So load light (power LED light/ inverter) comes on, provided switch S1 or S2 is on. At the same time, due to higher voltage across LDR1, IRF640 triggers. So load (LED light/inverter) remains off.īut when the surrounding area of LDR1 (dusk mode) is dark (at night), resistance of LDR1 becomes very high, no current flows through LED1 and it does not glow. At the same time, due to low voltage across LDR1, MOSFET IRF640 does not trigger. With daylight falling on LDR1 (dawn mode), resistance of LDR1 becomes low, a small current flows through LED1 and it glows. The n-channel MOSFET IRF640 is for the switching action of the LED light or the small inverter connected to the system through switches S1 and S2, respectively. LDR1 is the main component for actuation of the dusk-to-dawn sensing. LED1 is used as circuit de-activation indicator. Resistors R1 and R2 are used as a voltage divider and a current limiter in the circuit, respectively. The 12V battery-operated circuit is designed such that the common battery supply is used for operating the circuit as well as for load, that is, for power LED/small inverter circuit.

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