This is a stepper motor.

This is a stepper motor. It's a pretty simple little component. Not very big, not a lot going on. But it is the most common way of achieving movement in a lot of electronics. There are stepper motors mounted to every axis of things like 3D printers and CNC routers. And even though it gets controlled by a simple four-wire cable, there's a surprisingly large amount that goes into controlling one of these. There are some super useful shields like this one that can sit right on top of an Arduino Uno and control up to four stepper motors from one project. But it does use most of the pins available on the Arduino. So if you want to control it from just one or a couple pins, you might want to just go get a servo motor driver like this one. This is a stepper motor driver. I like the stepper motor driver for teaching purposes as well, because it has basically everything involved in controlling a stepper motor called out pretty clearly. Over half is the easiest to talk about. It needs voltage and ground, and it calls out right here that it can take between 9 and 42 volts DC. I've got it hooked up to a combo power supply that can do 12 volts or 24 volts. I could put it on 24 volts, but 12 volts works fine for this. Next, super simple, but important to get the orientation right. You have A+, A-, B+, and B- coming off the motor. And then going into these four coils. And then the top half looks like a lot, but it gets pretty simple when you remember half of them just get landed on zero volt DC. Enable, which will stop it or start it from running using a 5-volt signal. Direction, which will change what direction it turns using a 5-volt signal. And then pulse, which is the thing that actually tells it to take steps using a 5-volt signal. You can use something that can do pulse width modulation. Basically, if pin 3 is connected to ground, don't turn. But if it's connected to 5 volts, rotate. I can get it to turn. And if I remove it and land it on ground, I let it turn freely. If I take the direction signal and I put it on positive 5 volts, I can get it to turn. And if I put it back on zero volts, I can get it to turn back. So it may seem like quite a mess of wires, but it's really just doing a few simple things to achieve pretty cool control. And a stepper motor is a high-torque, precise way of getting motion.