Stepper Motor Controller with a Parallel Port

Controlling Stepper Motor with a Parallel Port Scheme

Controlling Stepper Motor with a Parallel Port Physical

This is an easy to build stepper motor driver that will allow you to precisely control a unipolar stepper motor through your computer's parallel port. With a stepper motor you can build a lot of interesting gadgets such as robots, elevator, PCB drilling mill, camera panning system, automatic fish feeder, etc. If you have never worked with stepper motors before you will surely have a lot of fun with this project.

How Stepper Motor Works?

Stepper motors are very different from a regular DC motors. Instead of spinning like DC motors do, stepper motor steps at a specific resolution for each pulse. The motor that we are using needs 48 steps / pulses just to complete a single revolution! That should be enough to tell about its precision.

Another advantage of stepper motors is the fact that their speed of rotation can be achieved almost instantly even if you change the spinning direction.

Stepper motor consists of a rotor - the permanent magnet that rotates inside, and stator - four coils (north, east, south, west) that are part of the case, and which don't move. Rotor can be moved by sequentially applying a pulsed DC voltage to one or two coils at a time.

Unipolar motor should have five or six connections depending on the model. If the motor has six connections like the one pictured above, you have to join pins 1 and 2 (red) together and connect them to a (+) 12-24V voltage supply. The remaining pins; a1 (yellow), b1 (black), a2 (orange), b2 (brown) should be connected to a driver (ULN2003) as shown on the schematic.

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