts ZD1 1k * we multiply by 100 as there 5W 47 * D2 are this many half cycles in 470 1 a 50Hz mains waveform per 22k IC1 PIC16F84 * second. The dissipation then 68k becomes 2.7W in the 1kΩ Q1 BC327 X1 22p resistor. 10MHz 4.7M 22p 39 4.7M* Selection of the resistance VR37 value is a compromise be*THESE COMPONENTS MOUNTED UNDER PC BOARD tween having low power disFig.4: the PC board has tracks on one side but components are fitted to both sides. At sipation when the Triac is off left is the ‘normal’ component side while the right diagram shows the copper (track) (which calls for a low value of side with the infrared receiver, capacitor and resistors. resistance) and reducing the 5.6V zener diode, ZD1. The 0.47µF mum brightness for the lamp. While surge current through the zener capacitor has an impedance of 6.77kΩ it appears to be fully bright, it is not diode when the Triac is fired (which at 50Hz. When combined with the quite as bright as if switched directly calls for a large value of resistance). series 1kΩ resistor this doesn’t give across the mains supply. The resulting DC supply is filtered an effective impedance of 7.77kΩ, as If the 0.47µF capacitor gives an with the 470µF electrolytic capacitor you might expect. It’s actually 6.84kΩ impedance of 6.77kΩ by itself, why and 0.1µF ceramic capacitor for IC2 due to the phase differences between include the 1kΩ resistor in series? One and the 47µF tantalum capacitor for the capacitor and the resistor. This reason is to limit surge currents if the IC1. The 0.1µF ceramic capacitor aids impedance limits the current flow in mains supply is connected during the the 470µF capacitor in suppressing ZD1 to 35mA. peak of the supply. However, there is high frequency noise on IC2’s supply The resulting supply is about 5V due another and more important reason which could cause erratic operation to the voltage drop across D2. and is because of the Triac. of this high gain device. The tantaOne thing to note here is that this When the Triac is fired, the charge lum capacitor provides both high 5V power supply can only be obtained on the capacitor is immediately dis- frequency filtering and also sufficient when the Triac is off. When the Triac charged through L1, the Triac, the energy storage for the current drive is on there is only about 1V across it zener diode and the 1kΩ resistor. So to the Triac. which is insufficient to develop the we need to limit this surge current Power is applied between pins 14 power supply voltage. through the zener diode, particularly and 5 of IC1 and between pins 3 and Thus the phase control is limited to when the capacitor is charged to 340V 2 of IC2. Pin 4 of IC1 is the reset input a minimum of 35° to make sure that (the peak of the 240V AC waveform). for the microcontroller and connects there will always be power available. Dissipation in the 1kΩ resistor is to the brownout circuit, comprising This phase angle also sets the maxianother consideration. If the Triac is Q1 and the associated resistors. The LOOP A EXTN KEEP WINDINGS CLOSE 4.7M VR37 4.7M 1M 47k 10k 10k .01F 0.1F 250VAC 1M 680k LAMP 4mm DIA. HOLE 3 TOP 6 4 4 SOLDER WIRE TO CENTRE LEAD 3 6 3 4 SHIELD IC2 LEAVE 75% OF CORE FREE OF WINDINGS L1 WINDINGS (24 TURNS OF 0.5mm ENAMELLED COPPER) Fig.5: L1 is wound with the turns at the top to minimise interference to the infrared pickup circuit. 28  Silicon Chip Fig.6: if your infrared receiver doesn’t come with a shield, you’ll need to fashion one from tinplate. Here’s how it’s done. Note how the cable tie passes through the PC board to secure L1 on the top side. www.siliconchip.com.au circuit is used to bring pin 4 low if the supply drops below a certain threshold. With a 5V supply, there is sufficient voltage on the base of Q1 to switch it on, pulling pin 4 to the 5V supply rail. If the supply rail drops, current through the 10kΩ and 68kΩ resistors at Q1s base will also fall. When the supply voltage reaches 4.68V, the current through the resistors is 60µA and so the voltage across the 10kΩ resistor is 0.6V. At this voltage Q1 just begins to turn off, pulling pin 4 of IC1 low to reset it. Crystal X1 operates at 10MHz to provide IC1 with an accurate clock signal for all the timing signals required in the phase control driver and remote control decoder functions. The 22pF capacitors provide the crystal loading to ensure a reliable oscillation when power is applied. Dimming control inputs are at pin 17 for the touch plate and at pin 18 for the extension. The touch plate is connected to pin 17 via two series-connected 4.7MΩ high voltage resistors. It is essential to use the resistors nominated (ie, Philips VR37). As well as limiting any current flow to a person touching the touch plate to below 26µA, these particular resistors give a good safety margin as they are rated at 2.5kV (AC) each. Two resistors increase the voltage rating to 5kV giving extra safety. Normally, the input from the touch plate (pin 17) is held at 5V via the 1MΩ resistor but if the touch plate is touched, the ground capacitance of the person will bring the touch plate to ground potential. This effectively pulls pin 17 down to the same level as pin 5 whenever the active line is above ground. IC1 can then detect this low voltage. The extension input at pin 18 is normally held low via the 10kΩ resistor. It is pulled high to the 5V supply, when the extension is activated (in the same way as the main touch plate above). The 47kΩ resistor to pin 18 is used to protect the input from transients or incorrect connections to the extension. Note that we need to use this extension input for extra touch plates. If we simply extended the pin 17 input to another switch plate the extra capacitance and pickup from the extra line length would trigger this high impedance input. www.siliconchip.com.au The whole assembly fits into a standard mounting box (as shown here) or can be attached to a standard mounting plate. The brushed aluminium cover which goes over the whole assembly forms the touch plate. IC2 receives and demodulates the codes from the infrared remote control. It incorporates an amplifier and automatic gain control plus a 38kHz bandpass filter to accept only remote control signals. It then detects and removes the 38kHz carrier. The resulting signal is applied to the pin 9 input of IC1 ready for code detection. The pin 2 and pin 3 inputs provide options for one of four remote control codes and are set by tying these pins either high or low with solder link connections. The high gain of IC2 makes this device susceptible to electrical interference from the switching Triac and from the suppression components. The software has been carefully planned so that the remote control coding is only monitored when interference is at a minimum. This interference, however, does cause the gain of the amplifier to be substantially reduced due to its internal automatic gain feature which is used to prevent overload in its circuitry. This throttling back of gain reduces the range of the remote control operation. To minimise the effect, we have included shielding around the device and have wound the suppression inductor in an unusual manner to substantially reduce any electromagnetic radiation. The zero voltage crossing point for the mains waveform is detected at pin 6 of IC1 via two series connected 680kΩ January 2002  29 Parts List – Touch/Remote Controlled Dimmer 1 PC board coded 10101021, 62 x 72mm 1 preprogrammed remote control (Jaycar ‘Big Shot 3’ AR-1710) or 1-TV preprogrammed remote control (Jaycar ‘Select 1’ AR-1703) 1 Clipsal CLIC2031VXBA blank plate and blank aluminium plate 1 clear capped LED bezel or 250VAC Neon bezel 1 iron powdered toroidal inductor, 28 x 14 x 11mm (Jaycar LO-1244 or equivalent) (L1) 1 4-way PC screw terminal block (Altronics P 2103 or equivalent) 1 18-pin DIL socket 1 10MHz parallel resonant crystal (X1) 2 M3 x 16mm countersunk Nylon screws 1 M3 x 10mm countersunk plated metal screw 2 3mm x 6mm untapped spacers 1 M3 tapped x 6mm metal spacer 2 M3 nuts 1 150mm cable tie 1 1.2m length of 0.6mm enamelled copper wire 1 9 x 20mm piece of tinplate (tin can material) 1 50mm length of 1.5mm spaghetti tubing Semiconductors 1 PIC16F84-10/P (or PIC16F84A-20/P) programmed with Dimmer.hex (IC1) 1 infrared receiver (Jaycar ZD-1952, DSE Z-1955 or equiv) (IC2) 1 SC141D 10A 600V Triac or similar (Triac1) 1 BC327 PNP transistor (Q1) 1 FR102 (UF102, 1N4936) or similar fast diode (D1) 1 1N4002 diode (D2) 1 BZV85C5V6 1.3W zener diode 5% (ZD1) (alternatives must be 5% tolerance) Capacitors 1 470µF (105° C) 16VW PC electrolytic 1 47µF 16VW tantalum 1 0.47µF 250VAC X2 class MKT polyester 1 0.1µF 250VAC X2 class MKT polyester 1 0.1µF ceramic 1 0.01µF MKT polyester 2 22pF ceramic Scope 7: this shows the mains waveform with a 1kHz control tone superimposed on it. The effective modulation is up to 50V peak-to-peak and can cause havoc in the zero voltage detection unless filtered out. the dimmer operates within the correct phase limits. The filtering is necessary to reduce the effects of electricity authority control tones which may be superimposed on the 50Hz mains. These could otherwise cause rather noticeable flickering in the lamp. The Scope7 oscilloscope waveform shows the mains waveform with a 1kHz control tone superimposed on it. The effective modulation can be up to 50V peak to peak and can cause havoc in the zero voltage detection unless filtered out. Gate triggering to the Triac is delivered by the paralleled pins 10, 11, 12 & 13 of IC1. Together these can sink a total of 100mA but we limit the current to the gate to around 50mA with a 39Ω resistor. Diode D3 reduces the 0.7V positive voltage which is present on the gate when the Triac is switched on from driving current back into these IC1 gates. Gate triggering pulses are shown in the “Scope 8” oscilloscope waveform. They are 80µs wide and repeat at 10ms intervals. Extension plates You can add another extension plate to the system to Resistors (0.25W 1% unless stated.) 2 4.7MΩ VR37 Philips high voltage (no substitutes) 2 1MΩ 2 680kΩ 1 68kΩ 1 47kΩ 1 22kΩ 2 10kΩ 1 1kΩ 5W 1 39Ω resistors connected to the A2 terminal of the Triac. Detection of the zero crossing is only made at the negative transition. If the Triac switches on, the A2 terminal will cause the input to go high. So zero detection is only available when the A2 terminal goes low, at the end of the positive half cycle of the mains waveform. The zero voltage detection signal is also filtered with a .01µF filter capacitor. This capacitor causes a substantial shift in the detected zero crossing point but this is adjusted in software so that 30  Silicon Chip Scope 8: these are the triggering pulses, which are 80µs wide and repeat at 10ms intervals. www.siliconchip.com.au RESISTOR COLOUR CODES    No. Value  2 4.7MΩ  2 1MΩ  2 680kΩ  1 68kΩ  1 47kΩ  1 22kΩ  2 10kΩ  1 39Ω 4-Band Code (1%) yellow violet green yellow brown black green brown blue grey yellow brown blue grey orange brown yellow violet orange brown red red orange brown brown black orange brown orange white black brown give both touch and infrared control at a second, or even third location. We’ll look at the way this works and how to put it together next month, when we also run through the recommended testing procedure. We’ll also look at coding the remote controls. Construction The dimmer is constructed on a PC board coded 10101021 and measuring 62 x 72mm. It is installed into a Clipsal Classic blank plate with a matching blank aluminium touch plate. The completed dimmer will fit inside a standard metal wall box where these are fitted in a brick wall or simply to a Gyprock wall. Alternatively, it can be placed on a standard 30mm deep mounting block. Begin by checking the PC board against the published pattern to ensure there are no shorts between tracks or any breaks in the copper. Repair these as necessary. Now check that the holes are drilled to the correct sizing for the larger components. The screw terminal mounting holes need to be 1.5mm in diameter, while the PC board mounting holes, the touch plate connection and the cable tie holes to secure L1 should be 3mm or 1/8" in diameter. Install the resistors (except for the two 4.7MΩ values and the 1kΩ 5W resistor) first, noting that some are mounted on-end. Use the colour code table to guide you in selecting each value. You can also check the values with a digital multimeter. Now install the socket for IC1, along with the capacitors. The tantalum and electrolytic types must be oriented with the correct polarity, as shown on the overlay. Diodes can be installed next making sure they are also placed with the correct orientation and that the correct type is placed in each www.siliconchip.com.au 5-Band Code (1%) (NA – must be VR37 type) brown black black yellow brown blue grey black orange brown blue grey black red brown yellow violet black red brown red red black red brown brown black black red brown orange white black gold brown position. The Triac can be placed in position as well as the screw terminal strip. Transistor Q1 and crystal X1 can now be soldered in place. The 1kΩ 5W resistor mounts end-on with spaghetti sleeving over the wire ends. It stands proud of the PC board by about 5mm to clear diode D2. Inductor L1 is wound using 24 turns of 0.5mm enamelled copper wire around the toroid as shown in Fig.5. It is not wound in the conventional manner with even spacings of the windings around the core; rather the windings are concentrated over about 25% of the circumference. This unusual winding method is to keep any stray fields away from the infrared detector which is susceptible to picking up interference and producing erratic results. Do not use a commercially wound inductor as this will CAPACITOR CODES Value 0.47µF 0.1µF 0.01µF .0047µF 22pF IEC Code 470n 100n 10n 4n7 22p EIA Code 474 104 103 472 22 have even winding spacings around the core and will prevent the infrared receiver from operating properly. When you have finished winding the core, pot the windings in some 5- minute epoxy. This will reduce the audible buzz caused by the vibration of the windings when driving the lamp with phase control. When the epoxy has set, place the inductor in position on the PC board with the windings oriented towards the top and secure in place with a cable tie wrapped around the circumference and through the two holes in the PC board under the core. The wires from the core are soldered into the PC board by first cleaning off the insulation and tinning the wire ends. The windings will be in close contact with the Triac tab, however, the windings and tab are at essentially the same voltage so there is no particular reason to be concerned about insulating the windings from the tab. You may, however, wish to place a short The Clipsal CLIC2031VXBA blank wall plate shown here assembled with the PC board. The two nylon PC board mounting screws are on the left, the metal pan-head screw is at the bottom (its head is marginally above the plate surface to ensure contact with the aluminium cover plate), while the infrared receiver “lens” (actually part of an old neon bezel) is at the top. January 2002  31 length of insulating tape over the to be located as close as possiwindings in the vicinity of the ble to the inside surface of the Triac. plate for best reception of the infrared signal. Work can now begin on the underside of the PC board. The PC board is attached to the plate using countersunk Nylon The 4.7MΩ resistors are mountscrews adjacent to the screw ed first. You must use the specterminals and the countersunk ified Philips VR37 types here metal screw which secures into because they are rated at 2500V. the 6mm tapped standoff. The Use of standard 1W resistors will board stands off from the plate jeopardise the electrical safety of with two 6mm spacers for the the dimmer. You can recognise Nylon screws. Use M3 nuts to the VR37 types by their light blue secure the board in place. body and yellow tolerance band rather than a gold one. Note that you must use Nylon screws and not metal ones for the Cut the excess lead length off mounting points adjacent to the on the top of the PC board. Sol- Fig. 4: same-size PC board pattern for the main screw terminals. This is to ensure der the 6mm tapped spacer to unit. The extension will be published next month. electrical safety. the board by first securing it in The hole for the metal touch contact position with a screw from the As we mentioned earlier, screw is also countersunk a little. Don’t contact is made between the metal top side of the PC board. This will make this too deep, as the screw needs position the spacer correctly before plate and the circuit via a 3mm metal to sit proud of the top face by about machine screw. We used a pan-head soldering. 0.5mm to make reliable contact with (ie, slightly raised) countersunk If the infrared receiver does not the metal plate when it is attached. screw which, when installed, was come with an earthed metal shield, The hole for the infrared sensor just proud of the plastic surface by you will need to make one for it. It must have some form of permanent about half a millimetre or so. When can be made using some tinplate covering over it to prevent anyone the aluminium dress plate was salvaged from a tin can or lid. Cut (little people especially!) poking an- snapped into place, this screw made it out to shape with tin snips and ything inside the hole and possibly reliable contact. drill out the hole for the receiver making contact with the live parts lens. Now fold the shield around the And finally, another warning! inside. body of the receiver. Solder a short We used a clear LED bezel cover length of wire between the centre Just in case you missed the warning which was cut down in length and messages published elsewhere in this ground pin to the shield. The unit glued into the plate with super glue. is now secured to the underside project, let’s reiterate: Alternatively, you could cut the lens of the PC board as shown. This is a mains-powered project end off from a 240V neon bezel to cover with most parts floating at mains poNote that the shield and the copper over the hole on the plate. Mark out the tential. Do NOT attempt to operate it area below the sensor are at different position for the infrared receiver lens outside of a protective case or box – in potentials, so if the shield makes conon the plate and drill out this hole to fact, leave the testing until next month tact with the board it will short out suit the size of the plastic bezel. the 5V supply. Make sure there is no when we show you how to do it safely. Now attach the metal plate to the likelihood of shorting here. And if you are going to install it into plastic wall plate and drill out this your home, under current legislation A 0.1µF ceramic capacitor is solhole to suit the outer diameter of dered between the shield and PC you must be a licensed electrician the bezel lens. The bezel should not to even unscrew a wallplate or light board. protrude too far into the inside of switch. Hopefully, that may change Place the PC board onto the Clipsal SC the plastic plate as the sensor needs plastic wall plate with the infrared in the future! receiver to the side which has the mounting screws stowed away (unNext month: testing, installation, remote controls and extensions less, of course, you have already That’s about all there is to removed the screws!). This side has the basic dimmer. However, mouldings which encroach inside of we have yet to look at the the wall plate. testing procedure (which is Now mark out the hole positions done with low voltage for for the two mounting holes adjacent safety), the types of remote the 4-way screw terminals and for the controls suitable and how to touch contact screw which secures set the dimmer codes to suit, into the 6mm spacer next to the installation and also the oper4.7MΩ resistor. Drill 3mm holes for ation and construction of the each. The two mounting holes should remote touch panels/infrared be countersunk from the top side so receivers. We’ll cover all of that the Nylon mounting screws are this in February SILICON CHIP. flush with the top face. 32  Silicon Chip 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 P38! www.siliconchip.com.au January 2002  33 SERVICEMAN'S LOG Not enough information – or too much? It is seldom that I devote a whole column to just two sets of the one brand. One exercise left a lot of unanswered questions and the other was a job that nobody wanted – only nobody told me. And then there was the manual that was too big to be helpful! Mr Greenspan won his TV set in a competition, so his per­ception of it probably differs from that of most customers. Because you haven’t actually had to shell out your hard-earned shekels, you tend not to appreciate its true value. As a result, when it has the temerity to break down, your loyalty to it is limited. It didn’t cost anything, it doesn’t owe you anything, so if it is anything serious . . . well, easy come, easy go. Mr Greenspan’s good fortune was 34  Silicon Chip an expensive 1992 Philips Matchline 16 x 9 aspect ratio TV set, model 36ML8906/00B, employ­ing an FL 1.2 AA chassis. The tube is a W67EW­ 5001X42 but to me that is rather mean­ ingless in conveying size because of its aspect ratio. The manual says there are four picture sizes – 21in, 25in, 28in & 33in – but I really don’t know which one this is. Its diagonal measurement gives a 76cm (29in) viewable area. Anyway, Mr Greenspan’s set was dead and considering that he had won it and it was now nine years old, he wasn’t sure whether he wanted to spend real money on it to have it fixed. I told him I would have a go and spend an hour’s labour on it to come up with an estimate. He could then make a decision on that basis. I removed the back to reveal a large flat split chassis interspersed with a few modules. Access to the copper side of the main board looked particularly awesome and I was so intimidated by the technology that I felt I just couldn’t proceed without a service manual. Fortunately I was able to order one. While waiting for it to arrive, I had a good look at the setup during coffee breaks and while dealing with other sets in the queue. The biggest problem appeared to be that I couldn’t reach the copper side of the mother boards while the set was on. This is not the sort of set one can roll onto its side or even upside down. The chassis could be removed by unplugging it and sliding it back after pressing four locks on either side of both boards. Later, when I acquired the manual, it suggested assembling the two panels with a red clip attached to the signal panel at 90 degrees, though exactly how this was supposed to help access escapes me. In the meantime, I decided on a course of careful and de­tailed observation. In fact, no component could be found to have failed visually, and strategic measurements with an ohmmeter confirmed that the set should work. But I did discover a lot of faulty joints all over the power supply and horizontal stages. Rather than wait for the circuit, I impatiently soldered everything in sight. I also checked for dried out electrolytic capacitors but could find none. Satis­fied, I reassembled it all back in the cabinet. I wasn’t really very optimistic that I had achieved anything much, so I was really surwww.siliconchip.com.au prised to find that I now had both picture and sound and that even the remote control worked. However, I soon realised that the picture was far from perfect. It was dark, small and with a tendency to bloom. Never­theless, I felt that I was probably half way home. Voltage measurements Later, when I received the poorly photocopied version of the service manual, the first thing I did was measure the main HT at TP57, the cathode of D6237. I can never understand why import­ant test points do not provide easy access, with a real test point. D6237 is buried in among heatsinks and it is not easy to attach a crocodile clip to it, although I eventually managed. Instead of 141V there was only approximately 105V, depending on the picture tube beam current. Varying VR6370 on the SOPS (Self Oscillating Power Supply) Control Module varied the HT but not by much. I then spent some time checking all the voltage sources in the power supply and established that all the secondary voltage rails were low. The only exception was that of the separate standby power supply (fSOPS). This gave a higher voltage output than was marked on the circuit. VSTART measured over 20V and is marked 17.5V at TP60 but 5V STBY at TP50 was spot on. I decided that these later observations were irrelevant. And the conclusion was that the control module was the most likely culprit. The irritating thing was that this control module was shown only as a block diagram. There is no circuit, no part number, nor any reference to it in the chassis service manual. I contacted Philips for more information but noone had any at all. The only thing I could get was the “SOPS REPAIR KIT 4822 310 31932” for a trade price of $134.09. Well, it was crunch time for Mr Greenspan. I told him all I knew – which admittedly wasn’t much – and the likely costs that might be involved. He sensibly decided to abandon the set and we struck a deal that I could keep the set in lieu of any labour costs I had incurred so far. I then invested in the repair kit – taking a punt on wha­tever that was. Two weeks