This low cost board from Pololu Robotics can control a single bi-polar stepper motor at up to 2.2 amps and 45 volts (1.5 amps without additional cooling). However, there are now many low cost solutions such as the DRV-8825 bi-polar stepper driver: ![]() This changing polarity requires a more complex driving circuit. Bi-polar stepper motors are called bi-polar because current needs to alternate directions across the coils to change the magnetic poles. You can tell the motor is bi-polar because it has 4 wires (2 for each coil). speed curve which is helpful in selecting a motor (among many other factors). The stepper motor datasheet should provide a torque vs. The faster the motor’s rotation the less torque. When a motor turns, its torque is reduced. Holding torque assumes the motor isn’t turning. This measure of strength means the stationary motor can hold a weight of 570 ounces on a 1 inch radius pulley. NEMA 23 just refers to the dimensions of the face plate (2.3″ x 2.3″). ![]() ![]() Here’s a NEMA 23 570 oz-in bi-polar stepper motor from a CNC router: This makes them very popular for 3D printers, CNC routers and robotics. Stepper motors are brushless DC motors whose rotation is divided into a distinct number of steps which provides very accurate positional control and repeatability.
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