Introduction: Overbalanced Wheel (Fake Perpetual Motion Machine for Fun)

Picture of Overbalanced Wheel (Fake Perpetual Motion Machine for Fun)
Of course, perpetual motion does not exist. But lots of great inventors, including Leonardo da Vinci, played around with the idea so I feel like I'm in good company. I think anyone who is interested in engineering, mechanics, and physics or the history of these fields will enjoy building this project.

I've always been facinated by the "Overbalanced Wheel", which is basically a wheel with weights that slide or move from a position close to the center of the wheel to a postion near the edge of the wheel as it turns; basiclaly shifting more weight to one side of the wheel to keep it turning in that direction.

I decided to build my "Overbalanced Wheel" out of an old CD (always great for DIY projects), some screws and metal brackets I bought at Lowe's and a few "secret" components that will be revealed in Step 5.

NOTE: Don't look ahead to Step 5 unless you want to take the fun out of perpetual motion!

First, check out the video!

Step 1: Materials & Tools (Non-Secret)

Picture of Materials & Tools (Non-Secret)

Non-Secret Materials Needed:

1 - CD
8 - 6-32 Cap Nuts
8 - 6-32 Screws
8 - 6-32 Washers
8 - 6-32 Nuts
6 - 1/2" x 4.5" x .035" Metal Mending Plate (Lowes 364404)
4 - 1/2" x 1-1/2" x 1-1/2" Metal 90D Plate (Lowes 364311)
1 - 1/2" x 3" x .035" Metal Mending Plate (Lowes 364323)
1 - 2" Metal Gear Shaft
1 - 1" Diameter plastic gear (to fit shaft above)
2 - Rubber grommets (same diameter as gear shaft)

Non-Secret Tools Needed:

Cutting Tool
Hot Glue Gun

Step 2: Designing and Building the Wheel

Picture of Designing and Building the Wheel

My Wheel Design

I decided to cut slots in the CD and use weights made of screws, nuts, and metal caps to slide back and forth in the slots. I figured the slots needed to be angled from the center of the CD out toward the edges so the weights would slide "out" as each slot reached the falling edge and slide "in" as each slot reached the rising edge of the CD when turning clockwise.

STEP 1: Lay out the design on paper by dividing the CD into eight equal sections.

STEP 2: Add a 1/8" hole 1/4" from the edge of the CD for each dividing line.

STEP 3: Measure half the distance between each hole and the center of the CD and add another 1/8" hole for each dividing line.

STEP 4: Join the holes to make a 1/8" slot for each hole pair. (See the first photo).

STEP 5: Cut out and tape the pattern to a CD. See my note at the end about protecting the CD while drilling and cutting.

STEP 6: Drill the holes first being careful not to crack the CD.

STEP 7: Use a Cutout Tool with a 1/8" cutting bit to make the slots between each set of holes. Make sure you securely brace the CD and cut in a slow, smooth motion. Otherwise, you will likely crack the CD.

STEP 8: Clean up the slots using a Dremel. The weights must slide freely, so be sure to remove any burs or narrow areas in the slots.

STEP 9: Hot glue the plastic gear to the back side (label side) of the CD making sure to center it. I added a piece of silver tape under the gear to hide the gear teeth from the front of the CD. Some CD labels cover this area so the tape won't be needed.

STEP 9: Insert screws, washers, and cap nuts through the slots. The cap nuts should face the front (shiny side) of the CD.

NOTE: As you can see from the photos, I scratched up the surface of the CD quite a bit during the building process. In retrospect, I should have protected it better during drilling, cutting, and sanding.

Step 3: Building the Frame

Picture of Building the Frame

I built a simple triangle frame using hobby metal from Lowes.

STEP 1: Assemble a triangle using three 4-1/2" flat plates and two 90 degree plates leaving the top screw & nut out.

STEP 2: Assemble a second triangle as shown in figure 2.

STEP 3: Add a 3" flat plate to the back of the frame to stablize it.

STEP 4: Insert the wheel by sliding the the gear shaft through the top holes in the frame.

STEP 5: Add 90 degree plates to each side (3rd hole up) to further stablize the frame.

