This book does not go into the theory behind any of the sensors shown, nor does it go into any of the theory behind the electronic and optoelectronic parts required to build any of the circuits shown. It is basically just a library of different kinds of alarm circuits complete with theory of operation and parts list for each circuit. The reader should therefore already be familiar with the basic techniques of designing circuits that include discrete electronic parts such as LED’s and BJT’s.

It is a useful book of ideas if you are looking for a complete description of an alarm circuit that you can use for a larger circuit you are building. I cannot vouch for the overall accuracy of the book’s circuits, but I have built about five of the circuits included in this book over the last two years, and they all worked OK without modification. The book is unique in that it shows you detailed circuit diagrams and parts lists for detecting humidity, earth movement, twilight, smoke, and fluids. It is relatively short at under 300 pages, but at its low price I consider it a bargain if you think you will ever be faced with designing any kind of alarm circuit. If you want to get more into the theory of the sensors that are showcased here, might I recommend Jacob Fraden’s “Handbook of Modern Sensors”, since it is heavy on theory and lighter on circuitry, making it the perfect companion for this book.