Cleans the commutator. It’s a little honing stone that you inserted where one of the brushes was usually located that cleans off the carbon buildup.
I replied without actually looking at the picture 😅 That looks like a power supply for running the motor during the process. There was a fair bit of “voodoo” regarding motor performance, breaking your motors in, clocking the bell to adjust timing, etc.
I’m reading the docs and it seems capable of running up into the MHz range although at higher frequencies the duty cycle resolution is reduced. Although I wouldn’t expect most multimeters to detect a frequency that high, anything should pick up the voltage.
Do you get an error on the serial monitor? It should report if the frequency/duty-cycle range you’re requesting isn’t possible.
E (196) ledc: requested frequency and duty resolution cannot be achieved, try reducing freq_hz or duty_resolution. div_param=128
What’s limiting your PWM frequency? You want it above 25 KHz so it’s outside the range of human hearing.
Those gold RC10 tubs :-)