STEP 6: Insert grommets on each side of the grear shaft to keep the CD centered in the frame

Step 4: Testing It Out

Picture of Testing It Out

Since we've already established that perpetual motion is impossible, I didn't expect this to work. However, I had no idea it would fail so miserably! Fact is, IT DOESN'T WORK AT ALL! It doesn't even start to work when I give it a nudge. If I spin it fast, it will run about as long as a wheel with no weights at all; maybe not even as long as that.

Now that that's over, please move on to Step 5 where the real motion begins...

Step 5: The Real Deal (Non-Perpetual Motion)

Picture of The Real Deal (Non-Perpetual Motion)

SPOILER ALERT - If you haven't gone through steps 1-3 or you want to keep believing in perpetual motion, please don't read this step.

Okay, so perpetual motion failed miserably. Now it's time to add some real motion to the project! I wanted to hide all of the electronics behind the CD (and remember the CD has slots cut in it), so everything had to be small; very small!

My first thought was to use a simple DC motor with a battery and a switch. But there is no good way (that I could figure out) to make it turn slow enough (and with enough torque) to resemble perpetual motion. I tried a potentiometer, gears, and PWM. Nothing worked to my satisfaction. 

So I decided a servo and microprocessor were needed, but they had to be very SMALL. The smallest servo motor I could find was the HD-1440A from Pololu . This is a great little servo with plenty of torque.

Next, I needed a really small microprocessor to handle the PWM to drive the servo at the desired speed. For this, I used a Teensy 3.0. Luckily, I happened to have a Teensy on hand since I was a contributor to their successful KickStarter campaign. The Teensy was perfect for this project; very small and easy to program (Arduino compatible). Plus, as a bonus, the Teensy has a special feature called "Touch Sense" that let me start and stop the wheel by simply touching the frame. This way I could give the illusion of starting the wheel by giving it a nudge!

Secret Materials Needed:

1 - Teensy 3.0 Microprocessor
1 - Teensy Arduino IDE
1 - Mini servo (HD-1440A)
1 - USB connection to a computer
1 - Small plastic driver gear
1 - 1/2" x 2" x .5" Metal Slotted Angle (Lowes 364266)

Secret Tools Needed:

Solering Iron
Helping Hands

Step 6: Preparing the Servo Motor

Picture of Preparing the Servo Motor

As with most servo motors, this one was configured for 180 degree motion. I needed continous rotation to turn the wheel, so I hacked it as follows:

STEP 1: Remove the two small screws from the bottom of the case.

STEP 2: Cut the label along the seam near the bottom of the case and gently pull the bottom cover loose.

STEP 3: There are three wires that connect the circuit board to the potentiometer. Detach those wires from the POT.

STEP 4: Since we only need the wheel to turn in one direction, you can just solder a 2k (approx) resistor between the two wires indicated in the photo. I had to experiment a bit to figure out which two wires needed to be connected to give a clockwise rotation.

STEP 5: Cut the access leads and cover the resistor with electrical tape (or shrink wrap) and carefully put everything back in the case.

STEP 6: Hot glue the plastic drive gear on top of the very small gear of the servo. Be sure to center this gear. I used a small nail in the center to line them up while glueing.

Step 7: Programming the Teensy

Picture of Programming the Teensy

Before programming the Teensy, you'll want to download the Teensy Loader and  Teensyduino add-on for the Arduino IDE. After that, copy this simple sketch, compile, and load your Teensy. Notice the "touchRead" command that senses touch by reading capacitance. More info is available here: (search for Touch Sensing).

#include <Servo.h>

// Overbalanced Wheel
// Using Teensy 3.0
// by Mike Soniat
// 12/24/2012

Servo servo;
int servoSpeed = 170;
int servoPin = 14;
int touchPin = 22;
int touchReading = 0;
boolean isStarted = false;

void setup()
void loop()
  touchReading = touchRead(touchPin);
  if (touchReading > 3000)
    isStarted = !isStarted;
  if (isStarted)

Step 8: Connecting the Servo to the Teensy

Picture of Connecting the Servo to the Teensy
The next step is to wire the servo to the Teensy and add a wire for the "Touch Sense" feature.

