| Electronics > Projects, Designs, and Technical Stuff |
| Phase shift mains AC to de-flicker LEDs |
| << < (5/7) > >> |
| strawberry:
I recommend reduce LED bulb/TV current by ~20% to double useful life. As manufacturers push them to the limits to earn more money. PFC choke could boost voltage up to LED threshold level and therefore limit fliker |
| Someone:
--- Quote from: Lupin III. on March 20, 2020, 01:52:01 pm --- --- 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. --- End quote --- But asking for everyone else to donate their time is no expense.... --- Quote from: Lupin III. on March 20, 2020, 01:52:01 pm --- --- 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. --- End quote --- How do you know it will overheat on DC?.... --- Quote from: Lupin III. on March 20, 2020, 01:52:01 pm ---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. --- End quote --- If it does overheat on DC then they have set the current limit to work with the rectified AC duty cycle, run it on DC and adjust the current limit so the heating (RMS) losses remain steady (or lower). As mentioned above modifying a badly designed bargain priced device is usually a loss making exercise, throwing good money after bad (https://en.wikipedia.org/wiki/Sunk_cost#The_fallacy_effect). Any solution is likely to cost more in time and resources than simply buying a more appropriate device to begin with. |
| greenpossum:
--- Quote from: StillTrying on March 20, 2020, 03:24:10 pm ---LOL I'm checking suspicious websites all the the time, that one isn't. --- End quote --- I'm not worried about my browser, but I don't want to support sloppy websites and their sloppy maintainers. |
| NiHaoMike:
Connect a large capacitor in parallel with the bridge rectifier, then connect another capacitor in series with the AC input to limit the current. (Use an AC power meter to check if you got the right value, making sure it's the same or lower compared to the unmodified power usage.) It might be more economical to use a series inductor if you're supplying a lot of modules. |
| Siwastaja:
Think about the fundamental physics: The flicker happens because the mains cannot provide power to the LED during low line voltage part of the period. How do you "shift phase"? By adding a delay. How do you add the delay? By storing energy and releasing it. Now, how do all the proper, non-flickering LED lights work? By storing energy! No special gimmicks required: just add the filter cap to the rectified mains. Buying non-flickering lamps off-the-shelf obviously solves the problem. If you want to bodge the existing drivers, I'd just try to find where the DC link is and add capacitance there. |
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