В книге содержится описание 110 схем электронных сигнализаций различного применения. Все конструкции, содержащиеся в книге были разработаны, собраны и проверены автором. This is the latest addition to the authors popular series of electronics project books. It brings together 110 useful alarm circuits of a variety of types to intrigue the amateur, the student and the engineer. Electronic alarms have a multitude of applications in the home, in industry and in the car. They can be designed to be activated by physical contact or proximity, by variations in light or heat levels, or by variations in voltage, current resistance or some other electrical property. They may give high-level audible outputs, as in the case of burglar alarms and car anti-theft alarms, or low-level visual outputs, as in the case of instrumentation alarms. The operating principle of each circuit in this book is explained in concise but comprehensive terms, and brief constructional notes are given where necessary. All the circuits have been designed, built and fully evaluated by the author. They are designed around a variety of types of readily available semiconductor devices of American manufacture.