Introduction: Simple Homopolar Motor

Picture of Simple Homopolar Motor

The first homopolar motor was demonstrated by Michael Faraday in 1821. He was experimenting with magnetism and electricity when he discovered the first circular force then known in nature.

This simple motor is a great beginner project for young makers!

YuKonstruct is the first makerspace in Canada's north. Our mission is to provide access to shared space, quality tools, available expertise, and a collaborative environment to help makers build anything!

Step 1: Materials

Picture of Materials

Materials needed:

  • A few neodymium Magnets
  • AA battery cell (or use a C or D cell)
  • Bare copper wire, around 30 cm (12 inches) long

Step 2: Add a Dimple to the Battery

Picture of Add a Dimple to the Battery

Begin by taking the AA battery and make a small dimple in the cap on the positive end.

To make the dimple, use a small nail, screw driver or even a multi-tool.

Be careful not to strike the battery too hard, just hit it with enough force to leave a small dimple visible in the cap. Don't hit it hard enough to break through the end of the battery, or crush the cap.

Step 3: Place the Battery on a Stack of Magnets

Picture of Place the Battery on a Stack of Magnets

Place the battery on top of a stack of small neodymium magnets, stacked high enough to leave a surface for the wire to contact.

Step 4: Prepare the Wire Coil

Picture of Prepare the Wire Coil

Inspect one end of the wire, and if it's cut flat, cut it on an angle with wire cutters, or a multi-tool, to sharpen the wire to a point.

Using the sharpened end as the beginning, form a vertical loop, then begin forming the shape of a spiral. Form the coil either clockwise or counterclockwise, and make it two to three times the diameter of the battery, finishing off the loop in a smaller diameter.

Place the pointed end in the dimple at the top of the battery and if the coil is too short, or too long, you can stretch or squeeze the coil until it's the proper height.

Let the coil hang freely and see if the free end of the wire contacts the magnet below the battery.

If it does, a current will pass through the wire, and if the wire has a light enough contact with the magnet, the wire will begin to move, either clockwise or counterclockwise, depending on the polarity of the magnets.

Step 5: Watch It Spin!

Picture of Watch It Spin!


If the coil does not move, you will have to adjust the balance of the coil by tweaking the shape of the bottom of the coil, or move it closer to the center of gravity, or further away, until the hanging wire gently brushes the surface of the magnet.

Once this balance has been achieved, the motor will begin to rotate.

By reversing the polarity of the magnet, by flipping it over and placing the battery on the opposite end, the motor will change the direction of rotation.

One direction of rotation or the other could work better to make the motor spin, and experimentation will show the best way to place the magnets. With a well balanced coil the motor should work fairly well in either direction.

Note: The battery will heat up if the motor stalls as it then becomes a direct current short circuit. Also, if the motor is running for too long the battery could heat up. Please monitor this experimental motor carefully.


achalendrakarthik (author)2017-06-26


kennycfrmtenec (author)2017-06-22

very cool

jgerry22 (author)2017-02-28


The CrystalP made it! (author)2017-02-27

I am doing this for my 4th-grade science fair project! I didn't have the pictures for the project but I have typed the steps and ect

laith mohamed (author)2016-09-11

That is funny and simple .

Starlyte (author)2016-08-31

Nice, and the prospective utilisations are flooding in ... :D

jvvj made it! (author)2016-08-31

Nice, simple, funny and informative.

Keywizard (author)2016-08-15

Dope was a chemical suspension used to make flying model airplanes in the early twentieth century. The original term doop meant a suspension of material in a liquid medium (glue, paint, soup, and medical concoctions were called doop mixtures but in the early 1900's Dope usually meant a specific type of mixture). We would build a balsa wood frame, then cover the plane with a special paper that was very thin and made with silk threads, that, when covered with Dope would tighten up and turn rigid. The Dope was made with chemicals that were poured on cloths and then sniffed by teens looking to catch a buzz. These chemicals caused lung and brain damage when breathed repeatedly, causing dizziness, loss of memory, and general cognitive damage. This led to asking people who made less than intelligent statements, "What are you, a dope?" indicating one who got Doped Up by sniffing paint and dope and other doops. When certain chemicals became illegal to teens, making certain paint and other products hard to get by non-adults other products were developed for model plane building. Now we use shrink to fit plastics and laser cut balsa wood to build model airplanes.