STEP 1: Cut the connector off the servo wires and solder the wires to the Teensy board as follows:
  • Brown (-) wire: Solder to any GND pin. I used the one at the bottom center of the board.
  • Red (+) wire: Solder to either of the 3.3V pins. I used the one next to the GND pin at the bottom of the board.
  • Gold (signal) wire: Solder to any "PWM" or analog pin. I used pin 14.

STEP 2: Solder a length of wire to any "Touch Sense" pin. I used pin 22.

Step 9: Putting It All Together

Picture of Putting It All Together
Now, it's time to add the non-perpetual components to the "perpetual" ones.

STEP 1: Place a piece of double-sided tape on one side of the servo and attach it to the angle bracket.

STEP 2: Attach the angle bracket to the back of the frame as shown and adjust the postion of the servo gear to mesh with the CD gear.

STEP 3: Place another piece of double-sided tape on the back of the Teensy board and attach it to the back of the frame as shown.

STEP 4: Run the "Touch Sense" wire around the top of the board and attach it to the frame as shown.

STEP 5: To hide the USB power lead from sight during operation, cut a slot in a box or other base and run the USB cable up through the slot to the Teensy board. Tie wrap the cable to the frame if needed.

STEP 6: Turn the base around and you're ready to amaze your friends (as long as you keep them a few feet in front of it)!

Here's the video again in case you missed it in the Intro:


RohanG56 (author)2017-08-30

how long does it turn for without the motor, after given a bit of a push

Flying_MashedPotatoes (author)2012-12-30

Do really need more fake perpetual motion machines to perpetuate the world's stupidity?

I had no intention of perpetuating stupidity. I said right up front that it was "for fun". I also thought it was an interesting project and many people here seem to agree.

MichaelS983 (author)mikesoniat2016-08-23

It was interesting and clearly demonstrated at least part of the fallacy of the perpetual motion.

mrjunkie (author)mikesoniat2015-01-19

i agree alot of fun misleading us dont lie based on your failures keep at it until u succeed and then make a instructable i firmly believe this does work u just have to make it correctly lol

bakunin (author)mikesoniat2013-05-27

I am one of the agreeers! I think the process of building a perpetual motion machine, and then seeing it not work, is an excellent way to learn about the conservation laws of physics.

Irish Nutter (author)2016-04-03

You can here the electric motor in the background.

JohnD42 (author)2015-05-12

If this device was called a variable fulcrum machine, no one would have any objection. It translates pure g's into motion at a rate determined by the average distance of the load arm over the average distance of the effort arm. I made some graph paper, modifed the shapes the Leonardo used, did some calcs, and found that you might expect an output of about 2/11 of whatever weight you use. That doesn't take into rpm, which will top out, but an increase in speed is an increase in output. Just remove the backslashes to see for yourself. The calcs are on the preceding page (use the wikitrail) \http\:\/\/\/Neighbors\/pmwiki.php\?\n\=Overunity.Project1013-c

billjoh (author)2012-12-30

I like this even tho its doesn't work. But what seems strange to me is every one thinks there is no perpetual motion machine when if you look down at your feet your standing on one. The earth.....?

ShirleyK1 (author)billjoh2015-01-04

Er, the earth is slowing down and would ultimately fall into the sun as its orbit decays (if the sun doesn't turn into a red giant first and swallow it up first - likely).

Possibly the Universe itself recycles and might be considered to be perpetual motion. No-one knows the answer as yet.

Treknology (author)billjoh2012-12-31

According to historical records, Earth days and years were shorter than they are today. Either our clocks are suffering a temporal anomaly or the Earth is really slowing down.

The earth is slowing down because of tidal locking with the moon (there's a what-if.xkcd about this), not necessarily from friction. Space is very close to a perfect vacuum, so the friction effects are negligible.

JasonH4 (author)Dilong_paradoxus2014-10-15

Not so. Solar winds and the magnetic fields are known to have non-neglible (but small) effect. Given enough time and lack of meteors hitting the Earth to speed it back up, the Earth would eventually stop spinning

I didn't mention friction in this case, just that the Earth's rotation and revolution are slowing down. If you want to argue about Luna and tidal forces, do a basic Google check on tides in different areas, and you will find that the data does not match with Luna/tide theory. Some bodies of water exhibit FOUR tides a day instead of the "traditional" two.

