This gearmotor is a miniature high-power, 6 V brushed DC motor with a 100.37:1 metal gearbox. It has a cross section of 10 × 12 mm, and the D-shaped gearbox output shaft is 9 mm long and 3 mm in diameter. This version also has a 4.5 × 1 mm extended motor shaft.Key specs at 6 V: 320 RPM and 120 mA with no load, 30 oz-in (2.2 kg-cm) and 1.6 A at stall.

These tiny brushed DC gearmotors are available in a wide range of gear ratios—from 5:1 up to 1000:1—and with five different motors: high-power 6 V and 12 V motors with long-life carbon brushes (HPCB), and high-power (HP), medium power (MP), and low power (LP) 6 V motors with shorter-life precious metal brushes. The 6 V and 12 V HPCB motors offer the same performance at their respective nominal voltages, just with the 12 V motor drawing half the current of the 6 V motor. The 6 V HPCB and 6 V HP motors are identical except for their brushes, which only affect the lifetime of the motor.

The HPCB versions (shown on the left in the picture below) can be differentiated from versions with precious metal brushes (shown on the right) by their copper-colored terminals. Note that the HPCB terminals are 0.5 mm wider than those on the other micro metal gearmotor versions (2 mm vs. 1.5 mm), and they are about 1 mm closer together (6 mm vs. 7 mm).

Versions of these gearmotors are also available with an additional 1 mm-diameter output shaft that protrudes from the rear of the motor. This 4.5 mm-long rear shaft rotates at the same speed as the input to the gearbox and offers a way to add an encoder, such as our magnetic encoder for micro metal gearmotors (see the picture on the right), to provide motor speed or position feedback.

With the exception of the 1000:1 gear ratio versions, all of the micro metal gearmotors have the same physical dimensions, so one version can be easily swapped for another if your design requirements change.

Please see the micro metal gearmotor datasheet (2MB pdf) for more information, including detailed performance graphs for each micro metal gearmotor version. You can also use our dynamically sortable micro metal gearmotor comparison table for search for the gearmotor that offers the best blend of speed, torque, and current-draw for your particular application. A more basic comparison table is available below.

Note: Stalling or overloading gearmotors can greatly decrease their lifetimes and even result in immediate damage. The recommended upper limit for instantaneous torque is 35 oz-in (2.5 kg-cm) for the 1000:1 gearboxes and 25 oz-in (2 kg*cm) for all the other gear ratios; we strongly advise keeping applied loads well under this limit. Stalls can also result in rapid (potentially on the order of seconds) thermal damage to the motor windings and brushes, especially for the versions that use high-power (HP and HPCB) motors; a general recommendation for brushed DC motor operation is 25% or less of the stall current.

In general, these kinds of motors can run at voltages above and below their nominal voltages; lower voltages might not be practical, and higher voltages could start negatively affecting the life of the motor.

Exact gear ratio: ``(35×37×35×38) / (12×11×13×10) ~~ bb(100.37:1)``

In terms of size, these gearmotors are very similar to Sanyo’s popular 12 mm NA4S DC gearmotors, and gearmotors with this form factor are occasionally referred to as N20 motors. The versions with carbon brushes (HPCB) have slightly different terminal and end-cap dimensions than the versions with precious metal brushes, but all of the other dimensions are identical.

Dimensions of versions with carbon brushes (HPCB)

Dimensions of the Pololu micro metal gearmotors with carbon brushes (HPCB). Units are mm over [inches].

Dimensions of versions with precious metal brushes (LP, MP, and HP)

Dimensions of the Pololu micro metal gearmotors with precious metal brushes: low-power (LP), medium-power (MP), and high-power (HP). Units are mm over [inches].

These diagrams are also available as a downloadable PDF (262k pdf).

Wheels and hubs: The micro metal gearmotor’s output shaft matches our assortment of Pololu wheels and the Solarbotics RW2i rubber wheel. You can also use our Pololu universal mounting hubs to mount custom wheels and mechanism to the micro metal gearmotor’s output shaft, and you can use our 12mm hex wheel adapter to use this motor with many common hobby RC wheels.

Pololu wheel 32×7mm on a micro metal gearmotor.

Black Pololu 70×8mm wheel on a Pololu micro metal gearmotor.

A pair of Pololu universal aluminum mounting hubs for 3 mm diameter shafts.

12mm Hex Wheel Adapter for 3mm Shaft on a Micro Metal Gearmotor.

Mounting brackets: Our mounting bracket (also available in white) and extended mounting bracket are specifically designed to securely mount the gearmotor while enclosing the exposed gears. We recommend the extended mounting bracket for wheels with recessed hubs, such as the Pololu wheel 42×19mm. Our micro metal gearmotors will also work with our 15.5D mm metal gearmotor bracket pair.

