4 ms·

For traditional lightbulbs, a PWM signal actually makes the light noticeably dimmer, and has a very simmilar effect to simply reducing the current. This is beca

For traditional lightbulbs, a PWM signal actually makes the light noticeably dimmer, and has a very simmilar effect to simply reducing the current. This is because the mechanism for them is heating up the filement, which happens on a much slower time scale then the PWM duty cycle. In practice, traditional dimmers are not quite PWM as they do not generate a square wave. Instead they generate a sin wave with portions of each cycle clamped to 0. LEDs already need driver circutry to condition the relativly high AC voltage into a stable lower voltage DC. Dimmable LEDs create a stable DC power supply from the chopped up AC power, then use the width of the active portions of the AC as a signal to drive their own dimmer logic.

fc417fc802 2y ago
That's a good PWM explanation but I think GP was asking a different question. Walter claimed that if the PWM was high enough frequency you would perceive it as full brightness while using less power. It obviously wouldn't work that way when lighting a room, but what about for an LED indicator light that you look at directly? I don't know enough to form an opinion.
- MadnessASAP 2y ago
  Without any more information on frequencies and measurements it's impossible to know. My guess is either A) They did not perceive the dimming, and/or B) The frequency was high enough that the inductive and capacitive effects of the circuitry became relevant and was filtering the PWM signal to DC signal that still drew the same amount of power as it did when fed the full voltage DC signal