Hacker News Reader

Comment by oniony | Hacker News Reader

If I were able to see the flicker of mains supplied LED lighting (which I cannot), then I would be very tempted to install low-voltage DC LED lighting, which presumably does not flicker.

View on HN

An AC/DC power converter works the same, either built into the bulb or in a separate unit. But yes, a separate power converter is almost certainly going to do a much better job of removing the 50/60Hz voltage drop. Not sure if it would be cheaper, given the economies of scale on AC bulb manufacture. Higher quality AC bulbs may come out ahead for flicker free lighting.

It only doesn't flicker if there's no power driving circuitry - eg just LEDs and a resistor.

Otherwise, if there is a power IC present, there is flicker, though fast enough for most humans to not perceive normally (you can still check it by waving your hand in front of the light and seeing the strobed afterimage.)

Yes! And this after image is distracting.

That's not strictly true. The very simplest of DC LED drivers flicker, such as the classic single-transistor battery saver circuit, but a slightly more complex DC LED driver circuit will not. One of the best ways to drive an LED is with a constant current source, which typically involves putting an inductor in series with the LED and switching the supply to that at a reasonably high frequency, which would mean the LED does not flicker at all.

If it's hooked directly to AC power, isn't there by definition a flicker? With a power IC, a poorly implemented power circuit will also visibly flicker. With high enough rate and the right power characteristics it should not be noticeable. Do you notice flicker in a quality phone or monitor screen?

Reply on news.ycombinator.com