Street light control circuit four

The circuit is simple and uses a capacitor to step
down and then stabilize the voltage to provide working power for the trigger circuit. When it is dark, the resistance of
    the photoresistor RG is very large, the transistor VT is turned on, the triac V is triggered and turned on, the relay KA is closed, and the street light is lit. Adjusting the resistance of resistor Ri can change the action brightness setting value (ie, the sensitivity of the device).