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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 Christopher Wilson Phone (02) 9979 5644 Mobile 0419 23 9375 Regular Contributors Brendan Akhurst Garry Cratt, VK2YBX Julian Edgar, Dip.T.(Sec.), B.Ed John Hill 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: $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 On the track of lightning Every year at about this time thunderstorms and lightning become an important part of the weather. This applies no matter where you live in Australia although in some parts the storms are often a great deal more severe. In the tropical north, thunder­storms during the “Wet” are an almost daily occurrence while in the more temperate southern regions, thunderstorms invariably sweep in from a particular direction and can cause a great deal of damage. Many people, those who would rather watch television than go outside to see what the weather is like, are blissfully una­ware of the forces unleashed in a large thunderstorm. Others, much fewer in number, are greatly in awe of the almost mind-numbing energy being released and the ways in which it happens. Think about it for a while. A big band of thunderstorm cells can originate as far north as the Kimberleys and then will move southwest in a period of 24 hours or so. It will move into northern NSW, pass over Dubbo or thereabouts and continue on to lash Sydney or the Gosford region. A day or so later, its rem­nants can be seen in the evening, far out in the Tasman, still active with lightning, thunder and lots of rain. To try and comprehend how much energy has been released during such a period of thunderstorms is impossible. Not only may millions of tonnes of rainfall have been dumped over several states with widespread flooding, but fierce winds may have caused further damage, unroofing buildings and downing trees. Lastly, there is perhaps the most fearsome aspect, the lightning. This may have run at several thousand strikes an hour over a front which may be a hundred kilometres wide or more. The total energy release may easily be equivalent to several 100 megaton bombs. These thoughts have been triggered by our feature article this month on the subject of tracking thunderstorms, beginning on page 4. Even while this article was being written, we experienced several severe thunderstorms, a timely reminder that summer is with us again. So read the article and enjoy it. And next time a thunder­storm passes over your area think of the forces involved. Think about protecting all your electrical and electronic gear too - the only sure way to so is to disconnect it while ever the storm is in progress. And if the time between lightning strike and thunderclap is three seconds or less, the lightning is directly overhead! Lastly, if a thunderstorm is in progress, stay off the telephone – the next victim could be you! 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