Free Circuit Diagram

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:

This pulse width modulator circuit need external pulse train input to trigger the the 555 [...]

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 position modulation might substitute pulse-width modulation in some application. The main difference between pulse position modulation (PPM)  and pulse width modulation (PWM)  is that  unlike PWM, [...]