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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.) Robert Flynn Ross Tester Rick Walters Reader Services Ann Jenkinson Advertising Manager Brendon Sheridan Phone (03) 9720 9198 Mobile 0416 009 217 Regular Contributors Brendan Akhurst Rodney Champness Garry Cratt, VK2YBX 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. A.C.N. 003 205 490. All material copyright ©. No part of this publication may be reproduced without the written consent of the publisher. Printing: Macquarie Print, Dubbo, NSW. Distribution: Network Distribution Company. Subscription rates: $59 per year in Australia. For overseas rates, see the subscription page in this issue. Editorial & advertising offices: Unit 8, 101 Darley St, Mona Vale, NSW 2103. Postal address: PO Box 139, Collaroy Beach, NSW 2097. Phone (02) 9979 5644. Fax (02) 9979 6503. E-mail: silchip<at>siliconchip.com.au ISSN 1030-2662 and maximum * Recommended price only. 2  Silicon Chip Making do with old computers This month we feature an article on making use of a stan­dard computer power supply. There is a dearth of information on this subject and circuits for these power supplies are about as rare as copper oxide rectifiers, so all the information in the article has been gleaned from physical examination of a range of these supplies. As this stage though, we know next to nothing about their over-voltage and over-current protection and a host of other details. So having produced the power supply article this month, we would have liked to take the subject much further and at some stage in the future we hope to do so, as we obtain more detailed information. For example, wouldn’t it be a great idea if we could turn a standard 250W or 300W power supply into something really useful – like having it power a big audio amplifier. Such a modification would not be simple though. The trans­former would have to be rewound and we’re not sure how much trouble that would involve since we understand that some of these transformers are wound with Litz wire (multi-strand wire with each strand separately insulated). The fast recovery rectifiers and filter components would also have to be upgraded but the end result would be very compact and efficient. Such a 300W switchmode power supply would cost only a frac­tion of a conventional power supply with its large power trans­former and expensive electrolytic filter capacitors. And it would have the advantage of an inbuilt fan to possibly provide cooling for the amplifier as well. If you happen to have done this sort of conversion, we’d like to hear from you. There must be a lot of other opportunities to make use of existing consumer electronics technology which might otherwise go to the tip. Some examples might be as simple using a defunct VCR as a TV tuner, using a dot matrix printer as a scanner or maybe using a VCR as a 7-day programmable timer/controller. How about uses for a defunct microwave oven? There’s all that hardware and a big (dangerous) power supply; it must have some use when the magnetron or other key component fails. Again, maybe it could be used as fancy timer. What about some wilder suggestions? Could the transport mechanism of a defunct CD player or CD-ROM drive be used as a slow motion drive for a working model on a model railway layout? Consider that there are several drive systems employed here, for the drawer, for laser tracking and for focusing. Could the turnt­able drive in a microwave oven be put to a similar use? It’s amazing just how many motors and drive systems are employed in modern consumer gear – how can they be used when the appliance fails? Why not tell us your ideas for using defunct consumer ap­pliances? Perhaps we can publish a few articles along these lines and thereby do our bit to slow the waste of good resources. Leo Simpson