Homopolar Motor

In this Instructable I show you how to make a simple homopolar motor. In the previous YouTube project I made a Maglev train. For this I purchased a number of Neodymium magnets. While searching for what else is possible with these magnets, I came across a number of homopolar motors. They are often very simple but I continue to find them fascinating to see.

How it works:

The homopolar motor is driven by the Lorentz force. As it moves through a magnetic field, the conductor is pushed through a magnetic field by opposing forces. This force induces a torque around the axis of rotation. Because the axis of rotation is parallel to the magnetic field, and the opposing magnetic fields do not change polarity, no commutation is required for the conductor to keep turning.

Video tutorial:

For this simple project you need the following parts:

• Neodymium magnets
• Copper wire
• AA battery

I have chosen to use the spiral shape as an example in this Instructable. Many more shapes are possible, in the last step I show a few more that I have made. For the motor to function properly it is important that the weight of the copper wire is well distributed. One end of the copper wire comes on top of the + pole of the battery, the other part must balance on this.

To make a nice spiral I looked for an object that has a slightly larger diameter than the battery. A permanent marker pen has the ideal diameter. Wrap the copper wire around the marker a few times.

The copper wire I used has no protective layer and therefore conducts well. Copper wire with protective coating can also be used, but the layer must be removed from the contact points.

As indicated in the previous step, one end of the copper wire comes on the + pole of the battery. Bend the end so that it is centered on the + pole, the spiral must still have slack on all sides of the battery.

Mount the magnets to the - pole of the battery.

Neodymium magnets are very strong! watch out that no skin gets in between ...

Now bend the other end of the copper wire so that it touches the magnets and completes the circuit. You can already feel that the copper wire wants to turn.

The homopolar motor is ready! Place the battery with the magnet down on a level surface and put the copper wire on it. As mentioned, you can make many different shapes. It is important that the copper wire is well balanced, if this is not the case, it will run off the + pole and stop spinning.

My personal favorite is the triangle shaped one. This is where electronics, magnetism and gravity come together, I love it.

Video tutorial