later I received a small box with some components, a list, and a new control module! The ES7028 www.siliconchip.com.au multi­lingual list was extremely brief and insisted that I replace all 11 components and the module. I hate being told what to do, so I carefully examined the circuit and noted which parts they were wanting me to replace. The first five parts were the main fuse and bridge rectifi­ers. Then there was another fuse, a chopper transistor, two more diodes and capacitors and a regulator transistor – all of which were working perfectly in this set. Admittedly, a few of these had been modified but only superficially and I really couldn’t see this making much dif­ference. In the end, I just plugged in the new module and switched the set on. And would you believe it? – the picture was now per­fect and the main HT was spot on at 141V. At this point, I imagined that would be the end of the exer­cise. However, as a matter of course, I put the set on test and left it. Each day, I switched it on for the full working day and switched it off with the remote control before the master power switch was turned off. The set baulks After a few days I noticed that the set didn’t want to switch on. By jiggling the power on/off switch several times I could sometimes make it come on and then it would stay on for the rest of the day with all functions working perfectly – including the remote control and main power switches. Gradually, it became worse until finally I had to remove the back and look inside. Just jiggling the module was enough to get it started again and it stayed on. But the problem persisted; every time I switched the set on from cold in the morning, it baulked. Finally, I could only start it by putting in the old module, switching the set on, then switching it off and refitting the new module. By now, I really wasn’t sure whether Items Covered This Month • • Philips Matchline TV set, Model 36ML8906/00B (FL 1.2AA chassis). Philips Matchline TV set, Model 33CE753/42R (3A chassis) it was the new module that was at fault or whether it was another problem altogether. Eventually, after much investigation, I concluded that the new module was faulty and should be returned. Acting on this turned out to be a drama of its own. First, Philips Spares was in the middle of moving and second, they didn’t really believe that the new part was faulty. Eventually, I managed to persuade the Spare Parts Manager to exchange it for another but in view of their move and also lack of stock, I felt that perhaps it wouldn’t be a good idea to hold my breath. He told me to keep breathing and eventually something would be done, so I posted the kit back and prepared to wait. In the meantime, I regularly glared at the old module whe­never I had spare time, trying to guess what the cause of the low HT might be. I particularly looked at the voltage comparator components around transistor 7370 and started to replace some of the surface mounted components such as the 6.2V zener in its emitter. As the days turned into weeks, I gradually ended up by checking almost every component on this module. The module is actually split into two sections – one section is cold and the other hot and they are connected via an optocoupler very similar to many other Philips TV sets of that generation. Well, during one coffee break I made an interesting ob­servation and that was to do with the VSTART voltage. (I am January 2002  35 Serviceman’s Log – continued talking about the old module now; the new one was still with Philips Spare Parts) This voltage comes into the module and goes to a 5.6V zener diode in series with a diode (1N4148) and then to transistor 7371 (all surface mounted). These two diodes were marked 6373 and 6372 respectively. I then realised that these two diodes were also identically marked on the circuit as being on the motherboard. At first, I thought this was just a circuit mistake but a check confirmed that these two diodes were actually on the motherboard, so this configuration had been duplicated. However, when I looked at the circuit of the new module, which I had drawn earlier, these two components were missing! So, to summarise, I had a set with a motherboard carrying these two components plus a module - apparently the original – in which these component were duplicated. But on the second (new) module (now with Philips), these components had been left out and had been replaced by links. What a mix-up; and what did it all mean? In an attempt to clarify the issue, I replaced extra components on the old module with wire links and plugged it back into the set. And when I switched the set on, the picture was perfect and the HT could be adjusted so that it was spot on 141V. A riddle I felt elated that I had fixed the 36  Silicon Chip problem but recognised that I hadn’t solved the riddle. There was a whole swag of ques­tions still to be answered but it appears that Philips made two (at least) versions of this set: one with the two diodes mounted on the motherboard but missing from the module; and one with the diodes in the module but missing from the motherboard. It is hard to imagine a setup more likely to create a mix-up. Supposedly, this set had worked properly for years with this module in it – or had it? Had Mr Greenspan always had a small picture but just wasn’t fazed by it? After all, there is much confusion among owners as to what size and aspect ratio the picture should be: 16 x 9, 4 x 3, or letterbox. Besides, before January this year, it probably was always 4 x 3 and a 16 x 9 set was really superfluous in 1992. Also, Mr Greenspan may have thought it was normal that he was receiving a 4 x 3 picture with the set in 16 x 9 mode. Or had someone else had a go at Mr Greenspan’s set? Getting a set’s history out of some owners is like pulling teeth. I’m not supposed to ask “silly questions” like that. In any case I can’t really raise the matter with Mr Greens­ pan now, so I can only conjecture as to why a set fitted with the wrong module turned up on my bench. Finally, why did the new module fail intermittently? It will be interest- ing to see if the replacement module works when it returns from Philips. In the meantime, the set continues to work flawlessly. Postscript Subsequently, since writing the above, two events have occurred. First, a new SOPS Control Module arrived and, initially, appeared to be working properly. Unfortunately, it failed after a couple of days and I may be able to write more about this later. But was this really a new module or had the previous one with the intermittent fault found its way back to me in the confusion caused by the move. Stranger things have happened. Second, after spending months trying unsuccessfully to acquire a circuit of the SOPS Control Module from Philips, a colleague finally tracked one down. He is an experienced techni­ cian who works by himself from home and found it loose with the instruction book for the set. It is not for an FL1.2 chassis, but actually for an FL1.1S (Part No: 4822 727 6395.1/ SV00.wk.9148). So there we are – but where are we? Another Philips Mrs Adams’ set was a 1989 Belgium-made Matchline 33CE753/42R (3A Chassis) which she had been trying to get fixed. I only found out later www.siliconchip.com.au that she had had the set looked at by several techni­cians who didn’t want to know about it. Had I known this I, too, would have been more cautious – much more cautious. As it was, I was told that it was dead and I was cheaper than the authorised agent. This is always a bad omen – I hate the thought of being contracted just because I am cheap! Still, I take comfort from the fact that the NASA spacecraft components are also constructed (supposedly) by the companies that submit the lowest tenders. So there I was, at her house, looking at this monster 80kg 84cm TV set, having been given the impression that it had only a faulty fuse - or something equally simple. The set had already been put aside and another placed in its place. My heart was in my boots – I just knew that this was going to be difficult but this is my profession and I need the money. The back unclipped easily to expose a chassis which must have few rivals for poor access. The whole thing is enclosed with concealed plastic catches and supports. All I could confirm was that power was getting past the power switch and fuse and onto the main chassis. Apart from that, the set was completely dead and I could find no other easily accessible voltage to check. The set obviously had to go back to the workshop and I also needed a service manual. Initially, I planned to order a new service manual, until I was advised of the cost for a photocopy – $300! I settled for renting it instead. When the manual arrived, I could see why it was so expen­sive – it was huge. The main reason is that it covers all the models employing this chassis and all the possible options. So it covered the basic sets, the projection models, plus the medium and highend versions. My first problem was identifying this particular set’s chassis – and that wasn’t very easy. The serial number started with AGO6, which told me it was a later series after AGO3. It had PIP (Picture-in-Picture), SVHS and hifi sound, Teletext and Multisystem – in fact it seemed to have everything. I never really did discover what VHP, IPP and SYMMETRIC WITHOUT LOUDSPEAKERS meant. More to the point, there was not one complete section or circuit which covered this model in detail. It was a case of a bit of circuit here and a bit there, making the whole thing a schemozzle. Also, while there were fault find­ing trees, they were just too difficult to comprehend. In the end, I settled on using basic principles and mud­ dling through. Removing the entire chassis from the cabinet involved raising two clips (B) at the rear and pulling it out. But this gives only limited access to the components on top and virtually nothing underneath. I found a plug, M17, with a link between pins 5 and 6. This was the 140V HT feed to the horizontal output stage and there was no voltage on this – but neither were there any short circuits, which indicated that the line output transistor 7618 was probably OK. By removing this plug and connecting a 100W globe to pin 6, I could measure 140V. By now, I had also inspected some of the components on the top of the main board and quite a lot didn’t look healthy. I therefore felt that it was a good time to remove the board and give it a detailed examination. Using an indelible felt tip marker to identify everything, I unplugged the sockets leading to the front controls, the tube and the peripheral modules, before getting it out. Once out, I had to remove two screws holding the AV connectors plus remove a fixing bracket E which holds the modules in. I then released two clips and six screws on either side before the main (mono-carri­er) panel would slide out – grudgingly – to the rear. Now that I could have a good look at what I had, I could see that several electrolytic capacitors needed replacing. I also noticed that R3698 (470Ω) was burnt out and there were a several faulty joints. I replaced capacitors C2638, C2555, C2644 and C2701 on spec, along with C2618 (.001µF 2kV) which had cracks in it. C2609 (.0082µF, 1.6kV) had been replaced at some stage in the past with the wrong value and capacitor type, so this too was changed. The horizontal output transformer also looked a little the worse for wear but, for the time being, I just resoldered the pins and repaired a few cracks in the PC board near pin 14. My main worry at this point was to determine what had de­stroyed R3698, which is from the gate of SCR6698 to chassis – it would need a fair bit of grunt to burn a 470Ω resistor, yet the SCR measured OK. I replaced the resistor and C2698 for good measure before putting it all back together and trying it. Early on in this story, when I first checked the set in the customer’s home, I had neglected to label one of the single plugs coming out of IK13 on the PIP interface panel 1710. Now I could­n’t work out where it went and the service manual was completely useless. Eventually, I found it in the MINI SUPER DRILL KIT IN HANDY CARRY CASE. SUPPLIED WITH DRILLBITS AND GRINDING ACCESSORIES $61.60 GST INC. www.siliconchip.com.au January 2002  37 Order Form/Tax Invoice Silicon Chip Publications Pty Ltd ABN 49 003 205 490 PRICE GUIDE- Subscriptions YOUR DETAILS (all subscription prices INCLUDE P&P and GST) Your Name________________________________________________________ (PLEASE PRINT) Organisation (if applicable)___________________________________________ Please state month to start. 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Folded: $A5.95 inc p&p within Australia; elsewhere $A10 inc p&p. *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 38  Silicon Chip 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, www.siliconchip.com.au Australia 2097 * Special offer applies while stocks last. 03-01 Serviceman’s Log – continued back of the 100Hz section where it is shown as going to plug IM27 on the main board (which is conveniently hidden under a plastic bracket). On some circuits, this is also shown as 1M17 and is the 5V standby but quite where it goes to isn’t shown on the circuit diagrams. I suspect it goes to the front panel but time prevented me from tracing this further. And I still had no power at all, even with M17 connected. Next, I shorted the base and the heatsink of the horizontal output transistor, effectively cutting it off. The lamp still glowed when I did this, so it looked as though I was looking for some protection circuit fault. I removed the chassis again and started an exhaustive DC resistance check. This revealed all sorts of bad news. First, D6702, a 47V zener, was short circuit and F1601, a 315mA button fuse, was open. It was about now that I was beginning to realise that there was a significant similarity between the 3A chassis and the more popular 2B chassis. With F1601 blown, it was fairly obvious that the horizontal output transformer (5620) was shorted. And guess what – it is identical to the one used in 2BS chassis (EHT6140 substitute). A new one was fitted and the set reassembled but it still refused to start. This time I followed the circuit from the gate of the SCR via plug M7 pin 2 and onto the Power Amplifier Sound (PAS) module 1003, where I found resistor R3229 burnt out on the collector of transistor 7226 (BC558), which was shorted. The difficulty here was that R3229 is not shown in any circuit at all and in the end I just fitted a link instead. Now when I switched on, I had sound and picture but there were still problems. The purity was all over the place and I made a mental note to replace PTC 3653, the dual posistor to the degaussing circuit. There was a lot of intermittent chirping noises from the horizontal output stage and when I tapped the horizontal output transformer, the sound would change its pitch. I tried this several times, then suddenly I had no vertical deflection and the set died completely. The chassis www.siliconchip.com.au came out again and this time the horizontal output transistor (7618) was shorted and fuse F1601 had blown. I replaced the 2SD1710 with a 2SD1577 as shown on the circuit and I found two long, barely visible cracks between adjacent pins of the horizontal output transformer which were breaking some of the copper tracks. I repaired all these and replaced D6646 which supplies the 26V to the vertical output stage. I also found cracks in the degaussing sockets (M18 and M19), which I also replaced when re­placing the PTC. Getting there That finally fixed the more urgent problems but unfor­tunately there were still some minor faults. I still hadn’t fixed the intermittent chirping noise and traced that to the deflection yoke before deciding the customer must have always had this and could live with it. In any case, it only happens during the first few minutes from switching on. This she subsequently admitted and she also told me that the set had had a new tube fitted while it was still under warranty. The next problem was that it took ages for the picture to come on and sometimes it didn’t come on at all. This can be indicative of a “flat” (low emission) tube. However, in this case, the collectors of some of the colour output power amplifier transistors had broken their copper PC tracks. I repaired these and made two modifications to improve the turn-on time, to reduce it to about 10 seconds. One modification involved changing R3492 to 3.3kΩ (was 1.8kΩ) for peak white and the other was to add 150kΩ from IP12 (12V) to 2P12 (Beam Current Information Limiter). This desensitises the auto cutoff control to IC7355 TDA4580. And that was it. The repair wasn’t cheap and even then I didn’t charge for all the time taken. However, Mrs Adams accepted the cost and, after a long soak test, I organised for it to be returned. She was ex­tremely suspicious about every move I made while setting it up but it all worked properly and she paid promptly. I do hope I don’t get too many more SC of these. WHAT’S THAT SEMI? Don’t know what it is? Number rubbed off? Can’t identify leads? Need to match gain? The PEAK ATLAS ANALYSER will tell you -Automatically and in just a few seconds! FO? MORE INit vis c.co.uk peakele DIODES JFETS TRANSISTORS TRIACS SCRS LEDS MOSFETS      Auto identifies semis Auto identifies leads Auto identifies faults Checks transistor gain Matches semis Indispensable aid for technicians - designers engineers - laboratories - hobbyists - everyone! Available now from: PAVIKA MANAGEMENT 15 Gilda Ave, Penrith Sth NSW 2750 Ph (02) 4732 4813 Fax (02) 4732 4836 email: pavika<at>bigpond.com January 2002  39 REFERENCE GREAT BOOKS FOR DIGITAL ELECTRONICS – A PRACTICAL APPROACH AUDIO POWER AMP DESIGN HANDBOOK By Douglas Self. 2nd Edition Published 2000 By Richard Monk. Published 1998. 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. 85 $$ $$ 65 With this book you can learn the principles and practice of digital electronics without leaving your desk, through the popular simulation applications, EASY-PC Pro XM and Pulsar. Alternatively, if you want to discover the applications through a thoroughly practical exploration of digital electronics, this is the book for you. A free floppy disk is included, featuring limited function versions of EASY-PC Professional XM and Pulsar. 249 pages, in paperback. VIDEO SCRAMBLING AND DESCRAMBLING for Satellite & Cable AUDIO ELECTRONICS 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. 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. By John Linsley Hood. First published 1995. Second edition 1999. TV by Graf & Sheets 75 $ NEW 2nd Edition 1998 NEW 4th EDITION 3rd W 3rd NE NEW ON:: ITION ED EDITI ME SA SAME ICE!! PR PRICE UNDERSTANDING TELEPHONE ELECTRONICS 2001 By Stephen J. Bigelow. Fourth edition published 2001 In keeping With the distinguished tradition of its .. predecessors, Understanding Telephone Electronics, FOURTH EDITION, covers conventional telephone fundamentals, including both analog and modern digital communication techniques. It provides basic information on the functions of each telephone system component, how electronic circuits general dial tones, and how the latest digital transmission techniques work. 65 $$ GUIDE TO TV & VIDEO TECHNOLOGY By Eugene Trundle. First pub­­lished 1988. Second edition 1996. Eugene Trundle has written for many years in Television magazine and his latest book is right up to date on TV and video technology. The book includes both theory and practical servicing information and is ideal for both students and technicians. 382 pages, in paperback. 59 $$ 40  Silicon Chip 99 $ 85 $ EMC FOR PRODUCT DESIGNERS By Tim Williams. First pub­­lished 1992. 3rd edition 2000. Widely regarded as the standard text on EMC, this book provides all the information necessary to meet the requirements of the EMC Directive. It includes chapters on standards, measurement techniques and design principles, including layout and grounding, digital and analog circuit design, filtering and shielding and interference sources. The four appendices give a design checklist and include useful tables, data and formulae. 299 pages, in soft cover. ELECTRIC MOTORS AND DRIVES By Austin Hughes. Second edition published 1993 (reprinted 1997). 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. 65 $ www.siliconchip.com.au BOOKSHOP WANT TO SAVE 10%? SILICON CHIP SUBSCRIBERS AUTOMATICALLY QUALIFY FOR A 10% DISCOUNT ON ALL BOOK PURCHASES! ENQUIRING MINDS! (To subscribe, see page 38) ALL PRICES INCLUDE GST PIC Your Personal Introductory Course ANALOG ELECTRONICS NEW NEW NEW NEW NEW NEW by John Morton – 2nd edition 2001 By Ian Hickman. 2nd edition1999. 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. 85 $ $ TELEPHONE INSTALLATION HANDBOOK by Steve Roberts $ 67 The definitive guide to home and small business installation - extensions, modems and telephone systems. Provides a practical guide to installation of telephone wiring. Ranges from the single extension socket to the Private Automatic Branch Exchange (PABX), with the necessary tools, test equipment and materials needed by installers. 178 pages in soft cover. NEW NEW NEW NEW NEW NEW NEW NEW NEW NEW NEW NEW 43 Concise and practical guide to getting up and running with the PIC Microcontroller. Assumes no NEW prior knowledge of microcon-trollers, introduces the PIC’s cpabilities through NEW simple projects. Ideal introduction for NEW students, teachers, technicians and electronics enthusiasts – perfect for NEW use in schools and colleges. NEW 270 pages in soft cover. NEW VIDEO & CAMCORDER SERVICING AND TECHNOLOGY by Steve Beeching (First 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. SILICON CHIP'S COMPUTER OMNIBUS First published 1999 SILICON CHIP'S ELECTRONICS TEST BENCH First published 2000 Hints, tips, Upgrades and Fixes for your computer from articles published in SILICON CHIP in recent years. Covers DOS, Windows 3.1, 95, 98 and NT. A must for the computer user. $12.50 (Aust); $A15.95 NZ (prices include P&P) O R D E R H E R E P&P A collection of the “most asked for” Test Equipment projects and features from the pages of Australia’s “most asked for” electronics magazine. Exceptional value at $13.20 (Aust); $A15.95 NZ (prices include p&p).  ANALOG ELECTRONICS..................................................$85.00  AUDIO POWER AMPLIFIER DESIGN...............................$85.00  AUDIO ELECTRONICS.....................................................$85.00  DIGITAL ELECTRONICS ..................................................$65.00  ELECTRIC MOTORS AND DRIVES (2ND EDIT)................$65.00  EMC FOR PRODUCT DESIGNERS...................................$99.00  GUIDE TO TV & VIDEO TECHNOLOGY............................$59.00  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..........................$75.00  SILICON CHIP TEST BENCH.................................... (see above)  SILICON CHIP COMPUTER OMNIBUS.................... (see above)               ORDER TOTAL: $...................... 