I've succesfully spun my motor with a microcontroller manipulating an h-bridge circuit chip on a breadboard. The problem is, I couldn't figure out how to use a second voltage for the motor. It's rated at 9v, but i could only get it to spin if i connected the "motor power source" pin to my 5v supply. Not good, i know. I tried adding a 9v battery on the opposite rail of the breadboard, but i'm unsure how to ground it all out? Do I connect the ground of the 9v rail to the ground of the 5v rail? ( i tried that with a 10 uF cap in between, no success )