F
Fred Bloggs
Guest
On Sunday, September 10, 2023 at 11:28:53â¯AM UTC-4, Martin Brown wrote:
If you have a single LED I-V, then stacking them in series in effect creates a composite I-V that is the same with V-axis multiplied by the number in the stack. That could be quite a softening effect. For them to use 60 makes me think they were counting on that effect. It should work pretty well or not depending upon sensitivity of light output to differential I. If they were going for max lumens, they were probably working the LEDs too hard. Apparently significant derating of the operating power dissipation is key to longevity.
On 10/09/2023 16:18, Fred Bloggs wrote:
On Sunday, September 10, 2023 at 10:57:40â¯AM UTC-4, Martin Brown wrote:
On 09/09/2023 15:11, Fred Bloggs wrote:
On Saturday, September 9, 2023 at 9:01:28â¯AM UTC-4, Lasse Langwadt Christensen wrote:
lørdag den 9. september 2023 kl. 14.46.48 UTC+2 skrev Fred Bloggs:
On Friday, September 8, 2023 at 11:25:43â¯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.
No one is interested in an example of degenerate ad hoc engineering that was completely abandoned, and for good reason.
They were made like that presumably to be as cheap and nasty as
possible. When they worked they were fine and instant on with true rated
brightness unlike the previous generation of CFLs which came on dimly
and almost never reached the brightness that their packaging claimed.
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.
If you have a single LED I-V, then stacking them in series in effect creates a composite I-V that is the same with V-axis multiplied by the number in the stack. That could be quite a softening effect. For them to use 60 makes me think they were counting on that effect. It should work pretty well or not depending upon sensitivity of light output to differential I. If they were going for max lumens, they were probably working the LEDs too hard. Apparently significant derating of the operating power dissipation is key to longevity.
That was their undoing. I expect you can still buy them on fleaBay.
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Martin Brown