Light Controlled LEDs

180

04:09:33

Two light controlled LED circuits. The potentiometers represent light dependant resistors. Lower their % setting to simulate the sun setting. When the LDR's resistance rises above 10k ohm (when it's dark) the LEDs will light. The one on the top right works best. Two transistors are used instead of one to amplify the signal from the voltage divider formed by the LDR and a resistor. Any tips on reducing the quiescent (off) current without reducing sensitivity appreciated. Tested IRL, 220k works better than 60k for the resistor. Using a 2n2222 for the PNP and an S9012 for the NPN. 

published 9 years ago

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