EEVblog #1253 - LED Flicker 2: Electric Boogaloo

Part 2 of the LED Flicker investigation.
Modding the driver for input and output capacitance and it's effect on power factor correction and thermal performance.

#LED #Flicker

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[Stefan_Payne]

pls more power electronics/PSU Related stuff!

[AndreasKoepkeAU]

At first glance I thought the thumbnail screen said something else.... 🤣

[kenseastrand]

Thank you, this gave me a whole new understanding about led driver circuits.

[zapindo]

i got stuck in building a circuit for a week . finally worked and im so relaxed....

[WolfgangMahringer]

You should have connected the primary filter cap /behind/ the 2 filter chokes, that would have smoothened out the current peak a good bit, and so improve the PF!

[bostedtap]

Excellent insight and hands on of LED drivers, and why capacitance is not the answer in efficiency.
Electronics thicko here.
Thanks for sharing and best regards from the.

[peterhaan]

Wow, I'm impressed that your Aussie politicians can even appreciate the subtleties of power factor! It would be a rare day when any US politician could spell his name the same way twice on any given day!

[ProfessorFartsalot]

I downloaded that font just because it looks like it says a whole different thing.

[jameskoch]

Your main B+ should have went up considerably with the primary filtering you added. That would raise the VCC to the switching IC, you probably need to change those dropping resistors to compensate.

[Fifury]

9:15 - are you forgetting someone did? That shed full of salvaged parts!?

[jonathanwilhelm]

Thank you @eevblog excellent video. I have some led panels for my office that have the questionable driver, I think it could be a fun project to make my own and pot it

[JohnBurgessMusic]

Love these videos. I wonder why there aren't (easily found) room-level solutions. i.e. if you have multiple LED panels in a room, why not have one main AC/DC converter with good PF, efficiency, and EMI, rather than 10x mediocre AC/DC supplies. Then each panel can have its own DC CC driver.

[dukeibzusa]

The problem with big input capacitors is the nasty inrush current seen from the line at power up. That was a nightmare for people that designed electrical protection equipment like ups or automatic voltage regulator based in SCR's or IGBTs, easily a small room with older pc's could produce hundreds of amps.

[timg]

I would of loved this when I was in college for education. Could assign groups to experiment and see who could come up with the best PF and lowest ripple.

[Machineius]

Love the reference in the name. I know what era you grew up in.

[plemli]

17:18 this IS the place to go into details.

[DAVIDGREGORYKERR]

There is an un-soldered leg on the input side of that six pin chip.

[FulvioGa]

This one was a super interesting video. I do not understand how you calculate all those results, because I do not know electronics, but the conclusions are very useful. Thanks.

[petehiggins]

The flicker from that cheapo LED driver is no worse than the good old flourescent strip light that we have been happily using for the last seventy years or so. Admittedly there were always one or two people in the office that complained that the flicker was giving them headaches or other ailments but when the lamp drivers were upgraded to electronic versions switching at 50kHz or so with negligible output ripple, they still complained.

[edwardhartmann]

I wonder if there was some design reuse happening here. The primary side filtering is suspiciously similar to what many triac dimmable led drivers use. It seems logical that they might just modify an existing higher end design to just be as cheap as possible. It would simplify BOM inventory and be much quicker to market with half the design already done. Both the board and case being designed for screw terminals yet having wires directly soldered on lend credence to this.