Schematic Volt

Light Detector

This is a schema diagram of light detector. This schema can be used as a sensor of automatic lamp switch, thic schema also can be used for anti theft alarm schema.

Schematic diagram:

Use variable resistor R1 to adjust the light threshold at which the schema triggers. R1s value is chosen to match the photocells resistance at darkness. The schema uses a CMOS 4001 IC. Gate U1a acts as the trigger, U1b and c form a latch. S1 to reset the schema. You may used piezo buzzer or LED as output indicator, you may use both of them.