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 67 $$ 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 anuary 2002  41 ALL TITLES SUBJECT TO AVAILABILITY. PRICES VALID FOR MONTH OF MAGAZINE ISSUEJONLY. ALL PRICES INCLUDE GST 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. Regulator for solar battery charger Some solar regulators are complicated and tricky to set up, and may also have relay chatter. This version is easy to set up and works positively. The relay is a 12V 400-ohm coil type with 10A contacts (such as Dick Smith P-8017). Q1 monitors the battery being charged via the 330kΩ and 10kΩ resistors feeding its base. While the battery voltage is below the threshold set by trimpot VR1, Q1 is off, Q2 is on and the relay is energised to pass current from the solar panel and diode D1. Q2 also lights LED1. When the battery voltage rises above the threshold set by VR1, Q1 turns on, removing base cur­rent from Q2 which then turns off the relay. The 220µF capacitor at the base of Q1 prevents relay chatter. Once the relay is open, a trickle charge can be maintained via a suitable incandescent lamp which bypasses the relay con­tacts. The meters and changeover switch can be regarded as option­al. To set the cutoff voltage (eg, 13.8V), apply 14-15V to the battery terminals and adjust trimpot VR1 until LED1 goes out at the desired voltage. E. Sherman, Kawhia, New Zealand. ($30) Simple time switch for battery-operated projects The use of this simple timer will prevent batteries from going flat because you forgot to turn off the power. It uses a momentary pushbutton switch to apply power to the controlled device and then, after a delay of about eight minutes, power is automatically cut. Timing can be restarted at any time during the 8-minute interval. The 4060 14-Stage Ripple Carry Binary Counter governs the ON timing duration with the R/C combination at its clock inputs, pins 9, 10 and 11, providing the rate of clock pulses. Q1 switches power in the positive line to the device to be controlled when IC1’s Q14 output goes low. A high-brightness LED is included as an ON indica­tor but can be deleted if not required. IC1 is permanently connected to the battery supply but draws just a few microamps of current when dormant. This current flows through a 100kΩ resistor and insufficient voltage is induced across the base-emitter junction of Q1 to turn it on. The Reset pin of the 4060 is held low by a 47kΩ resistor and as a result, output Q14 (pin 3) is set high. This also holds pin 11 high via D1, preventing the clock from pulsing. When the pushbutton is pressed, two events take place. The Reset pin of IC1 now becomes momentarily high, resetting all Q outputs Low. With Q14 low, Q1 then turns on to power the external circuit. After about 42  Silicon Chip eight minutes, the count sets Q14 high again and Q1 turns off. The timing duration can be varied by using a different capacitor value on pin 9 of IC1. Supply voltages from 5-15V are acceptable but the 3.3kΩ resistor should be tailored to provide about 5mA base current to Q1. Colin Christensen, Redcliffe, Qld. ($40) www.siliconchip.com.au +5V 22k 47 4.7k 68k 100k 1M 5k 8 LED1 DSE Z3235 4 7 6 50k 2 47F 3 IC1 555 3 5  2 10k 1  1 4.7F 4.7k Q1 BC558 B OPTO1 DSE Z1955 180 330pF 4.7k 2.2k 8 E 2 C 3 LED2 2 7 8 IC2 LM311 4 4 6 .01F 7 IC3 555 3 5 1 1   .001F 1M 47F 10F 1k WHITE CAR OR TRUCK REFLECTOR FLASHING LED AND/OR PIEZO BUZZER REG1 7805 Door monitor for a dog This circuit was produced to monitor the movement of an old dog which at times during the night must be let outside. A door monitor set low off the ground would have sufficed but it needed to discriminate against cats as well. The first 555 pulses the infrared LED at 38kHz and the light output reflects off a car or truck reflector to be picked up by the infrared detector IC. When it picks up infrared, its output goes low to turn on the visible LED via the BC558 transis­tor. This LED serves both +5V OUT IN 9V DC PLUG PACK COM as a power on indicator and is used to set up the reflector. The height of the transmitter and receiver (optically iso­lated but in the same box) was set a little below the shoulder height of the dog. To prevent false alarms from cats’ tails occurring, an RC time delay was included, comprising the 1MΩ resistor and 47µF capacitor at pin 3 of the LM311 comparator. This comparator goes low 10F .01F to provide a clean trigger signal to the second 555 timer, which operates as a mono­stable to drive a flashing LED and/ or a piezo buzzer for 10 seconds. Paul Walsh, Montmorency, Victoria. Paul Walsh is this month’s winner of the Wavetek Meterman 85XT true RMS digita l multimeter. ‘ANTENNA’ +9–12V Q1 MPF102 G D 2.2k S Q2 BC558 RELAY E B C 2.2k VR1 50k D1 1N4004 220k 10F C B E Q3 MPSA14 (REFER TEXT) — Electric field proximity switch This little circuit does not pretend to compete with the Body Detector sensor featured in the October 2001 issue of SILI­CON CHIP but its sensitivity for so simple a circuit is very high. The circuit will respond to both RF and electrostatic fields. The proximity switch behaves rather like the automatic door-opener at www.siliconchip.com.au the entrance to many stores. A person approaching will activate the device and open the doors but if the person then stops and remains still, the doors will close. With no moving objects within its range, the field strength varies slowly and has no effect on the device. But a large body such as a person entering its zone of operation results in large changes in the field strength. continued on page 44 January 2002  43 1k 220pF 82k 82k Q1 BC548 1k 220 470pF 10k Q2 BC548 Q4 2SD965 E White LED torch circuit uses flash parts This circuit is essentially the same as in the December 2000 article but has a current regulator to drive the white LED. In effect, the current regulator senses the LED current and adjusts the pulse width from the two-transistor multivibrator to vary for the charging of the inductor. The discharge time for the inductor remains constant. Hence, with a fresh battery, the multivibrator runs fast and gradually slows as the battery runs down. This circuit will allow operation down to a battery voltage of 0.8V with a useful light output. With a battery voltage of 1.5V the LED current is approximately 20.5mA. A battery of 1.2V, gives a LED current of approximately 19mA. The efficiency of the circuit varies between 52% and 58%. Silicon Chip Binders REAL VALUE AT $12.95 PLUS $ 5 P&P AUST. ONLY Just fill in & mail the handy order form in this issue; or fax (02) 9979 6503; or ring (02) 9979 5644 & quote your credit card number. 44  Silicon Chip 2SD965 B C CELL CURRENT SENSE D1 1N914 Q3 BC548 47F TANTALUM BC548, BC557 Q5 BC557 L1 SEE TEXT 0.1F 24 (2 x 12) SWITCH  LED1 (WHITE) C B E The main switching transistor is a 2SD965. It is available for free, along with the small inductor (a transformer with a 8.5mm x 8.5mm core) that is used in this circuit. These parts along with many other useful bits and pieces come from the elec­tronic flash units that are fitted into cheap disposable cameras. To get them, go to a 1-hour film processing shop and kindly ask for any disposed cameras from their rubbish. Most places are helpful. Sometimes you even get the alkaline battery which is still useful. Get several different cameras because the transis­ tor and tiny inductor come out of different makes of camera. WARNING: when taking these cameras apart, be aware that the flash reservoir capacitor may still be charg­ ed up to about 300V DC. This can be LETHAL. Be sure to discharge this capacitor before working on the unit. The transformer comes apart very easily. Remove it from the flash unit. Unwrap the tape around the core and heat the core on the barrel of your soldering iron for a short time. The wax holding the core together will soften. Using rags to protect your fin­ gers, gently open the core. While the core is still hot wipe off as much wax as you can. Be gentle as the ferrite and former are delicate. Remove the windings from the former. Wind on 24 turns of 0.3mm or 0.4 mm enamelled copper wire. Wire size is not too critical. Reassemble the core onto the former and wrap with insulation tape. When testing, use a 150Ω resistor as the load. The voltage across the load will be close to 3V. If operating the torch from a 3V battery, increase the current sense resistor to 27Ω. Duncan Graham, Hamilton, NZ. ($40) Electric field proximity switch – ctd from page 43 stays on for up to 30 seconds. In use, trimpot VR1 should be adjusted for maximum sen­sitivity by setting it at the point where the output just turns off. This is preferably done before installing the 10µF capaci­tor. The circuit may be susceptible to certain nearby elec­ trical appliances but not normally overhead lighting. In some situations, the unit can sense the presence of a person from two metres away but its performance depends on the clothes worn, the level of friction generated, the dryness of the air, etc. It reacts violently to polythene film. In its standby state, it draws less than 1mA, depending on the setting of VR1. J. A. Lee, Old Reynella, SA. ($30) Referring to the circuit diagram, the sensor is nothing more than a stiff piece of wire, insulated or bare, standing vertically like an antenna, approximately 15cm long. This is connected to the gate of FET Q1 which is connected as a source follower and operates as a high-impedance buffer with a low output impedance. The source of Q1 drives the base of PNP transistor Q2 which charges the 10µF capacitor at its collector in response to vol­tage changes picked up by the antenna. Q2 also drives Darlington transistor Q3 via a 220kΩ resistor and this, in turn, drives the relay. The 220kΩ resistor and 10µF capacitor provide a delay so the relay 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 A cheap’n’easy MOTORBIKE ALARM Design by Mick Gergos* With car manufacturers (finally!) getting smarter with security, motorbikes often make a “softer” target for thieves. Here’s an alarm which is very simple to build, very simple to fit to almost any ’bike – and very easy to operate. Arming and disarming is done with the ignition key! www.siliconchip.com.au January 2002  53 M any motorbikes today cost almost as much as – and of ten more than – a small car. Their value and their mobility makes them targets for thieves – whether joyriders (hate that word – there’s no joy for the owner!) or professional crooks. It’s somewhat surprising then to find how few ’bikes are fitted with alarm systems. That’s probably because alarms for bikes have been in the “too hard” basket – they are exposed to the weather (with all the problems that creates); they are vulnerable because they can’t be hidden “inside”; they are too big for a small bike; you can’t hide operating switches; you need to get at the wiring harness . . . and so on. Here’s a motorbike alarm which addresses all those problems and more. It’s heatshrunk to protect it, it’s tiny enough to be hidden just about anywhere, it doesn’t need any external controls – and it suits virtually all ’bikes. As long as they have a battery and a headlight, this alarm should suit. The alarm is “armed” automatically. When you turn the ignition off, you have 20 seconds to get off the bike. After this time, if anyone attempts to get on the bike or move it, they’ll hear a series of warning “chirps” followed by four seconds of quiet. It’s then in a “heightened alarm” state: touch it again within 30 seconds or so and the alarm screams its head off for 45 seconds! If someone is still trying to interfere with the bike, the cycle will repeat three times (giving 3 x 45 second alarms). It won’t keep continually going off because noise pollution laws in most states prohibit this. If it is not touched again within the 30-second heightened alarm state, it goes “back to sleep” and waits for the next person to have a go. To turn the alarm off while it is sounding, you simply turn the ignition key on then off. This resets and rearms the alarm. But what if you don’t want the alarm on, for some reason? That’s easy: you simply turn the ignition key on and off twice – ie, on-off-on-off. This resets the alarm but disables it – and tells you with an acknowledgement “chirp”. Next time you turn the ignition on, you will reset the alarm again ready for use when the ignition is turned off again. As you can see, operation is foolproof and all done with the ignition key – there are no hidden switches to worry about, no keypads to go faulty – nothing except the ignition switch. And if that goes faulty, you have a few more problems than an alarm that doesn’t work! The sensor Two types of sensor are recommended – you can choose either or both if you want a belts-and-braces approach. The first is a non-position-sensitive motion detector which simply detects any movement of the bike. The second is a mercury switch, arranged as a “tilt” switch: when the ‘’bike is on its stand, the mercury switch is positioned so it doesn’t conduct. Take if off the stand, or move it in some other way and the switch does conduct. Both of these switches are “normally open” types so, if you wish, you can fit one (or even more) of each type in parallel. How it works The circuit itself is very simple because, once again, a microcontroller does most of the work. First, though, let’s look at the supply. As you will note from the circuit, there is a connection to the ‘+’ side of the ’bike’s battery but no apparent connection to the ‘–’ side. How come? What would normally be regarded as the ‘–’ or chassis connection is in fact connected between the light switch and the headlight. When the headlight is switched off, there is a low-resistance path (through the headlight filament) to chassis. If, say, the headlight is 50W, from Ohm’s law we can work out that the resistance of the filament is about 3Ω (in fact it’s much less than this when it is cold). The complete alarm, shown with a small piezo siren which can be mounted anywhere on the bike with access to free air (so the sound isn’t muffled). Just keep in mind that most piezos don’t like water one little bit! 54  Silicon Chip www.siliconchip.com.au BATTERY + Parts List – Motorcycle Alarm HORN + D1 1N4007 IC1 12C508A REG1 78L05 OUT IN HORN GND 4 3 2 GP3 VDD B 6 1k 5 GP4 GP5 GP1 VSS GP0 7 C E Q1 MJE3055 GP2 120k D2 1N4148 8 0.1F 1 PC board, 38 x 20mm, code 05101021 (OR Veroboard, 10 tracks x 18 holes – see text) 1 60mm length 30mm heatshrink 1 cable clamp 1 motion detector switch AND/OR mercury switch – see text 1 piezo siren (Jaycar LA5225 or similar – see text) Suitable lengths automotive wire 1 COM 0.1F* 10F TANT HEADLIGHT (+) *MOUNTS ON COPPER SIDE OF PC BOARD SW1: SHOCK/TILT SENSOR SWITCH 78L05 MJE3055 C SC 2002 MOTORCYCLE ALARM IN OUT COM B C E It couldn’t be much simpler: just ten components make up the motorcycle alarm. That amount of resistance to chassis won’t affect the operation of this circuit at all. If both the headlight and ignition are switched on, both supply lines are at the same potential, so the alarm is disabled. Back to the supply again: it passes through a polarity-protection diode (just in case!), and then a 5V regulator to give IC1 the voltage it requires. It also goes direct to the horn or siren ‘+’ side, with a hefty transistor, controlled by the microcontroller, switching its ‘–’ side. This transistor is extreme overkill given the likely current of the horn or siren but this is one component you would not like to see go short circuit! The output current switched by this transistor mustn’t exceed 1A anyway, because that’s the rating of the reverse-polarity protection diode. (Most piezo sirens would draw only a couple of hundred milliamps or so). Every time the microcontroller is powered up, it looks for a “high” from its 1-bit external memory device (the 10µF tantalum capacitor). If it is not high, the PIC makes it high for three seconds, then makes it go low, which then goes to the “armed” routine. Should the device be powered down during this 3-second period, the high would remain because the capacitor would stay charged. Next time the device is powered up, a high would be present. The microcontroller senses this and it goes into the “disarmed” routine. The 120kΩ resistor and 1N4148 diode control the charging and discharging of the tantalum capacitor. Construction Because of the few components in this project, we’re going to break one of our unwritten rules: as well as presenting it on a PC board, we’re also going to show how to assemble it on Veroboard. Yeah, yeah, we know. We don’t like Semiconductors 1 12C508A pre-programmed microcontroller IC (IC1) 1 MJE3055 NPN power transistor (Q1) 1 78L05 low power 5V regulator (TO-92 package) (REG1) 1 1N4007 silicon power diode (D1) 1 1N4148 silicon signal diode (D2) Capacitors 1 10µF 25VW tantalum electrolytic 2 0.1µF ceramic or polyester Resistors (0.25W, 1%) 1 120kΩ 1 1kΩ it much either because almost invariably, constructors manage to make a mess of it. But in this case, it really is so simple . . . but we’d suggest that if you have your druthers, we’d druther you use the PC board! Which ever you choose, assemble the board in the normal way: lowest profile components first (resistors, diodes, etc), moving on to the capacitors, regulator, switch and finally the IC and power transistor. Note that the power transistor is secured to the Veroboard with a 3mm nut and machine screw – this forms the connection to the siren/ horn “ground” track. Before applying power, check and double check your component placement and orientation – most components are polarised so make sure you Front and rear photos of the assembled PC board. Note the 0.1µF capacitor on the back of the board. This board must be encased in heatshrink (or even mounted in a small box) to protect it from the elements, spray, etc. www.siliconchip.com.au January 2002  55 0.1 120k 1k IC1 D2 1 0.1F D1 10F 1 120Q1 10150 MJE3055 2002 05101021 2002 05101021 2002 HORN + SW1 HEADLIGHT (+) REG1 TOP SIDE OF PC BOARD 1 BATT (+) HORN GND UNDERSIDE OF PC BOARD Component overlays for the top and bottom of the PC board, along with the board pattern itself reproduced same size. get them the right way around. The assembled board (PC or Vero) is “encased” in a length of heatshrink to give some protection from the elements and also to insulate the components from the ’bike. Before you do this, it’s a good idea to check the circuit out and make sure it works! It’s probably easiest to check without installation, by simulating the bike using a 12V battery, a suitable switch and a hefty 12V globe. And you can simulate the alarm sensor with either a pushbutton switch or even a pair of wires to short. Connect them up as per the circuit diagram. Remember when the alarm goes off the siren is going to be very loud. Just warning you! OK, apply power. The voltage between pins 1 and 8 of IC1 should be very close to 5V. If not, check that you actually do have around 12V going in to the regulator. Turn the “ignition” switch off and wait for 30 seconds. Now short the sensor contacts momentarily. You should hear a series of chirps from the siren, followed by silence. About ten seconds after the last chirp, short the sensor contacts again. The siren should now be sounding (we told you it was going to be loud!) and will continue to do so for about 45 seconds. When it stops, short the contacts again and make sure the alarm sounds again. Now you’ll be very pleased to turn the alarm off. Turn the ignition switch on then off again. The siren should go quiet. Thank heavens! Check the disarm feature by repeating the above but when the siren sounds, turn the ignition switch on, off, on, off. The siren should stop and the you should hear a chirp, telling you the system is disarmed. Installation If all is OK, it’s time to seal the circuit board in some heatshrink. The idea is to make it as weatherproof/ waterproof as possible. Seal the open end of the heatshrink with a pair of to be reliable but you don’t want false alarms when, for example, the bike is parked on a hill. As far as the bike wiring is concerned, you only need to make two connections to the bike itself: to the unswitched battery supply and to the power line to the headlight, between the headlight switch and the lamp. Try to add the wiring so that it is as undetectable as possible – you don’t want a crook simply cutting wires. Even though the currents involved The alternative layout on Veroboard. The easist way to cut the tracks is to use a 1/8in drill and twist the point in the appropriate place between the fingers. Practice on a scrap piece first and you’ll get the idea! pliers while it is still hot and place a cable tie on the other (cable) end, again while the heatshrink is still hot. You need to find somewhere safe, out of sight and out of spray, to locate the alarm module. Most sirens also do not like water too much. Each bike is different so we’ll leave that part up to you. Likewise the location of the sensor – choose where it will go carefully. If you are using only a mercury switch, you’ll probably need to experiment a little to get a perfect angle. You want it are fairly small, we have shown heavy-duty automotive figure-8 cable in our photos. This has much better SC insulation than hookup wire.  Wheredyageddit? Preprogrammed 12C508A microprocessor: Available from Mr Mick Gergos, 13 Bunya Street,­Bushland Beach, Qld 4818, for $25.00 plus $5.00 P&P (no longer purchaseable from this address)  Non-position-sensitive motion sensors: Available from Farnell Components (Cat 540-626) or RS Components (Cat 235-7566)  Mercury switches (position sensitive) and piezo sirens:    Available from Jaycar, DSE, Altronics, etc.  Here’s what it should look like once the heatshrink has been shrunk, gripped with pliers (on the left) and fastened with a cable clamp (on the right). 56  Silicon Chip PC boards:   Available from RCS Radio (02) 9738 0330.­­ 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 David Polkinghorne today on (02) 9979 5644 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 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 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! Hy-Q International Pty Ltd MicroZed Computers Fax: (03) 9562 9009 WebLINK: www.hy-q.com.au Tel: (02) 6772 2777 Fax: (02) 6772 8987 WebLINK: www.microzed.com.au 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. ALLTAC INTERNATIONAL P/L Tel : (02) 9411 3088 Fax : (02) 9412 1855 WebLINK: www.jedmicro.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. Tel:(03) 9562-8222 We stock varieties of hard to find selectors, cables and adaptors, and as well home theatre all at competitive prices. We believe lines between computer, networking, home theatre and video editing are becoming blurred these days. Please call us if you need any help in this aspect. WebLINK: www.alltac.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°. Wiltronics Pty Ltd Tel: (03) 9762 3588 Fax: (03) 9762 5499 WebLINK: www.wiltronics.com.au 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! Av-COMM Pty Ltd Tel:(02) 9939 4377 Fax: (02) 9939 4376 WebLINK: www.avcomm.com.au WebLINK: www.silvertone.com.au VGS2 Graphics Splitter 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. Silvertone Electronics Tel:(07) 4639 1100 Fax: (07)4639 1275 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. 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. www.siliconchip.com.au www.siliconchip.com.au QUESTRONIX All mail: PO Box 348, Woy Woy NSW 2256 Ph (02) 4343 1970 Fax (02) 4341 2795 Visitors by appointment only January March 2002  57 Building the Part 3: By GREG SWAIN & LEO SIMPSON Ultra-LD 2 x 100W Stereo Amplifier In this final article, we continue with the assembly of the power supply and loudspeaker protector modules and give the full wiring details. We also describe the setting up and the test procedure. Power Supply Board Assembly The next step is to build the Power Supply Module – see Fig.18. This board carries the four large 8000µF 63VW filter capacitors for the ±52.5V rails, plus all the parts for the ±55V regulated power supply. Begin by installing the eight 1W resistors (6 x 15Ω and 2 x 8.2kΩ), mounting them all about 1mm proud of the board. This done, install the remaining resistors, diode bridge BR2, the wire links, the two multi-turn trimpots and the two zener diodes (ZD2 & ZD3). Make sure that BR1 and the zener diodes are correctly oriented. The male quick connects can be mounted next, followed by the electrolytic capacitors. Note that the two 470µF capaci­ tors must be rated at 100VW – 63VW is not good enough since the input voltages to the positive and negative regulators are about +71V and -71V respectively. Take extra care to ensure that the capacitors are installed with the correct polarity, especially the 8000µF units. Get one of these wrong and you’ll soon know about it the first time power is applied. The TIP33B transistors (Q17 & Q18) and the two 3-terminal regulators (REG1 & REG2) can now be bolted to the flat aluminium heatsink. These This is the completed Power Supply module with the heatsink removed. Note the hot-melt glue around the four 8000µF filter capacitors – this prevents the cans from moving & placing stress on the solder joints. 