Mouse Ball Type Sensor

Other Hardware Sensors
1

Do you remember the old mice with a rubber ball in it.

They were made using two rollers to sense the two directions. I was wondering if anyone knew where one could buy one of those roller sensors.

Or even one of the sensors you find in modern mouses ( mice? )

Basically i want to be able to track motion just like a mouse. must be a small setup.

2

The old ball mice used a interrupted optocoupler and a slotted rotating disc. They did not detect the ball directly. I still have one and must disassemble it occassionaly to remove car fur stuck in the slotted disc. Digikey and Mouser each have dozens.