Though more complex than standard DC motors, stepper motors have many advantages, including easy control by computer, precise control of rotation and high torque at low speeds. If you're building your own robot or other system that uses a stepper motor, you'll need to choose a DC power supply to run the motor. Stepper motors work better at voltages several times higher than their rated voltage. Electronic parts distributors stock a range of power supplies specially suited for stepper motors.
Determine the number of stepper motors in your system design that have the same voltage requirements. Add their current ratings together to determine the total current they will need. For example, if you have three motors, each needing 1/2 amp of current, your total current requirement is 1.5 amps.
Examine the stepper motor specifications and find the voltage rating on the motors. Multiply the voltage by 10 to arrive at the voltage the power supply needs to produce.
Look through the power supply section of the electronics distributor catalogue. It may have a dedicated section for stepper motor supplies. Select an unregulated power supply with the voltage and current ratings you determined in earlier steps. If your budget allows, choose a power supply with a voltage rating 20 times higher than the stepper motor's.
The amount of current a stepper motor needs depends on the mode in which you plan to use it. A full-step mode has higher current demands than a microstep mode. This will affect the total amount of current your power supply must provide.