Step 1: Components Needed
2. LDR (Light Dependent Resistor)
3. Relay 6 volt DC (SPDT)
4. Diode 1N4001
5. Resistor 1K and 330R
6. Transistor BC547 (2)
Step 2: Setting the Circuit
Connect 1K resistor with Vcc and another end with Collecter pin (i.e., 1st pin) of Transistor BC547.
Connect the Emitter pin (i.e., 3rd pin) of Transistor BC547 with Ground Voltage
Connect the Emitter pin with Ground Voltage
Step 5: Introducing Relay
Connect anode side of same Diode with Collecter pin of Transistor BC547.
Connect 'A' terminal of 6volt (SPDT) relay with Vcc and 'B' terminal with Diode's anode side.
Step 6: Setting the Bulb With Relay
Connect one wire with 'POLE' and another with 'NO' of the relay.
Step 7: Adding 6Volt DC
Don't switch on the circuit now.
Step 8: Adding 230 Volt AC
Connect the Bulb with the 230v AC.
Step 9: Its Ready Now...
If your circuit is in dark, the Bulb automatically lights
If your circuit is in light, the Bulb automatically switch to off.