how to wire a DC gear motor with an AC adapter?

I finally found just what I was looking for here if anyone else is interested:

http://www.halloweenforum.com/halloween-prop-building-group/74930-project-1-instructor-thread-2.html

AC to DC

I had to do the same thing with a few wiper motors. It was the only way I could use a 12 volt 5 amp power block to run my motor.

-r

(1) AC to DC Voltage Adapter, 12 VOLT, 200 to 500 milliamp rated (or similar)

I built two of these with the same motor. I have two dc power supplies that I used my volt meter to test. One runs at about 11 volts which gets me a good slow motion I really like and the other is around 13-14 which is a little faster than I would like but still okay. If you have a way to test the volts on the ac-dc power supplies do, I had one that said its out put was 12v and it was over 20 so it can vary quite a bit.

I used old PC power supplies. These have several output wires of various configurations, one of which is a DC 12v (about 5 amp) suitable for a gear motor. The power supply box should have a label that identifies which cord is which. To control the motor speed, I used a Qkits DC motor controller - QKits Electronic Kits: MX033, PWM DC Motor Speed Control Module - which fit nicely inside the power supply box. This controller allows you to dial down the motor speed without losing any of the motor's torque, something that will occur if you try to use a light dimmer switch. All for about 25 bucks!