Any old "wall warts" (AC power adapters for electronics) can be a treasure trove for DC motors. For example, if you have an 18V DC motor and use a 6V AC power adapter you will only turn the motor at 1/3 it's speed. On the other hand if your computer is close by, you can actually power a turner with a USB port. USB only draws about 5 volts DC (+/-). Just take an old USB mouse and cut the wire at the mouse for a 6 foot cord to work with. Use the red(+) for the load and the black(-) for the ground and disregard the white and green wires.