Circuits-Schematics.Com

Simple Night Light Circuit

(C) 2016 By: Circuits-Schematics.Com
Return To Our Master Circuits Menu
Simple Nite Light Circuit
About as simple as it gets! When daylight is detected, the LTR phototransistor turns on slightly, this turns on the first 2N3904, which pulls the base of the second 2N3904 to ground, and preventing the LEDs from turning on.

When it’s dark out, no current can flow through the phototransistor or the first 2N3904, which allows the base of the second 2N3904 to be pulled high through the 5 k transistor, which turns on the LEDs through the second transistor. Use a couple of small voltage LEDs for D1 and D2, your choice of colors.