This simulation shows a 555 timer operating as a pulse-width modulation (PWM) generator. The timer produces a constant-frequency square wave, while a sinusoidal control voltage is applied to the control pin through a capacitor and diode path. Instead of changing frequency, the circuit smoothly adjusts the duty cycle of each pulse according to the sine wave level. As the control voltage rises, the pulse stays high for a longer time; as it falls, the high duration shortens. The resulting stream of

This simulation demonstrates pulse width modulation generated using a classic 555 timer and an analog control signal. The 555 is configured to produce a fixed-frequency pulse train, while the control voltage input dynamically shifts the internal threshold levels. As the low-frequency sine wave is applied, it continuously changes the comparator reference inside the 555, causing the output pulse width to expand and contract while the frequency stays constant. On the waveform display, this shows up