Do switch mode power supplies flicker in time with mains?

[William Gothberg]

You would if it was a really shitty PSU with half wave rectification.

[William Gothberg" <"William]

I don't swing that way.

[William Gothberg]

"Human vision is adversely affected by light fluctuations at frequencies up to 200 Hz, even though people can only directly perceive fluctuations at frequencies up to about 70 Hz. The fundamentals of the sensitivity of the human eye to rapidly changing light (transient light artifacts or TLAs) as a function of frequency have been well known to science for a decade or more. Despite this, the lighting industry has so far limited itself to only characterizing light sources over the range of frequencies which the human eye can perceive directly. This range is below 100 Hz. However, it is well documented that human visual performance is degraded by the presence of light fluctuations at frequencies in the range from 100 to 200 Hz. Here we will describe a new flicker metric/tool that includes consideration of higher frequencies and further discuss an AC-LED light engine relative to performance against the new metric."

[William Gothberg]

I'm definitely getting 100Hz flicker from it, I timed it using a slow camera shot (1/10th of a second) while moving the LED across the camera's field of vision. There were exactly 10 bright spots, although they were only 8% brighter than the dim spots. The LEDs don't go off completely. It's enough of a flicker for me to see with my eyes if I scan past the light, and I can detect anomalies when watching something rotating, like a drill chuck. I've got an oscilloscope on order, then I'll be able to check the signal to the LEDs (and in other parts of the supply) accurately.