Square-wave modulator has variable frequency and pulse width

The circuit in Figure 1 satisfies all these criteria. The circuit delivers a unipolar (adjustable from 0 to 12V) pulse with adjustable frequency and pulse width. The first half of a dual, retriggerable monostable multivibrator, IC1A, generates the frequency of the pulse train. The 100-k potentiometer, R1, along with R2 and C1, sets the adjustable frequency. R3, R4, and C2 set the adjustable pulse width in the second section of the multivibrator, IC1B.

Recommended videos

  • Duty cycle, frequency and pulse width--an explanation
    Duration: 8:53.
  • Pulse Wave Oscillator with PWM
    Duration: 1:43.
  • Oscillators- Pulse Width Modulation
    Duration: 4:44.


  • Hackaday
    Hackaday The 555 operation is almost identical to the astable , however the trigger input is not connected to the timing capacitor. This means the circuit does not “self trigger”, requiring an input (in this case from the astable
     17 September 2015