58  Silicon Chip www.siliconchip.com.au This view shows how the heatsink is fitted to the Power Supply module. Note that all the devices must be isolated from the heatsink – see text. devices must all be isolated from the heatsink using silicone washers and, where necessary, insulating bushes – see Fig.13 in Pt.2. Don’t tighten the mounting screws just yet, though – that step comes after the assembly has been mounted on the PC board. Note that the TIP33B (or TIP33C) transistors can came in either a TO218 package (as shown in Pt.1, Fig.4, p29) or in a TO-3P package as used on the prototype. If you have the TO-3P package devices, then you don’t need the insulating bushes. Conversely, if you have TO-218 package devices, the insulating bushes are required. Make sure that you don’t inadvertently swap REG1 & REG2 when attaching them to the heatsink. The heatsink assembly can now be mounted on the PC board. Push the assembly down as far as it will go so that the plastic bodies of the regulators are about 3-4mm above the board surface and make sure that everything is square before soldering the leads. It’s a good idea to tack solder a couple of leads on either side initially. That way, you can easily make any final adjustments before soldering the rest of the leads. As before, use a multimeter to confirm that the device leads and metal tabs are all correctly isolated from the heat­sink. Hot-Melt Glue Time As shown in the photographs, we applied hot-met glue fil­ lets to the bottom edges of the four 8000µF capacitors. This stops the large capacitor www.siliconchip.com.au Fig.18: the parts layout for the Power Supply module. Make sure that all the electrolytic capacitors go in the right way around. cans from moving and placing stress on the solder joints. In short, the hot-melt glue treatment is a good idea but watch the hot tip of the gun – it’s all too easy to damage the sleeving around one of the large January 2002  59 Fig.19: follow this parts layout diagram to build the Loudspeaker Protector module. Note that brass screws, nuts and star washers are used to mount the eight quick connect terminals for the amplifier and loudspeaker connects. Next, install the transistors, electrolytic capacitors and bipolar capacitors, taking care to ensure that the correct tran­sistor type is fitted to each location. Note that the four 47µF bipolar capacitors can go in either way around but watch the orientation of the 10µF and 1000µF electrolytic capacitors. Regulator REG1 is bolted to a micro-U heatsink (25 x 30 x 12.5mm) before it is soldered to the PC board. A thermal washer isn’t necessary here since the heatsink doesn’t touch any other components – just secure the regulator using a 6mm M3 screw, flat washer and nut. The procedure for mounting REG1 is exactly the same as for Q8 & Q9 on the power amplifier modules – ie, insert the leads into the board, smear the mating face with thermal grease, attach the heatsink and push the assembly all the way down before sol­dering the leads and tightening the mounting screw. Of course, you could fit the heatsink with the device off the board. However, if you do that, the heatsink will swivel when you attempt to tighten the mounting screw and you’ll get thermal grease everywhere. Follow the steps outlined above and you’ll end up with a much neater result. Finally, you can complete the board assembly by fitting the two relays, the 2-way terminal blocks and the 2-way header. By the way, our prototype board shows a couple of PC stakes in place of the pin header, which was a later refinement. Our final board also has four less quick connect terminals than the prototype board shown in the photographs. That’s because we originally intended to drive the headphones via the Loudspeaker Protector Module. We later changed our minds and decided to drive the headphones directly from the Power Amplifier modules instead. OK, now that all the PC board modules are completed, you’re ready to mount them in the chassis and install the wiring. Preparing The Case electrolytic capacitors if you’re not careful. Loudspeaker Protector & Fan Control Module Assembly The last board to assemble is the Loudspeaker Protector & Fan Control 60  Silicon Chip Module. Fig.19 shows the details. Mount the resistors and diodes first, then fit the male quick connects. Be sure to use brass screws, nuts and star wash­ers to mount the quick connects for the eight loudspeaker termi­nals, as shown on the overlay. As supplied, the case features a tough powder-coating that’s also a good insulator. However, we must ensure that all sections of the case, including the side panels, lid and heatsink – are correctly earthed and that means ensuring they make good www.siliconchip.com.au Use an oversize drill to remove the powder coating from under the screw heads, so that all sections of the case are correctly earthed (see text). Fig.20: mounting details for the mains earth quick connects. The second nut locks the first nut, so there is no possibility of the earth lugs coming loose. electrical contact with each other. There are two reasons for this: (1) all sections of the case must be connected to the mains earth to ensure safety; and (2) correct earthing is necessary to keep RF inter­ference out of the audio circuitry. The first job is to ensure that the side panels and the lid are earthed to the bottom section of the chassis. This is done by using an oversize drill to remove the powder coating from the countersunk screw holes (see photo). Use a drill that’s slightly smaller in diameter than the screw heads and be sure to remove the powder coating right back to the bare metal. Don’t just do this for one or two holes – do it for all seven holes in each side panel and for all three holes in the lid. Provided you use a drill that’s not too big, the bare metal will later be covered by the screw heads. Next, scrape away the powder coating around the screw holes on the inside of the side panels, the underside of the lid and from the matching contact areas around the screw holes in the chassis. That way, when the case is assembled, earthing takes place via the screws themselves and via direct metal-to-metal contact between the various sections. The transformer mounting bolt should also be earthed and this means that you have to remove some of the powder coating from around the mounting hole on the outside of the chassis (ie, from under the bolt head). The front panel doesn’t require any special preparation. Instead, it’s later earthed by running a lead from a quick con­nect terminal that’s welded to the panel back to the main chassis earth (see photo). Don’t attach the front panel to the chassis at this stage. Leave it wrapped up so that it doesn’t get scratched or damaged in some other way. It doesn’t You need a ratchetdriven crimper One essential item required to build this amplifier is a ratchet-driven crimping tool, necessary for crimping the insulated quick-connect terminals to the leads (except for the power transformer, which is supplied with quick connect termi­nals already fitted). Suitable crimping tools include the Altronics Cat. T-1552, Dick Smith Electronics Cat T-3535 and the Jaycar TH-1829. These all feature double-jaws so that the bared wire end and the insu­lation are crimped in a single action. Don’t try to use one of the cheap (non-ratchet) crimpers that are typically supplied in automotive crimp kits. They are not up to the job for a project like this, as the amount of pressure that’s applied to the crimp connections will vary all over the place. By contrast, the ratchet-driven crimpers apply a preset amount of pressure to ensure consistent, reliable connections. Table 1: Resistor Colour Codes Power Supply Module       No. 2 2 2 2 6 Value 8.2kΩ 6.8kΩ 180Ω 47Ω 15Ω         No. 1 2 4 2 1 1 1 Value 220kΩ 56kΩ 22kΩ 22kΩ 2.2kΩ 1.5kΩ 22Ω 4-Band Code (1%) grey red red brown blue grey red brown brown grey brown brown yellow violet black brown brown green black brown 5-Band Code (1%) grey red black brown brown blue grey black brown brown brown grey black black brown yellow violet black gold brown brown green black gold brown Loudspeaker Protection Module www.siliconchip.com.au 4-Band Code (1%) red red yellow brown green blue orange brown red red orange brown red red orange brown red red red brown brown green red brown red red black brown 5-Band Code (1%) red red black orange brown green blue black red brown red red black red brown red red black red brown red red black brown brown brown green black brown brown red red black gold brown January 2002  61 RUBBER BOOT SCREW-ON RUBBER FOOT RUBBER BOOT SCREW-ON RUBBER FOOT Use cable ties to secure the mains wiring and fit rubber boots over both the mains switch (left) and the IEC socket (right). Note the additional rubber feet (arrowed) that are fitted over the ends of the mounting screws for the external feet. take much of an accident to spoil the panel’s appearance. Be sure to do the nuts up nice and tight, to ensure a reli­able earth. Mounting Feet Screws Installing Hardware The screws used to secure the rubber mounting feet protrude about 5mm into the chassis and could easily pierce the 26-way cable insulation on the righthand side. To prevent this, you can either remove the sharp ends of the screws using a Dremel tool or screw additional rubber feet over them. Do the same for the mounting feet screws at the front-left and rear-left of the chassis. Admittedly, they pose no real danger to the mains wiring but it’s best to make absolutely sure (see photos). OK, you can now start installing the hardware in the case. Begin by mounting the IEC power socket, then smear the underside of the 35A bridge rectifier (BR1) with heatsink compound and bolt it to the chassis using an M4 screw, star washer and nut. Fig.21 and the photos show BR1’s mounting location. Orient it as shown, with its positive DC output at top left (as viewed from the front of the chassis). The RCA input socket module can go in next and is secured from the rear of the chassis using three 6g x 10mm pan-head self-tappers. Don’t over­ tighten these screws – you’ll strip the plas­tic threads formed by the self-tappers if you do. We initially mounted this board upside down (see page 23 of the November 2001 issue) but in the end decided to mount it component side up. This ensures that the board sits closer to the floor of the chassis and also makes it far easier to dress the 26-way connecting cable that plugs into the pin header. The drawback (if you could call it that) is that the inputs run in the op- Chassis Earth Lugs Fig.20 shows the mounting details for the main chassis earth lugs. This assembly consists of two double-ended quick-connect terminals which are bolted to the chassis using a 10mm M4 machine screw, two star washers and two nuts. The second nut on top is a “belts ‘n braces” measure to lock the first nut, so that there’s no possibility of the earth lugs coming loose. Altronics has indicated that the earth lug mounting area in kit versions of the chassis will be free of powder coating. However, if this hasn’t been done, you will have to remove the powder coating yourself. To do this, temporarily bolt one of the double-ended quick connects to the chassis and use a pencil to outline the contact area. The quick connect can then be unbolted and the powder coating removed using a a sharp implement or a Dremel tool fitted with a grinding bit. 62  Silicon Chip TABLE 1: BOARD SPACERS Preampli�er Board 4 x 20mm spacers + 4 x 3mm nuts Power Ampli�er Boards Power Supply Board Loudspeaker Protection Board 2 x 25mm spacers 4 x 15mm spacers 4 x 20mm spacers posite direction to the source switch labelling – ie, the CD inputs are to the right (as viewed from the front of the amplifier) while the CD switch position is to the left. But really, who cares which way the inputs run? As long as the CD player is plugged into the CD inputs, the DVD player into the DVD inputs and so on, they will all be correctly selected at the indicated switch position. Now for the loudspeaker terminals. Begin by cutting two 120mm lengths of figure-8 speaker cable and solder these to the two terminal panels – see photo. This done, fit the other ends of the leads with blue quick connects, then secure the two terminal panels to the chassis using four 6g x 12mm countersunk self-tappers. Next, fit four 20mm tapped spacers to the Loudspeaker Pro­tector module (use 6mm x M3 screws and washers) and secure it to the rear panel. Similarly, mount the Power Supply module in position on 15mm spacers but leave the top screws loose for the time being – this will make it easier to lift the board up to run leads under it later on. Cable-Tie Mounts As shown in one of the photos, the wiring is all secured to the floor of the chassis using cable-tie mounts and cable ties. Before installing the mounts, it’s necessary to mark out their locations. To do this, temporarily secure the power amplifier module in the chassis and use a pencil to mark these positions: (1) the location of the heatsink and its three wiring channels; www.siliconchip.com.au (2) the locations of the individual amplifier boards; (3) the locations of the PC tracks carrying the class-B currents from the paralleled 1.5Ω resistors on each side of the two boards; and (4) the locations of the central earth tracks that run back to the 0V terminal from the two 1000µF capacitors (see Fig.21). The reason for this is that it’s important to correctly route the supply wiring under the power amplifier boards, to ensure the lowest possible distortion. The ±55V and 0V leads are routed directly under the earth track in the centre of each amplifier, while the ±52.5V leads radiate out at right angles beneath the tracks carrying the heavy class-B currents for the output stages. Once you have everything marked out, remove the amplifier module and install cable-tie mounts at the following loca­tions: (1) on each side of the heatsink immediately opposite the three wiring channels. (2) near the edge of the heatsink in line with the central earth track of the righthand power amplifier; (3) at the central locations under the power amplifier boards where the ±52.5V leads branch off at right angles; (4) on the floor of the chassis just inside the edges of the amplifier PC boards where the ±52V leads emerge to join onto their terminals; (5) on the floor of the chassis, directly under the 0V terminals on the amplifier boards; (6) directly under the centre two loudspeaker terminals of each amplifier board; and (7) directly between the two amplifier boards but with the cen­tral tie point clearing the front of the boards by about 5mm. Additional cable-tie mounts are installed along the right­hand edge of the chassis to further secure the mains wiring. These are located behind the power transformer and towards the front of the chassis. The accompanying photograph shows the locations of most of the cable-tie mounts. 26-Way Header Cable The next step is to fit the headers to the 26-way flat ribbon cable. First, cut the 26-way cable to exactly 550mm, www.siliconchip.com.au Use this photo and the wiring diagram of Fig.21 as a guide when placing the cable-tie mounts and installing the supply wiring. then fit a header socket to one end by feeding the cable through and squeezing the assembly together in a vyce. There are a couple of points to note here: (1) the lead with the red stripe must go to pin 1 of the header socket (indicated by a small arrow in the plastic moulding); and (2) the cable must by fed through from the side opposite the arrow (ie, the end of the cable is on the side with the arrow). Once the assembly has been “clamped” in the vyce, the cable is looped back over the top of the header and the strain relief clamp clipped into place. The header at the other end is fitted exactly the same way. It’s a good idea to test fit everything before fitting the second header – once the headers are clamped to the cable, they are virtually impossible to remove. The cable can now be installed in the chassis. First, plug one end into the RCA input board, then fold the cable at right angles and then at right angles again so that it runs along the edge of the chassis (red stripe to the outside). The cable is then folded at right angles twice more at the front of the chas­sis, so that pin 1 of the header mates with pin 1 on the Pream­plifier & LED Display module. Preamplifier Mounting Before mounting the Preamplifier & LED Display module, it’s necessary to attach the shielded audio output leads. These audio output leads will probably be supplied as a length of figure-8 shielded cable. Cut the cable to a length of 210mm and lightly tin the leads (ie, the braids and the bared ends of the insu­ lated wires) before securing them to the terminal blocks. It’s a good idea to fit a 10mm length of heatshrink tubing to the figure-8 cable at the terminal block end. That way, when the figure-8 cable is later separated (so that the leads can go to the power amplifier inputs), the heatshrink tubing prevents them from separating right at the Preamplifier end. January 2002  63 26-WAY IDC CABLE 26-WAY IDC HEADER AUX TUNER DVD -55V _ CD (8) 0V (5) + TAPE 50VAC 50VAC TAPE OUT 0V +52V 0V -52V 0V 0V (6) (7) -52V +52V +55V SPKR+ + _ LEFT OUT- A 12V DC FAN K RIGHT SPEAKER OUT+ LEFT SPEAKER SPKR- SPEAKERS LED OUT- BR1 BR1+ BR1- + RIGHT SPKR+ Fig.21: the loudspeaker cables and the DC supply leads to the Power Amplifiers account for most of the wiring. Route all cables exactly as shown, to ensure the lowest possible distortion from the Power Amplifier modules. _ FANFAN+ TH1 TH1 8 7 15V 4 3 2 1 15V 6 5 15VAC 15VAC 0V +12V SECONDARY T1 INSULATE ALL EXPOSED MAINS CONNECTIONS! W LLO YE A N BRO E W N MALE IEC SOCKET WITH INTEGRAL FUSE CHASSIS EARTH N/ GRE E PRIMARY 64  Silicon Chip 250VAC MAINS CABLE BLU E www.siliconchip.com.au GREEN/YELLOW SPKR- OUT+ -52V FO N+ 4 5 3 7 1 8 N.C. O INPUT + _ INPUTS SPKR- FON- SPKR+ FON+ +52V + RIGHT SHIELDED CABLE SHIELDED CABLE + _ _ + OUTPUTS + + SPEAKERS LED A -52V + +55V 26-WAY IDC HEADER SOCKET PIN 1 0V + 6 2 -55V ROUTE 52V CABLE UNDER PC BOARD & POSITION EXACTLY AS SHOWN HEADPHONE SOCKET TH1 INPUT + _ + +12V THESE 3 PAIRS PASS UNDER SECOND HEATSINK CHANNEL 15VAC F LEFT + K www.siliconchip.com.au + + + + + + N+ January 2002  65 0V SPKR- FON- SPKR+ FON+ +52V 250VAC MAINS SWITCH (REAR VIEW) TOP FRONT PANEL EARTH POINT GREEN/ YELLOW 3. INSTALL RUBBER BOOTS OVER THE REAR OF THE IEC MAINS SOCKET & THE MAINS SWITCH. 2. REFER TO PHOTOGRAPHS FOR LOCATION OF CABLE TIEDOWN POINTS. 1. THICK BLACK LINES DENOTE TWO OR THREE WIRES TWISTED TOGETHER (EXCEPT FOR PREAMP OUTPUTS, WHICH ARE SHIELDED CABLE). NOTES: +55V 15VAC 0V -55V The rear panel of the amplifier carries the IEC mains socket, the loudspeaker terminals and the RCA input sockets. This done, you can plug the input cable into the header pins and mount the Preamplifier & LED Display module on its standoffs. The insulated headphone socket can also be installed at this stage – it’s mounted on the chassis “dimple” immediately to the left of the Preamplifier board, so that its front later sits flush with the front panel. Wiring Up Now for the internal wiring. It’s not nearly as intimidat­ing as it appears at first sight, since most of it consists of supply wiring to the power amplifier boards plus the loudspeaker wiring. Note that all the supply leads and the loudspeaker leads should be tightly twisted together. This not only keeps the wiring neat but also minimises hum pickup since the hum fields are effectively cancelled out. There’s an easy way to twist leads together and that’s by using a hand drill. All you have to do is secure one end of the leads in a vyce and the other end in the drill chuck. You then rotate the drill handle until you get a nice even twist along the full length of the leads. Make the twists reasonably tight but don’t overdo it – the wire will break through the insulation if you do. Once the leads have been twisted, trim the ends to remove any damaged insulation and fit quick connect terminals to one end only. The leads at the other end are also later fitted with quick connect termi66  Silicon Chip nals after they have been run to their destination and cut to the correct length. Fig.21 shows the wiring routes. Note that all the supply wiring goes through the lefthand wiring channel in the heatsink. The loudspeaker leads and the leads to the thermal switch go through the channel next to the fan. Here are the leads that you have to run: (1) Three twisted heavy-duty (7.5A) leads from the +52.5V, -52.5V and 0V connections on the Power Supply board to each Power Amplifier board. (2) Three twisted heavy-duty leads from the +55V, -55V and 0V connections on the Power Supply board to TORODIAL TRANSFOMER WIRE COLOUR CODING RED (1) 35V RED (2) RED (3) YELLOW PRIMARY (240VAC) WINDING 35V RED (4) GREY 15V GREY BLUE 15V YELLOW BLUE WHITE (5) 50V WHITE (6) BROWN (7) 50V BROWN (8) Fig.22: this diagram shows the colour coding used for the toroidal power transformer. each Power Amplifier board. Important: the power supply ends of one set of leads must be fitted with piggyback in-line quick connects. The other set of leads is fitted with “ordinary” quick connects which then plug into the piggyback terminals. (3) Two twisted leads from the Loudspeaker Protector module to each of the Power Amplifier boards (use the heavy-duty 2 x 90/0.18 Whopper speaker cable fitted with blue quick connects). (4) Two twisted heavy-duty leads from the +12V and 0V terminals on the Loudspeaker Protector module to the +12V and 0V terminals on the Preamplifier module. (5) Two twisted medium-duty leads from the 2-way header on the Loudspeaker Protector module to the headphone socket switch and from there to the “Speakers” LED on the front panel. These leads are fitted with a matching 2-way header plug at one end and are directly soldered to the headphone socket terminals and the LED leads at the other. Fitting the 2-way header plug isn’t difficult – just light­ly solder and crimp the leads to the small header pins that are supplied, then push them down into the plug body until they lock into place. (6) Two twisted medium-duty leads from the Loudspeaker Protec­tor’s TH1 terminals to thermal switch TH1 on the heatsink. Once you’ve done all this, the power amplifier/heatsink module can be mounted in the chassis. The ends of the cables are then cut to length, fitted with quick connects and connected to www.siliconchip.com.au The powder coating must be removed from around the mounting holes that are used to secure the lid (and from matching contact areas on the lid itself). the power amplifier boards, the thermal cutout and the preampli­fier board. The headphone socket wiring is next on the list. Route the leads slightly in front of the amplifier boards, along with the 15VAC and 12V DC wiring to the preamplifier. The leads can all then be secured using cable ties. Finally, the amplifier wiring can be completed by connect­ing the shielded audio leads from the preamplifier to the screw terminal blocks. Power Transformer Wiring The toroidal mains transformer can now be bolted into posi­tion and its secondary leads connected. Note that www.siliconchip.com.au the transformer is supplied with two neoprene rubber washers – one sits under the transformer while the other sits on top, with the metal cup washer stacked on the top of that. The mounting bolt passes through the centre of the trans­former and the assembly secured by fitting a nut to the top. Do the nut up firmly but don’t overtighten it, otherwise you’ll distort the metal chassis. As mentioned last month, the transformer leads are all the correct length to reach their destinations and are pre-fitted with female quick connects. All you have to do is twist the various lead pairs together and plug them into the relevant quick connect terminals – ie, on BR1, the Power Supply module, the Loudspeaker Protector module and the Preamplifier & LED Display module. It’s important to connect the two 35V windings (red) with the correct phasing, otherwise you’ll get 0V out of the bridge rectifier (BR1). This simply means connecting the leads as shown in Fig.21 – ie, leads 1 & 4 go to BR1, while leads 2 & 3 go to the two centre (0V) terminals on the Power Supply module. The same goes for the two 50V windings (white & brown). Leads 5 & 8 go to the 50VAC terminals, while leads 6 & 7 go to the adjacent 0V terminals. Two short leads fitted with quick January 2002  67 Parts List For Ultra-LD Stereo Amplifier Hardware & Miscellaneous 1 custom-made rack-mounting case with heatsink & 80mm fan (case supplied drilled & with all cutouts made; heatsink supplied drilled, tapped & with channel cutouts in base) 1 front-panel (screened lettering) 1 heatsink for power supply 1 300VA toroidal power transformer, 2 x 50V, 2 x 35V, 2 x 15V secondaries 1 mounting kit for transformer 1 pushbutton DPST 250VAC switch (Altronics Cat. S3245) 2 knobs to suit rotary switch and potentiometer 1 IEC male power socket, chassis mount with insulating boot (Altronics P8324) 1 3A slow-blow M205 fuse 1 insulating boot for power switch 2 panel-mount gold-plated binding post terminal pairs (Altronics P2016) 1 6.35mm chassis-mount insulated stereo headphone socket (Altronics P0074) 1 pack 25 adhesive cable tie mounts (Altronics H4120) 50 100mm cable ties (Altronics H4012) 2 26-pin IDC in-line crimp sockets with strain-relief clips (Altronics P5326) 4 screw-on rubber feet (Altronics H0902 Preamplifier & LED Display Module 1 PC board, code 01112012, 246 x 166mm 1 26-way DIL pin header 2 2-way mini PC terminal blocks (Altronics P 2038) - 5mm pitch 1 2-pole 6-position switch (Altronics S 3022) (S1) 1 10kΩ 16mm stereo log pot (VR1) 2 F29 ferrite beads Semiconductors 2 NE5534AN op amps (IC1,IC2) (Altronics Z2792 – do not substitute NE5534N) 68  Silicon Chip 1 TL072 op amp IC (IC2) 2 LM3915 display driver ICs (IC3,IC5) 1 7815 3-terminal regulator (REG1) 1 7915 3-terminal regulator (REG2) 2 1N4004 diodes (D1,D2) 4 1N914 diodes (D3-D6) 16 green thru-panel LEDs (LEDs 1-8, 11-18) (Altronics Z0711) 2 yellow thru-panel LEDs (LED9, LED19) (Altronics Z0713) 3 red thru-panel LEDs (LED10,LED20,LED21) (Altronics Z0710) Capacitors 2 1000µF 25VW PC-mount electrolytics 2 100µF 25VW PC-mount electrolytics 9 10µF 35VW PC-mount electrolytics 4 10µF 50VW bipolar electrolytics 2 0.22µF MKT capacitors 2 0.01µF MKT capacitors 2 390pF ceramic capacitors 2 33pF ceramic capacitors 6 10pF ceramic capacitors Resistors (0.25W, 1%) 2 680kΩ 2 2.2kΩ 2 330kΩ 2 1.8kΩ 2 220kΩ 3 1.2kΩ 2 150kΩ 4 150Ω 2 100kΩ 2 100Ω 2 82kΩ 2 33Ω 2 6.8kΩ 1 10Ω 2 4.7kΩ RCA Input Module 1 PC board, code 01112013, 110 x 32mm 3 2 x 2 PC-mount gold-plated RCA sockets (Altronics P 0214) 1 26-way DIL pin header Power Amplifier Modules 2 PC boards, code 01112011, 176 x 108mm 8 M205 PC mounting fuse clips 4 M205 5A fuses 2 coil formers, 24mm OD x 13.7mm ID x 12.8mm long (Philips 4322 021 30362) 2 200Ω multi-turn trimpot, Bourns 3296W series (VR1) 3 metres 1mm diameter enamelled copper wire 4 micro-U heatsinks, 19 x 19 x 9.5mm (Altronics H 0630) 8 TO-3P insulating washers (silicone) 4 TO-220 insulating washers (silicone) 2 TO-126 insulating washers (silicone) 4 TO-220 insulating bushes 2 2-way mini PC terminal blocks – 5mm pitch (Altronics P 2038) 8 PC stakes Semiconductors 4 Motorola MJL1302A PNP power transistors (Q13, Q14) 4 Motorola MJL3281A NPN power transistors (Q15, Q16) 2 Motorola or On Semiconductor MJE15030 NPN transistors (Q11) 2 Motorola or On Semiconductor MJE15031 PNP transistors (Q12) 2 Motorola MJE340 NPN power transistors (Q10) 2 BF469 NPN transistors (Q8) 2 BF470 PNP transistors (Q9) 6 BC546 NPN transistors (Q5-Q7) 8 BC556 PNP transistors (Q1-Q4) 2 3.3V 0.5W zener diodes (ZD1) – do not substitute 1W device Capacitors 4 1000µF 63VW electrolytic 2 220µF 63VW electrolytic 2 100µF 63VW electrolytic 2 100µF 16VW electrolytic 2 2.2µF 25VW electrolytic 2 0.15µF 