Pololu Motor with 48 CPR Encoder

This is the motor and encoder portion of the low-power (LP), 6 V versions of our 25D mm metal gearmotors with 48 CPR encoders. It does not include a gearbox.

Key specs at 6 V: 6100 RPM and 40 mA free-run, 1 oz-in (0.07 kg-cm) and 2.4 A stall.

This motor with integrated 48 CPR (counts per revolution) quadrature encoder is intended as a replacement low-power (LP) 6 V motor with encoder for our 25D mm metal gearmotors. It is intended for use at 6 V, but in general, these kinds of motors can run at voltages above and below this nominal voltage. Lower voltages might not be practical, and higher voltages could start negatively affecting the life of the motor.

The motor has a diameter of 24.2 mm (0.95 in) and a length of approximately 43 mm (1.7 in) from the top of the motor can to the bottom of the encoder. The top of the motor has two mounting holes threaded for M3 screws. These mounting holes are 17 mm apart and form a line with the motor shaft at the center. The mounting holes have a depth of approximately 6.5 mm.

Pinion Gear Specs

• Metric with module m = 0.4
• Number of teeth: 12
• Face thickness: 2.5 mm
• Pressure angle: 20°
• Gear position: 4.5 mm from top of motor to top of gear

Using the Encoder

A two-channel Hall effect encoder is used to sense the rotation of a magnetic disk on a rear protrusion of the motor shaft. The quadrature encoder provides a resolution of 48 counts per revolution of the motor shaft when counting both edges of both channels. To compute the counts per revolution of the gearbox output, multiply the gear ratio by 48. The motor/encoder has six color-coded, 11" (28 cm) leads terminated by a 1×6 female header with a 0.1″ pitch, as shown in the main product picture. This header works with standard 0.1″ male headers and our male jumper and precrimped wires. If this header is not convenient for your application, you can pull the crimped wires out of the header or cut the header off. The following table describes the wire functions:

The Hall sensor requires an input voltage, Vcc, between 3.5 and 20 V and draws a maximum of 10 mA. The A and B outputs are square waves from 0 V to Vcc approximately 90° out of phase. The frequency of the transitions tells you the speed of the motor, and the order of the transitions tells you the direction. The following oscilloscope capture shows the A and B (yellow and white) encoder outputs using a motor voltage of 6 V and a Hall sensor Vcc of 5 V:

Do you have a question about a product? Do you have a suggestion for the description or even found an error? Contact us!