Black micro metal gearmotor mounting bracket pair with included screws and nuts.

White micro metal gearmotor mounting bracket pair with included screws and nuts.

Pololu micro metal gearmotor bracket extended with micro metal gearmotor.

Quadrature encoders: We offer several quadrature encoders that work with our micro metal gearmotors.

Magnetic Encoder Kit for Micro Metal Gearmotors assembled with ribbon cable wires.

Example of an installed micro metal gearmotor reflective optical encoder.

Note: The HPCB versions of our micro metal gearmotors are not compatible with our #2590 and #2591 optical encoders or our older #2598 magnetic encoders (the terminals are too wide to fit through the corresponding holes in the encoder boards). However, they are compatible with our newer #3081 magnetic encoders.

Motor controllers and drivers: We have a number of motor controllers, motor drivers, and robot controllers that make it easy to drive these micro metal gearmotors. For the 6 V micro metal gearmotors, consider the DRV8838 single-channel motor driver carrier, the DRV8833 dual motor driver carrier, and DRV8835 dual motor driver carrier (or DRV8835 shield for Arduino). For the 12 V micro metal gearmotors, consider the MAX14870 single-channel motor driver carrier, DRV8801 single-channel motor driver carrier, and A4990 dual motor driver carrier (or A4990 shield for Arduino).

DRV8838 Single Brushed DC Motor Driver Carrier.

Pololu A4990 Dual Motor Driver Shield for Arduino, bottom view.

DRV8835 dual motor driver carrier.

Current sensors: We have an assortment of Hall effect-based current sensors to choose from for those who need to monitor motor current:

ACS711EX current sensor carrier -15.5A to +15.5A.

ACS714 current sensor carrier -5A to +5A.

We also incorporate these motors into some of our products, including our Zumo robot and 3pi robot :

Assembled Zumo 32U4 robot.

Pololu 3pi robot.

We offer a wide selection of metal gearmotors that offer different combinations of speed and torque. Our metal gearmotor comparison table can help you find the motor that best meets your project’s requirements.

Some of the Pololu metal gearmotors.

People often buy this product together with:

This potentiometer is a two-in-one, good in a breadboard or with a panel. It's a fairly standard linear taper 10K ohm potentiometer, with a grippy shaft. It's smooth and easy to turn, but not so loose that it will shift on its own. We like this one because the legs are 0.2" apart with pin-points, so you can plug it into a breadboard or perfboard. Once you're done prototyping, you can drill a hole into your project box and mount the potentiometer that way.

This 1K potentiometer is a two-in-one, good in a breadboard or with a panel. Its a fairly standard linear taper 1K ohm potentiometer, with a grippy shaft. Its smooth and easy to turn, but not so loose that it will shift on its own. We like this one because the legs are 0.2" apart with pin-points, so you can plug it into a breadboard or perfboard. Once you're done prototyping, you can drill a hole into your project box and mount the potentiometer that way.

When you need a lot of options, you need a Mini 8-Way Rotary Selector Switch. This is basically a single-pole to 8-throw switch. As you rotate the knob around, the middle pin will make contact with each of the outer pins. Rotary switches are very simple to use and are also nice and compact. This one is easy to panel mount, thanks to the included washer and hex nut. It has a T18-size shaft so you can pick one of our T18 knobs to go with it for easier turning.

Round and round it goes, this nice round "scrubber" knob is the perfect mate to a rotary encoder.  It's got a wide 34.7mm diameter with a nice finger groove on its face so it's easy to turn with just one finger.  It works best with our rotary encoder, just snap it on and away you go.

Please note: this knob won't work with our potentiometers which have T18 spline shafts! While rotary encoders look similar to potentiometers, they're actually very different.  Rotary encoders rotate all the way around continuously, which is why a knob like this is handy, you can twist it around very fast.

Does not come with a rotary encoder

We also sell potentiometers in the Adafruit store and plenty of knobs to match if you're really just a knob fanatic.

This slim and modern potentiometer is small and compact, yet looks good and has a nice feel. We hand selected the best knobs for your project in different sizes and varieties.  This one is the Slim Metal Knob 10mm diameter x 15mm Tall (T18 Splines).

It's a brushed aluminum knob with a shiny black (anodized?) coating.  It kind of looks like the type of knob you'd find in a very fancy, modern kitchen.  There's a silver mark on the black finish so you can know where you are and figure out where you're going.  It's a good knob if you're looking for something basic and subtle and it's super tiny and subdued, we also have a shorter version.

This knob will not work on our Rotary Encoder (which has a D shaft)! It will work, however, on all of our Potentiometers (which have T18 shafts)

Knobs are a great way to finish off your project and make it easier to adjust the level of your death ray. This knob mates to a 6mm (+/- 0.3mm) shaft. The knob slides onto the potentiometer and holds tightly with a strong friction fit.

