Light sensor circuit diagrams

Dark-activated LED or Lamp Flasher

Simple photo-sensitive circuit. 3V battery supply

Laser Communication System

This is a simple Laser communication system. It can transmit and receive signal from any audio device.

Dark-activated 230V Lamp

Compact circuitry using small-size parts only Can be wired in parallel to existing switches

Dark Activated Switch

This circuit will activate a relay when light falls to a preset level. Light level can be adjusted with VR1 and the relay contacts may be used to operate an external light or buzzer.

Electronic Night Light

This circuit for an electronic night light was submitted by Adam from Canada.

Parking Light Switch

This is a simple parking light switch. The idea is that you drive your car towards your garage. You shine your headlights at the sensor, which switches on an external light . If you don't have a garage the sensor can be placed on a wall or post, and the external light will illuminate the area while you park and leave your vehicle. The circuit also has manual on and off controls.

Light Detector Circuit

The circuit uses a CMOS 4001 IC. Gate U1a acts as the trigger, U1b and c form a latch. S1 resets the circuit.

Push-bike Light

Automatic switch-on when it gets dark. 6V or 3V battery operation

Sound of Light Circuit

The circuit uses a solar cell as the input transducer, blocks the DC produced by the cell, but amplifies the light received by the cell. Sunlight, moonlight, torchlight all produce sound which is amplified by this circuit.