WorkshopMotorControl

Note: This Page is Still Under Construction

Motors are one of the most common ways we move things with electricity in the physical world. You can scavenge them from optical disc readers, printers, or toys and use them for your own projects. The most common reusable types are brushed DC motors (found in most smaller items) and stepper motors (in more industrial places, or really old printers).

This workshop is going to focus on brushed DC motors because those are the cheapest and found in the sorts of toys you'll find in thrift stores for less than the original cost of the motors themselves. The added bonus here is that the motors are still attached to something interesting! A neat example is a toy car that can be re-purposed as a robotics platform. Many already even have the circuits needed for controlling the motors, and all that's needed is to send the right signals.

We'll be working from the ground up though, so make sure you've got the supplies you need and come by to work with us.

Required Supplies

• Laptop (for following along)
• Arduino (optional)
• A good attitude :D

Kit Contents ($20)

• 10 transistors (PN2907ABU, 40V @ 800mA)
• 10 diodes (Almost any will do, they're for shunting)
• 4 resistors
• 2 push buttons
• 1 breadboard
• A toy containing motors to control (mostly cars)

Pre-class Preparation

There's actually very little needed before coming in for this one. If you're interested in trying to run your project from your own Arduino, feel free to bring one. We'll have one pre-programmed to show off speed control.

In-class work

We'll be working our way up from controlling the motors with bare wire to controlling them with push buttons that could later be replaced by an Arduino. Let's get started!

Now, a motor is just a set of electromagnets that can spin. There is lots of information online as to how they work, so we'll just treat them as magic for now and you can look them up later. What we care about is how to control them so we can use them to make neat stuff like robots or toys.

The easiest way to turn a motor on and off is to connect them directly to a DC power source. DC power is what all of our handheld devices use, and what comes out of USB ports and batteries. It means that the electricity flows only one way from the source. So, let's try this out.

Step 1: Hook up a motor

The kits should have four wires, two sets for each motor. If you don't have a kit, you can take apart a broken CD/DVD/BluRay drive or player and steal some out of there. It's a great excuse to find out how those are put together anyway.

We'll need to get two of those motor wires connected to the two power leads through the breadboard. Now, a breadboard has connections between each hole. For the ones in the middle, they run from left to right, breaking in the middle. There are also lines that run from top to bottom, but the vertical lines in the kits only run in sets of three. You should be able to see this from the bottom of our breadboards, but you can also read more on breadboards and see an example at Sparkfun!

Troubleshooting

Make sure the transistors are the right way! This could be a challenge. They have a little D shape to them, so make sure they're all facing the same direction.