Fullscreen HTML5Med Res (??MB)HTML4

Publisher & Editor-in-Chief Leo Simpson, B.Bus. Editor Greg Swain, B.Sc.(Hons.) Technical Staff John Clarke, B.E.(Elec.) Robert Flynn Rick Walters Reader Services Ann Jenkinson Advertising Enquiries Leo Simpson Phone (02) 9979 5644 Regular Contributors Brendan Akhurst Garry Cratt, VK2YBX Marque Crozman, VK2ZLZ Julian Edgar, Dip.T.(Sec.), B.Ed John Hill Jim Lawler, MTETIA Philip Watson, MIREE, VK2ZPW Jim Yalden, VK2YGY Bob Young Photography Stuart Bryce 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: $49 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 Smoke detectors are not a health hazard This month’s topic is prompted by our publication in this issue of a Geiger counter. This itself was prompted by the French, scheduling nuclear tests in the Pacific. Now let me say, at the outset, that I don’t believe that Australia will experi­ence any increase in radiation because of these tests, either now or in the future. We are too far away for that to happen. That does not justify the tests though – nothing can. Australia is right to protest loud and long about the tests, if only to pro­tect the rights of the small nations in the Pacific. But to get to the topic which was prompted by the Geiger counter – smoke detectors. As part of the article on the Geiger counter we have suggested that readers can partly dismantle a smoke detector to expose the radioactive source within. No doubt there will be some readers who will be upset at this but what we are proposing is perfectly safe. Sure, if someone decides to be stupid and eats the minute amount of Americium 241, they will probably die in the fullness of time. I am sure that the vast majority of readers would agree that smoke detectors present no hazard at all but would you believe that the NSW Environmental Protection Authority is really worried about them. Their scenario goes like this: now that governments have made it mandatory for all new houses to have smoke detectors installed, millions of these devices will eventu­ally be thrown out and will end up in landfill and thereby con­stitute a future hazard. The EPA therefore wants all smoke detec­tors to be returned to the manufacturers when they are ultimately disposed of. Now a few moment’s thought will show that this is yet another example of rampant bureaucracy. Let’s say that a million smoke detectors all ended up dumped in the same landfill in 20 years time. Americium 241 has a half-life of 400 years, so the alpha source will have barely deteriorated at all. So each smoke detector contains 0.9 microcu­ries and they constitute a total radioactive deposit of 0.9 curies and therefore could constitute a danger to the environ­ment! Clearly, this is utter nonsense. The same landfill would also contain several million tonnes of other garbage and there­fore the radioactivity of the whole dump would be no more than the rest of the landscape. The garbage would “dilute” the radio­activity. And any runoff from the landfill would no doubt contain far more lethal chemicals than Americium 241. The very concept of returning smoke detectors to the manu­facturers is crazy. These devices can presently be purchased at around $8.00 from large retailers like Woolworths. At that price, today’s manufacturers (in Asia, of course) are not likely to be able to afford to recycle millions of dud smoke detectors. The big advantage of smoke detectors is that they can save lives. Let’s not complicate their use by requiring that they must be returned for recycling at some time in the future. 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