400VW MKC, Philips 2222 344 51154 or Wima MKC 4 10 0.1µF 63V MKT polyester 2 .0012µF 63V MKT polyester 2 100pF 100V ceramic Resistors (0.25W, 1%) 4 18kΩ 2 330Ω www.siliconchip.com.au 2 12kΩ 1W 4 150Ω 2 3.3kΩ 6 120Ω 2 2.7kΩ 5W 8 100Ω 2 1.2kΩ 4 47Ω 2 1kΩ 2 10Ω 2 390Ω 2 6.8Ω 1W 2 330Ω 1W 16 1.5Ω 1W 4 220Ω 5W (for current setting) Miscellaneous Heatsink compound, tinned copper wire for links, insulation tape Power Supply Module 1 PC board, code 01112015, 199 x 93mm 2 2kΩ multi-turn trimpots, Bourns 3296W series (VR2,VR3) 1 drilled aluminium heatsink, 100 x 67mm (1.5-2.0mm thick) 2 TO-3P insulating washers (silicone) 2 TO-220 insulating washers (silicone) 4 TO-220 insulating bushes Semiconductors 2 TIP33B NPN power transistors (Q17, Q18) 1 LM317 adjustable positive 3-terminal regulator (REG1) 1 LM337 adjustable negative 3-terminal regulator (REG2) 1 PA40 or KBPC3504 400V 35A bridge rectifier (BR1) (Altronics Z0091) 1 KBPC604 or PW04 400V 6A bridge rectifier (BR2) (Altronics Z0082) 2 33V 5W zener diodes (ZD2, ZD3) Capacitors 4 8000µF 63VW chassis-mount electrolytic capacitors (Altronics R6720). Do not substitute Altronics R6722 as cans will foul chassis lid. 2 470µF 100VW electrolytics 2 100µF 63VW electrolytics Resistors (0.25W, 1%) 2 8.2kΩ 1W 2 47Ω 2 6.8kΩ 6 15Ω 1W 2 180Ω Loudspeaker Protector & Fan Control Module 1 PC board, code 01112014, 193 x 68mm www.siliconchip.com.au 2 12V SPDT PC-mount relays, 16A contacts (Altronics S4197) 1 micro-U heatsink, 25 x 30 x 12.5mm (Altronics H0635) 1 thermal circuit breaker, 60°C, normally closed (TH1) (Altronics S5600) 1 2-way PC-mount pin header (Altronics P5492) 1 2-way header plug (Altronics P5472) 2 2-way mini PC terminal blocks – 5mm pitch (Altronics P2038) Semiconductors 5 BC547 NPN transistors (Q1, Q3, Q4, Q6, Q7) 2 BC557 PNP transistors (Q2, Q5) 1 BC327 PNP transistor (Q8) 1 BC337 NPN transistor (Q9) 7 1N4004 1A 400V diodes (D1-D7) 1 LM7812 3-terminal regulator (REG1) 1 red thru-panel LED (LED1) (Altronics Z0710) 1m green heavy-duty (7.5A) hook-up wire 250mm figure-8 shielded cable 2m red medium-duty hook-wire 2m black medium-duty hook-up wire 100mm 3mm-dia heatshrink tubing 100mm 5mm-dia heatshrink tubing 750mm 26-way IDC cable (Altronics W 2626) Screws & Nuts Resistors (0.25W, 1%) 1 220kΩ 1 10kΩ 2 56kΩ 1 2.2kΩ 4 22kΩ 1 1.5kΩ 2 22kΩ 1W 1 22Ω 5W 4 25mm tapped brass spacers 8 20mm tapped brass spacers 4 15mm tapped brass spacers 1 M4 x 16mm screw 42 M4 x 10mm screws 43 M4 nuts 100 M4 star washers 12 M4 x 10mm brass screws 12 M4 nuts 12 M4 star washers 24 M3 x 10mm screws 40 M3 x 6mm screws 15 M3 nuts 50 M3 flat washers 10 M3 star washers 3 6g x 10mm pan head selftappers (to secure RCA socket pairs to chassis) 4 6g x 12mm countersunk screws (to secure the loudspeaker terminal pairs) 2 No.4 x 9mm universal head self-tapping screws (to secure IEC mains socket) (Altronics H1139) Wire & Cable Quick Connects Capacitors 1 1000µF 25VW PC electrolytic 1 220µF 25VW PC electrolytic 4 47µF 50VW non-polarised PC electrolytic 1 10µF 35VW PC electrolytic 1m 250VAC 3-core mains flex 2m 2 x 90/0.18 figure-8 “Whopper” speaker cable 3m red heavy-duty (7.5A) hook-up wire 3m black heavy-duty (7.5A) hook-up wire 3m white heavy-duty (7.5A) hook-up wire 1m blue heavy-duty (7.5A) hook-up wire 53 doubled-ended male quick connects (Altronics H2261) 50 red female in-line quick connects, 6.3mm (Altronics H2001A) 25 blue female in-line quick connects, 6.3mm (Altronics H2006A) 3 red piggyback in-line quick connects, 6.3mm (Altronics H2011A) Where To Buy A Kit Of Parts A complete kit of parts for the Ultra-LD 2 x 100W Stereo Amplifier will be available from Altronics, 174 Roe St, Perth. Phone (08) 9328 1599. You can order on-line from www.altronics.com.au January 2002  69 that the heatsink mounting screws cannot possibly penetrate the mains wiring. The channel position also ensures that the leads take a natural path so that they clear the self-tapper that’s just in front of the heatsink. Speaker LED Mounting The loudspeaker indicator LED is mounted on the front panel using a modified cable-tie mount (see text). A dab of superglue or hot-melt glue can then be used to hold the LED in place. connects at either end are used to make the DC connections from BR1 to the Power Supply module. Use heavy-duty cable for this wiring and be careful not to get these two connections transposed. Once all the leads have been connected, they can be an­chored by fitting the cable ties. Additional cable ties can also be fitted at various points between the cable-tie mounts, to keep the wiring tidy. Mains Wiring Take extra care with the mains wiring – it must be in­stalled exactly as shown in Fig.21. The best place to start is at the IEC socket end. Begin by stripping about 100mm of the outer sheath from the mains cable, then feed the brown and blue leads through the rubber boot that comes with the IEC socket. That done, crimp red quick connects to the ends and connect the Active (brown) and Neutral (blue) leads to their respective IEC socket terminals. The Earth lead (green/yellow) from the mains cable goes directly to the chassis earth – see Fig.21. A second green/yellow mains-rated earth lead (about 240mm long) connects the earth terminal on the IEC socket to a chassis earth. Be sure to also feed this lead through the rubber boot before fitting quick connects to both ends. The third chassis lug is connected via a 250mm-long lead to a 0V terminal 70  Silicon Chip on the Power Supply module. Now double-check your wiring to the IEC socket, to make sure it is correct. That done, slip the rubber boot over the IEC socket and fit a cable tie to the leads as close to the boot as possible (this prevents the boot from coming off). Additional cable ties can now be used to secure the wiring and to secure the mains cable to the cable-tie mounts. You will find this job easier with the side panel removed. Important: you must secure the mains cable so that it is well clear of the self-tapper screws that are used to secure the side panel. In particular, note that the mains cable sheath should start well forward of the bottom rear self-tapper (see photo). This will allow the leads to be routed well away from this self-tapper and secured using cable ties. Note also that the righthand heatsink channel has been positioned so WARNING! All transistors with “MJL” and “MJE” type numbers in the power amp­lifiers (ie, transistors Q10-Q16) must be genuine Motorola or On Semiconductor devices. Do NOT substitute devices from other manufacturers – they do not have the same characteristics as the specified devices and can cause instability. The Speaker LED mounts directly on the front panel and the best way to go about this is to hold it in place using a modified cable-tie mount. First, drill a 5mm hole in the top of the cable tie mount, then use a sharp knife to cut a clearance hole in the adhesive contact area (leave the backing paper in place during this proce­ dure). The cable-tie mount is then affixed to the front panel (directly in line with the LED Speaker hole), the LED pushed in and a dab of superglue or hot-melt glue used to hold it in place. Don’t try using superglue to attach the LED directly to the front panel – it’s all too easy to make a mess and spoil the panel’s appearance. Hot-melt glue won’t work here either because it doesn’t adhere properly to the powder-coated surface.. Once the glue is try, the leads from the headphone socket can be soldered directly to the LED. Cut the LED leads short, so that they cannot foul other parts on the preamplifier board. Mains Switch Wiring Now for the mains switch wiring. This switch should be mounted on the front panel with terminals 1a and 2a towards the top. It’s then simply a matter of cutting a 10mm-long slit in the back of the protective boot, feeding through the various leads and connecting them to the terminals. This done, the protective boot is pushed over the switch body (it’s a tight fit) and is secured by fitting cable ties to the wiring. The earth lead from the mains cable connects to an earth lug on the front panel (note: the front panel is supplied with this earth lug attached). Leave enough slack in the switch wiring so that the front panel can be opened out to provide access to the nut that secures the volume control pot. Also, take great care not to scratch the front panel when working on the amplifier. It’s supplied wrapped in bubble plastic and this makes a handy “mat” to lay the front panel on when it’s detached from the chassis. www.siliconchip.com.au All wired up and ready for action – use cable ties to secure the transformer secondaries and other wiring to the Power Supply module. Once all the switch wiring has been completed, the front panel can be slipped over the LEDs and fas­tened in position. Don’t forget to fit the earth lead. Switching On The First Time Don’t do it – at least, not yet. There’s a step-by-step power-up sequence that must be observed, so that something doesn’t fry. Before applying power, check that the 8000µF and 470µF electrolytic capacitors on the Power Supply module are all correctly oriented and that the connections to BR1 are correct. Electrolytic capacitors have a very nasty habit of exploding if installed the wrong way around or if power is ap­plied with reverse polarity. Basically, you have to go through three main procedures to power up and adjust the amplifier: (1) check that the power Supply Module is delivering the correct voltages; (2) apply power to each of the Power Amplifier www.siliconchip.com.au modules in turn and adjust the quiescent current; and (3) apply power to the Preamplifier and Loudspeaker Protection modules. Here’s the full step-by-step procedure: STEP 1: disconnect all the ±52.5V & ±55V leads from the Power Supply WARNING! High DC and AC voltages are present on the Power Supply and Power Amplifier modules when power is applied. In particular, make sure that you don’t get across the two 50VAC terminals. The 50VAC transformer windings that connect to these terminals are wired in series, so there’s 100V AC between them! Similarly, the two 35VAC windings are in series, so there’s 70VAC between the AC terminals on bridge rectifier BR1. In short, don’t touch any of the high-voltage AC or DC (52.5V DC& 55V DC) terminals otherwise you could get a very nasty shock which could even prove fatal. module, the 15VAC leads from the Loudspeaker Protector module and the 15VAC & 12VDC leads from the Preamplifier module. STEP2: connect an IEC power cord to the amplifier and use a multimeter to check for continuity (ie, 0Ω) between the earth pin of the plug and chassis earth. STEP 3: install the 3A mains fuse in the IEC socket, apply power and check that the unregulated ±52.5V rails are correct (to within about a volt or so). Important: this should be done with the multimeter leads running out the back of the amplifier and with the lid sitting in place (this is a safety measure to pro­tect your eyes in case something is wrong). If the meter reads 0V, switch off immediately, recheck the connections to BR1 and check the phasing of the 35V transformer windings. If the phasing is incorrect, the two windings will operate in anti-phase and there will be no output voltage. STEP 4: check the regulated ±55V rails using the procedure outline in Step 2. If you get “ballpark” figures (they January 2002  71 15VAC FROM CAV51T1 D2 V21+ 680k 0.01F 82k 1.2k _ V0 + + + 1 10F 33 IC5 LM3915 LED17 LED19 10F + + LED11 LED13 LED15 K LED14 0.01F 82k 1.2k A 1 K IC3 LM3915 LED21 33 LED16 680k LED9 LED7 LED12 10F 10F + LED1 LED3 LED5 A D5 D6 LED6 10pF 1N 4148 1N 4148 33pF + LED4 0.22F LED2 220k 330k TERMINAL BLOCK R LED8 LED10 150k IC2 + ng d10 LED18 LED20 1.2k + A 10F 12V DC FROM SPEAKER PROTECTION PC BOARD 100F + REG1 7815 + 100F 1000F REG2 7915 + Preamplifier Modification D1 2x 1000F 1N4004 NOTE: QUICK CONNECTS (SHOWN DOTTED) ARE MOUNTED ON COPPER SIDE OF PC BOARD We recently discovered that our prototype Preamplifier board had a problem during wet weather, with some of the LEDs in the bargraph displays lighting when the amplifier was turned on from cold (ie, with no audio signal applied). The LEDs would then progressively go out over a period of several minutes. This turned out to be due to moisture on the PC board, which was allowing leakage between the copper tracks. As the amplifier warmed up, the moisture evaporated and the LEDs behaved normally, even if the unit was switched off and then back on again. The Altronics kit will be supplied with solder masked PC boards and this by itself should eliminate the moisture problem. However, we have decided to modify the circuit just to make sure. The “cure” is to connect 82kΩ resistors between D3’s cathode and ground and between D5’s cathode and ground, to shunt this leakage resistance. We have modified the Preamplifier PC board to accept these extra resis­tors and this new board will be supplied with the Altronics kit. Fig.22 shows the affected section of the PC board. The additional 82kΩ resistors are adjacent to pin 9 of each LM3915 display driver IC (IC3 & IC5). Fig.22 (left): the modified preamplifier board includes an extra 82kΩ adjacent to each LM3915 display driver IC. + RIGHT _ OUTPUT L 10pF TL072stage), the150k _ won’t be exact at this power wind VR1 slowly clockwise until the 1 LEFT supply is working OK although it’s a meter reads 4.4V. This is equivalent to OUTPUT + 33pF 330k good idea to wear safety glasses while a quiescent current of 20mA (ie, 10mA D4 0.22 F 220k through each output transistor). making adjustments. Adjust trimpots D3 SEE TEXT & PHOTOS VR1 MOUNTING VR2 & VR3 to obtain exactly ±55VFOR DC. Let the amplifier run for about 10 DETAILS 10F Check the phasing of VR1 the 50VAC minutes, then readjust VR1 if necestransformer windings if there is no sary. Finally, switch off, remove the + voltage at the output of bridge recti- 220Ω 5W resis­tors and fit the fuses. 10k 10pF fier BR2. STEP 8: connect the ±52.5V & ±55V 10pF 10F 10F restore all + supplies STEP 5: switch off and to the second power amplifier 10F 10F + the connections to the Power Supply and repeat steps 5 & 6 to set the quies+ IC1 IC3 10F module. Connect5534 the ±52.5V & 5534 ±55V NP cent current for this module. 1 1 NPAmplifier supply wiring to one Power STEP 9: connect the 15VAC leads to 4.7k 4.7k only. Disconnect all supply wiring the Loudspeaker Protector module. 390pF 390pF from the other Power Amplifier. Apply power and check that the re1.8k 1.8k STEP 6: remove the fuses and solder lays turn on after about four seconds. 10F 150 220Ω 5W resistors between the two Check that the Loudspeaker LED lights NP sets of PC stakes on the board. Now100k when the relays turn on and that the 10F wind VR1 fully anticlock­wise, apply6.8k relays turn off when headphones are NP power and check the voltage at the6.8k plugged in. FERRITE output of the amplifier (ie, the voltage2.2k Next, check that the DC fault proBEADS between the loudspeaker terminals). It2.2k tection works by discon­necting only should be less than ±30mV. the positive leads from one amplifier 1 voltIf not, check the base-emitter and connecting 3V DC (2 x 1.5V cells) ages of the transistors; they should all between the terminals instead. Do the S1 be 0.6-0.7V. Check also that the correct same for each channel – in each case, transistor is installed at each location the relay should immediately turn off. and that all transistors and other parts Now remove one of the leads from are the right way around. the thermal cutout (TH1) on the amSTEP 7: monitor the voltage across plifier heatsink. Check that the fan 1 one of the 220Ω 5W resistors and immediately starts running and that 1N 4148 100 1002 C 72  Silicon Chip L 150 10pF 150 10pF 100k R REIFILPMA DL-ARTLU R L 150 R L 21021110 YALPSID/PMAERP 100 1N 4148 it stops when the lead is reconnected. STEP 10: check the +12V supply from the Loudspeaker Protector then switch off and connect the 15VAC and 12V DC leads to the Preamplifier module. Be sure to get the 12V leads the right way around – transpose them and smoke signals are guaranteed. Apply power and check that the Power LED lights (the bar­graph LEDs may also flash briefly). Check the outputs of the two 3-terminal regulators – you should get +15V from REG1 and -15V from REG2. Listen To The Music! Now for the big moment. Connect your CD player and loud­ speakers, switch on and listen with your ear close to the loud­speakers but without any music playing. Even with the volume control turned right up, there should only be a barely percep­tible “hiss” from the speakers. Finally, turn the volume control back to “normal”, place your favourite CD in the tray, hit the “Play” button and sit back to enjoy the sound. Try varying the volume – you should see the bargraph LEDs “jump” up and down in response to the music. SC www.siliconchip.com.au (NEW) 40X2 Hyundai LCD's These 40´2 LCD module are new and manufactured by Hyundai. Standard Hitachi chipset. No backlight. There is lots of information on the internet to drive these displays. PCB size is 180mm x 35mm and the window size is 160mm x 30mm. Check the following website for more information: http://www.allamerican.com/direct/results.asp?SH OW=50&MFG=_HYNL, .$25 each (limited quantity) 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. Manufacturing cost was around $30. We have a good quantity in stock for a small fraction of their retail price - $11 each. (NEW) 20X2 LCD BACKLIT DISPLAY: Made by Optrex model #DMC2059, (data is available for similar 20 x 2 displays). 6mm x 8mm characters, 122mm wide x 30mm high. PCB dimensions 151mm wide x 56mm high. Uses standard Hitachi chipset (HD44780) with LED backlight (DL8) $11 each or 3 for $27 (NEW) SMALL SERVO MOTOR: This is not a standard servo motor. It has a small motor, six wires and a feedback pot. The feedback pot is not connected to the motor. It draws about 200mA of current and runs from 8 volts: (MS3) $4 (NEW) BOPLA Card Enclosure System These Bopla boxes (RCP-2500) are Brand New and are made of Polystyrene. Dimension is 214 X 257 X 128mm and are grey in colour with clear lid. Check the following website for more information http://www.bopla.de/ katalog/index_en.html. (RCP-2500): $15 each $5 INFLATABLE COW PATTERN CHAIR TOUGH PVC ADULT SIZED 92 x92cm 9 4 $1 AS REVIEWED IN THIS MAGAZINE MORE NEW STOCK FOR JANUARY! SPECIAL!!! (NEW) MOTOROLA MICROPROCESSORS P a r t n u m b e r XC68HC705P9P. 28 pin package, 5 volts. These are hard to find, as they may be obsolete. $8 each We have more used test equipment. we need to clear some to make way for the next lot. But you may have already missed it. The only way to make sure you don’t is to subscribe to our bargain corner & receive advanced notice Just send us a blank E-Mail to.... bargaincorner-subscribe <at>oatleyelectronics.com CK O ST !!! W W NE N NO I SOOPER SNOOPER / PARRABOLIC MICROPHONE/ STETHOSCOPE Listen to things from a distance, like bird calls & wildlife etc. Or by attaching the microphone to a screwdriver handle you can listen to white Ants chewing! Also ideal for detecting engine & bearing knocks etc. Kit inc. PCB, all onboard com-ponents, stethoscope pickup, electret Microphone. KIT (K175) $22...300mm Aluminium Parabolic Dish: (K175D) $25 ...Suitable small plastic Case: (HB1) $2.50 ...Power switch: $2.50... Long Screwdriver with FREE BONUS WITH EVERY ORDER Solid plastic Handle: $1 SOLAR FURNACE / PARABOLIC REFLECTOR This dish is used in our Sooper Snooper. It is mill finished & is reflective enough to ignite paper almost instantly, Some car cutting compound / polish would make it highly reflective:$25 ULTRA-VIOLET LEDS!!! LEDS AND LASERS BOSTON ACOUSTICS (NEW) OPTO 22 Relay I/O Module These Relays are manufactured by APTech in Japan. AC Output is 24-280 VAC, with 5 VDC Logic. Check the following website for more information:..http://www.opto22.com/Ordering/Pr oductDrillDown.asp?IK=182\ $ 8 each 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:(153 X 101 X 114mm)... (GCS300): $22 - limited quantity. 395nM UV LED's... 200mCD $4.70 Blue LED's 3.5CD $3.50 White LED's 6CD $2.50 10CD $4 15CD $6 650nM LASER MODULES 3mW $18 6mW $36 10mW $90 25mW $200 BRAND NEW TELESCOPIC ANTENNAS There are many different types but all have some kind of mounting. Some of the antennas also have swivels. Length ranges from 0.5 to 1.2 meter. We sell these in a mixed pack of 7 different types. (NEW) HYUNDAI FLASH (NEW) HP FIBRE OPTIC PORT These HP Fibre Optic cable MEMORY IC: Organized as 512K x 8 bits. connectors (HFBR-1533) are The 32pin surface mount made in Singapore. It is use as a HY29F040 IC has been connector between Fibre Optic assembled on a larger PCB cables and PCB's. It has 4 pins, that has 0.1" pin spacing (32 possibly transceivers, and two pins in total): (GMEM1) $6 pins for mounting to PCB's. These are hard to find, as they each might be obsolete. Good for Experimenter's. $ 2 each k $5 ac er p p TAKEN IN JANUARY IF YOUR ASK FOR YOUR FREE COW GEARED AC MOTORS Brand new small mains operated geared motors, very strong, made for rotating microwave turntables, 240V/ 50Hz/3W/5RPM., $4Ea. or or 4 for $12. www.oatleyelectronics.com Orders: Ph ( 02 ) 9584 3563, Fax 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_JAN_02 COMPUTER TROUBLESHOOTING Tracking down software problems: a step-by-step approach What’s the first thing many people do when the strike computer problems? Answer: they reformat the hard disk and rein­stall everything. But that’s the hard way of fixing problems and it doesn’t necessarily guarantee a good result. By STEPHEN DAVIS I vaguely remember having read somewhere that when someone asked Tesla how he was able to understand and invent complex electrical devices he replied: “By breaking the concepts underly­ ing them down into simple parts, understanding those simple parts, and realising that complexity has an underlying simplici­ty”. An attitude like this prevents the mindset of being over­whelmed when confronted with problems that inevitably occur when using the complex technology of today. And of all the electronic devices that cause frustration, home computers would have to be right up there, along with setting up (and subsequently using) video recorders. The added frustration that a home computer user has is that even the so-called professional’s solution to a computer user’s software problems is often destructive – ie, reformat the hard disk drive and start again or, at best, reinstall Windows from scratch. However, a little bit of knowledge and some careful analysis may be all that are required to save your PC’s current setup from obliteration. It often amuses me that some people who profess to be “au fait” with computers often describe themselves as software or hardware orientated and then shy away from gaining knowledge about that side of computers they feel doesn’t interest them. This is a mistake, because if you are interested in solving com74  Silicon Chip puter related problems, a reasonable knowledge of both areas is necessary. After all, hardware faults can masquerade as soft­ ware faults and vice-versa, so you have to be prepared to deal with both possibilities when troubleshooting. The hardware and software in your PC is inexorably linked and this must be fully appreciated in order to solve problems as they arise. A typical software problem A good example of a software problem is one that recently happened to me. What follows is the step-by-step method that I used to solve the problem. You can use the same procedure to track down similar faults. The problem occurred after I had foolishly installed several programs on my computer in quick succession. It is inad­visable to install programs in this fashion, because when soft­ware problems or conflicts occur, they are harder to track down – simply because you don’t know which application introduced the fault. This was a classic case of me not following my own advice and the problem occurred as a result of it. Everything seemed to be working well initially until, about a week later, I tried to fire up Microsoft Visual C++ (a component of Visual Studio) and found myself staring at an error message that said, “Msdev caused an invalid page fault in MFC42.dll”. The program would then exit gracefully after my acknowledgement of the fault. The first thing to do in a case like this is to go on to the Internet and, using a good search engine (I use Google at present), do a search for the above phrase. This has the poten­tial of giving you an exact reason for your problem but in this case, nothing of relevance came up. I then searched the Microsoft Knowledge Base using the above phrase but again drew a blank. Under these circumstances, the best thing to do is to unin­ stall and reinstall the program to see if this fixes the problem. The obvious disadvantage of this technique is that it does not aid in understanding why the fault was there to begin with. However, at the time, I was just eager to get the program going. Unfortunately (or perhaps fortunately, otherwise this article would not have been written), the same error reared its ugly head and continued to do so no matter how often I uninstalled and reinstalled the program. My next step was to uninstall all the programs I had in­stalled subsequent to Microsoft Visual C++ working correctly. After doing this, I cleaned the Registry to delete any references to these programs that may have been www.siliconchip.com.au What’s A DLL And