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SILICON CHIP PUBUSHER'S LE'I-IER Publisher & Editor-In-Chief Leo Simpson, B.Bus. Editor Greg Swain, B.Sc.(Hons.) Technical Staff John Clarke, B.E.(Elec.) Robert Flynn Advertising Manager Paul Buchtmann · Lightning: more dangerous than you think Regular Contributors Neville Williams, FIREE, VK2XV Bryan. Maher, M.E. B.Sc. Jim Yalden, VK2YGY Garry Cratt, VK2YBX Jim Lawler, MTETIA John Hill David Whitby Photography Bob Donaldson Everyone acknowledges that lightning is spectacular and dangerous but during thunderstorms most people carry on their normal activities as if nothing is happening. Because our electricity supplies are so rarely interrupted during thunderstorms these days, because the lights rarely even flicker, we take it for granted that everything is as normal. But during an electrical storm everything is definitely not normal. The amount of energy released during a typical thunderstorm beggars the imagination. And there are indications that thunderstorms are becoming even more severe than used to be the case. If you talk to people in the power transmission or broadcasting industries they can tell lots of stories of installations which were designed to withstand severe lightning strikes and yet have been destroyed. The trouble is that not a lot is known about lightning - how it develops, where it might strike and what damage it might do. So even though electricity supplies and radio and TV broadcasts are rarely interrupted and the phone service keeps going, that is not to say they are not severely effected during thunderstorms. This is why we have published the article on the effects of lightning . on electronic appliances this month. It had become obvious to us that people just did not realise the risk to their appliapces, particularly those such as microwave ovens and VCRs. They are big casualties during thunderstorms. So turn 'em off and disconnect 'em during storms. Editorial Advisory Panel Philip Watson, MIREE, VK2ZPW Norman Marks Steve Payor, B.Sc., B.E. SILICON CHIP is published 12 times a year by Silicon Chip Publications Pty Ltd. All material copyright (c). No part of the contents of this publication may be reproduced without prior written consent of the publisher. Kitset suppliers may not photostat articles without written permission of the publisher. Typesetting/makeup: Magazine Printers Pty Ltd , Waterloo, NSW 2017 . Printing: Masterprint Pty Ltd, Dubbo, NSW 2830. Distribution: Network Distribution Company. Subscription rate: currently $42 per year ( 12 issues) inside Australia. For overseas rates, refer to the subscription page in this issue. Liability: 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. Address all mail to: Silicon Chip Publications Pty Ltd, PO Box 139, Collaroy Beach, NSW 2097 . Phone (02) 982 3935. ISSN 1030-2662 * Recommended and maximum Australian price only. 2 SILICON CHIP 1 Since this article was prepared the stories are now starting to come out about the large numbers of facsimile machines that were damaged during the' severe thunderstorms in Sydney during December. These stories reinforce the message. It seems that telephone lines are much more vulnerable to lightning induced voltage surges than are power lines. So if you have equipment connected to both the phone lines and mains supply it is doubly important that you disconnect it during thunderstorms . In fact, next time there is a severe electrical storm make sure that you do go around your household and disconnect all the appliances as suggested in this month's article. Then turn off your lights, go to the nearest window and look up at the sky. The electrical performance is likely to be far more spectacular than anything on TV at the same time. Leo Simpson