Generate PWM signal using NE555

Published by MKDas on

This is a small article with a basic feature of LM555 or NE555 timer IC. This timer IC is very common and can be used in different circuits in different operating configurations. In this article, we are going to generate a PWM pulse with a NE555 timer IC.

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What is PWM (Pulse Width Modulation)?

PWM or Pulse Width Modulation is a kind of digital signal where the frequency is kept in a fixed range and the duration of the on-time and off-time is varied. This digital signal is mostly used in DC loads to deliver variable power or controlled power.

The frequency of the signal is 1/T where T = total time.

Where, Total time = on time + off time.

Depending on this on time and off time, duty can be calculated.

duty = on time/ total time X 100 %

PWM signal generation using NE555 Timer IC:

We can use NE555 timer IC to generate PWM with this circuit diagram:

Here the timer IC is operating in free-running mode. A pot and two signal diodes are used to make feedback to the threshold pin. A timing capacitor C1 is used and the output frequency is depending on this capacitor. The RV1 variable resistor is used to control the on-time and off-time that means the duty cycle of the PWM signal.

Simulation Result:

This article is small but the use of this circuit is not so small. This circuit can be used in different systems where high frequency PWM signal is required and EMI is involved. So I’ll request to take it seriously.

I hope this project was helpful to you. If you make one for yourself, it will be a great pleasure for me. Anywhere you need help, let me know. Please share this project and subscribe to my blog. Thank you.


Mithun K. Das; B.Sc. in EEE from KUET. Blog:


Eze · April 8, 2021 at 9:08 am

Please complete this circuit to become pwm inverter circuit

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