This instructable will show how to reuse an old stepper motor I found at the amazing Trash for Teaching warehouse in Gardina CA. This resource for educators houses industrial cast-offs which could be used in the classroom for Art, Science or general Maker projects.
Recently T4T got a shipment of these . . . thingamabobs, which happened to contain some kind of motor inside. Unsure of whether they were working or not, I did some research and what you are about to read is the benefit of my labor.
Step 1: About Stepper Motors
After removing the motor from the casing by taking off the two screws on the back side and clipping the wires, I took a look at what I had.
This type of motor is called a stepper motor. If you haven't worked with one before, I recommend the great SparkFun tutorial on motors, available here. The basic idea with stepper motors, is that each of the signal wires needs to be lit up in sequence, moving the internal geared motor step by step (hence the name, stepper motor).
The problem with using an Arduino for this is that an Arduino simply doesn't carry enough charge to power such a hefty motor. It pulls 5 Volts, where these motors require 18.
One solution is to use a motor shield.
Step 2: Motor Shields
I happened to have a Grove Motor Shield on hand, which was perfect for working with the higher voltages necessary for this motor. While I used the Grove motor shield, there are a variety available from Sparkfun or Adafruit.
There are two screw poles on one end for an external power supply, and four for connecting the terminals of the motor. The image shows how the colored wires should be attached to this motor.
I powered this via a desktop variable power supply at 18 V (see image). The power should be plugged into the remaining two screw holes in the shield, power and ground.
Step 3: The Code
The code below shows how to control the motor through an Arduino sketch.
Upload this through your Arduino IDE to your board and you should be good to go. It simply makes one full rotation of the motor, then rotates the opposite direction.
If you have questions - hit me up in the comments!