How to reverse the action of a small 12V DC MOtor

[ja7703a]

Hey Guys !
I am working on a personal project, and I was hoping you could give me some help and advices.
I am looking for a tool/device that would reverse the action of a small 12V DC motor (make it operate clockwise and then counter-clockwise for example).
And I was also wondering what kind of rheostat use in order to control its speed.
Thank you in advance !

 

[mdjensen22]

You'd have to check the information on your motor to make sure, but typically, direction is changed by changing the direction of current flow through the motor. To do this, the wires need to be flipped. A simple way to do this is by either a switch or by a relay (DPDT in either case).

Speed control for these motors is also typically done through a PWM circuit.

 

[HarryA]

also see:
http://www.allaboutcircuits.com/vol_6/chpt_3/7.html

The rheostat depends on how 'small' your dc motor is.

As mdjensen22 pointed out PWMs are best but they are not cheap.
Jameco sells PULSE WIDTH MODULATOR for 25$.
http://www.jameco.com/webapp/wcs/stores/servlet/Product_10001_10001_120539_-1

 

[schip666!]

For a small motor controller look at the L298 H-bridge chip. It can run two 2amp motors, bidirectionally, and takes a pulse-width and a direction signal as input. You can generate the pulse-width signal with a 555 timer or, if you want to get fancy, a micro-controller.