Homopolar Led Lighting




Introduction: Homopolar Led Lighting

About: Computer and Technology Teacher (Spain, Andalucía)

"A homopolar motor is a direct current electric motor with two magnetic poles, the conductors of which always cut unidirectional lines of magnetic flux by rotating a conductor around a fixed axis that is parallel to the magnetic field. The resulting EMF (Electromotive Force) being continuous in one direction, the homopolar motor needs no commutator but still requires slip rings. The name homopolar indicates that the electrical polarity of the conductor and the magnetic field poles do not change ... 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." (https://es.scribd.com/document/254189611/Homopolar...)

While I was reading this article, I thought it would be cool to add led lighting to the device.

To achieve this goal I have built a special configuration of the homopolar motor doesn´t use batteries but a 3 V power supply and more magnets to increase the contact surface and so the Lorentz force.

The main difficulty of this project has been to achieve the leds light while the conducting wire turns.

Here is the result I hope you like.


  • Acetate sheet
  • (20) Countersunk Magnets
  • Tin rods
  • Wire
  • Screw and nut
  • 3 V power supply
  • (3) 3 mm. green led
  • Methacrylate
  • Wooden rods

Step 1: Build an Acetate Cylinder (Main Body)

Step 2: Build the Negative Pole Terminal

Open a center hole in a wooden wheel to insert the magnets as you can see in the first image.

In the reverse side, use a piece of cooper sheet, a little screw and several magnets to connect the negative pole (black wire) as you can see in the second image.

Step 3: Build the Positive Pole Terminal and Insert It in the Main Body

Using a screw, a nut, a piece of wire and several magnets you can build the positive pole terminal as you can see in the first image. After that glue it in one of the extreme of the main body.

Step 4: Mounting the Base

Glue the positive pole to a methacrylate base with four wooden legs.

Previously I have opened a center hole in the methacrylate base.

Step 5: Soldering the Led Lights

In this project I have soldered three 3 mm green leds

Step 6: Conducting Wire Shape

To achieve the leds light at the same time the conducting wire (tin rod) turns, is not possible.

Then, why the leds are lighting?

Because the conducting has been built with two branch: the first branch maintain the contact between the poles of the power supply and the second branch is used to light the leds. Both branch are soldered and in contact with the positive pole, but both branch are in contact with the negative one but not soldered as you can see in the first image.

So, when both branch touch the negative pole, the conducting wire turns but the leds doesn´t light. Only when the conducting branch doesn´t touch the negative pole and the leds branch touch it, the leds light.

To improve the contact with the positive pole, I have placed a piece of coil sheet with a magnet as you can see in the second image

Step 7: Connecting the Power Supply

In this project I have used a 3 V power supply to generate the intensity needed.

WARNING: you have into account that whatever battery or power supply you connect, will work in short circuit almost all the time and a very high intensity is generated by the motor that may damage it.

Step 8: How It Works

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