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points by nik282000 3 days ago | 0 comments

PWM drivers should be banned, the quality of lighting is horrendous and it murders LEDs. You have an rms currernt that is in spec but the peak is way too high.

anecdote: I work in a factory, we have thousands of light fixtures. The older constant current LED fixtures have lasted a decade, the new PWM driven lights have had a ~1% failure rate.

[–] skew-aberration 3 days ago

How do you know the difference? Constant current is almost certainly a PWM controlled buck/boost regulator. The flicker is attenuated by inductance, more or less depending on the design.

[–] nik282000 3 days ago

I guess the distinction is 'filtered' vs 'unfiltered' then. If you look at the lights that fail early using a high framerate camera (1k fps) they flicker between full brightness and fully off. The lights that last longer have some ripple but its 5-10% brightness.

[–] dchristian 3 days ago

Use a fidget spinner to see the difference. Spin up a 3 lobe fidget spinner and catch the reflection of the LED on it's surface. As the speed changes, a flickering LED will freeze the motion of the spinner. Even more fun with spinners :-).

Yes, adding an inductor will fix the problem, but that costs money. Not enough customers are complaining about the light flicker to justify the higher price.