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 “Super Light Sensor” responds to minute fluctuations in light level, auto-adjusting over the range from about 200 lux up to 60,000 lux (ie, from a modestly lit room to direct sunlight). It has ...

The battery-powered device detects movement in front of the window using radar technology and begins to flash visibly through ...