Super Simple Unipole Motor

Introduction: Super Simple Unipole Motor

About: I think a blank piece of graph paper is a most beautiful thing! Just think of the possibilities! I dabble in a lot of things, as you can see by my interests. Wish I had more time to do instructables, and to…

This is my version of a unipolar motor example that has very few parts, and is arguably the simplest motor to construct. It uses no coils!
These are the parts needed:

battery                          - I used a AA, but any size will work!
small wood screw     - I used a 1.5" deck screw, but don't use the coated type!
wire                               - I used 5" of solid #24 or 26 AWG, but any size will work!
magnet                        - I used... see picture... Walmart has these. But... any (strong, preferably round) magnet will work!

Altoids tin                    - If you can fit your battery in it, of course,... any size will work!
Apprentice                  - All together now, "Any size will work!"

Step 1: Sizing the Parts Up...

You want a magnet and screw that can be set up like this.
The magnet is on the head of the screw. The screw hangs upside-down with the screw tip holding to the positive "button" of the battery by the extended magnetic field.
If the magnet is too powerful, it will flip around or jump up to the battery - not good.
If its not powerful enough, or if the screw is too big or heavy, they will fall off the battery, not good.
You can add an extra magnet if your screw is bigger/heavier.

You might have to take your battery and magnet to a hardware store to pick out just the right size screw.
Find one with a good sharp point, that point becomes your bearing. Don't forget, don't pick a coated or painted screw, it must be able to conduct through the point and head surfaces.

Step 2: The Unipole Motor Set Up

To run the motor, just add the wire. Hold it to the top (negative) side of the battery with your finger, and touch the side of the magnet with the other end.

I added a paper disc to make the motion more visible. Another magnet underneath holds it on.

See a video at:
(If that doesn't get you there, look up techhobbit on

Once the motor starts turning, you just have to touch the magnet now and then to keep it going. If you hold the connection closed, it will drain the battery pretty quick - there are no coils, no resistance or inductive reactance, just a dead short.
So... how does this thing work? ...think about it!

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    10 years ago on Introduction

    I guess you read my instructable... >insert grin here<

    How do you like it?

    By the way, thanks for following...

    (I don't think I've said a proper thanks.)


    Reply 10 years ago on Introduction

    Hi. I've been so rushed to finish mine I hadn't been watching, and was quite surprised to see we did a similar concept! I wanted to do more, actually make a speed governor out of paper, wire, popsicle sticks... that would allow the wire to touch the magnet when it slows down but then pull away when it speeds up. This intermittant contact would solve the one main problem with unipolar/homopolar motors - that they are a straight short!

    ...never enough time, I think too big on these Weekly Challenges!

    You did a good job on that ible. I think I tend to get too wordy (just like my comments/replies!) and mine only had two steps, so I probably will be eliminated.

    I did see your Looper and I would like to build one of those! But probably won't do an ible.

    Hey, I thought you might like to see a project I'm still working on, its got a bug or two... but I got a proof of concept done. If you get a chance, please check out this video and let me know what you think.

    And, I should be thanking you! You gave me my first patch! I'm following because you seem to be pretty prolific, and I like your choice of projects (we think alike!). Keep up the good work.


    Reply 10 years ago on Introduction

    Sorry for the typos on the patch...

    Anyways, your video is very nice...question, is it supposed to quiver like that? Also, did you use a servo motor or a gear-boxed one?

    Do you have a schematic? Even a hand-drawn one will work...

    The looper is really nice...will be recording a video soon.


    Reply 10 years ago on Introduction

    I used two modified servos - servo boards removed. They are cheap, make a nice gearhead motor, and run on dc, no 555 or timing required.
    The jitter is from the head hitting the final micro switch (park position), turning power to motor off. Thus, the motor relaxes and the head falls away a bit, releasing the micro switch, activating the circuit again, driving head to the parked position again... and it repeats. I can fix it with a counter weight, or other electrical options, requiring another relay and wiring it like an industrial control on/off circuit. The little switch I hold on is just a kill switch (main power) for use while tweaking the circuit, (so it doesn't self-destruct if something goes wrong!) and would finally be removed. I won't do an 'ible on it until I have a chance to clean up the jitter.
    I have the circuit and would be glad to share it with you. Give me a few days to get a clean hand drawn circuit. Then I could send it as a gif or jpeg.


    Reply 10 years ago on Introduction

    When I made my useless squared project I had found out the same thing. I had originally wanted to use two tactile switches but it didn't work out too well because it did what your robot did. Clever, though.