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Phase shift mains AC to de-flicker LEDs
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Lupin III.:
I have a few COB LEDs with integrated mains "power supply" (like these: https://www.ebay.com/itm/20W-LED-COB-Chip-110-220V-Smart-IC/232273725866 ). They are really cheap. Maybe not the best for living room ligthing, but definitely good enough for shop or workbench lights. The only problem I got with them is that because they ride the mains voltage sine they have visible flicker when you move your eyes quickly.

So I was thinking, if you get two of those, but shift the mains AC phase to one of them by a series capacitor, the visible flicker could be substantially reduced. Similar to how you create another "phase" with a series capacitor if you want to run a 3-phase motor on a single phase.

This should work, but what value capacitor would I need approximately to shift enough for a 20, 30 or 50W COB? Would something similar work with an inductor in series to shift in the other direction?
Zero999:
Stupid question: why not just use LEDs with a proper filter capacitor which doesn't flicker?

Trying to bodge crappy LED drivers isn't worth the expense.
Circlotron:
Maybe put the mains into a bridge rectifier and filter capacitor then feed this dc to the LED lamp.
richard.cs:

--- Quote from: Lupin III. on March 20, 2020, 12:18:06 pm ---This should work, but what value capacitor would I need approximately to shift enough for a 20, 30 or 50W COB? Would something similar work with an inductor in series to shift in the other direction?

--- End quote ---

This was historically done on some fluorescent fittings. One tube with an inductive ballast and one with a capacitive one so the two flicker out of phase. I suspect for what you want a better LED driver would be the preferred solution (by far).

If you do want to try it I suspect your first step should be to de-goop one and reverse engineer the supply circuit used. This might work without modification from DC, though this is far from guaranteed. Almost certainly they just conduct over the top portion of the AC waveform and if they regulate current at all they may do so at a value that blows them up if you go to 100% duty cycle by feeding them DC. Note that you will need to drop significant voltage across your reactance to get a phase shift approach to work, this might mean running 110 V devices from 220 V, which means if you're in a 110 V country the idea may be unworkable.

Lupin III.:
Please stay on topic. If you know it won't work, tell me why. If you know it will work and how to calculate the capacitor value, I would appreciate it as well, if you'd tell me. But "Why..." or "Why not..." is not helpful.


--- Quote from: Zero999 on March 20, 2020, 12:28:15 pm ---Stupid question: why not just use LEDs with a proper filter capacitor which doesn't flicker?

Trying to bodge crappy LED drivers isn't worth the expense.

--- End quote ---

Putting a capacitor that costs less than 1€ in series with a <2€ LED is hardly an expense, neither in time nor money.



--- Quote from: Circlotron on March 20, 2020, 12:37:08 pm ---Maybe put the mains into a bridge rectifier and filter capacitor then feed this dc to the LED lamp.

--- End quote ---
The drivers need the off-time, because that's what they are built for. On DC they'd overheat. Also a bridge rectifier and a smoothing cap for an up to 50W device would be quite big.
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