square wave generator

555 Timer Square Wave Generator | Astable Multivibrator

555 IC Project


Hey geeks, hope you are doing fine. Do you know how a 555 timer ic will work in astable mode?

well if not then don’t worry we are here for you. In this article, we are going to make a square wave generator using the astable mode of a 555 timer ic.

Both the states in the astable mode are unstable so the output continuously changes between these two states. Mostly 555 timer ic in the astable mode are used in the making of the oscillators (relaxation oscillators).

We will see the transition in the output due to the charging and discharging of the capacitor. You can also check the projects on Arduino and IoT. So let’s begin.

square wave generator

Working of the Square Wave Generator

square wave generator
  • Let’s talk about the internal structure of the 555 timer ic, so there are two comparators and a flip flop inside it which are responsible for generating the output.
  • The comparators generate the logic signals as per the voltage of the charging and discharging of the capacitor and the supply voltage. At the output, we are receiving a square wave.
  • The duty cycle of the square wave will depend on the resistors used in the circuit.
  • We have connected an LED at the output pins of the 555 timer ic. Connect a 5 volts dc supply to the negative and positive rails of the breadboard.
  • You can connect an LED, a speaker, or a CRO at the output pins. We are using an LED in this project.  

You can also check out the electronic mosquito killer using 555 ic made by us.

Components Required

components required for square wave generate
  • 555 timer ic
  • Connecting wires and a breadboard
  • Resistors 1K, 100K ohm
  • LED
  • Capacitors 10 nF and 1 uF

Square wave generator Circuit Diagram

Square wave generator Circuit Diagram

Take a 555 timer ic and place it on the breadboard.

  • Identify the pin numbers by finding the notch on the top of the ic.
  • Then connect pin 1 of the ic to the negative rail of the breadboard.
  • Join pin 8 of the ic to the positive rail of the ic.
  • Attach a wire between pins 4 and 8.
  • Take a 10 nF capacitor and connect its positive leg with the pin 5 of the ic and negative leg with the negative rail of the breadboard.
  • Join pins 2 and 6 together. Connect a 1 uF capacitor with its positive leg to pin number 2 and the negative leg to the negative rail.
  • Attach a 1K ohm resistor between pin 7 of the ic and the positive rail.
  • Join pins 6 and 7 via a 100K ohm resistor. Use pin number 3 and the negative rail of the breadboard as the output pins.
  • Now your circuit is ready for testing. You will get a square wave output at the output pins.

PCBWay PCB Prototyping Services

I have assembled the whole circuit on a breadboard. As you know breadboard assembly is not effective for this type of projects. So, PCBWay offers Rapid PCB Prototyping for Your Research Work. I personally, recommend PCBWay because you can get your first-try boards right in 24 hours!

PCBWay website

The prototyping stage is the most critical period of time for engineers, students, and hobbyists. PCBWay not only makes your boards quick but also makes your job right as well as cost-effective. This greatly reduces your cost and shortens the time for developing your electronic products.

PCBWay can provide 2 Layer PCBs to highly advanced HDI and flex boards. Even though the PCBs they produce differ a lot regarding functionality and areas of use. I am impressed with the quality of the boards, the delivery time, and the cost-effectiveness.

Let’s test the Circuit

square wave generator

We hope that you understand the working of the square wave generator using the astable mode of 555 timer ic.

So if you have any queries related to this project then feel free to ask them in the comments section given below. Also, do check out more tutorials on Arduino and Raspberry Pi written by us.

Thanks for reading.

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