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Comment by alexpoulsen | Hacker News Reader

The LEDs should be in 2 or more groups that each pulse at AC speed but offset by a fraction of the wavelength, that way there is little to no flicker. Or convert to DC and power it that way.

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That's WAY too complicated. Just run the power through a high-frequency tank oscillator to convert from 60Hz to a much higher frequency with just a coil and capacitor.

Or, do what I did. Just make the rectifier directly out of LEDs itself - https://www.youtube.com/watch?v=jDnCHyF7o5U And from there you can power your devices with the leftover DC power.

LEDs are seriously far more robust than they were a decade ago.

Not sure this makes sense, when you PWM something like an LED, there is no 'leftover DC power'; the energy unused by the LED each cycle is not wasted.

Yes, there is "leftover DC power" as a diode only allows power in one direction and whatever is left after the LED voltage drop is rectified DC. If I put 12V of LED on a 120V leg, I'll have 108VDC rectified left over after the LEDs take their voltage drop. If no other device uses that power, it just gets dumped out to ground, but it's still unused DC power.

That's not PWM in the video. That's raw mains frequency.

What's the frequency of the 12V AC supply in that video? Is it the same as 110V AC going into the transformer? What is causing the lights to pulse every few seconds?

Yup, same 60hz power mains, it's a simple 10:1 step-down transformer with a resistor and filter cap wall-wart. My camera is recording at 29.97 FPS so you get to watch essentially which sets of diodes on the rectifier are operating on the waveform peak/trough (or would actually see which ones had I had this on an o-scope.) The weird star-trek transporter effect is just the intensity of the lights screwing with the camera + the progressive-scan nature of the camera sensor.

Here's one directly on the mains power. NO CONTROL CIRCUITRY.

https://www.youtube.com/watch?v=AE9QkHmeA-o

You don't want to power LEDs with DC if you want the highest light output. This is because the junction heats up and lowers the efficiency of light output. When LEDs are pulsed at a high enough rate, the junction temperature can stay lower at higher currents. This leads to higher light output.

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