Automatic Street Light Circuit Diagram Project

A simple street light circuit is typically used to control the state of light. It can be further complex by adding various inputs, such as sensors for pedestrians and vehicles.

A basic circuit can be designed with just a few components. You can easily get a state machine’s circuit by implementing its logic using HDL, which is a hardware description language. One of the most important factors that will be considered is how the circuit should communicate with peripherals, such as traffic lights and sensors.

Street Light Schematic Circuit diagram

This diagram shows a street light circuit that can be used to automatically turn on and off its lights when the darkness falls and the sun rises. This type of circuit can also be used to create other automatic night lights.

Automatic street light circuit diagram
Automatic street light circuit diagram


  • Adjusting the circuit’s sensitivity can be accomplished through the use of POT R2.
  • You are free to use any wattage bulb you like; the only requirement is that the relay should have the appropriate rating.
  • A 9V DC power supply that has been regulated can be used to power the circuit.
  • A 9V SPDT relay can be used for the relay K1.

How does automatic street light work?

The light-detecting circuit uses a light-dependent resistor known as LDR. When there is light, the resistance of the LDR will be low, which will cause a significant loss in voltage. This turns on the transistor Q1. The light will not be turned on, and the relay and collector will be turned off.

When the light starts to fall, the LDR’s resistance rises, which lowers the voltage across POT R2. When darkness ends, the transistor Q1 is turned off, which turns ON the relay and the bulb will start to glow.

Some street lights are known to automatically switch on and off their lights at night and in the morning. These lights are powered by photoresistors or light-dependent RDRs, which sense the sunlight and adjust the state of light according to its environment.

These lights are powered by photoresistors or light-dependent RDRs, which sense the sunlight and adjust the state of light according to its environment. The LDR senses the light’s resemblance to our eyes and automatically switches off the lights when the sunlight hits our eyes.

What are the disadvantages of automatic street light?

Additionally, there are some drawbacks to automatic street lights.

  • The initial cost of an automatic street light system is higher than that of a regular street light.
  • The weather has everything to do with how much energy a solar street light can make.
  • The automatic street light system is more likely to be stolen because it is not wired and costs a lot.
  • Automatic street lights need to have their rechargeable batteries changed a few times.
  • Snow, dust, or moisture can build up on PV panels, which can stop them from making energy.

The light from nearby buildings, shops, industry, and housing can be used to trigger automatic street lights. If the lights are not activated by a photo sensor, then a timer is required to keep track of the seasonal variations of the light.

The installation of automatic street lights has probably led to the reduction of the number of people needed to maintain the lights.It will take longer to get a failed street light replaced if it is automated.