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Publisher & Editor-in-Chief Leo Simpson, B.Bus. Editor Greg Swain, B.Sc.(Hons.) Technical Staff John Clarke, B.E.(Elec.) Robert Flynn Darren Yates, B.Sc. Reader Services Ann Jenkinson Sharon Macdonald Advertising Enquiries Leo Simpson Phone (02) 979 5644 Mobile phone (018) 28 5532 Regular Contributors Brendan Akhurst Garry Cratt, VK2YBX Marque Crozman, VK2ZLZ John Hill Jim Lawler, MTETIA Bryan Maher, M.E., B.Sc. 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) 979 5644. Fax (02) 979 6503. PUBLISHER'S LETTER Most security lighting is a waste of electricity Someone has to say it: most security lighting is a waste. It doesn’t stop burglaries and it wastes electricity. Anyone who drives or walks around the cities and suburbs at night must be aware of a huge farce: the booming growth of security lighting. Homes and factories are sprouting these lights which stay on for most of the night. Now what is the point of security lighting? It is supposed to stop burglaries isn’t it? Well, anyone who cares to look can see that most security lighting, particularly that around homes, would actually help rather than hinder a burglar. For a start, many people use their outside lighting when they are not at home. So straight away the potential burglar has a beacon to guide him to a likely prospect. Second, the lighting is usually aimed from the house out to the street and like as not, straight into the eyes of the neighbours. So the neighbours are dazzled if they actually do look across the street and could not see anybody breaking in. If security lighting was designed to enable burglars to be seen, it would be aimed at the house in question and project no glare at the likely observer. Nor would there be any deep shadows to provide cover for the burglar. That is almost impossible to achieve unless many lights are used and there is no shrubbery at all between the house and street. But the fact is that many, if not most, house break-ins occur during the day. Does this mean that security lighting is so effective that burglars now only work during the day? I hardly think so. But even if security lighting was shown to stop burglaries at night, you still have to ask, “Why have it on during all hours of darkness?” Not only does it waste electricity but it is incon­siderate to the neighbours who must now sleep with curtains drawn and so on. If you take a typical home security lighting setup, there will be a minimum of 300 watts of lighting and it will operate at least eight hours a night, every night of the year. On current Sydney Electricity domestic rates at 10.25 cents per kilowatt-hour, that will cost a minimum of $89 per annum. Yet by including a PIR (passive infrared) sensor to turn on the lights only when they are needed, that bill could be reduced to almost zero and cut out all the light pollution too. If you must have security lighting, the use of PIR sensors at least adds to the element of surprise to a burglar making an attempt on your prop­erty. In fact, just recently I had occasion to talk to an in­surance assessor about the best measures to reduce the possibili­ty of burglary. I asked him about such things as dial-back-to-base burglar alarms, security lighting (all of which our commer­cial premises have) and so on. His answer was simple: ensure you have good perimeter security (ie, locks on windows and doors). There is little else you can do against someone who is determined to be a thief. 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