Small DC Motors with Encoders.
12 to 55 VDC PWM operation.
10 Jan 10
Model       DCMTR-20

Motor diameter                  1 inch 
Motor length                       1.5 inches
Output shaft diameter        0.093 inches
Output shaft length              0.375 inches
Encoder diameter              1.25 inches

Small motor and large motor shown together for comparison.
Motor selection
Motor                  Size            Volts       Encoder Dia      Slots in encoder   Price
DCMTR-201       Small          12-24       1.250                      16                           $19.00
DCMTR-203       Small          12-24       1.250                      35                           $19.00
Showing motor with high count encoder
EncoderGeek / EncoderGeek
These DC motors uses 2 phase (quadrature) incremental encoders to detect the speed of the motor and the distance it has travelled. 

These motors are designed to run at 6 to 24 volts DC and they draw less than 3 amps w/locked rotor.   (This is normally referred to as the stall current and is usually  the maximum current draw for the motor).  Motors are rated at 12 VDC but can be kicked up to 24 VDC for short periods to get a higher power level if the amplifier used to run the motor can provide the needed power.

Controller and Amplifiers for these motors should be able to provide a continuous current of 3 amps and extremely short bursts of 6 amps.   Popular, amplifiers and controllers based on the National Semiconductor LMD18200 series chips will do this.
Connector Kit      CK-1

Provides two four pin encoder connector with pins and housings and a male/female power connector to simplify the connection of the motor to the controller and the motor power supply.
Go to Page
Price                     $5.00 ea.
Small motors shown with coarse encoders