Automatic Street Light Control System using 555 Timer IC & LDR

(Last Updated On: July 6, 2020)

Automatic Street Light


Automatic Street Light control system using 555 Timer IC- The Automatic street light control system is seriously an amazing project and no doubt this is one of my favorite projects. This is a very small project build around a few electronic components. In this project, you will learn how to make an automatic street light control system using 555 timer IC and an LDR. You can also use this circuit in lawns and in laser-based security systems. Before, I am going to explain the circuit; first, I would like to explain why we need this circuit in the first place and how this project works.

In my previous tutorial, I explained everything about the 555 timer IC including the pinout, basic working principle of the 555 timer IC, different modes of operation, Monostable, Astable, and Bistable. So, if you have never used the 555 Timer IC, then I highly recommend first watch my previous tutorial and then you can resume from here.

555 Timer Tutorials:



Note: In this project, 220Vac is used to power up the AC light Bulb. Use protective gloves, because such a high voltage can be lethal. Make it at your own risk.

For the step by step explanation of the Automatic Street Light control system, you can watch video given at the end of this article.

Without any further delay, let’s get started!!!

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555 Timer IC:
556 Dual Timer IC:
LDR” Light Dependent Resistor”:

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Automatic Street Light

A lot of electricity is wasted when there is no automatic switching.

Automatic Street Light

The lights remain ON in the morning because there is no one to switch off the street lights or lawn lights. This results in increased bills and wastes a lot of electricity.

For such a small project, it’s not practical to use the Arduino board. Such a simple task can be accomplished by using the 555 timer IC. This way, we can keep the project overall cost low.

Automatic Street Light Circuit Diagram explanation:

Automatic Street Light

As per the datasheet, the supply voltage Vcc can be up to 16 Volts. But I will be using 12 volts to power up the 555 Timer IC as a 12-volt adaptor can be easily arranged. J1 is the female power jack and this is where we can connect a battery, Solar Panel, and a 12 Volt adaptor. As you can see this power supply is based on the LM7812 voltage regulator. A 470uf capacitor is connected to the output of the regulator.

At the output of the 555 timer IC, an LED is connected which you can replace with a relay to control higher AC/DC loads. An LDR “light dependent resistor” is connected in series with a 10k variable resistor or potentiometer. The advantage of using the variable resistor is that we can adjust the light sensitivity by rotating the knob of the variable resistor. The LDR and the variable resistor make a voltage divider. A wire from the middle of this voltage divider is connected with the Trigger pin of the 555 Timer IC. The voltage on the Trigger pin varies as the light intensity changes. Let me explain in detail how the Automatic street light control system works.

The voltage on the trigger pin of the IC “which is the inverting input of the comparator” which is coming from the voltage divider “formed by the LDR and variable resistor” is compared with the voltage available on the non-inverting input of the comparator which 1/3 of the Vcc. So, when the voltage available on the non-inverting input is greater than the voltage available on the inverting input of the comparator, the output will be 1, which is given as the input to the S pin of the Flip Flop which is converted into 0. The output stage has an inverter that converts 0 into 1. So the output of the 555 timer IC will be high.

Now let’s say if the voltage coming from the voltage divider circuit formed by the LDR and a variable resistor is greater than the voltage available on the non-inverting input of the voltage comparator, the output of the comparator will be 0 which is converted into 1 by the Flip Flop and is again converted into 0 by the output stage. So, the output of the 555 timer IC will be Low.

As you can see the Threshold pin is connected with the 12 volts. So the output of the first comparator will always be high.

So in this project, the output of the 555 timer IC entirely depends on the voltage available on the trigger pin which is coming from the LDR circuit.

Now let’s check this circuit in the Proteus Simulation Software.

Proteus Simulation of the Automatic Street Light Control System:

Automatic Street Light

Download automatic street lights Proteus simulation: simulation

When the darkness is detected by the LDR, the 555 timer turns on the street lights or lawn lights. The circuit should be placed in the area where the street lights never fall on the LDR. In the morning when the Sunlight falls on the LDR the street lights are automatically turned OFF.

The simulation worked perfectly, the LED can be turned ON and turned OFF, you can watch this in action in the video given at the end. Before I am going to start the soldering, first I am going to check this on the Breadboard.

Automatic street light checking on Breadboard:

It’s a good designing practice to check all the connections on the breadboard before, you start the soldering.

Automatic Street Light

Initially, I connected an LED directly with the output pin through a 1k resistor. I successfully turned ON and turned OFF the led by changing the light falling on the LDR. But as I am using a fixed value resistor that’s why I am not able to adjust the light sensitivity. Now, to control the sensitivity, I replaced the fixed value resistor with a variable resistor or potentiometer.

Automatic Street Light


After, replacing the fixed value resistor with a potentiometer, I was able to adjust the sensitivity, and at this point the circuit was even able to detect the shadows. After everything was clear, then I decided to use a 2n2222 NPN transistor.

Automatic Street Light

This time I used 2n2222 NPN transistor to control this LED. This transistor can be used to control a relay which can be used to control higher loads. After performing the basic testing and once I was completely satisfied then I started the soldering processing which you can watch in the video given at the end of this article.

Automatic Street Light

This is a small low-cost automatic street light controller circuit based on the 555 timer and an LDR. Apart from the street lights, this circuit can be used in areas where you need to control anything on the light basis.

So many other projects can be built using the 555 Timer IC. I will try to add more projects based on the 555 Timer. I hope this tutorial helps you. If you have any suggestions or questions let me know in a comment.

Watch Video Tutorial:


Related Projects:

555 Timer IC:

555 Timer IC Working, Pin Diagram, Examples (Astable, Monostable, Bistable)


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About the Author: Engr Fahad

My name is Shahzada Fahad and I am an Electrical Engineer. I have been doing Job in UAE as a site engineer in an Electrical Construction Company. Currently, I am running my own YouTube channel "Electronic Clinic", and managing this Website. My Hobbies are * Watching Movies * Music * Martial Arts * Photography * Travelling * Make Sketches and so on...

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