Let’s build an electric motor. “An electric motor is an electrical machine that converts electrical energy into mechanical energy.” We won’t go into exactly how the electricity makes this motor work because that would be a book all on its own, so let’s build this motor and have fun! To learn more about the technical knowledge of electric motors I suggest you start by reading the Wikipedia page.
Bill of Materials (BOM):
2 – Paper Clips
1 – Battery or power supply: D cell, 9 volt, AA, 2 AA, benchtop power supply
1 – Bread Board, card board, piece of wood to mount the motor or rubber bands to hold paper clips to end of D cell battery
1 – Magnet – Can be a bar, circular, or just about any shape. I used 2 – 13mm diameter Neodymium magnets, and 1 5mm diameter magnet stacked one on top of the other. I drilled a hole in the board to prevent the magnets from snapping to the paperclip axles. These rare earth magnets are extremely powerful. Our motor with these magnets turns at 180 RPM and seems to have much more power than you would get using plain ceramic magnets.
1 – Magnet Wire 22 AWG. It is a lacquer coated copper wire. You can try using insulated wire but your results will probably not be as good as you would get using the proper wire.
1. Wind the 20 AWG magnet wire into a 20mm circle, making about 12-15 loops. It helps to wrap the wire around a cylinder of some sort to get better results. The coil you have just made is called a rotor. You want to have a lead coming from each side of the coil about 20mm in length.
2. Holding the coil upright put one of the leads on a flat surface. Using a razor knife or a small piece of 220 sandpaper, remove the lacquer coating from only the very top surface of the wire. Leave the coating intact on the sides and bottom. Remove the lacquer from the wire from the very end to right up to where the lead meets the rotor.
3. Remove the lacquer from the other lead completely, 360 degrees around. Again from the tip of the lead all the way to where it meets the rotor.
4. Straighten your paperclips and make an axle rest at one end. Needle nosed pliers are very handy for this part of the build. You should make them about 25mm long. Place your axles 60mm apart.
5. Place your magnet in the center between your axles. Hot glue is good to prevent the magnets from snapping to your metal axles. I drilled a deep hole that could hold all three of my magnets. Using the rare earth magnets which have a very powerful attraction, drilling a hole in your base is a good way to prevent your magnets from snapping over onto your paperclip rotor supports.
6. You can also drill a very small hole in the base to place your axles into for a strong motor. You can also thumbtack them down, or use any other method you can think of, you just want them solid enough to stand upright.
7. Now set the rotor onto the paperclip axles. You want your rotor directly over the magnets and close to them as well. You can place cotton from a cotton ball into the hole to raise the magnets, or any thing that will shim them to just below the path of the rotor as it spins.
8. Connect your power to your rotor supports by whatever means you have available. If you’re using a benchtop power supply you can connect your alligator clips to the axles. That is a great way to adjust the height of your axles also, letting the alligator clips hold the paperclips at the right height. If you’re using a D cell battery you can stand an axle at each end of the battery and wrap the rubber band around the entire setup. I don’t suggest doing it that way but it does work.
9. Turn on your power supply at 3.3 volts to begin with and increase if needed. Or connect your battery. The neodymium magnet motor sometimes started spinning on its own as soon as the power was turned on. This happened when sending 5v to the motor. You probably will have to bump the rotor slightly to get it started. You should see which direction it has a tendency to spin and that is the direction you want to push the rotor to start it spinning.
In this video the motor is powered by two AA rechargeable batteries that supply 1.2v and 2700mA each. Watch it go!
10. If all is well you should have it running now. Usually some fine tuning is needed to get things working perfectly. Cutting a small disc from a business card and placing on the rotor leads can prevent the rotor from moving laterally and falling off the axle supports.
If your motor still does not run, double check your work! Make sure the lacquer coating was removed exactly as instructed.
When you’re finished turn off the power and put away your tools, any scraps of wire that may have fallen on the floor, etc. A clean and orderly workshop is a safe workshop. Also you don’t want to leave a mess for someone else to clean up. The electronic hobby is a great way to learn, have fun, and make wonderful things that will improve your quality of life. It also is a great way to share your time with your children. This is a fantastic hobby so treat it with respect and be safe. We hope you have enjoyed creating this motor, and reading this tutorial as much as we have had making it. Putting this together for you and spreading the knowledge of the hobby of electronics has been a privilege.
Volthaus Electronics Laboratory
Sept. 27, 2015