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How to Build a Stepping Motor Circuit

Stepping motors are brushless motors driven by electricity. Essentially, they are composed of two major parts: the inner rotor and a stator. The rotor is a metal gear and sits on a shaft upon with is rotates. The rotor and the shaft are encircled by the stator, which as teeth similar to those of the rotor gear, except there are metal coils wound around the teeth, or poles, of the stator. When an electric current passes through the coils, the poles of the stator become magnetized. The teeth of the rotor are attracted to the poles of the rotor, turning the shaft by a short predetermined distance (usually between 7 and 15 degrees).

Things You'll Need

Microcontroller
Voltage source
Resistors
Capacitor
Breadboard
Wire
Soldering gun
Solder
PCB
Etchant solution
Circuit design software

Instructions

- 1
  Select the motor type. There are innumerable applications for a stepper motor, and its purpose determines the type of motor necessary for your project. Very small stepper motors are used in consumer electronics such as DVD players and hard drives. On the other hand; larger devices such as Segways need larger, more powerful stepper motors.
- 2
  Determine the project parameters. The size of your power source, and the amount of current that other components in the electronic device draw, also plays a part in motor selection. Ideally, you want to run the motor at its maximum power dissipation level for cost efficiency reasons.
- 3
  Design the circuit. Generally, a stepper motor driver circiut consists of the motor itself and an integrated circuit. Other elements may include a microcontroller, sensors and more. Designing the circuit on a computer ensures the layout is clean. CadSoft̵7;s Eagle PCB is a computer-aided design (CAD) program that allows for easy design and even tests for proper connectivity. A demo version of the program is available at the CadSoft website.
- 4
  Design circuit. Generally, a stepper motor driver circuit consists of the motor itself and an integrated circuit. Other elements may include a microcontroller, sensors and more. Designing the circuit on a computer ensures the layout is clean. CadSoft̵7;s Eagle PCB is a computer aided design (CAD) program that allows for easy design, and even tests for proper connectivity. A demo version of the program is available on the CadSoft website.
- 5
  Assemble circuit on a breadboard. If your ultimate goal is to permanently put this motor into another device, this step might seem unnecessary. However; testing the circuit now on the breadboard now saves headaches later, after you finish soldering. Though it is possible to desolder components, the process is especially annoying; avoid it in the first place, if you can.
- 6
  Design the PCB. After you design the circuit on the computer, print it out onto transfer paper and use an iron to transfer the drawing to a blank piece of printed circuit board (PCB).
- 7
  Etch the PCB. Remove the paper and submerge the PCB in an etching solution until excess copper is dissolved. Submerge the PCB in soapy water for 10 minutes. Use a Q-tip to wipe off the remaining ink. Drill holes into the PCB where component leads are to be soldered.
- 8
  Solder the components onto the PCB. Poke leads through the holes and apply solder. Once finished, snip excess wire leads.
- 9
  Apply power to the circuit and test.

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