The main body of these knobs is metal with a plastic insert. The outside is knurled for precise adjustment.

Features

14mm high

24mm diameter

Knobs are a great way to finish off your project and make it easier to adjust the level of your death ray. This knob mates to a 6mm (+/- 0.3mm) shaft. The knob slides onto the potentiometer and holds tightly with a strong friction fit.

The main body of these knobs is metal with a plastic insert. The outside is knurled for precise adjustment.

Features

14mm high

24mm diameter

Add quadrature encoders to your LP, MP, or HP micro metal gearmotors (extended back shaft version required) with this kit that uses a magnetic disc and hall effect sensors to provide 12 counts per revolution of the motor shaft. The sensors operate from 2.7 V to 18 V and provide digital outputs that can be connected directly to a microcontroller or other digital circuit.Note: This version is not compatible with the HPCB micro metal gearmotors; it is only compatible with LP, MP, and HP dual-shaft micro metal gearmotors.

Discontinuation notice: This encoder is not compatible with our HPCB micro metal gearmotors (the HPCB motor terminals are too large to fit the corresponding PCB holes), but it is compatible with the LP, MP, and HP versions of our micro metal gearmotors. We have released a new version of this board that enlarges the motor terminal holes so they are compatible with all our micro metal gearmotors. The new version is functionally identical to this older version and can serve as a drop-in replacement. We will be discontinuing this product when the remaining stock is gone.

These older encoders are now only available by large-volume special order. Please contact us for more information.

Magnetic Encoder Kit for Micro Metal Gearmotors (old version; not compatible with HPCB micro metal gearmotors).

Magnetic Encoder Kit for Micro Metal Gearmotors (HPCB compatible).

This kit includes two dual-channel Hall Effect sensor boards and two 6-pole magnetic discs that can be used to add quadrature encoding to two micro metal gearmotors with extended back shafts (motors are not included with this kit). The encoder board senses the rotation of the magnetic disc and provides a resolution of 12 counts per revolution of the motor shaft when counting both edges of both channels. To compute the counts per revolution of the gearbox output shaft, multiply the gear ratio by 12.

This compact encoder solution fits within the 12 mm × 10 mm cross section of the motors on three of the four sides, and it only extends 0.6 mm past the edge of the fourth side (note: if you need it to be flush with that last side, you can carefully grind the board down a little and solder to the remaining half-holes). The assembly does not extend past the end of the extended motor shaft, which protrudes 5 mm beyond the plastic end cap on the back of the motor.

Note: This sensor system is intended for users comfortable with the physical encoder installation. It only works with micro metal gearmotors that have extended back shafts.

The encoder board is designed to be soldered directly to the back of the motor, with the back shaft of the motor protruding through the hole in the middle of the circuit board. One way to achieve good alignment between the board and the motor is to tack down the board to one motor pin and to solder the other pin only when the board is flat and well aligned. Be careful to avoid prolonged heating of the motor pins, which could deform the plastic end cap of the motor or the motor brushes. Once the board is soldered down to the two terminals, the motor leads are connected to the M1 and M2 pads along the edge of the board; the remaining four pads are used to power the sensors and access the two quadrature outputs:

The sensors are powered through the VCC and GND pins. VCC can be 2.7 V to 18 V, and the quadrature outputs A and B are digital signals that are either driven low (0 V) by the sensors or pulled to VCC through 10 kΩ pull-up resistors, depending on the applied magnetic field. The sensors’ comparators have built-in hysteresis, which prevents spurious signals in cases where the motor stops near a transition point.

Encoder A and B outputs of a magnetic encoder on a high-power (HP) micro metal gearmotor running at 6 V.

The board’s six pads have a 2 mm pitch, so they do not work with common 0.1″ connectors. One option for connecting to the board is to solder in individual wires, such as in the example below:

Alternatively, you can solder a 2mm-pitch connector to the board. The examples below show a male header, which gives you the option of making a detachable cable terminated by a 6-pin 2mm-pitch female header. If the pins are angled over the motor, as shown in the picture below, they will just barely protrude through the holes in the board. Note that in this orientation, there is room to plug in a female header even when our extended micro metal gearmotor bracket is being used.

If the pins are pointed away from the motor, they will need to be angled so that they sufficiently clear the magnetic disc. With a decent soldering iron, it is possible to solder them in this orientation even after the encoder has been installed on the motor.

Once the board is soldered to the motor, the magnetic encoder disc can be pushed onto the motor shaft. One easy way to accomplish this is to press the motor onto the disc while it is sitting on a flat surface, pushing until the shaft makes contact with that surface. The size of the gap between the encoder disc and the sensor board does not have a big impact on performance as long as the motor shaft is at least all the way through the disc.

This schematic is also available as a downloadable pdf (125k pdf).

People often buy this product together with: