Automatic Street light using LDR


We have faced many problems in our busy lives, so we forget to turn off lights such as street lights, outdoor lights, etc. They are still “ON” in the daytime, which seems to rise electric bills to make us in trouble, so here we get the solution to this problem.

Parts Required:

  1. ldr
  2. transistor type PNP bc557 or bc558
  3. relay 12vdc (SPDT)
  4. resistor R1=10k, R2=470R
  5. potentiometer 1M
  6. diode 1N4007 (flyback)
  7. 12v power supply
  8. small Vero board
  9. some connectors


All the above parts are 1 piece each required.


When it is dark, the resistance of LDR increases, and the transistor will turn on and the lights glow, In daylight resistance of LDR increases, and the transistor becomes turned off and the lights shut off.


Here, is a circuit diagram mentioned below:


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