How Do They Cause Problems? So just what is a “dll” file and why do they sometimes cause problems? Since this explanation is for the layman and not for pro­grammers, the following is a simplification of what actually occurs. A “dll” is simply an enclosed set of different procedures that a program could call. For example, if I wish to save a file to disk from my program, I just simply call a set of instructions (a procedure) within a dll (in this case kernel32.dll) to do it. There are many dlls for many varied functions within Windows and programmers can also write their own dlls. When computers first started becoming popular, all programs were self-sufficient, with the details of saving to disk, retrieving information, etc included within each program itself. However, it didn’t take programmers long to realise that this was an inefficient way of doing things, because the same code for saving to disk would have to be included in every single program. Why not have the code required for saving to disk written sepa­ rately, outside each program, so that all programs that save to disk could easily access it? This would save memory space and also the programmer’s time. All that the programmer would need to know would be that if he wants to save information to disk he simply writes ‘saveto­disk’ or its equivalent, depending on what the original program­ mer called it. The operating system would then track down the dll containing this procedure and the procedure itself would start left behind (I used the shareware program “Reg Vac” which has had good reviews on the Internet). I then reinstalled Visual C++ but the error was still present. It was time to look at the error more closely by examining what it was saying. What’s a page fault? A page fault is something that occurs normally with pro­grams running under Windows. When a piece of information is paged out to virtual memory (the swapfile) on the hard drive (eg, due to lack of space in www.siliconchip.com.au operating. Thus the code for saving to disk could be written to a separate module and linked to any program that required it – hence the concept of a linked library. However, what if we were doing things on the computer that didn’t require the “save to disk” procedure? Memory would be wasted holding code that was not going to be used. Hence the concept of a dynamic linked library (dll), where the actual calling of a procedure from a program is what first puts it into memory. Before it is called, it just sits as a file on the hard disk drive. To explain how dlls can cause problems, imagine a program­mer writing a simple piece of code for an arithmetic program aimed at elementary school children. The program introduces the concept of the squaring of numbers and because of the age group of the children, only integers can be used within the program. Our programmer then turns this piece of code into a dll because he imagines other programmers may find this code useful for their own arithmetic programs. All they would have to do is link this piece of coding into their program and write “square­ number” (depending on what the programmer called it) and they would get the required results – all based on the efforts of the programmer who originally wrote it. Everything would be fine until someone decided to include this dll in a program for use by secondary schools where real and complex numbers are being explored. The RAM), a page fault occurs whenever the RAM is accessed and the required information isn’t there. The page fault then points the program to the area in the swapfile where the information is stored. This information is then put back into RAM to allow it to be accessed by the data bus. At the same time, the least-used information currently in RAM is swapped out to virtual memory. An invalid page fault occurs when the area of swapfile that is required to be transferred back into memory is not valid for the application. Further information on this concept for people programmer responsible for the dll would still like programmers to be able to write “squarenumber” and get a result and so he would put out version 2 of the dll, with the coding altered to give a result other than an integer when required. So how would the dll know whether to deliver an integer result or not? The dll could look for certain bytes within memory that signify one version or the other of the program that uses it. The program would have assigned an area of memory for its own use in order to place the flag bytes and it would be the responsibility of the operating system to prevent this area of memory from being overwritten by another program. Now imagine the case of a version 2 dll overwriting the original dll on a PC that uses the elementary program. The original program would not have reserved an area of memory for flag bits and so when the dll checks for these flag bits, a protection fault would result if this area of memory has been grabbed by another program. Basically, the Windows operating system always preserves memory integrity by terminating programs that invade another program’s reserved RAM. This simplistic example explains how software conflicts can occur due to memory and dlls. It only takes a small piece of programming that is less than optimal to cause a cascade of problems that leads, at best, to the termination of one program or, at worst, to a complete crash. new to it can be found at: http://www. howstuffworks.com/question175.htm MSDev.exe is the Microsoft development environment execut­ able which, among other things, has to load MFC42.dll – a Micro­soft foundation class dynamic linked library (see panel: “What’s A DLL And How Do They Cause Problems?”). So it appeared that the error was occurring whenever MSDev.exe attempted to load MFC42.dll. A Microsoft knowledge base article at http://support.micro­soft.com/support/kb/articles/q286/1/80.asp talks about the vari­ous causes of invalid January 2002  75 Computer Troubleshooting – ctd page faults. The two that concern us here are the possibilities that either one of the two files is cor­rupted (and therefore allocating memory in an incorrect fashion) or that they are interfering with each other because of a lack of synchronisation with respect to memory. This latter possibility could occur if the dll being used was the wrong version. Neither scenario seemed particularly likely considering that the Visual C++ had been installed and uninstalled many times already but I was running out of ideas. As a result, I decided to install Visual Studio on a friend’s computer, first to see if the CD itself had somehow become corrupted and second, to have a closer look at these two files. Visual Studio worked perfectly on my friend’s computer and so I copied both MSDev.exe and MFC42.dll onto floppies and took them home. I then compared these files with those on my hard disk drive and to my surprise, I found that the version of MFC42.dll in my hard drive’s c:\windows \system dir­ ec­tory was 6.00.8447.0 whereas the version on the floppy was 6.00.8141.0. So, it appears that a newer version of the dll had over­written the older version (this is normal behaviour) but poor programming had resulted in a dll that was obviously not fully backwards compatible with the older one (as it should have been). The next step was to replace the version of the dll in the system directory with the version of the dll that the program apparently needed. Using correct computer procedure (ie, the three “Bs” – backup, backup and backup), I tried to back up the version of MFC42 that was in the c:\windows\ system directory but I got an error saying, “Cannot delete MFC42.dll. Access denied. Make sure the disk is not full or write protected or that the file is not currently in use”. Suddenly a bell started ringing (actually more a mental buzz – the neurons were now firing). Obviously, my previous attempts at uninstalling and reinstalling Visual C++ would have had no effect on this file if it was being used by a TSR (a program that 76  Silicon Chip runs quietly in the background) – ie, the file could not be replaced or deleted while ever the TSR was running. However, it did annoy me some­what to think that the programmer responsible for the uninstall routine of the Visual C++ module could have been a little more explicit in messages about which files were not being unin­stalled. Now that I knew what had happened, it was a simple matter of using the three-finger salute (ctrl-alt-del) to remove all of the background programs except for Explorer and Systray and then replacing one version of MFC­ 42.dll with the other. After reboot­ing (to re-enable the TSRs), Visual C++ worked perfectly. Norton’s clobbered It was now interesting to observe that the Norton Utilities portion of Norton System Works 2001 no longer worked. Instead, it simply displayed a very unhelpful message which said “Internal error”. Of course, replacing the Visual C++ version of MFC42.dll in the c:\windows\system directory with the other version (which I’d copied to another floppy) allowed Norton System Works to operate again – but at the expense of Visual C++. I wanted both programs to work, so I thought about this problem and eventually decided to leave the dll required by Visual C++ in the c:\windows\ system directory and to place a copy of the other dll in the “Norton Utilities” folder where the executable for this “sub-unit” of Norton System Works was stored. In programming, there is often a sequence required for the program to find required files and usually the folder uti­lised by the executable itself is the first folder to be searched. This type of programming methodology is exemplified by the “path” environmental variable utilised by DOS (ever heard of it?) during the dinosaur era. In this case, the idea paid off and I now have Norton System Works and Visual Studio happily coexisting with each other. Be methodical As the above story demonstrates, it’s important to be me­thodical when tracking down software faults. A technique I have used in the past is to put pen to paper, list all the possibili­ties, and then methodically follow chains of logic. I also frequently use the Internet to gain knowledge about the problem at hand. In the above case, I perhaps could have found the source of the problem sooner if I had done a search on keywords such as “MFC42.dll”, problems, incompatibility, etc. I would have soon discovered that this dll is one of a number known to cause what is known as “dll hell” (do an Internet search using this little phrase and see what pops up). Also, Norton Utilities is notorious, particularly in some of its earlier incarnations, for causing problems with other software. However, in this case, the problem is purely Micro­soft’s because MFC42.dll is a Microsoft file. By now, some of you may be thinking that there is always a message at the start of most installation routines that says “Make sure other programs are not running during this installation routine” or words to that effect. Had I diligently followed this instruction and turned off all of the TSRs, the problem would not have happened. My excuse for not following this instruction is that I had not thought deeply enough about it to consider applying this directive to background running programs – and I doubt that the majority of people installing programs would consider it either. However, doing things the long way, or sometimes the wrong way, is not something I necessarily regret if it gives me a greater under­standing of my hobby. And really, isn’t that what its all SC about? www.siliconchip.com.au Raucous Alarm . . . the alarm that everyone will hate hearing Make no mistake: this alarm sounds quite horrible. You don’t build it to make pleasant sounds to lull you or someone else into a state of contentment. Build it to gain immediate attention. Build it and turn it on, only to hear someone say, “turn that b—dy thing orff!” By THOMAS SCARBOROUGH The inspiration for this circuit came from one of those doorbells that played the same tedious repertoire (eight tunes) over and over again. Why not, I thought, design a doorbell that would play an infinite variety of notes? Thus the idea for a random doorbell was born. But while the circuit described here will play about 20 million different sequences of notes on a single setting – most of them never previously combined, few people would actually want to use it as a doorbell, unless they were utterly tone-deaf. It sounds pretty horrible, let me tell you. Which is why this circuit rapidly “morphed” from a doorbell to a rauwww.siliconchip.com.au cous alarm. It’s now the alarm you build to get people’s attention and then, because they will hate the sound it makes, they will do whatever is required to stop the alarm. And isn’t that what you want an alarm to do? Make it awful The key to designing an effective random alarm lies in creating a series of tones which not only sound unmusical in isolation but which are musically unrelated and then produced in a random sequence. If too many random notes are played in too rapid a se­quence, one begins to approach “white noise”. If too few notes are played, or too slowly, the sound seems repetitive. The Raucous Alarm therefore plays eight notes in various sequences, and of varying duration, at a speed of about 150 beats per minute. This seemed to represent a good compromise. The Raucous Alarm is based on an RC oscillator (IC1d). It CAN be seen from the circuit diagram (Fig.1) that five resist­ances (VR2 and R4-R7) are wired in parallel to make up the value of “R” – three of these being combined more or less at random. Several resistors and capacitors set the pitch and duration of the Raucous Alarm’s notes, and any one of these could be altered to change the “fundamental” sound. I chose to make just two of these components variable, with the aim of creating the maximum variation of sound with just two adjustments, for pitch and tempo. This means that there is a fairly wide scope for variation besides that already built into the “random” circuit. The Tempo adjustment (VR1) sets the duration of four of the eight notes, while VR2 sets the amount of variation (or pitch) of the other four notes. Thus, the Raucous Alarm may be adjusted over a wide range of pitch and temJanuary 2002  77 IC1: 4093 1 14 IC2: 4066 IC1a 3 2 C 330k 4 6 VR2 220k IC2a 13 D1 IC2 PIN 14 IC2b 5 3 H 4 220k E TRIGGER INPUT: LOGIC HIGH TO F OR LINK E-F 10 9 A F 100k IC1c 8 B 22k 6 100k 8 470F 120k Q1 BUZ10 G BUZ10 S D1 1N4148 13 10F 9 22k 12 10F IC2c D VR1 1M TEMPO 10F SPKR 8 1.5W 10k 180k 5.6k D 10 IC1d 11 12 7 0.1F G IC2d D SC S 7 11 10k K 2002 +4 – 12V G D2 1N4001 2 PITCH IC1b 5 22F J 0V RAUCOUS ALARM Fig.1: the circuit is based on a Schmitt trigger oscil­lator involving IC1d. Three other Schmitt trigger oscillators control analog switches (IC2) to rapidly vary the charging re­sistance for IC1d and thus rapidly vary the frequency. po – all of which can sound pretty raucous, something like fiendish arpeggios played by a demented musician. Circuit description The Raucous Alarm makes very economical use of just a few simple components. The “economy” of this design is achieved by harnessing each of the circuit’s two ICs to fulfil more than one function. IC1, a 4093 quad 2-input NAND gate package, provides an oscillator and timer and it determines the duration of the notes. IC2, a 4066 quad analog switch, determines the pitch of the notes and also provides a buffer for the oscillator. The result is a cheap and simple circuit which produces far more (ghastly) varie­ ty than one would expect from its apparent simplicity. At the heart of the Raucous Alarm lies a simple RC oscilla­tor, based on a 2-input NAND gate IC1d (see Fig.1). “R” is deter­mined by five resistances wired in parallel, three of which are switched in and out of circuit “at 78  Silicon Chip random” by IC2a-IC2c. One of these three resistances is variable, so that more variety is added to the range of sounds produced. Diode D1, in conjunction with the series 5.6kΩ resistor, reduces the markspace ratio of the pulse waveform delivered from pin 11 of IC1d and this has the effect of reducing current con­sumption while still maintaining a high (raucous) level of sound. Switched resistors As already noted, three resistors are randomly switched in and out of the main oscillator circuit (IC1d) by analog switches IC2a-IC2c. Each of these analog switches is controlled by a sepa­rate oscillator, based on NAND gates IC1a-IC1c. Each of these oscillators uses a 10µF capacitor between the inputs and 0V while having different resistors to further “randomise” the duration of each switched “note”. Potentiometer VR1 is used in conjunction with IC1c so that the switching time for IC2c can be varied over a wide range. The fourth analog switch in the package, IC2d, actually functions as a buffer stage for oscillator IC1d. Or you could think of it as an inverter, so that each time the output of IC1d goes high, IC2d is switched to pull the gate of Mosfet Q1 low. Q1 drives the 8Ω loudspeaker directly from the positive supply rail and since it is an inductive load, diode D2 is con­nected to damp the voltage spikes that would otherwise be pro­ duced each time the Mosfet switches off. Once the Raucous Alarm has been powered up, the three oscillators based on IC1a-IC1c run continually “in the back­ground” (that is, without being heard). When the pin 13 input of IC1d is pulled high, IC1d is enabled as an oscillator and so sound (plenty of it) is heard from the speaker. Our prototype was wired with the trigger input operated by a pushbutton, by the way. When the pushbutton is pressed, just a slice of the Raucous Alarm’s continual activity is played out loud. The instant that pin 13 of IC1d is pulled high, the associated 22µF capacitor is charged up, so that oscillator IC1d is activated. After removing one’s finger from the pushbutton, the www.siliconchip.com.au 22µF capacitor discharges through the parallel 120kΩ resistor, causing a delayed “shutdown” of the Raucous Alarm. In its “background mode”, the Raucous Alarm draws around 5mA and about 160mA (at 12V) when activated. Thus a 12V plugpack rated at 200mA (about 2.5W) would suit. PITCH POT TEMPO POT Taming the output 1 D 22F TRIG IN F E 2002 IC1 10F 10F CS 4093 180k 10k 120k A 10F DC INPUT SOCKET 220k 330k K 1 D G 0.1 22k 4148 4066 G B D1 5.6k BUZ10 SPEAKER C 22k 100k 120101Q1 30 IC2 S H D2 4001 10k 100k The Raucous Alarm is very loud (nearly 2W RMS into a 8Ω speaker with a 12V DC plugpack) and will easily be heard through­out an entire home – if not by the neighbours as well! This may be reduced by wiring a resistor in series with the loudspeaker – a 220Ω 0.5W resistor will make it bearable. The alarm may also be quietened considerably by reducing the supply voltage down to as little as 4V or 5V, although this also lowers the pitch of the notes. Another thing to note is that the DC supply to the alarm should be the same as that of any external circuit which provides the trigger signal. So if it is to part of an alarm system which runs from 6V for exam- – 470F + J TEST BUTTON Fig.2: you can build this alarm as simply as you wish. Here we show it wired up with Tempo and Pitch controls and a pushbutton to sound it. Be warned - it is surprisingly loud when run from a 12V DC plugpack. SC 2002 03101021 Fig.3: above is the full-size etching pattern for the PC board, while at right is the board with all the parts installed. Note that this prototype board differs slightly from that shown in Fig.2. Resistor Colour Codes  No.   1   1   1   1   2   2   2   1 www.siliconchip.com.au Value 330kΩ 220kΩ 180kΩ 120kΩ 100kΩ 22kΩ 10kΩ 5.6kΩ 4-Band Code (1%) orange orange yellow brown red red yellow brown brown grey yellow brown brown red yellow brown brown black yellow brown red red orange brown brown black orange brown green blue red brown 5-Band Code (1%) orange orange black orange brown red red black orange brown brown grey black orange brown brown red black orange brown brown black black orange brown red red black red brown brown black black red brown green blue black brown brown January 2002  79 If you measure across Mosfet Q1 with a scope, this is the sort of waveform you can expect to see. The jitter in the wave­form is due to the rapid fluctuation (modulation) of the frequen­cy. 1 PC board, code 03102021, 74 x 49mm 1 plastic case, 148 x 80 x 48mm, or equivalent 1 2.1mm chassis-mount DC power socket 1 12V 200mA DC plugpack with 2.1mm power plug 1 8Ω loudspeaker, rated at 2W or more 10 PC pins 2 14-pin dual-in-line IC sockets (optional) 1 on-off switch (optional) 1 pushbutton switch (optional) 1 1MΩ linear potentiometer (VR1) 1 220kΩ linear potentiometer (VR2) ple, the Raucous Alarm should also run at 6V. Construction The PC board of the Raucous Alarm measures 74 x 49mm and it accommodates all the components apart from the speaker and the Tempo (VR1) and Pitch (VR2) controls. Note that VR1 and VR2 could be wired directly onto the PC board as trimpots or you could substitute fixed resistors once you have determined the values you want. Construction is straightforward – just follow the wiring diagram of Fig.2 to assemble the board and wire the speaker, potentiometers VR1 & VR2, the (optional) pushbutton and the DC socket. Component values and types will make little difference, although ICs from Motorola (the MC14093BCP and MC14066BCP) are recommended. If a BUZ10 is unavailable, any rough equivalent Mosfet such as an MTP­3055 or IRF610 can be used instead. Semiconductors 1 4093 quad NAND Schmitt trigger (IC1) 1 4066 quad analog switch (IC2) 1 BUZ10 Mosfet (Q1) 1 1N4148 diode (D1) 1 1N4001 diode (D2) Capacitors 1 470µF 16VW PC electrolytic 1 22µF 16VW PC electrolytic 3 10µF 16VW PC electrolytic 1 0.1µF MKT polyester or monolithic 80  Silicon Chip TEST TEMPO PITCH SILICON CHIP www.siliconchip.com.au Resistors (0.25W, 5%) 1 330kΩ 2 100kΩ 1 220kΩ 2 22kΩ 1 180kΩ 2 10kΩ 1 120kΩ 1 5.6kΩ Begin by fitting the 10 PC pins, the nine wire links and then the resistors. Continue with the capacitors, diodes, Q1 and finally the CMOS ICs. You can use sockets for the ICs if you wish. Note that the Mosfet and ICs are static sensitive and require appropriate handling (discharge your body to earth before handling these). Our prototype was assembled into a plastic utility box measuring 148 x 80 x 50mm. This box comfortably accommodates the PC board, the small loudspeaker and the controls. If you are using the same approach, you will need to drill holes in the lid to mount the potentiometers and pushbutton switch (if used). At one end of the case you will need to drill a hole for the DC socket and finally, you will need holes in the base of the case for the loudspeaker, to let the sound out. The case can then be fitted with four adhesive rubber feet, so that the sound RAUCOUS ALARM Parts List Fig.4: this full-size artwork can be used as a drilling template for the front panel of the Raucous Alarm. www.siliconchip.com.au Our prototype alarm was housed in a plastic box with Tempo and Pitch controls but it does not need to be that complicated. 