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Publisher & Editor-in-Chief Leo Simpson, B.Bus., FAICD Editor Greg Swain, B.Sc.(Hons.) Technical Staff John Clarke, B.E.(Elec.) Robert Flynn Rick Walters Reader Services Ann Jenkinson Advertising Manager Brendon Sheridan Phone (03) 9720 9198 Mobile 0416 009 217 Regular Contributors Brendan Akhurst Garry Cratt, VK2YBX Julian Edgar, Dip.T.(Sec.), B.Ed John Hill Mike Sheriff, B.Sc, VK2YFK Ross Tester 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: $54 per year in Australia. For overseas rates, see the subscription page in this issue. Editorial & advertising offices: Unit 34, 1-3 Jubilee Avenue, Warrie­ wood, NSW 2102. Postal address: PO Box 139, Collaroy Beach, NSW 2097. Phone (02) 9979 5644. Fax (02) 9979 6503. PUBLISHER'S LETTER Corrosion problems can be minimised Ever thought about corrosion and how much it costs you each year? Most people, when they think about corrosion, think about rust in their car and that is serious enough. After all, rust is the main reason why most cars are finally pensioned off, at least in those Australian states where annual registration inspections are required. But I am thinking of the problem of corrosion in electronic and electrical installations. Perhaps the most glaring of these are involved in domestic TV antenna installations. At one time, a TV antenna installation could be expected to last 20 years or more but with more people doing their own installations, the antenna life might only be a few years and that amounts to a big waste of time and money. A large part of the problem now is that fixtures and fit­tings which used to be hot dip galvanised are now very lightly zinc plated or worse, cadmium plated and passivated. Steel fit­tings that are zinc plated have a blue-white shiny appearance while those that a cad-plated and passivated have a yellowy golden appearance. Now while cadmium plated and passivated steel may be OK for the chassis of electrical equipment used indoors it is pretty useless outdoors. In coastal areas and areas with industrial fallout, such fittings will rust heavily within 12 months. Bright zinc plated fittings are not much better. The same can be said of screws, bolts and nuts which are zinc plated - they rust out quickly. This tendency to install cheap metal fittings is now very widespread, partly because many stores, particularly hardware stores and supermarkets, only stock the cheap rubbish. Have a look around your own home and where you work and note how many of the metal fixtures and fittings are rusting or corroded. You might be quite surprised at how things are deteriorating right before your eyes. Anodised or powder-coated aluminium fittings also often fare poorly in coastal districts and areas of high fallout and are also to be avoided. In the long run, it is much better to use steel fittings which are hot dip galvanised. And if you live within say, two or three kilometres of the coast, use only stainless steel. Stain­less steel hardware is a lot more expensive but you will never have to replace it. When you consider how much corrosion there is in all the buildings across Australia, the cost runs into bil­lions of dollars each year. With a little thought and slight extra initial cost, much of this can be avoided. Leo Simpson ISSN 1030-2662 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. 2  Silicon Chip