How to design an Automatic Street Light using 555 Timer IC & LDR

Basically, Street lighting is a critical concern for public authorities in developing countries because of its existence for economic and social stability. Currently, a manual system is used where the light will be switched ON in the evening and switched OFF in the morning. Hence there is a lot of wastage of energy between the ON/OFF. This is one of the major causes of shifting to the automatic system since there is less wastage of power and thus saving a lot of monetary expenses. This proposed system is to design an Automatic Street Light control system using 555 Timer IC and LDR.

Automatic Street Light Using 555 timer IC

The Automatic street light control system is an amazing small project made up of only a few electronic components. You will learn how to create an automatic street light control system utilizing a 555 timer IC and an LDR in this project. This circuit can also be used in lawns and laser-based security systems. Before I explain the circuit, I’d like to clarify why we need this circuit and how this project works.


  • To avoid  unnecessary Waste of light
  • Provide efficient, automatic, and smart lighting systems.
  •  Totally  based on Renewable energy sources
  •  Longer life expectancy. Energy Saving.

Components Required 

The circuit is very simple and cheap as well. It can be implemented using the following components:

  • L.D.R (Light Dependent Resistor)
  • IC NE555 with Base
  • LED1 & LED 2 (Light Emitting Diode)
  • Variable Resistance of 47 KΩ
  • On/Off Switch
  • 9v Battery with strip
  • 47K Trimmer or Preset
  • 330E Resistor

Now assemble the given circuit below in zero PCB or Vero board as per the circuit diagram.

Circuit Diagram

Automatic Street Light using 555 timer circuit

Working of the Automatic Street Light using 555 Timer Circuit:

The value of a Light Dependent Resistor (LDR) is determined by the amount of light falling on it. When in total darkness, it has a resistance of nearly 1 megaohm, but when exposed to full brightness, it has a resistance of roughly 5k ohms. Pin 6 is connected to the positive terminal of the IC 555 timer, which is utilized to control the operations of the comparator circuit. When pin 2 (trigger pin) reaches one-third of the supply voltage, the output goes high. When the output exceeds one-third of the voltage, it also becomes low. The LDR is employed as a resistor to modify the circuit voltage for light detection.

The circuit is inexpensive and simple to construct. On a larger scale, the circuit can be utilized with a solar cell as an energy source during the day and a large light source during the night, with automatic operation replacing manual operation.

Automatic street light checking on Breadboard:

  • Checking all of the connections on the breadboard before starting the soldering 
Automatic Street Light

Initially, I used a 1k resistor to connect an LED directly to the output pin. By altering the light falling on the LDR, I was able to switch on and off the led. However, I am unable to modify the light sensitivity because I am using a set value resistor. I replaced the fixed value resistor with a variable resistor or potentiometer to control the sensitivity now.

Automatic Street Light
  • I was able to change the sensitivity after replacing the set value resistor with a potentiometer, and the circuit was even able to detect shadows at this stage. I opted to use a 2n2222 NPN transistor after everything was clear.
Automatic Street Light
  • To control this LED, I used a 2n2222 NPN transistor. This transistor can be used to operate a relay, which controls larger loads. After completing the basic tests, begin the soldering procedure.
Automatic Street Light

Based on the 555 timers and an LDR, this is a simple low-cost automatic street light controller circuit. Aside from street lights, this circuit can be used in any situation where you need to control something based on light.


I hope all of you have understood how to design an Automatic street light using 555 Timer and LDR. We MATHA ELECTRONICS will be back soon with more informative blogs.

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