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 ! • • • can be clearly heard. Once the PC board is complete, check your work very care­fully, the connect the loudspeaker (solder pins G and H), push­button S1 (pins E and F) and the two potentiometers (pins A & B and C & D). Connect the DC socket to pins J & K, with its centre pin to positive (to pin I). If desired, an on-off switch can be inserted in the posi­tive supply line, or you can simply pull out the power plug when you wish to silence it. Using it No special setup is required for the Raucous Alarm. It is ready to go as soon as the power is plugged in. However, you might wish to begin as follows. First, turn the two front-panel potentiometers roughly to their mid-positions, then plug in a 12V 200mA (or greater) power supply. Note www.siliconchip.com.au that the centre pin must be positive, otherwise damage could result. If in doubt, check this with a multimeter before plugging it in. Now press pushbutton S1. Every press of the pushbutton should yield a different sequence of notes. Beware – the Raucous Alarm has an ear-piercing volume! If the unit does not function as described, unplug the power immediately and recheck the wiring. Most faults are missed solder joints, diodes in the wrong way or shorts due to solder splashes on the copper side of the PC board. Now experiment with front panel controls VR1 and VR2. VR1 adjusts the sound from a sedate to a lively warble, while VR2 alters the pitch of half of the notes, from sequences that sound something like standard scales, to much more varied arpeggios. SC • • • • • 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 Delivery 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 January 2002  81 PRODUCT SHOWCASE Boston Acoustics BA7500G Dolby Digital Speaker System Looking for a real bargain? This multimedia speaker system with built-in Dolby Digital (AC-3) surround decoding normally sells for more than $500 but Oatley Electronics have them for just $150! That’s a great price for a great set of speakers. If you really want to boost your PC gaming experience or gain greater enjoyment from DVD movies, you need a decent speaker system. And by “decent” we mean something with a subwoofer to give some real bass rumble and Dolby Digital decoding to give realistic surround sound. Originally made for Gateway, the Boston Acoustics BA7500G system provides true AC-3 Dolby Digital processing and outputs 5 channels of surround sound without requiring a separate amplifier in the back of each speaker to let you do this). One of the or decoder. It consists of three loudspeakers: a subwoofer stands includes the four volume controls: Master Volume, which also houses the Dolby Digital decoding circuitry Surround Volume, Surround Balance and Subwoofer. and analog power amplifiers, plus two flat-panel satellite Digital drive speakers. The rear satellite speakers are not included and will have Unlike the BA7500s, the BA7500Gs require a digital be purchased separately (but not from Oatley). signal input. This can come from the SPDIF output of your The subwoofer is housed in a cabinet measuring 299 x 178 soundcard or from the digital output of a standalone DVD x 372mm and features an 80mm (approx.) port in the front player. There are no analog inputs on the BA7500Gs, so if to augment the bass response. It uses a 165mm driver which your soundcard doesn’t have a digital output, you’ll have is claimed to have a -3dB response right down to 45Hz. to update. Inside the subwoofer, a single PC board accommodates Most decent soundcards now available, including recent the Dolby Digital decoding circuitry plus two 4 x 12W Soundblaster Live cards, will have a digital output, so there TDA8561Q power amplifier ICs. Our bet is that one IC are no worries on this score. Some computer CD-ROMs and provides 2 x 24W channels for the front speakers, while DVD-ROMs also feature a digital output. the other provides 2 x 12W channels for the (optional) rear If no Dolby encoding is present, the system is capable speakers and 1 x 24W bridged output for the subwoofer. of providing Virtual Dolby Surround sound. You can use No power output figures are specified for the amplifiers, this to enhance the sound from audio CDs if you wish. The although the maximum sound pressure level (SPL) is list- system is also fully compatible with 4-channel sound cards ed as 107dB. Suffice to say, lack of power output is not a (eg, for 4-channel games). problem with this system. Turn the volume right up after How do they sound? Well, they can really enhance your dark and the neigh­bours will call the cops - that’s if you enjoyment of DVD movies by providing realistic sound don’t mind putting up with the racket effects with tonnes of bass – just like Contact: before they arrive. you get at the movies. Oatley Electronics The two satellite speakers slide onto Admittedly, the BA7500Gs were PO Box 89, Oatley NSW 2223 neat little plastic stands to raise them originally designed to do with a PC but Ph: 02 9584 3563 Fax: 02 9484 3561 of the desktop surface but can also be they also make a great speaker system www.oatleyelectronics.com.au mounted on the walls (there are slots for your lounge room. Australia’s largest amateur radio & communications show next month February 24th is the date for the Central Coast Amateur Radio Club’s annual Field Day, which boasts to be the largest of its type in the Southern Hemisphere. More than 2000 people from 40 clubs and organisations will converge on Wyong Racecourse to view, participate in, listen to, buy, swap and sell all facets of amateur radio, 82  Silicon Chip CB radio, shortwave listening and scanning, computer communications, project building, vintage and historical displays and of course, the famous flea market, disposals areas (truckloads of pre-loved equipment!) and trade/ commercial shows. Throughout the day there will be seminars and workshops covering many interesting subjects. Some sites are still available – contact the organisers on 02 4340 2500 or via www.ccarc.org.au. Gates open an 8.30am. There is plenty of off-street parking inside the Wyong Showground and refreshments are available on site. Entrance is $10 for adults, $5 for students, pensioners & seniors, with children under 12 free. www.siliconchip.com.au Hard-to-get A/V cables, accessories and adaptors Jaycar Electronics has long been a source of unusual and hard-to-get audio/video cables, accessories and adaptors for the electronics enthusiast and the company has expanded its range. The Jaycar range includes adaptors, converters & joiners for almost any conversion imaginable including SCART to RCA, TOSLINK to OPTO 3.5mm, TOSLINK to S/PDIF CO-Axial and S-Video to RCA. Jaycar also carries a range of premium quality ready-made cables with gold-plated connectors and 100% shielded metal-body plugs. There are also twisted-pair audio cables that do not need to be shielded, perfect for up-market audio installations or anywhere a quality, durable, compact and attractive RCA cable is required. For more information, contact your nearest Jaycar store or visit the website. Contact: Jaycar Electronics PO Box 6424 Silverwater NSW 1811 Ph: 02 9741 8555 Fax: 02 9741 8500 Website: www.jaycar.com.au Vishay’s new Solid Niobium capacitors have “equivalent performance to tantalum” Described as a technology breakthrough by Vishay Inter-technology, the company’s research teams have created solid capacitors using niobium as the anode material. Niobium is lower in density than tantalum and is also more readily available but until now a number or technical challenges have prevented its use – among these susceptibility to thermal and electric shock during manufacture. The new capacitors are intended for filtering in mobile phones, PCs, DC-DC converter modules and a wide range of portable electronic systems. Voltage ratings are up to 10VDC with capacitance ranges from 10µF to 1000µF. Vishay components are distributed in Australia by Support Components Pty Ltd. Contact: Support Components Pty Ltd 1st Flr, 26 Danita Dve, Warrandyte Vic 3113 Ph: 03 9844 9022 Fax: 03 9844 0933 www.supportcomponents.com.au DECT cordless phones offer better clarity Digital Enhanced Cordless Technology, the communication standard in Europe, is now available in Australia with the introdcution of two new Uniden DECT phones by Dick Smith Electronics. Not only do DECT phones offer greater clarity, they are less prone to interference and unlike standard cordless phones, the call is secure. That is, it cannot be “eavesdropped” by anyone with a scanning receiver. There are two new models – the $228 Uniden 1811 DECT (pictured) is a 10-channel phone which offers 10 hours of talk time and 200 hours of battery stand-by time (before it needs recharging). It has the capability of having up to five additional handsets www.siliconchip.com.au connected to it. Calls can be transferred from handset to handset or it can be used as an intercom between handsets. Also available is the $298 DORO DECT 360 which has a large LCD display and caller ID built in, along with additional features. Up to six handsets can be connected on this model. TOROIDAL POWER TRANSFORMERS Manufactured in Australia Comprehensive data available Harbuch Electronics Pty Ltd 9/40 Leighton Pl. HORNSBY 2077 Ph (02) 9476-5854 Fx (02) 9476-3231 Broadcast quality PCI Audio Balancing Card Broadcast specialists, Perth-based Elan Audio have introduced this PCI format balancing board which interfaces PC sound cards to professional sound systems. The card is just one of the extensive range of broadcast and professional sound products from Elan Audio. Further details may be obtained from the company’s website. Contact: Elan Audio 2 Steel Crt, South Guilford WA 6055 Ph: 08 9277 3500 Fax: 08 9478 2266 Website: www.elan.com.au Contact: Dick Smith Electronics Ph: 02 9642 9100 Fax: 02 9642 9153 Website: www.dse.com.au January 2002  83 Silicon Chip Back Issues 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. April 1989: Auxiliary Brake Light Flasher; What You Need to Know About Capacitors; 32-Band Graphic Equaliser, Pt.2. Ultrasonic Switch For Mains Appliances; The Basics Of A/D & D/A Conversion; Plotting The Course Of Thunderstorms. May 1989: Build A Synthesised Tom-Tom; Biofeedback Monitor For Your PC; Simple Stub Filter For Suppressing TV Interference. 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. 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. 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. 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. October 1989: FM Radio Intercom For Motorbikes Pt.1; GaAsFet Preamplifier For Amateur TV; 2-Chip Portable AM Stereo Radio, 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. 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. March 1992: TV Transmitter For VHF VCRs; Thermostatic Switch For Car Radiator Fans; Coping With Damaged Computer Directories; Valve Substitution In Vintage Radios. 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. January 1990: High Quality Sine/Square Oscillator; Service Tips For Your VCR; Phone Patch For Radio Amateurs; Active Antenna Kit; Designing UHF Transmitter Stages. April 1992: IR Remote Control For Model Railroads; Differential Input Buffer For CROs; Understanding Computer Memory; Aligning Vintage Radio Receivers, Pt.1. 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. 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. 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. 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. 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. April 1990: Dual Tracking ±50V Power Supply; Voice-Operated Switch With Delayed Audio; 16-Channel Mixing Desk, Pt.3; Active CW Filter. 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. June 1990: Multi-Sector Home Burglar Alarm; Build A Low-Noise Universal Stereo Preamplifier; Load Protector For Power Supplies. March 1993: Solar Charger For 12V Batteries; Alarm-Triggered Security Camera; Reaction Trainer; Audio Mixer for Camcorders; A 24-Hour Sidereal Clock For Astronomers. 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. April 1993: Solar-Powered Electric Fence; Audio Power Meter; Three-Function Home Weather Station; 12VDC To 70VDC Converter; Digital Clock With Battery Back-Up. 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. June 1993: AM Radio Trainer, Pt.1; Remote Control For The Woofer Stopper; Digital Voltmeter For Cars; Windows-Based Logic Analyser. 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. 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. 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. 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). 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 TwoTone 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 In To Satellite TV, Pt.2. September 1991: Digital Altimeter For Gliders & Ultralights; 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. 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. 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 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. 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 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 Station; Build A Reliable Door Minder. 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 ___________ 84  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 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. 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. Lighting Pt.1. December 1997: Speed Alarm For Cars; 2-Axis Robot With Gripper; Stepper Motor Driver With Onboard Buffer; Power Supply For Stepper Motor Cards; Understanding Electric Lighting Pt.2; Index To Vol.10. January 1998: 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. November 1995: Mixture Display For Fuel Injected Cars; CB Trans­ verter For The 80M Amateur Band, Pt.1; PIR Movement Detector. 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. 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. 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. 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. 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. 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. 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. 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. July 1998: Troubleshooting Your PC, Pt.3; 15-W/Ch Class-A Audio Amplifier, Pt.1; Simple Charger For 6V & 12V SLA Batteries; Auto­matic Semiconductor Analyser; Understanding Electric Lighting, Pt.8. 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. 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. 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. 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. August 1996: Introduction to IGBTs; Electronic Starter For Fluores­ cent Lamps; VGA Oscilloscope, Pt.2; 350W Amplifier Module; Masthead Amplifier For TV & FM; Cathode Ray Oscilloscopes, Pt.4. 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. 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 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. 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. 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. 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. 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. 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. 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. 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. 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. 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? 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. 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. 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. 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. 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. 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. August 1999: Remote Modem Controller; Daytime Running Lights For Cars; Build A PC Monitor Checker; Switching Temperature Controller; XYZ Table With Stepper Motor Control, Pt.4; Electric Lighting, Pt.14. September 1999: Autonomouse The Robot, Pt.1; Voice Direct Speech Recognition Module; Digital Electrolytic Capacitance Meter; XYZ Table With Stepper Motor Control, Pt.5; Peltier-Powered Can Cooler. October 1999: Build The Railpower Model Train Controller, Pt.1; Semiconductor Curve Tracer; Autonomouse The Robot, Pt.2; XYZ Table With Stepper Motor Control, Pt.6; Introducing Home Theatre. November 1999: Setting Up An Email Server; Speed Alarm For Cars, Pt.1; LED Christmas Tree; Intercom Station Expander; Foldback Loudspeaker System; Railpower Model Train Controller, Pt.2. 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. 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. 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. 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. 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 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. www.siliconchip.com.au 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. 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. June 2000: Automatic Rain Gauge With Digital Readout; Parallel Port VHF FM Receiver; Li’l Powerhouse Switchmode Power Supply (1.23V to 40V) Pt.1; CD Compressor For Cars Or The Home. 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. 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-ToBuild 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. 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). 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. 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. 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. PLEASE NOTE: November 1987 to March 1989, June 1989, August 1989, December 1989, May 1990, December 1990, February 1991, April 1991, June 1991, August 1991, January 1992, February 1992, July 1992, August 1992, September 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. We can supply photostat copies (or tear sheets) from sold-out issues for $7.70 per article (includes p&p). When supplying photostat articles or back copies, we automatically supply any relevant notes & errata at no extra charge. A complete index to all articles published to date can be downloaded free from our web site: www.siliconchip.com.au January 2002  85 VINTAGE RADIO By RODNEY CHAMPNESS, VK3UG Philips Philetta & the Titan Tiny This month, we publish a few more details on the intri­guing Philips Philetta and take a close look at the Titan Tiny. The latter is a compact, hot-chassis set and is a real death­ trap for the unwary. The article on the Philips Philetta in the November 2000 issue sparked quite a bit of interest. In that article, I men­tioned that I had not seen the circuit of this intriguing little set and Ross Paton of Auckland, New Zealand kindly sent a copy of the circuit and much of the technical data as originally supplied by Philips. The circuit diagram covers both the B3D32A and B3D33A models – the only apparent difference is the cabinet style. It is interesting to see how the set achieved its various functions. As it turned out, my “guestimations” on how the set was engineered were quite close to the mark. It still pays to be cautious when making assumptions, though. For example, a number of radio manufacturers built generic sets for other companies. However, with a little experience, even an unlabelled set can often be identified – whether by the type of cabinet housing the set or how the chassis is wired or labelled. Getting back to the Philetta, Ross reports that this set is typical of the many small table radios made by Philips from the late 1950s through into the 1960s. In fact, many were brought to Aus­tralia and New Zealand during this period by migrants. According to Ross, the ECC85/6AQ8 RF amplifier valve is not particularly reliable in this set, as the valve is run with no high-tension voltage for lengthy periods when FM is not being received. This causes the cathode to become poisoned. If the 6AQ8 is unavailable, the 6BQ7A/ECC180 is worth considering as a re­placement. It is pin-for-pin compatible but its inter-electrode capacitance is different and this upsets the alignment which has to be tweaked. The various functions in the set are achieved by a large number of switch contacts and it is not a circuit that you can find your way around easily. On the other hand, it showed how a good-quality European set was put together. The Titan Tiny The Titan Tiny was a basic compact 4-valve receiver designed for the bottom end of the market. It was housed in a white bakelite cabinet and has just two controls: a handspan tuning knob and a combined on-off/volume control. 86  Silicon Chip Now we go from discussing a well-designed and reasonably sophisticated receiver to a set that was designed for the bottom end of the market. I was visiting Brian Lackie at Urunga on the north coast of NSW some time back and he showed me an intriguing little set called the Titan “Tiny” – and “tiny” it is. This set has yet to be restored, as can be seen from the various photographs. The front view shows a very plain small white Bake­ lite cabinet, with what appears to be a direct drive tuning control and an on/off switch/volume control (with its www.siliconchip.com.au Fig.1: the Titan Tiny is a 4-valve superhet design with inductance tuning. This is a “hot-chassis” set with one side of the mains directly connected to chassis (via a fuse) and the other side connected to chassis via a transformer winding. Hot-chassis sets are real deathtraps, since the metal chassis (and anything connected to it) can operate at 240VAC. knob missing) underneath. The tuning control is quite small, so tuning the set with its “hand span” type dial is a little tricky. The rear view of the set reveals a tightly-packed chassis. However, there is sufficient room to remove and replace the valves if necessary. The rear view also shows that the cabinet has a series of “slits” (near the power transformer) – these ensure that there is enough airflow to keep the temperature inside the set at a reasonable level. Also shown are the four mounting screw-holes (one in each corner) that are used to secure the back of the set. This partic­ular set is missing its back cover and that’s an extremely seri­ous safety issue, as will be explained later. What intrigued me was the size of the set and this can be gauged by comparing the chassis size with a ballpoint pen (see photo). However, despite its small size and the number of compon­ents used, the chassis isn’t too crowded and this makes it rela­ tively easy to service. Circuit details Fig.1 shows the circuit details of the Titan Tiny. It’s a conventional superhet www.siliconchip.com.au This front view of the Titan Tiny chassis clearly shows the induct­ ance tuning coils at the top. which uses a 6AN7 converter, a 6N8 IF amplifier and detector, and a 6M5 audio stage. The HT is recti­fied by the ubiquitous 6X4. At a quick glance, the converter stage appears normal and apparently uses capacitive tuning. However, close inspection reveals that this is not January 2002  87 Photo Gallery: AWA Radiola 80 TRF Receiver Manufactured by AWA in Sydney in 1930, the Radiola 80 featured a “coffin top” style cabinet and a matching loudspeaker in a separate cabinet. This set is a 6-valve TRF receiver and employed the following valve line-up: 3 x type 22 (1st RF amplifier, 2nd RF amplifier & detector), 2 x L410 (1st and 2nd audio) and P410 (audio output). (Photo and information courtesy Histor­ical Radio Society of Australia). true. T1 and T2 are not tuning capaci­ tors but are instead high-frequency (1600kHz) trimmers for the aerial and oscillator tuned circuits. However, the circuit sym­bols used here are for a normal tuning gang and would fool anyone who casually glanced at the circuit (other Titan circuits use rec­ ognised symbols for trimmer capacitors). Actually, this set is inductance tuned by sliding iron-dust cores inside the aerial and oscillator coils. If you carefully examine the photographs of the chassis, you can see the dial cord mechanism that’s used for sliding the cores in and out. Dial cord Behind the tuning knob, the dial cord is attached to a shaft in much the same way as in many Astor sets. One end then comes up to the top of the set and does a right angle turn around a dial cord pulley so that it runs parallel to a horizontal metal plate. As it progresses across the plate, an iron-dust core is attached to it at a strategic point and this is then threaded through one of the coils. The cord then continues WARNING! The Titan Tiny set featured in this article is a hot-chassis set, with one side of the 240VAC mains directly connected to chassis via a fuse and the other side connected to chassis via a trans­former winding. This means that the metal chassis itself and any parts connected to it could easily be operating at 240V AC and this applies even if the fuse (which is actually a dial lamp) blows. Under no circumstances should any part of a hot-chassis set be touched while it is plugged into the mains. Hot-chassis sets are extremely dangerous and should be left strictly alone unless you are very experienced and know exactly what you are doing. 88  Silicon Chip around another two pulleys and then traverses back across the plate and through the second coil (via another iron-dust core). Finally, the cord goes over another pulley and disappears down to the other side of the dial drive mechanism. It is a very simple version of the Astor tuning system but I don’t believe it is as good. Some other sets, such as the Barlow Wadley XCR30, also used ferrite or iron-dust cores attached to a dial cord for tuning. However, the Barlow Wadley uses just one core, a cam switch and three coils in line to tune the RF stage from 0.5-30MHz with 300° of control rotation. There is certainly nothing wrong with inductance tuning but getting it just right can sometimes be a problem. Adjusting the two tuned circuits does not appear to be a particularly easy job in the Titan Tiny. Theoretically, it would be possible to shift a slug along the dial cord or to shift the actual location of the coil for best alignment of the circuit. However, it appears to me that it was a once in a lifetime align­ment job although a determined restorer should be able to wring the last little bit of performance out of the set. Padder coil Most vintage radio restorers have become used to padders being either fixed or adjustable capacitors of around 400-450pF. There is no such thing in this set. If you believe the circuit notations implicitly, it has a padder coil across the oscillator coil. So how does this work? The inductance of the oscillator coil is less than the aerial coil in most domestic receivers. In this set, however, it appears that the oscillator and aerial coils are the same – both electrically and physically. By paralleling another inductance, the effective inductance of the oscillator coil is reduced to a value equivalent to what other sets use in this position. It also includes a conventional 350pF padder capacitor as well. The aerial coil has a capacitor to couple it to the aerial proper. This is a low value “gimmick” capacitor, which ensures that the aerial does not load the aerial tuned circuit to any degree. This receiver also includes bias and delayed AGC for the 6AN7 and 6N8 valves. This bias (about 0.8V) and www.siliconchip.com.au Looking for an old valve? or a new valve? 