Quote Originally Posted by Alexandr0s View Post
Anyone able to answer my last question regarding the potentiometer?
although the creator of this circuit used the NE555 a little bit different than the datasheet suggests for PWM operation, the formula to calculate the PWM base frequency should still be valid. but it looks like its working, so who cares.

anyway, changing either C3 or R2 will change PWM base frequency.

in your circuit this should result in 1440Hz:

f = 1,44 / (R2 * C3) = 1,44 / (100.000 * 0,00000001) = 1.440Hz

you can go lower on either R2 or C3 to increase PWM base frequency. the datasheet suggests to use a value larger than 1nF for C3. taking this into account, i would recommend the following values for some example frequencies:

PWW freqency=6kHz C3=12nF R2=20k
PWW freqency=12kHz C3=12nF R2=10k
PWW freqency=21kHz C3=6.8nF R2=10k