Sorry, I said that badly in my first comment. I didn't mean to contradict you, just to add clarifying information in the last sentence. Anyway, tidal locking doesn't have to mean actual tides in water. The moon is tidally locked with earth, so the same side always faces us, and the moon probably hasn't ever had significant amounts of water. Also, that's pretty cool about the four tides a day, although I suspect that's more due to harmonics in the water basin and delay between the passing of the moon and the actual high tide.

When it comes to tidal harmonics, you have hit the nail on the head. Most of the moons in our system are "locked" so that only one side faces the host planet. However, Luna is the only one that has such a slow orbit that it never goes "retro-grade" in relation to the Sun.

Murdoc222 (author)2014-12-05

If you increase the number of slots will that increase the spin speed?

teknohawk (author)2014-10-14

I agree! That is such an awesome project! Well done!

teknohawk (author)2014-10-14

I agree! That is such an awesome project! Well done!

teknohawk (author)2014-10-14

I agree! That is such an awesome project! Well done!

Beekeeper (author)2012-12-30

I have often wondered whether one could make a 'perpetual motion' machine using magnets to push a wheel around, instead of weights rolling or sliding towards the centre. I imagine a different number of magnets on an outer wheel such that there is some push and then pull. The whole thing suspended on magnetic bearings. If it worked, would one be using the energy inputted to originally make the magnets and it would only last until the magnets gave out?
Perhaps some of you geniuses out there would try it or tell me it is impossible.

dreadengineer (author)Beekeeper2012-12-31

Unfortunately it is impossible. Though magnets seem mysterious, the way to think of them is like a "hill" in energy. (Or rather like a valley next to a hill, if you're considering the north and south pole forces on another magnet.) In order to get energy by rolling something down the hill (i.e. getting repelled by the magnet), you have to first put in exactly the same amount of energy when you push it up the hill to begin with. No matter how you arrange hills and valleys, you can't make a closed circular path that has net downhill movement. (As a proof of that: it has to get back to the same initial height, so it's net up/down movement must be zero.)

Beekeeper (author)dreadengineer2013-01-01

That sounds logical but..... I believe one can shield one side of a magnet so that it has less effect on one side than the other. To take your analogy, wouldn't that mean that the hills are higher than the valleys? You can get more push than pull?

dreadengineer (author)Beekeeper2013-01-01

I think I understand what you're saying. Unfortunately it's not possible to shield a magnet such that it's easy to approach in one direction and hard to approach in another.

You can do things to make the "slope" short and steep or long and gentle, but it ends up being the same total amount of energy. It's not possible to build a "one-way magnet" that pushes one way but not the other way, just like you can't build a "one-way hill" that is shorter to climb on one side than the other.

There's no reason not to buy some neodymium-iron-boron magnets and experiment though; there's still plenty of cool stuff you can do with magnets.

If you're interested in getting some more physics theory, there's a good series of intro to physics videos on Udacity:

I'm not sure if it covers magnets specifically but it does cover analyzing potential energy and related stuff, so it's a good background for experimentation.

Beekeeper (author)dreadengineer2013-01-02

Unless we humans have ideas, even if they don't work, we would still be living in caves. Thanks for sharing your expertise: I'll try giving my little grey cells something else to work on.

I have heard that if you spin a spherical magnet held in a vacuum above a cylindrical magnet it would be perpetual. But that requires a perfect vacuum and anyway there is no means of utilizing the spinning.


Benzyl (author)2013-01-01

The loud whizzing noise and coarse rotation rather give this away, less a fake perpetual motion machine than a simple Ferris Wheel model. Suspend some Lego people from it perhaps?

Treknology (author)Benzyl2013-01-01

Hmm. A "Ferris" wheel where the occupants' cages slide and thump their way from the center to the outside and back again could be a really scary ride. You could be onto something here.

mikesoniat (author)Benzyl2013-01-01

Thanks for your opinion, Benzyl. I' m honored that you took the time to comment on my Instructable. Too bad you don't have any projects of your own posted. I'm sure they would be far superior to anything I could cobble together...

