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AUTOMATIC_LIGHT_CONTROLLER_FOR_CARPORT

2017-01-17 07:40  
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AUTOMATIC_LIGHT_CONTROLLER_FOR_CARPORT
A 555 timer IC, operating in the one-shot mode, is triggered by light striking photoresistors. These normally have a resistance of several megohms but, in the pres-ence of light, that resistance drops to several hundred ohms, permitting current from the six-volt source to flow in the circuit. The R-C combination shown gives an on-time of about two minutes. Photoresistors PC3 and PC4 are mounted at heatlight-height. When headlights illuminate the photoresistor, the timer starts. That actuates a relay, RY1, and the lights are turned on. The lights are automatically turned off when the timer's two minutes are up.