Updated due to the relay I had is having about 1K ohm resistance, so I had to change the value of the resistor before the zener diode. Replace potentiometer with 500K LDR, R 1K is a 12V relay, Caution! This circuit is designed to work without using a step-down transformer, be extremely careful when you work with 220V AC voltage!!! Relay will be ON/OFF if LDR resistance is raised/drop between 60–70%. Lamp is just to indicate the relay is on or off, lamp to be controlled should be connected to the relay's switch(es)
