Introduction: Automatic Street Light

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Automatic Street light turns on whenever there is insufficient light intensity & automatically turns OFF when there is enough light.

Step 1: Parts

You need 4 parts as listed below:-

1) Transistor 2N2222 ( A basic switching transistor)

2) 220 K LDR (Light Dependent Resistor)

3) Resistors 1.5k ohm & 220k ohm.

4) LED

Apart from this You need a GCB & a battery cap.

You can Buy these Parts from HERE !

Step 2: Circuit Diagram

Step 3: Working

The transistor 2N2222 is used here as switch. The transistor is voltage divider biased.

  • When the intensity of light is enough the resistance of the photoresistor is low therefor the current gets bypassed instead of going into the base of the transistor. Therefore the transistor turns OFF.
  • When the intensity is less the resistance of the photoresistor is high & so current starts flowing through the base & the transistor turns ON.

Step 4: Applications

The main aim behind making an automatic street light is to save the power. As the light turns ON & OFF according to the requirement it saves the power & also decreases our work.