Generate PWM signal using NE555
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 signal using 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, the 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.
You may find this article helpful: Make simple AC dimmer using NE555
This article is small but the use of this circuit is not so small. This circuit can be used in different systems where a high-frequency PWM signal is required and EMI is involved. So I’ll request to take it seriously. Before applying this circuit to any field test the signals using an oscilloscope rather than testing only using a multimeter. Low price oscilloscopes are available in the market now-a-days. Because there may be distortions in the signal due to bad capacitors. So before applying this circuit, the signal must be checked.
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