tachometer suggestions anyone?

I am looking for a tachometer that has been used to monitor the speed of a ball shooter wheel in the past. Does anyone have any suggestions? I will use the tachometer to provide feedback for a velocity control loop to ensure that the cell shooter is always as a specific velocity no matter the robot’s battery voltage.

For our 2006 shooter we constructed a tachometer out of one of the other KOP motors
http://www.team358.org/files/electrical/DC_MotorTachometer.pdf

Mark,
Your program is so well documented. Impressive stuff!

I found it a few weeks ago when searching for Motor Tachometer on Google. It was the first result.

The RS-385 motor seems well suited for this task.