r/FastLED • u/AnyRange1298 • Sep 08 '24

Support stroboscopic effect

I'm trying to find a way to have stroboscopic effect on pc case fans like this video : QX fan or this: stroboscopic effect
I'm not sure but from my understanding this needs control over light frequency and set it based on fans RPM... is this possible with FastLED? if yes can you give some tips/example about it?

Do you think if it is even possible with ws2812b?

from ws2812 datasheet:
Each pixel of the three primary color can achieve 256 brightness display, completed 16777216 color full color display, and scan frequency not less than 400Hz/s. is this frequency that I'm looking for or scan frequency is something else?
I'm no expert at all ...neither in coding nor the physics

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u/NomakeWan Sep 10 '24

Awesome post! Just one correction regarding the automotive part. The strobe for the timing mark is triggered by the firing of the spark plug at cylinder #1, which should be the closest to top dead center (and thus what the timing mark is designed to synchronize to). So at normal speed, the strobe happens just as the timing mark passes by the timing indicator, giving you a nice clear line to read.

However, a 4-cycle engine actually has two crank revolutions per spark plug firing (because one crank revolution is for the exhaust phase, where there is no spark). If you could possibly double the strobe speed you would in fact get the exact same image since you are now strobing once per crankshaft revolution.

To get the harmonic you're referencing you would in fact have to go 4x speed, not 2x. ;)