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I have seen this motor attributed to various people lately. However, I saw it many years ago, in an old book with one of those titles like "101 Electrical Experiments Boys Like to Make", which unfortunately I no longer have. I'm sure it has be reinvented countless times. This is just my iteration.

The setup shown above is what I have students build. Grades 3 through High School have built these, with varying degrees of assistance.

Materials required (per motor): Two feet of 22 gauge magnet wire, a 1/2" PVC coupler or similar approximately 1 1/8" form to wrap the wire on, a switch (store bought or make one) 2 jumbo paper clips, 2 thumbtacks, a magnet, a block of wood around 1x4x6", a 6v lantern or 9v battery, and 3 jumper wires, which can be pre-made store bought ones or simply pieces of wire.

Radio Shack sells magnet wire in a 3 spool pack, containing one spool each of 30, 26 and 22 gauge, part #27813450. One such pack will see you through most of the experiments on these pages. One disadvantage of this wire is that the 22 gauge has a clear coating and is difficult to see when stripping the wire. Radio Shack also sells magnets, batteries and jumper wires.

The first step in making a simple motor is wrapping the coil that forms the armature. I use 22 gauge magnet wire. Other gauges will work, but you may have to experiment with the number of turns. Wrap 3 turns on to a form that is about 1 1/8" in diameter. I use ½" PVC couplers, available at any hardware store.

When finished wrapping, there should be 3 wraps on top and 2 wraps on the bottom. The next step is a little tricky for younger students. Take one end of the wire, and wrap it around the coil, as shown below.

Here is the tricky bit: Do the same with the other end of the wire, but it MUST be directly across from the first one. If it isn't the motor will be impossible to balance and make spin smoothly. This step can be difficult for younger students, but grades 6 and up generally have little trouble on their own. Go over this step carefully and in detail. Cut the wires to about 2".

The finished product is called an armature. When you look at the armature, you will see that it has 3 wraps on one side and 2 on the other. We will call the 2 wrap side top and the 3 wrap side bottom. This definition comes into play in the next step.

Now comes the hardest part, both to do and for me to describe. It's one of those things that is quite easy once you have done it. The magnet wire is insulated. In order for the motor to run, this insulation must be stripped in the proper manner or the motor will not work.

Take a pair of scissors, and strip one end of the armature all the way around. Make sure to get up close by the coil. The other side is done differently. Hold the armature so that the bottom (with 3 wraps) of the coil is facing down. Strip only the insulation from the bottom and a little from the sides lengthwise along the wire!

Note that an emery board or some sandpaper can also be used to strip the wire. Younger students often do better with this method.

Take 2 jumbo paper clips, and bend them as shown. Try to make them fairly even, but they can be adjusted later. This step can be difficult for younger students as the paper clips can be hard to bend.

Mount the paper clips using thumb tacks. I use pine 1 by 4 cut into 6 inch lengths to mount on. Place the magnets in position. In the picture below, I am using two doughnut style magnets. If larger rectangular magnets are available get them as they work better. Almost any magnet will work, however.

Be sure to tell students NOT to hook up the battery until this next step is complete.

Set the armature into the loops of the paper clips as shown, and then twirl it to see how well it spins. Straighten the armature until it spins freely. This step is important for the best possible performance of the motor.

Congratulations! You just finished your motor. The only thing that remains is to connect the switch and battery, and give your motor a try!

Start by connecting a wire between one side of the switch and the battery. Connect another wire from the other side of the switch to the paper clip on one side of the motor. Hook the other side of the battery to the other paper clip of the motor. For a circuit diagram, click HERE. Looking at the this picture at full size shows the connections as well.

Have one student depress the switch, and another spin the motor to give it a start. Make sure to firmly caution the students that if the motor doesn't spin to release the switch IMMEDIATELY. If the motor comes to a stop quickly, try spinning it the other way.

Safety Note: I usually let students take their motors home. If you do so, tell the students this: DO NOT CONNECT YOUR MOTOR TO CAR BATTERIES OR TO WALL OUTLETS! This will result in a shower of sparks and molten metal, and in the case of the wall outlet, blow the breakers or fuses, resulting in parents taking a dim view of science. Guess how I know this...

Troubleshooting: Most problems are due to one of three causes. Poor or incorrect stripping of insulation is by far the biggest culprit. One recommendation here is to get wire that is coated in red or green. The clear insulation I have is hard to see, so the next batch will be a different color! Misalignment of the armature is the next biggest offender, and poor connections the third. These motors have a limited life, as the insulation on the half-stripped side eventually wears off.

How does it work? As any of my students would be happy to tell you, anytime an electric current is passed through a conductor, it makes a magnetic field. So when we hit the switch on the motor, the armature becomes an electromagnet. Assuming that the magnet is sitting with the North side of it up (it doesn't matter which is up) this is the sequence of events:

You give the motor a spin. When it reaches the stripped part of the armature, current flows, forming an electromagnet. The North of the electromagnet is repelled by the North of the magnet, giving the armature a push, and it spins past the stripped insulation, and the current ceases to flow. Inertia carries it around until the stripped portion makes contact again.

This is why it is so important to strip only ½ of the insulation on the armature. If the current flowed uninterrupted, as soon as the South side of the armature reached the North side of the magnet, it would of course be attracted and cease to turn.