This Circuit can compare the Light level in an area. It uses a PN Photodiode as the light sensor and IC CA3140 as voltage comparator. The circuit is ideal as the front end of burglar alarm circuits.

This file type includes high resolution graphics and schematics. Front-end limiter circuits using Schottky and PIN diodes can provide needed protection in communications and other RF systems. However, ...

This fire sensor circuit exploits the temperature sensing property of an ordinary signal diode IN 34 to detect heat from fire. At the moment it senses heat, a loud alarm simulating that of Fire ...