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 The parts were all tightly packed in, as this under-chassis view reveals. The lamp in the bottom lefthand corner served as the mains fuse – crude and potentially lethal for the inexperienced serviceman! delayed AGC is provided by a voltage divider consisting of 50kΩ and 4kΩ resis­tors from the oscillator’s grid. The audio output stage is a little strange in that the screen of the 6M5 appears to be operating almost in a starvation mode. Most receivers have the screen coming directly off the HT line at the junction of the 2kΩ resistor and the HT supply to the receiver RF stages. A real deathtrap We now come to the power supply. At first glance, and with­out the benefit of a circuit diagram, the Titan Tiny appears to be a conventional mains-operated set with a power transformer. Brian initially thought so and so did I but to Brian’s dismay, the mains apwww.siliconchip.com.au peared to have a short to the chassis. As a result, Brian cut the power lead off so that a deadly mistake wasn’t made later on when he was endeavouring to restore the set. Some time later, however, the circuit turned up in the AORSM Manual No.11 (1952) and this showed that the set is a “hot chassis” type. So how come it’s got a power transformer in it? Yes, it does have a transformer in it but it is still hot-chassis. In this set, the transformer only supplies the valve filaments and dial lamps. The HT is achieved by wiring the 6X4 as a half-wave rectifier, with one side of the mains connected to the plates via two 350Ω resistors (these limit the peak rectifier current through the 6X4). In addition, a .005µF capacitor (mains rated) is fitted to each plate to suppress interference on the mains. The Neutral (hopefully) side of the mains goes to the chas­sis via a fuse, which is actually another dial lamp. We now return to the missing back on this set. Without a back, this set would be lethal if it’s the mains Active (and not the Neutral) that’s connected directly via the fuse to the chas­sis. In other words, the chassis and much of the circuitry – including the dial lamps – would all be at 240VAC! It all depends on which way around the mains is connected. But here’s the rub – this set is still dangerous even if it’s the Neutral that’s connected to the chassis via the fuse. As shown on the circuit, the Active is connected to the chassis via the power transformer’s primary. This means that if the fuse blows, the chassis will be at nearly 240V! If that happens, you yourself could act as the fuse and have nearly 240V placed across your body if you touch­ ed the chassis and anything else that is earthed. What a lovely death trap! Back in the 1950s and earlier, the January 2002  89 This rear view shows how the major parts fit into the space. The dial-cord is connected to tuning slugs which slide backwards and forwards inside the tuning coils. safety of the user was not considered as important as it is now. To make matters worse, the knob was missing from the volume control on this set and the metal shaft was protruding through the cabinet. Later sets used recessed metal or plastic shafts so that the possibility of an electric shock or worse was eliminated. I don’t know what sort of back was originally attached to this set but I suspect that it was probably a thick cardboard type with perforations for ventilation. The circuit shows a line switch but Brian’s set has no such line switch. Perhaps it was removed A vital part is missing from this Titan Tiny and that's the back. During operation, the chassis could be at 240V AC and that make it potentially lethal. at some time in the past, when the back was lost? Restoring the set This little set isn’t up and running yet. It has obviously been serviced in the past, as some of the parts have been re­ placed with newer components. And with the replacement of a few critical components, there is no reason why this set should not perform quite reasonably. Tuning of the IF stages should not be a drama but the front-end circuits may prove a bit of a challenge. The Titan Tiny was obviously designed Photo Gallery: Healing Model 24 TRF Receiver The Healing Model 24 is a small wooden 3-valve receiver manufactured by A. G. Healing in 1934. The set uses the following valves: 57 detector, 2A5 output and 80 rectifier. (Photo and information courtesy of Historical Radio Society of Australia). 90  Silicon Chip for the lower end of the market, with a simple box-shaped cabinet, a tiny dial scale and no outstanding features to get excited about. But as a kitchen set in a metro­politan setting, it would have been quite adequate. The biggest black mark against it is the fact that it is a hot-chassis set. This makes it a real deathtrap for the inex­perienced serviceman – anyone touching the bare metal chassis or any other parts could easily be touching the mains Active, even if the fuse has blown! Hot-chassis sets need to be designed with great care if they are to be safe for use by the general public. Some manufacturers were quite conscientious in their endeavours to make their sets safe but others made apparently little effort by today’s standards. Warning label Would I be pleased to have one of these sets in my collec­tion? Yes, I would – not because I think it’s marvellous but because it’s an example of a very simple little set that achieves some things in interesting ways. I would restore it and make it as safe as I could and plaster a big label on the back warning that it is a hot-chassis set. And I would run it through a 1:1 ratio isolation transformer as an additional precaution. Finally, my thanks to the reader who pointed out the correct spelling for “mantel” in Mailbag for November 2001. Yes, mantel radios were deSC signed to sit on a mantelpiece. www.siliconchip.com.au 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 Measuring mobile phone radiation Have you ever done a project that measures the radiation from mobile phones/towers? (F. C., Kensington, NSW). • No we haven’t. You need a calibrated yagi or dipole together with a calibrated signal strength meter and possibly a spectrum analyser as well. It is not a simple measurement. A shocker of a question I have some questions relating to electric shock. Why don’t we feel any electric shock when we touch a 1.5V DC battery? Is it the current too small? Why don’t we feel any electric shock when we touch 12V DC car battery? Would we feel any electric shock when we touch a 240V DC battery? How does electric shock occur? Does it depend on the strength of the electric current and the conductivity of a human being? What is the minimum current that causes a tingling feel­ing? (K. W., via email). • The severity of electric shock is directly related to the current that flows. A few milliamps causes tingling while 10mA is quite severe and enough to kill a child in some instances. In normal circumstances you need more than about 40V to cause a shock or tingle but where you make really good contact (ie, with both hands moistened and around large metal contacts) you can get a substantial shock with as little as 12V. A 240V battery could easily kill you. Triac for darkroom timer ELAN Audio The Leading Australian Manufacturer of Professional Broadcast Audio Equipment Featured Product of the Month PC-BAL Back in April 1995 you published a circuit for a Darkroom Timer. I’m trying to find a replacement for the MAC­320A8PF Triac as this device is no longer available. Can you help? (B. W., via email). • Use the Philips BT137F (F stands for isolated tab). You can buy it from Jaycar. 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. Some motors don’t like low speeds I have only just read the “Ask Silicon Chip” section of the September 2001 issue. Regarding the ‘Power Rating For Speed Controller’ question, even though the speed controller may be suitable for continuous use, the motor concerned may object to being used at a reduced speed for a long period. Motors are designed to run at their rated speed, usually being cooled by their own internal fan. When they run at a re­duced speed the cooling airflow is reduced and they can overheat sometimes to the point of burnout. If the motor concerned is a fixed one And we sell AKG and Denon Professional Audio Products 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 it may be possible to install a separate cooling fan (eg, computer fan) to keep it within its rated temperature. I hope this information is of use. (B. A., via email). PARALLAX BS2-IC BASIC STAMP $112.00 INC GST WE STOCK THE COMPLETE DEVELOPMENT SYSTEM www.siliconchip.com.au January 2002  91 Extra inputs for AV distribution amplifier I would like be able to add additional (switchable) inputs to the Audio/Video Distribution Amplifier featured in the Novem­ber 2001 issue, to cope with the situation of say using separate­ly a cable TV box, two VCRs & DVD, feeding a TV, and also feeding the output ‘back’ to the VCR’s line-input for recording/dubbing, plus (sound) to a hifi system. This situation must be quite a usual setup in the home and would cope with recording the ‘input’ • You make a good point although it is one that we have cov­ ered before albeit not in the constructional article. World TV frequencies I need to know the actual TV transmitting frequencies (not channel numbers) for the TV systems in UAE and Saudi Arabia. I have searched high and low. Please help. (M. A., via email). • The ideal source for this info is the World Radio & TV Handbook. It is available from Dick Smith Electronics at $47.88; Cat B-2101. Video sharpening with Dr Video I’ve recently bought the kit for the Dr Video and have tried it out. Although the picture was pretty good, it was not quite as good as I would have liked it to be. In the kit instruc­tions it says: “by varying the 330Ω resistor up or down you can change the amount of device at any time whether the TV was on or off. Is it just a case of buying a video switch box to use before the distribution amplifier or is there a more elegant solution? Or has a project been designed for this purpose? (B. F., Brighton, Vic). • The best way is to use an AV switch box ahead of the distri­bution amplifier, as you suggest. Trying to build input source switching into the amp would be messy. A switch box should be fine. But note that the audio channel output resistors should be reduced from 47kΩ to 1kΩ or so. high frequency video boosting given by the Sharpen switch”. What would be the absolute maximum I should vary it or what is the next best resistor value to use? I also have the same questions about the 82pF capacitor. (P. B., via email). • The limit to video sharpening comes about when you observe more noise and graininess in the picture. So vary the resistor and capacitor with this fact in mind. Bigger lamp for rev limiter I have just purchased a kit for the Rev Limiter published in the April 1999 issue. I want to know if it is possible to replace the indicator lamps with relays to operate a much bigger indicator light, say a 21W bulb , as I run a racecar and want an indicator that I will notice. (T. M., via email) • You can replace each lamp with a 12V relay and a diode, with the anode to the transistor collector and cathode to 0V; ie, the diode is reverse-biased. Testing frequency response of speakers I’m trying to find out how to measure the frequency response of my speakers. Can you help me? (A. H., via email). • Measuring frequency response of speakers is not simple and you would be wise to refer to a textbook on this subject. For the simplest of tests, you will need an audio generator or a CD with test frequencies on it, a calibrated microphone and an AC millivoltmeter with a wide bandwidth. Radfax decoder software Can you please supply the software for the Radfax decoder featured in the November 1989 issue of SILICON CHIP? I have contacted the Author, Michael Delahunty, but he can no longer supply it, due to a past computer crash. (A. M., Reservoir, Vic). • We do not have the software either but perhaps a reader can send it to us, whereupon we will send it to the author (and to you). How to stop rust on camera screws I have a question that you may be able to answer. I have an older video camera that had a problem with the zoom motor. Minor problem, easy to fix, however, after removing the original fac­tory screws, and putting them back again, the screws have ‘oxi­dised’ and are starting to rust very quickly. I had the same problem with the internal mechanism screws of my VCR. Is this a tamper-proof feature? Is there any way to prevent the screws from going rusty? (A. P., via email). • Our guess is that the screws originally had some protective clear enamel 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 More current for white LED torch I recently purchased a kit for the 6 white-LED torch (pub­lished May 2001) from Dick Smith Electronics. I notice that the LEDs are rated for a continuous forward current of up to 30mA (and can tolerate spikes of up to 200mA for less than 10 micro­seconds) but that the circuit delivers 18.5mA. You say that in practice the current is slightly higher than this but you don’t specify by how much. Am I likely to destroy the LEDs if I replace the 27Ω resistors in series with the LEDs with 20Ω or 18Ω resis­tors, giving a current of 25mA and 28mA respectively to each LED? I would like to make the torch over them which you have disturbed, allowing corro­sion to proceed. Possible tip: put clear nail varnish over the screws that have been disturbed. Surround sound amplifiers I recently built the surround sound decoder and digital delay board from the May 1999 issue of “Electronics Australia” and would like to build suitable amplifiers for the centre and rear surround channels. The rear channel usually has two speakers in parallel which would result in a 4Ω load. My main amplifier is capable of 50 watts RMS per channel. Could you advise me of the power output required for the rear and centre channels that would be a suitable mix for my current main amplifier? (Y. C., via email). • Have a look at the 50W module described in the March 1994 issue of SILICON CHIP. Kits are available from DSE, Jaycar, etc. We can supply the March 1994 issue for $7.70, including postage. Glue gun temperature control I am using a 10W 240VAC glue gun to make candles and I find it gets far too hot for the wax I am using. What is the best way to control the temperature? (A. Q., Adelaide, SA). www.siliconchip.com.au as bright as possible but I do not want to put the LEDs in jeopardy. (S. H., via email). • We do not recommend driving the LEDs with more current than that afforded by the 27Ω resistors. This is because the turn on voltage for the LED could be lower than the typical 3.5V, causing a higher current flow. The only realistic way to measure and reset the LED current to a higher value is to measure the voltage across each resistor and the replace the resistor with a value which will provide the desired current. Also the inverter driving the LEDs is not suitable for driving all six LEDs at 30mA as it does not have this much power output. MicroZed Computers HAS MADE THESE NAMES FAMOUS IN AUSTRALIA micro Engineering Labs, Inc. NOW WE INTRODUCE • Have a look at the article entitled “Power Control With a Light Dimmer” in the October 1996 issue. Although this article described power control for soldering irons, the idea is equally applicable to glue guns. Leakage on engine immobiliser I am enquiring about the Engine Immobiliser described in the December 1998 issue. The immobiliser board has about 0.4MΩ across collector and ground of Q1 when in the idle state. This is enough to affect the points and not allow starting when the unit is not turned on. Everything works well with the overall kit and all is OK once the standing 12V is removed from the board. Is there a correction for this or do I need to look at my own handiwork? (B. M., via email). • Try shorting the base and emitter of Q1. If this eliminates the 0.4MΩ, it suggests that you may have leakage in the earlier stages or across the PC board itself. Notes & Errata LP Doctor, January 2001: in order to avoid residual mains voltage across the transformer when the power switch is off, the associated .01µF/250VAC capacitor should be reduced to SC .001µF/250VAC. Basic Micro offer ATOM: a Stamp2 lookalike with extended capabilities available in an IC or OEM format. A development board with sockets for IC and OEM version with a breadboard space instead of solder pads. Basic Micro also offer BASIC compilers, programmers and a range of development boards for 18, 28 and 40 pin PIC Chips. MicroZed Computers PO Box 634, Armidale, NSW 2350 (296 North Cooke’s Rd) Tel: (02) 6772 2777 Fax: (02) 6772 8987 Mob: 0438 277 634 http://www.microzed.com.au January 2002  93 MARKET CENTRE Cash in your surplus gear. Advertise it here in Silicon Chip. CLASSIFIED ADVERTISING RATES FOR SALE 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. DAY/NIGHT COLOUR Camera with IR LEDs SEE-in-the-DARK Water Resistant for disturbance-free Baby - Bird - Animal - Porch - Driveway surveillance from $265 * www.allthings.com.au _____________ _____________ _____________ _____________ _____________ PC CCTV Surveillance Digital-Video-Recording W98/ME/2000 Web-Cam Remote-View Dial-In Dial-Out Paging 768 x 576 Resolution software from $99 ! www.allthings.com.au 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 TELEPHONE EXCHANGE SIMULATOR: test equipment without the cost of telephone lines. Melb 9806 0110. http://www.alphalink.com.au/~zenere SPEAKER REPAIRS. New surrounds and voice coils. New and reconditioned speakers, boxes and kits. (03) 5986 1128, 0418 125367. HAVE A PCB, BUT NO SCHEMATIC? Provide us with a sample and we will supply you with schematics. www.elcomtel.com.au Ph (02) 9711 9523 VCR Controller use your home VCR to Record Events Wireless IR Learning Remote from $30 www.allthings.com.au TRANSMITTING COLOUR SECURITY CAMERA AND RECEIVER $NZ550, Video sender kit $NZ250, both 2.4GHz, 1km+ line of sight, Headset-vox, Bone-conduction mic. Lots more. www.amalgamate2000.com/sales GAFFA TAPE, Limited Stock Black or silver 25m rolls, $9.90 each; 3 or more rolls, $8.00 each OFC SPEAKER CABLE, Can sell by metre length but price will vary. 30 x 0.16 strand ............. $55.00/100m 105 x 0.12 strand ........... $88.00/100m 259 x 0.12 strand ......... $198.00/100m 413 x 0.12 strand ......... $330.00/100m Fig 8. 14 x 0.2 strand ..... $27.50/100m Fig 8. 24 x 0.2 strand ..... $49.50/100m Teknicolour Ph: (02) 8850 4960. www.siliconchip.com.au 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) 5968 4863; fax: (03) 5968 5810, PO Box 18, Emerald, Vic., 3782. ACN 006 399 480. 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 KITS KITS AND MORE KITS! Check ‘em out at www.ozitronics.com Need prototype PC boards? SEE-in-the-DARK Camera with IR LEDs Water Resistant Case for disturbance-free Baby - Bird - Animal - Porch observation from $147 * NEW Wireless Version available NOW ! * www.allthings.com.au 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 Satellite TV Reception 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. Mark22-SM Slimline Mini FM R/C Receiver • • • • • 6 Channels 10kHz frequency separation Size: 55 x 23 x 20mm Weight: 25gm Modular Construction Price: $A129.50 with crystal Electronics PO Box 580, Riverwood, NSW 2210. Ph/Fax (02) 9533 3517 email: youngbob<at>silvertone.com.au Website: www.silvertone.com.au and sale of new and used radio and communication equipment at Wyong Race Course, just 1 hour north from Sydney. Gates open 8.30 a.m. Special Field Day bargains from traders and tons of disposals gear in the flea market. Exhibits by clubs and groups with interests ranging from vintage radio, packet radio, scanning, amateur TV and satellite. www.ccarc.org.au Ph (02) 4340 2500. MINI Cameras with Microphone only $44 ! COLOUR only $79 ! www.allthings.com.au NEED A PCB FOR YOUR IDEA? Supply us with your schematic. We can design and supply you with a PCB. www.elcomtel.com.au Ph (02) 9711 9523 Audio, Video, S-Video and VGA cables distribution amps, switchers, adaptors, price lists at: www.questronix.com.au HOME SOHO PAKS DIY only ! $82 / $109 ! Mono / COLOUR Camera & MICROPHONE + Plug-In 20 metre AV Cable Set + Plug Pack ! www.allthings.com.au CENTRAL COAST FIELD DAY, SUNDAY 24TH FEBRUARY. Don’t miss Australia’s biggest and best exhibition VIDEO amplifiers, Stabilisers, TBCs, Converters, Mixers, etc. QUESTRONIX (02) 9477 3596. www.siliconchip.com.au New New New BIG CLOCK (Silicon Chip, 3/2001) and TELEPHONE CALL LOGGER (Silicon Chip, 12/2001) available from www.ozitronics.com or ring (03) 9434 3806. DIY CCTV PAKS 4 Cameras Mikes & Switcher..... $265 4 COLOUR & Switcher............... $385 4 Cameras Mikes & PC DVR...... $311 4 COLOUR & PC DVR............... $431 4 Cams Mikes & QUAD .............. $347 4 COLOUR & QUAD ................... $637 Time-Lapse 24 hr VCR only $449! DIY INSTALL-PAKS Plug-In Cables – Power Supply – etc www.allthings.com.au FM TRANSMITTER/MODULATOR(S) – DX Antenna Systems, rack mount, PLL front panel tuning, 87.6 – 108.0Mhz, output adjustable to +50dBmV – 75ohm. Stereo audio line inputs, -10 - +10dBm. Quality unit with lots of uses. $220. (02) 9913 8575, 0408 403159. SMD LEDs for your phone mods and components go to www.lazer.com.au ELECTRONICS MAGAZINES: EA, ET PW and PE from early 60’s to late 90’s, almost complete 0408 339410 or watgully<at>wizard.teksupport.net continued next page January 2002  95 G.S. & W.M. MILLAR ELECTRONICS SUPPORT SOLUTIONS Electro-mechanical/Electronic repairs, rebuilds, maintenance, calibrations etc. Quality service at your site/s or in our workshop. PH: 0416 278-775 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. NEED A SPARE WHICH IS NO LONGER AVAILABLE OR TOO EXPENSIVE? We can design and supply a replacement. www.elcomtel.com.au Ph (02) 9711 9523 USB KITS: DDS-HF Generator, 4-channel voltmeter, 1- relay card. Also digital oscilloscope and temperature loggers. http://www.ar.com.au/~softmark 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 DOME CCTV Cameras from $49 / $75 Mono / Colour www.allthings.com.au DESIGN DEADLINES? If you have more work than you can cope with, then we can assist you with the design. www.elcomtel.com.au Ph (02) 9711 9523 KITS-R-US 08-82703175 Advertising Index More at www.bettanet.net.au/GTD $2 PACKS Buy 10 packs, get the 11th one free #001 20 x quality USA nylon cable ties #002 10 x 14-pin IC sockets #003 20 x 16-pin dip 8 x 47k resistor array #004 20 x 7408 quad 2 input and gate #005 10 x 1.5uF 6VW SMD chip capacitor #006 10 x 0.47uF 20VW SMD chip capacitor #007 10 x 2.2uF 2VW SMD chip capacitor #008 2 x 8MHz ceralock for PIC CPU chips #009 4 x Murata UHF 3pF trimmer cap #010 2 metres 40-way IDC cable #011 2 x 52-pin PLCC IC sockets #012 6 x BF86 no brand RF transistors #013 40 x 1N4148 signal diode ($5/100) #014 2 x DB series connectors your choice of any 9 to 50 pin M/F plugs and sockets, limited stocks. Alltac International.......................57 Allthings Sales & Services..... 94-96 Aust. Microelect. Network.............19 Av-Comm Pty Ltd.........................95 Dick Smith Electronics........... 22-25 eLabtronics..................................83 Elan Audio....................................91 Evatco..........................................89 Grantronics..................................95 G.S. & W.M. Millar........................96 Harbuch Electronics.....................83 Hy-Q International........................57 Instant PCBs................................95 Jaycar ................................... 45-52 JED Microprocessors................5,57 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 WANTED BACK ISSUES SILICON CHIP: May 1990; June, August 1991; Feb, May, July, Nov, Dec 1992; Jan, May 1993; Feb, March 1996; March 1998; Feb 1999. Will pay reasonable price. Contact Alan (03) 9460 3091. PO Box 219, Reservoir 3073. WANTED: US ARMY VHF FM POWER AMPLIFIERS: AM-4306/GRC. For parts. T. R. Briggs, 9 Norfolk St, Perth, Tasmania 7300. Ph. (03) 6398 2118.  Each binder holds up to 14 issues  Heavy board covers with 2-tone green vinyl covering  SILICON CHIP logo printed in gold-coloured lettering on spine & cover Price: $A12.95 plus $A5.50 p&p each (Australia only; not available elsewhere). Buy five and get them postage free. Just fill in & mail the handy order form in this issue; or fax (02) 9979 6503; or ring (02) 9979 5644 & quote your credit card number. Kalex............................................81 MicroZed Computers..............43,57 Oatley Electronics........................73 Pavika Management....................39 Premier Batteries...........................4 Printed Electronics...................... 95 Quest Electronics.........................57 WANTED Silicon Chip Binders 96  Silicon Chip Altronics.......................Loose Insert REAL VALUE AT $12.95 PLUS P & P RCS Radio...................................95 RTN..............................................91 RF Probes....................................57 Robotic Education Products.........39 Silicon Chip Binders.....................96 Silicon Chip Bookshop........... 40-41 SC EFI Tech Special................OBC SC Electronics Testbench..........IBC Silicon Chip Subscriptions...........38 Silvertone Electronics..................95 Smart Fastchargers.....................81 Solar Flair/Ecowatch....................95 VAF Research....................... IFC,57 Wiltronics.....................3,9,37,57,91 _____________________________ 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