Warning: Please be careful when experimenting or working on this circuit as the voltage in the circuit is 230V.
This is another automatic street light circuit; the circuit has some advantages over the previous circuit discussed here. Two of the things most if not all design engineers consider when designing are the cost and efficiency, this circuit has the two over the previous circuit. In addition to cost effectiveness and efficiency, it has another feature of being smaller in size as there is no bulky transformer in this circuit.
Automatic Street Light Circuit
The circuit is similar to dimmer circuit: it has radio interference filter circuit and triggering circuit which includes a x-rated capacitor C2, resistor R1, photocell and diac Q1. In the day, resistance of the photocell is low and the voltage across it is below the break-over voltage of the diac, so the triac can not be triggered at this time. In the night the resistance of the photocell will be at its maximum, and the voltage across it is well above the break-over voltage of the diac. This triggers the triac and current flows with full mains voltage supplied to the lamp.
Light dimmer circuit
1 step light dimmer circuit
Automatic street light circuit 1
Automatic street light circuit 2