Gear Head Motor - 7.2vdc 50:1 175rpm (6mm shaft) The motor can be obtained from lynxmotion.
The motors came with the lynxmotion frame kit. They have a reduction of 1:50 and have a rear shaft so optical encoders can be mounted for measuring rotational velocity and distance.
On the rear of the motors, optical incremental encoders have been mounted. These encoders count the revolutions of the motor shaft. For every rotation of a wheel, the motor shaft rotates 50 cycles (due to the 1:50 gear reduction). The encoders give 200 ppr (pulses per rotation).
The encoders have the following connection: