After playing around with some greeting card modules to modulate sound onto a LED i found out that the driver part of said greeting card modules are not audio drivers but PWM drivers (oscilloscope confirmed).
This made me wonder if normal PWM controllers could be used to drive more power full LEDs.
My idea was to just remove the potentiometer and feed in music from Aux at that point.
Is there a chance of this working?
Update: I just tryed if it works and sadly it dosent, LED gets modulated somewhat but there is not audio to recover from it afterward, its only noise.
I did not know that! Very interesting for sure :D
Based solely on this drawing -- since I don't have a datasheet for the PWM controller depicted -- it looks like the potentiometer is there to provide a DC bias for the input Aux signal. I draw that conclusion based on the fact that the potentiometer has its extents connected to Vref and GND, meaning that turning the wiper would be selecting a voltage somewhere in-between those two voltage levels.
As for how this controls the duty cycle of the PWM, it would depend on the operating theory of the PWM controller. I can't quite imagine how the controller might produce a PWM output, but I can imagine a PDM output, which tends to be sufficient for approximating coarse audio.
But the DC bias may also be necessary since the Aux signal might otherwise try to go below GND voltage. The DC bias would raise the Aux signal so that even its lowest valley would remain above GND.
So I think that's two reasons for why the potentiometer cannot be removed: 1) the DC bias is needed for the frequency control, and 2) to prevent the Aux signal from sinking below GND.
If you did want to replace the potentiometer with something else, you could find a pair of fixed resistors that would still provide the DC bias. I don't think you could directly connect the Aux directly into the controller.