Light/Dark Detector

This handy little circuit can tell the difference between darkness and light, making it very useful for switching on and off signs, porch lights or other things when it gets dark or light.

Schematic for Light/Dark Detector


Part Total Qty. Description Substitutions
R1 1 100K Pot  
Q1 1 2N3904 NPN Transistor 2N2222
Q2 1 NPN Phototransistor  
RELAY 1 9V Relay  
MISC 1 Board, Wire, 9V Battery Snap (if battery used), Knob For R1  


1. R1 Adjusts sensitivity

Title: Light/Dark Detector
electronic circuit
Published on: 2005-02-10
Reads: 1351
Print version: Print version

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