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Project Notes

#203 HomopolarMotor

Build a basic homopolar motor.

Here’s a quick video of the circuit in action:



The homopolar motor was the first electrical motor to be built. Its operation was demonstrated by Michael Faraday in 1821 at the Royal Institution in London. It is also the operating principle behind railguns!

The basis of operation is pretty simple, once you understand magnitic and electric fields - which back then was really the edge of science.

The homopolar motor is driven by the Lorentz force.

The current from the battery flows through the wireframe. This intersects the magnetic field of the neodynium magents which is roughly perpendicular. The right-hand rule simplifies the understanding of the resulting force, which causes the motion.


Scam Alert

There are lots of demonstrations that claim “free energy”. Unfortunately, there is no such thing. Electrical potential of the battery is consumed in running the motor. Although it may not seem like it at first, the wire frame actually (intermittently) completes the circuit from positive to negitive of the battery, establishing the electric field. In fact the demo video shows how easy it is to deplete a battery in such a configuration!


The Build

Credits and References

About LEAP#203 Kinetics
Project Source on GitHub Return to the LEAP Catalog

This page is a web-friendly rendering of my project notes shared in the LEAP GitHub repository.

LEAP is my personal collection of electronics projects, usually involving an Arduino or other microprocessor in one way or another. Some are full-blown projects, while many are trivial breadboard experiments, intended to learn and explore something interesting (IMHO!).

The projects are usually inspired by things found wild on the net, or ideas from the sources such as:

Feel free to borrow liberally, and if you spot any issues do let me know. See the individual projects for credits where due. There are even now a few projects contributed by others - send your own over in a pull request if you would also like to add to this collection.