@ccs-hello said in PWM board related:

OP is talking about driving motor(s), not LED

Yes. Please notice only OP wants to connect a motor to the PWM Expansion - not me.

(sink 25 mA max per channel.)

400 mA in all! It's not bad for this degraded "signalling-only" board.

What motor can be driven only using 25 mA?

Who knows? I'd be curious too.
See also the first paragraph of PWM Expansion

Back EMF, stall current, etc.??? Motor driver board is the way.

flywheel diode, snubber, no-load current, ...
A logic level n-channel MOSFET (or an NPN transistor) and a 1N400x diode are not enough - all we need is motor driver board! :-)