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SILICON CHIP www.siliconchip.com.au Publisher & Editor-in-Chief Leo Simpson, B.Bus., FAICD Production Manager Greg Swain, B.Sc.(Hons.) Technical Editor Peter Smith Technical Staff John Clarke, B.E.(Elec.) Ross Tester Jim Rowe, B.A., B.Sc, VK2ZLO Reader Services Ann Jenkinson Advertising Enquiries Lawrence Smith Benedictus Smith Pty Ltd Phone (02) 9211 8035 Fax: (02) 9211 0068 lawrence<at>benedictus-smith.com Publisher’s Letter Reader feedback is welcome This month, as in all months, we have some very good letters from readers, on a diverse range of topics. As you will see in the Mailbag pages starting on page 4, some are very complimentary and others, well . . . you can see for yourself. In particular, my answer to David Millist last month on the topic of current transformers brought forth a torrent of letters, both by email and by post. David Millist can take a bow because all the letters rushed to his defence. I must admit to being taken aback by the vehemence of some of the letters – we have only included a selection – and I thought “Oh dear, what have we unleashed this time?” As I went through the letters and talked to a few older readers, I realised that in stating that we failed to see how a current transformer can generate lethal voltages, I had completely overlooked the common type of current transformers widely used in power distribution systems. If an open-circuit occurs in the secondary winding, such transformers can be very dangerous indeed. Regular Contributors Brendan Akhurst Rodney Champness, VK3UG Julian Edgar, Dip.T.(Sec.), B.Ed, Grad.Dip.Jnl Mike Sheriff, B.Sc, VK2YFK Stan Swan And of course, after we ran a few current monitoring lashups, I had to admit an error in the operation of toroids. Expletive deleted. 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. I particularly like the fact that so many readers comment on the answers in “Ask SILICON CHIP”. Readers enjoy most sections of the magazine, but “Ask SILICON CHIP” consistently generates far more correspondence than any other section, both in questions asked and comments on the resulting answers. Printing: Hannanprint, Noble Park, Victoria. Distribution: Network Distribution Company. Subscription rates: $83.00 per year in Australia. For overseas rates, see the subscription page in this issue. Editorial office: 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 On reflection, I realise that such rapid feedback from readers, immediately after an issue has gone on sale, is a good thing. Many thousands of readers take SILICON CHIP very seriously indeed and are anxious that we continue to maintain a high standard. We like getting the compliments and therefore we must also accept the criticisms when they come. We have always known that our readers are vigilant, which is why I hate it when errors do appear in the magazine. That is one of the drawbacks of a print magazine – when an error occurs, it is there for all time. We can and do publish Notes & Errata but the error still remains on the printed pages. An on-line publication is different; if an error occurs, you can do a quick up-load and presto, it might never have happened. But our long-term destiny appears to be with the print magazine. While the on-line version of SILICON CHIP is popular with many people, the vast majority appear to favour the printed edition. It is so much easier to read, to digest and refer back to, and to spot those loathsome errors! Leo Simpson ISSN 1030-2662 * Recommended and maximum price only. 2  Silicon Chip siliconchip.com.au