Stepper Motor: Bipolar, 200 Steps/Rev, 20x30mm, 3.9V, 600mA

This small hybrid bipolar stepping motor has a 1.8° step angle (200 steps/revolution). Each phase draws 600 mA at 3.9 V, allowing for a holding torque of 180 g-cm (2.5 oz-in). With a weight of 60 g, this is the smallest stepper motor we carry.Note: As of July 16, 2012, this stepper motor has a D-shaft in place of the previously cylindrical shaft. The shaft diameter is still 4 mm, but now a section of the cylinder has been flattened by 0.5 mm. Adapters that worked with the previous shaft should work fine with the new shaft, and the flattened section lets the new shaft work better with set screws.

Bipolar stepper motor wires are terminated with bare leads.
Bipolar stepper motor wiring diagram.


This small hybrid bipolar stepping motor has a 1.8° step angle (200 steps/revolution). Each phase draws 600 mA at 3.9 V, allowing for a holding torque of 180 g-cm (2.5 oz-in). The motor has four color-coded wires terminated with bare leads: black and green connect to one coil; red and blue connect to the other. It can be controlled by a pair of suitable H-bridges (one for each coil), but we recommend using a bipolar stepper motor driver.

Our 4mm universal mounting hub can be used to mount objects on the stepper motor’s 4mm-diameter output shaft.

    Size: 20 mm square x 30 mm, not including the shaft (NEMA 8)
    Weight: 60 g (2 oz)
    Shaft diameter: 4 mm “D”
    Steps per revolution: 200
    Current rating: 600 mA per coil
    Voltage rating: 3.9 V
    Resistance: 6.5 Ohm per coil
    Holding torque: 180 g-cm (2.5 oz-in)
    Inductance: 1.7 mH per coil
    Lead length: 12 in


The following diagram shows the stepper motor dimensions in mm. The dimension labeled “Length” is 30 mm. The output shaft has a length of 15 mm and a diameter of 4 mm. Though not shown in the diagram, the output is a D-shaft with a section that is flattened by 0.5 mm.

The inside of a bipolar stepper motor.

Stepper Motor Applications

Stepper motors are generally used in a variety of applications where precise position control is desirable and the cost or complexity of a feedback control system is unwarranted. Here are a few applications where stepper motors are often found:

    CNC machines
    3D printer/prototyping machines
    Laser cutters
    Pick and place machines
    Linear actuators
    Hard drives



Size:     20 mm square x 30 mm1
Weight:     60 g
Shaft diameter:     4 mm
General specifications
Shaft type:     4 mm "D"
Steps per revolution:     200
Current rating:     600 mA2
Voltage rating:     3.9 V
Holding torque:     2.5 oz·in
Resistance:     6.5 Ohm2
Inductance per phase:     1.7 mH
Lead length:     12 in


1    Not including the shaft.
2    Per coil.