GS Gnaneshwar (author)2012-12-31

Hi Mike, Excellent! Your simple approach for making this small project instigated me to go for a bigger version of Electricity generation. Is it ever possible ? Kindly comment.
Gnaneshwar, Bangalore, India.

mikesoniat (author)GS Gnaneshwar2013-01-01

Thanks, but I'm not sure how this relates to electricity generation.

mr fat (author)2013-01-01

I absolutely love this project! I believe that it is a 15 out of 10 winner!

mikesoniat (author)mr fat2013-01-01

Thank you!

Treknology (author)2012-12-31

I love this, although the constant "click-clack" would get a little annoying.

mikesoniat (author)Treknology2012-12-31

I guess I better get used to it; after all it is perpetual!

Treknology (author)mikesoniat2013-01-01

At least it has an "Access Mode Ready" function that has replaced the "Standby" button which itself has replaced the appallingly stone-age "Off" switch!

mikesoniat (author)2012-12-31

Thanks, Kevin. The actual design was my own idea, but I was inspired by Bhaskara, Honnecourt, and da Vinci.

wjcarpenter (author)2012-12-30

I like the whole idea of this. It's in the sweet spot between simple and complex.

I wonder if you (or anyone) has some bright ideas for a more "finished" way of cutting into the CD. I know if I do it more or less by hand the way you did it, I'll end up with a sloppy mess (and blood in the streets). I've got a dremel and various other simple tools, but no SDI space-based laser weaponry.

mikesoniat (author)wjcarpenter2012-12-31

Thanks, WJ. I have to admit, cutting the CD was a challenge with my basic tools and limited skills. I'm sure someone could do a much better job with the proper equipment and experience.

Treknology (author)wjcarpenter2012-12-31

If I dare try building a similar project, I will use Hard Drive platters and a milling machine.

Treknology (author)2012-12-31

The earliest design along these lines was a wheel with angled spokes, and rails in the spokes for weighted balls. When spun, the wheel would continue for quite some time but, like all these ideas, friction would ensure that it ground to a halt.

The two examples of "perpetual motion" that almost achieve their aims are:
1. High frequency induction waves circulating in an aluminium disc----unfortunately the very act of measuring their presence depletes them.
2. An rounded-corner triangular shaped piece of metal with a bike-chain sliding around its outside edge. Friction does not appear to cause as much of a problem, but the wear-factor on the triangular plate means that as it gradually alters shape, it becomes defective.

lemonie (author)2012-12-30

Build a base that incorporates an intermittent magnetic-pull, you'd need some kind of sync' with an electromagnetic-pick-up. If your bearings are really-smooth you could get a nice steady motion, and control speed by moving the electromagnet about.


rimar2000 (author)2012-12-30

Very nice!

mikesoniat (author)rimar20002012-12-30

Thanks! I enjoyed making it.

JayGeeBSE (author)2012-12-29

I like the idea but the use of a processor seems way over the top. Why not connect your power supply direct to the motor in the servo and omit all the electronics? Maybe a series resistor to limit the speed. You can probably hide a switch under the base, so it runs when you press on the frame - tell people you have to steady it or it shakes too much. If you must drive the servo with pulses you can buy a servo tester with a speed (position really) tweaking pot for a small sum. Cheaper, smaller and simpler than your microcontroller but you do still have the switching problem. A small rechargeable pack behind the CD would make it easier to disguise the power source.

mikesoniat (author)JayGeeBSE2012-12-30

I actually tried a series resistor and a pot, but the results were unreliable. The biggest problem was getting enough torque to turn the wheel with the reduced voltage. I also tried using batteries, but the "Touch Sense" feature (which I really liked) didn't work well without the USB connection. Anyway, like I said in the text, I had the Teensy board because I backed them on Kickstarter. And I guess I was looking for an excuse to use it!

giocad (author)2012-12-27

very educational.

mikesoniat (author)giocad2012-12-30

Plus it was fun to build! Thanks!

Jimbok3 (author)2012-12-30

technically it is possible in space......

LaffyDuck187 (author)Jimbok32012-12-30

in space there is still friction

Jimbok3 (author)LaffyDuck1872012-12-30

not for free floating objects

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