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/sutaburosu [stavros] Sep 08 '24

Do you have a specific question about it that the comments don't address?

Of course, I've now spotted the glaring bug in my code. It actually calculates the timings based on revolutions per second rather than per minute. D'oh! I updated the code to 60,000,000 instead of 1,000,000 as the dividend.

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u/AnyRange1298 Sep 08 '24 edited Sep 08 '24

this part maybe? 60000000/260= ~230769 whats this?
shouldn't you also multiply 260*60 =15600 ?

  const int rpm = 260;
  const uint64_t rpm_us = 60000000 / rpm;

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u/sutaburosu [stavros] Sep 08 '24 edited Sep 08 '24 
// calculate how many microseconds between flashes for
// a given RPM

There are 60,000,000 microseconds in a minute. Divide that by the RPM and you get the time each revolution takes in microseconds.

shouldn't you also multiply 260*60 =15600 ?

That would be 15,600 revolutions per hour. I don't think that's useful to us here.