Metal Gearmotor with Encoder - 12V (9.7:1)

Sparkfun's Metal Gearmotor with Encoder is a 12V, low-power brushed DC motor, combined with a 9.68:1 metal spur gearbox. It includes an integrated 48 CPR (counts per revolution) quadrature encoder on the motor shaft, providing 464.64 counts per revolution of the gearbox’s output shaft. This cylindrical gearmotor is just shy of 25 mm in diameter, and features a D-shaped output shaft, 4 mm in diameter, which extends 12.5 mm from the face plate of the gearbox.

The gearmotor employs a two-channel Hall effect encoder to sense the rotation of a magnetic disk on a rear protrusion of the motor shaft. The quadrature encoder offers a resolution of 48 counts per revolution of the motor shaft when counting both edges of both channels. To calculate the counts per revolution of the gearbox output, simply multiply the gear ratio by 48. The motor/encoder comes with six color-coded, 20 cm leads terminated by a 1×6 female header with a 2.54mm pitch.

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. This allows you to determine the speed of the motor from the frequency of the transitions, and the direction of the motor from the order of the transitions.

Please note that the listed stall torques and currents are theoretical extrapolations. Units will typically stall well before these points as the motors heat up. Stalling or overloading gearmotors can greatly decrease their lifetimes and even result in immediate damage. The recommended upper limit for continuously applied loads is 4 kg⋅cm, and the recommended upper limit for intermittently permissible torque is 8 kg⋅cm. Stalls can also result in rapid thermal damage to the motor windings and brushes; a general recommendation for brushed DC motor operation is 25% or less of the stall current.

The Metal Gearmotor with Encoder features a voltage of 12V, a stall current of 0.9A, a no-load current of 60mA, and a gear ratio of 9.7:1. It has a no-load speed (RPM) of 580, a stall extrapolation of 1.3 kg⋅cm at 0.9 A, and a max power of 1.8W.