There are two types of stepper motors: unipolar and bipolar. For each motor, different circuits are required.
Unipolar stepper: This motor works with one winding with a center tap per phase. Each section of the winding is switched on according to the desired direction of the magnetic field. The magnetic pole can be reversed without switching the direction of the current. Note that these motors are less available in the market compared with bipolar ones, given that their efficiency is only up to 50%. This is a result of the unipolar steppers having twice as much wire as they can use at one time.
Bipolar steppers: In these motors, there is only one winding per phase. A more complex circuit is required to reverse the magnetic pole, given that the current in the winding needs to be reversed. This means that it usually needs an H bridge arrangement. Yet, bipolar motors are more powerful than unipolar ones. They are recommended for more sophisticated tasks, and also are more expensive than the former.
So… which one should I use?
Here’s a brief comparison to help you choose the correct motor for your project. When following a guided project, you will certainly get detailed information on the components required.
Pro Bipolar: Unipolar motors will only use half of the winding at a given time, while bipolar uses the entire winding. The last one uses a bidirectional current flow. As a consequence, torque will be greater in bipolar motors than in a unipolar one. Additionally, the thinner coil wire in unipolar motors implies that more wire is needed. this last factor increases the resistance in the motor. Its implication is higher power consumption.
Pro Unipolar: In favor of the unipolar motors, these motors are simpler to use and so require an easier circuit. Additionally, they are cheaper and will use less of your driving board’s capacity.
Therefore, according to your current proficiency level and budget you should decide for one or the other. Affordable motors of each type are readily available, as you can get our budget selection below. Additionally, forums and communities online can offer great support overcoming your beginner doubts.