3 ms·

For sure, they're definitely way more efficient. They just unfortunately give me migraines. I'd be open to trying some that have a filter network or some other

For sure, they're definitely way more efficient. They just unfortunately give me migraines. I'd be open to trying some that have a filter network or some other smoothing on the flicker. But I've also never lived in a house that has dimmers (they've all been old homes in the north eastern US) and I never use overhead lighting, so it's not something I need or would miss.

card_zero 1y ago
Apparently fourth-generation LED tube lights are designed not to flicker. https://en.wikipedia.org/wiki/LED_tube#History https://en.wikipedia.org/wiki/LED_tube#History
- throwaway290 1y ago
  Aside from that Wikipedia article, where 1 source is not available and the other one is in Finnish, there's pretty much nothing online. I googled for G4 LED tube PWM and got products that say they are G4 LED tubes that use PWM. Pretty sure 100% of LED products sold anywhere use PWM if you don't use them at full brightness. I sometimes walk around lightning stores with a slo mo camera and see PWM in every price bracket.
  - Kubuxu 1y ago
    It is always PWM under the hood, the question is, how much was spent (or not) on the filtering network out of the PWM. Is it closer to buck converter or is it straight up flicker at the output.
    - card_zero 1y ago
      Since these things have lots of LEDs, my first thought was to put a range of different tiny delays on them to induce destructive interference, so that the off parts of one LED's flicker are the on parts of another, to smooth out the overall output. Actually that's not true, my first thought was "just use a layer of phosphor excited by the LEDs", but fluorescent tubes do that and people used to make the same complaints about flicker, so. Looks like "flicker index" is a useful(?) search term, anyway.
leoedin 1y ago
Have you ever tested various PWM frequencies? 50/60Hz is very noticable - but if the PWM is switching at 1000Hz? 5kHz? There is presumably a rate at which it is imperceptible to you? Apparently Philips Hue uses 500-1000Hz. I wonder if there's manufacturers that use a much higher rate.
- leakycap 1y ago
  Beyond the Hz, the depth of the modulation matters. I am sensitive to poor PWM implementation, but Hue bulbs luckily don't bother me. On an old iPhone with basic slow-mo recording capabilities, typical Hue bulbs don't "blink" when the video plays back, but the PWM-dimmed iPhone in the same video recording was blinking/flashing like crazy. ~~ Another example of the PWM details mattering: I can't use any iPhone with OLED (anything from the X to current), but I am able to use a Note9 which has OLED with DC-style PWM.
  - leoedin 1y ago
    What do you mean by “the depth of the modulation”? The relative brightness? PWM at low duty cycles tends to be much more noticeable. But that’s where higher frequencies should solve the problem.
    - leakycap 1y ago
      I was referring to the extent of brightness variation in the flicker -- while many focus on a higher frequency (Hz) to reduce eyestrain, the key factor is how the screen behaves during the off cycle Some PWM implementations ramp the brightness up and down slightly (easier on eyes), while other manufacturers flip the switch on and off harshly (like strobing) The shorter time the screen is dark between being lit up results in a a shorter pulse duration, and the pulse duration and depth are more important than the Hz

card_zero 1y ago

Apparently fourth-generation LED tube lights are designed not to flicker. https://en.wikipedia.org/wiki/LED_tube#History https://en.wikipedia.org/wiki/LED_tube#History

throwaway290 1y ago
Aside from that Wikipedia article, where 1 source is not available and the other one is in Finnish, there's pretty much nothing online. I googled for G4 LED tube PWM and got products that say they are G4 LED tubes that use PWM. Pretty sure 100% of LED products sold anywhere use PWM if you don't use them at full brightness. I sometimes walk around lightning stores with a slo mo camera and see PWM in every price bracket.
- Kubuxu 1y ago
  It is always PWM under the hood, the question is, how much was spent (or not) on the filtering network out of the PWM. Is it closer to buck converter or is it straight up flicker at the output.
  - card_zero 1y ago
    Since these things have lots of LEDs, my first thought was to put a range of different tiny delays on them to induce destructive interference, so that the off parts of one LED's flicker are the on parts of another, to smooth out the overall output. Actually that's not true, my first thought was "just use a layer of phosphor excited by the LEDs", but fluorescent tubes do that and people used to make the same complaints about flicker, so. Looks like "flicker index" is a useful(?) search term, anyway.

leoedin 1y ago

Have you ever tested various PWM frequencies? 50/60Hz is very noticable - but if the PWM is switching at 1000Hz? 5kHz? There is presumably a rate at which it is imperceptible to you? Apparently Philips Hue uses 500-1000Hz. I wonder if there's manufacturers that use a much higher rate.

leakycap 1y ago
Beyond the Hz, the depth of the modulation matters. I am sensitive to poor PWM implementation, but Hue bulbs luckily don't bother me. On an old iPhone with basic slow-mo recording capabilities, typical Hue bulbs don't "blink" when the video plays back, but the PWM-dimmed iPhone in the same video recording was blinking/flashing like crazy. ~~ Another example of the PWM details mattering: I can't use any iPhone with OLED (anything from the X to current), but I am able to use a Note9 which has OLED with DC-style PWM.
- leoedin 1y ago
  What do you mean by “the depth of the modulation”? The relative brightness? PWM at low duty cycles tends to be much more noticeable. But that’s where higher frequencies should solve the problem.
  - leakycap 1y ago
    I was referring to the extent of brightness variation in the flicker -- while many focus on a higher frequency (Hz) to reduce eyestrain, the key factor is how the screen behaves during the off cycle Some PWM implementations ramp the brightness up and down slightly (easier on eyes), while other manufacturers flip the switch on and off harshly (like strobing) The shorter time the screen is dark between being lit up results in a a shorter pulse duration, and the pulse duration and depth are more important than the Hz