By the mid twentieth century the term dope had come to mean anyone who had a lower than normal mentality, or any material used to produce a buzz or high, specifically marijuana and illegally acquired and utilized drugs. In the late twentieth century the use of steroids became illegal in commercial sports, and because there were many who used steroids illegally, it also became known as doping because it became known that too much steroids again limits mental capabilities.

Eventually the people who used illegal substances were called dopes, and using the substances became known as doping. Those who sought out the most mind affecting chemicals and drugs as a form of entertainment would call high quality or high strength drugs and chemicals as "The Dope" indicating the highest form of the particular chemical or medication. To the under society of people who use these products "The Dope" has come to be used to indicate anything that is desirable in the best quality, or highest desirability.

JimH167 (author)Keywizard2016-08-17

as an amplification to the dope as a coating - full size aircraft used dope to finish fabric covered aircraft being most common during WWI but is still used today to restore aircraft to factory new. here an overview.

PaulGetson (author)Keywizard2016-08-15

Thanks, that was informative. I knew a lot of the information about airplane dope. I had found some when I was a teen that someone was throwing out in their trash. I kept it for a while, but I never did use it. Eventually, when I built some tissue covered balsa model planes, I just made a solution of white glue diluted in water for my 'dope'. It worked rather well to stiffen and strengthen the tissue, but was probably much heavier than using the proper 'dope'. The models were mainly for display, and not to be flown.

PaulGetson made it! (author)2016-08-15

This one was interesting. When placed on the battery, the balance point keeps it just hanging and not touching, but if I spin it a bit to start it up, the leg jumps up and twists around so it's touching backwards and dragged across the magnet instead of being pushed as I was expecting. You can see the armature doesn't actually form a complete coil around the battery.

WannaDuino (author)2016-08-15

DOPE means verry cool

thats street Slang (street Talk)

jabal23 (author)2016-08-12

It is dope

g4ipz (author)jabal232016-08-14

What is "It is dope" supposed to mean?

billbillt (author)g4ipz2016-08-14

no one seems to know..

g4ipz (author)billbillt2016-08-14

Ah well. My fault for having been brought up speaking a version of English that everybody can understand without instructions :-)

Chefmike66 (author)g4ipz2016-08-15

well, no one is born speaking any language... You have to learn it somewhere! :)

Angry_Skorpion (author)g4ipz2016-08-14

I was a prison guard for 20 years. "It is dope" is ebonics for "that is really cool". }8-)

wearethe (author)g4ipz2016-08-14

If you are junkie it means a lot :)

Linksep (author)g4ipz2016-08-14

jwilliamsen (author)g4ipz2016-08-14

"Dope" is slang for "excellent, cool, or very good"

technofossil (author)2016-08-15

Love it. It doesn't do any real work but it's still great. Thanks for sharing.

PaulGetson made it! (author)2016-08-15

Only one leg is touching in this one (though it's possible to have both legs touching and have it work). The other leg is acting as a balance weight to keep it from toppling off the battery.

PaulGetson (author)2016-08-10

Yes, I've made a few of these. You can also make different shapes for the armature, and not just a coil.

Please share!

Abe Sam (author)2016-08-12

A good activity for the inquisitive, and to spur them on to explaining the scientific principle in operation.

Jonathanrjpereira (author)2016-08-12

Interestingly Simple & Unique

spacepymp (author)2016-08-10

You can do this with an RF antenna instead of the battery! Jus make sure your around signal:)

dgwatson5 (author)spacepymp2016-08-11

A germanium diode would have to be involved to rectify the voltage. From there The real question would be if you can absorb enough energy to have it work. Theoretically it should be possible. Practically may be a different story.

wold630 (author)2016-08-10

My son just made one of these the other day! So fun!

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