[imhimmelkommter (Michael Toms)]

Originally Posted by bojan

Yes, you can join those power supplies together... however do not connect more than 30V, as this is the voltage limit for IC1.
You do not need resistors if you use 12V.... because 24ohm is the internal resistance of the motor winding.

However, if you use higher voltage, then for every volt above 12V you should use 4ohms... or thereabouts.
For example, if you have 15V, this is 3V above 12, your resistor should be 3V/250mA = 12ohms.

Thanks Bo Jan.