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

  • Popular 555 timer IC
  • Oscillators- Pulse Width Modulation
    Duration: 4:44.
  • multivibrator circuit with variable frequency and duty cycle, 10 Hz-20 KHz (schematic)
    Duration: 6:07.


  • 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
  • EDN.com
    EDN.com A voltage sense loop compares VC – a fraction of the output voltage – with reference voltage VREF2 to generate the reset pulse for the and consequently achieve the desired output voltage. The unit also has a feature of qu
     5 November 2013