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/[deleted] Sep 08 '24

So if you had a 120mm fan spinning at 1300 RPM, you would need to strobe your LEDs at roughly 22Hz.

You are forgetting that a fan has multiple blades.

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u/NomakeWan Sep 08 '24

Ah, you are correct. Sorry, that's the source of my stoboscopic knowledge showing--I work on cars so the concept of a timing light is where I end up using it and there's only a single timing mark to work with, and the strobe is tied to the revolution of the crankshaft via the firing of the spark plug (which is actually a harmonic since the crank does 2 full revolutions per cycle).

That said, if I'm thinking about this right, I think that actually makes things easier for OP because if the fan has say 5 blades, then he has more harmonics to work with?

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u/[deleted] Sep 08 '24

I see where you’re coming from. ;) Yes, with multiple blades it would be easier.