Saturday, July 25, 2009

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 ligh

Parts:


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


Notes:

1. R1 Adjusts sensitivity

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