Re: Kill LED lamp flicker

Sep 10, 2023 Last reply: 3 years ago 2 Replies

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Martin Brown 3 years ago

> lørdag den 9. september 2023 kl. 14.46.48 UTC+2 skrev Fred Bloggs:

>>> On Friday, September 8, 2023 at 11:25:43 AM UTC-4, John Larkin wrote: >>>>
>>>> Maybe you have cheap flourescent-replacement tubes.
>>> Uh-huh. LEDs don't flicker. They're all powered by regulated switching ***current*** sources operating in the 20kHz-30kHz range. LEDs are not directly powered by voltage, and the current sources are immune to voltage fluctuation.
>>>
>> some are linear, enough LEDs in series to add up to most of the rectified line voltage
>
> I'm pretty sure they've never used that method for the commodity lighting bulb market. Maybe for signs and indicator bulb types of applications where it has to be dirt cheap.

You are wrong. I have a dead one sat in a drawer somewhere nearby.

60 LEDs in series across rectified UK 240v mains.

One single LED in the chain has failed. It was the first LED bulb failure that I ever saw so I dismantled it to see why.

They are the cheapest and nastiest on the market, but at the time it was bought they sold for premium prices with exaggerated MTBF based on the expected failure time of a single LED. True MTBF is claimed/60.

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Don Y 3 years ago

I suspect that's designed with cost as the sole factor.

Most of my LED lights have just a few (e.g., less than 10) emitters. Hard to imagine a whopping dropping resistor to soak up ~100V of potential!

I should take one of mine apart (they can be disassembled but likely would be a nightmare to REassemble -- and have working!)

That's been the case with all of the newer lighting technologies. I have "commercial" (130V) incandescent flood lights in the living room which I can't recall replacing after their initial installation. They are much preferred to any of the other technologies because they can be dimmed to a level that can't be detected UNLESS your eyes have acclimated to total darkness (i.e., a house guest awakening in the middle of the night could navigate without having to figure out where the nearest light switch was located -- and risk blinding himself by the sudden onset of full light)

The CFLs, OTOH, never dimmed and would fail in relatively short order -- regardless of their life expectancy claims! (I have a CFL uplight in the office that seems like it will fail RSN... yay! one less!!)

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