Pulse width modulator produce a PWM signal, a pulse with a constant frequency but with the duty cycle vary according to a modulating signal. Here is the schematic diagram of pulse width modulator circuit using 555 IC as the active component:

pulse width modulator 555 circuit schematic

This pulse width modulator circuit need external pulse train input to trigger the the 555 monostable circuit. This trigger input sould be a square wave signal with a fixed frequency. The output of this pulse width modulator circuit will have same frequency with the trigger input, but with its pulse width proportional to the modulating input signal at pin 5. [Circuit's schematic diagram source: National Semiconductor Application Notes]



Possibly Related Articles:

  • Pulse Position Modulator
    Pulse position modulator can be easily built using 555 IC. Here is the schematic diagram of the circuit: Pulse position modulator modulate the on-period while keeping the fixed off-period. Pulse...
  • Fast Pulse Detector
    The circuit below is a schematic diagram of a fast pulse detector. At 100 ns  or wider pulse width, the detection should be error free. At 60 ns pulse width, ...
  • Pulse Generator (Oscillator) With Adjustable On-Off Period Using CA3130 Op-Amp
    One of the interesting features of CA3130 op-amp  is its high input resistance, because using such high  input resistance, we can build an astable multivibrator with high R/C ratios. The...
  • Programmable Levels High Speed Pulse Generator
    This is a Programmable Levels High Speed Pulse Generator circuit. This circuit consist of Lilliputian dimensions associated with the sub-micron geometries of many analog and most digital processes also advanced...