Penfold, RA Electronic Security Devices - BP56, 1979, 1982, 1983, 1985, and 1986 Bernard Babani Publishing Ltd Useful circuits - 4 stars Babani books were written for the British hobbyist - a high level of literacy and technical knowledge but no money - so the circuits are inexpensive but quite sophisticated. The circuits are usually well-designed and always work, provided you construct them properly*. "Security' is used here in its widest sense of "make me safe". The chapter headings provide a good summary of the contents 1.Switch activated burglar alarms - basic alarm, exit delay, entry delay and tone generators. 2.Other types of burglar alarms - infra-red, ultrasonic, Doppler, light activated and automatic light. 3.Other types of alarm - smoke, gas, water, high temperature, low temperature, baby alarm, door phone. All circuits and construction techniques are fully described and you could just sit down and build a working alarm straight from the book. Most of the components are still readily available or else substitutes are easy to obtain. The circuits are built on Veroboard and the layout descriptions are adequate if you are familiar with this type of construction but need explanation if you are not. The circuits are intended for the hobbyist and are not necessarily commercial quality. You may need to check with your insurer or local authorities before installing them. Babani books were meant to be an inexpensive resource so the paper and covers are cheap and the printing is not of good quality. The diagrams, however, are well drawn and helpful. The company still publishes books on computers but their numerous electronics titles are no longer published and are becoming harder to find. This has resulted in some books appearing on the second-hand market for extraordinary prices. Remember that these are small books 11 x 18cm usually about 100 pages on cheap paper and perfect bound (liable to fall apart unless handled correctly). *Why doesn't my circuit work? Here are my observations: 65% bad soldering, 12.5% wrong component in place, 12.5% right component but wrong way round, 8% design was OK but there was a problem with the wiring layout, 2% design problem,