How To Make Invisible Gears With Eddy Currents 

Drag due to eddy currents from a spinning magnet used to be how car speedometers worked - the same spinning drive from the wheel that incremented the odometer was also used to spin a magnet near an aluminum disk attached to the speedometer needle. A spring pulled it back to zero so it couldn't spin, but the faster the magnet turned, the bigger the angle the needle moved. Modern cars are using the feed from the ABS sensors, converting it to distance for the odometer and to speed to tell a stepper motor how far to move the needle (Or where to draw the needle if a LCD display is used).

Yo thanks so much for this! I’ve been trying to design a battle bot with a loosely connected weapon drive so that the motor doesn’t break during hits, and I think something like this but with both sides being magnet gears might be perfect

Now I know why induction cooktops don't get hot to touch but can boil water

You should compare how much the spinning magnets heat up aluminum compared to steel. There is a reason the inductive cooktops specify that cookware should be magnetic.

Nice video. Eddy currents are used in high speed trains as brakes. An alternating electromagnetic field induces an eddy current in the track which contactlessly pulls on the train, effectively applying a contactless brake force. Much like the oposite of the force that spins your disk Eddy current brakes are efficient for high speed braking because the track and not a piece on the train is warming up. At high velocities the energy to dissipate is high too (v-squared). At lower speeds the brake force is however not so high. Just like in your setup the torque is at its largest when the magnets were moving and the disk was not. When the ‘gears’ have an equal speed, torque is at its minimum. So when both the track and the train are at a stand still, the EC-brake provide no torque.

"Look how the water instantly boils on the coin!" *proceeds to pick up coin with bare hands*

Wow using my currents I see

Every time you release a new video I learn something new. Such smart demonstrations. Thank you

Always learning something new from you. Pretty cool stuff! Eddy currents are also what allows metal detectors to work. Transmitting coil creates Eddy currents in metal which in turn give off their own magnetic field and thus a sensing coil picks up that magnetic field. Depending on how close that return signal matches the transmitted signal determines how conductive it is and shows a higher number on the target ID or higher on the discrimination level.

I remember back in 69, I took apart a speedometer from a 1961 -" Ninety Eight" Oldsmobile and saw an aluminum cup-shaped metal on one end and a magnet attached to the cable that ran from the transmission. I knew very little then about magnetic uses in things but once I saw this combination, it hit me how it worked.

great demo! I’ve always been interested in eddy currents induced by magnets. Another neat thing is to see how a neodymium magnet like the ones you are using will slide slowly down a nearly vertical piece of aluminum and not fall off,, but I’m not telling you anything new here! its just cool. Love your channel !

Wow, love this channel. You never seem to run out of amazing new things to show. Keep it up!

Cool demo! I'm a bit surprised that James didn't try this in a vacuum, since there will inevitably be comments asking how much of the energy being transferred to one gear to the next comes from the air current created by each spinning disk. Air currents are clearly not the main reason for this effect given how fast the wheels turning, but I could also see how they would add a measurable amount of force that gets passed to each disk from the previous one.

We just finished the magnetism topic for my gcse and was ashamed when eddy currents were only mentioned briefly not covered because they are very interesting and I wanted to learn more about them and their uses so thank you for covering them

This was actually the subject of my capstone design project. We used eddy current disk braking to construct a dynometer for small electric motors. The math behind those eddy currents and how they relate to torque is oh so fun.

After so long I really understood what Eddy current is, I vaguely got it when I read about it multiple times but now after visualising it in a experimental form I could understand it.

I’ve always had no clue as to how induction stove tops work, this video explained it perfectly. Very interesting, keep up the good work!

2:23 Electroboom moment.

I love eddy currents. We, in sec. school, made an Eddy current waste separator. We were able to separate alumunium, brass like metals from waste misture. When waste materials were convayerd over the spinning neodymium magnets, chunks of non ferrous metals would jump out off the waste material and get collected in a separate bin.

I wonder if this could be used to make a torque converter for an automatic transmission. It might be a fluidless design.

Very cool video, I always found magnets interesting.

This is done with pumps and compressors where no shaft seal is allowed.

Вы умеете удивлять! Класс.

Amazing Gears... Absolutely Brilliant

I know this is how some water pumps work. Instead of having a shaft through housing and having to use special gaskets to keep water out, just use the magnetic field through the housing. To ensure a water tight component.

Have you tried making a demo of invisible bearings yet? Instead of ball bearings, magnets are used to eliminate friction.

Best demonstration of Eddy currents yet.. so thanks..

Actually, that same principle is the one asynchronous motors use: they have a non-magnet rotor spinning to avoid overcurrents during startup or load changes (as opposed to synchronous motors with a magnetic core). When three-phase current runs along the coils of the stator, it creates the variable magnetic field you make with the spinning magnets. This has the disadvantage of having a variable speed depending on the tork they have to overcome, but nowadays are more used than synchronous for big force requirements afaik.

That heating part was very nice 🔥

This channel is so underrated, love your content!

You're awesome brother! Millions of subscribers, yet underrated... Awesome vids🙌

Thanks a lot man I had no idea induction cooker was made using this principle , in fact I didn’t know that eddy current could heat up a conductive metal resting above ! Wow

Amazing demonstration, once again! This one is of particular interest to me. Keep up the great work!

You made basic versions of so many car parts in this video, from an alternator to a (really basic) automatic transmission. Love to see it. :)

You should try an actual gear inverter using magnets. You place a sandwich of these alternating magnets on a ring pattern with another ring with ferromagnetic materials in place of the magnets in the middle. When you turn one of the magnet rings the other ring will turn on the opposite direction without touching. Gear reduction also works by using different number of magnets.

Thank you sir for giving us such demonstrations.

2:22 I thought only ElectroBOOM would do so but you grabbed the coin that flash-boils water with your bare hands! I was laughing so hard!

I wonder how this would work as a torque converter in a transmission instead of a liquid based one. 🤔

Works a lot better with magnets in the reciever gear, gear reduction and direction is based on ratio.

I think it would be cool if you did another video just like this, but include a copper disc or another type of non magnetic metal disc to compare them!

I think it'd be really cool if you made the receiver "gear" disk as thin (i.e. as light) as possible, and maybe beefed up the propeller a bit in terms of thrust (and not weight ideally). Then, with a bit of luck and some precision placement, ideally you could get it to levitate above the spinning coil -- it would spin up so fast that it would start rising and getting further from the coil, inducing a feedback loop wherein being closer causes to spin faster and move further, which then causes it to spin slower and move closer, etc. until it (hopefully!) finds a nice stable equilibrium

This was one of the coolest Things you ever showed! Anything about Magnets actually!

Ok, this is one of the coolest experiments to date!

Thank you for this insipirational video!

My son and I love watching your videos. They are entertaining and educational! We hope you continue to make any more.

I never taught eddy currents to be interesting in my class 12! But this video did something!!😶‍🌫️

This has got to be one of the most interesting videos in the channel for me so far. Just the very sight of aluminum interacting with the magnetic field blew my mind away!

Just reminded me of the magnetic clutch used in the old Big Trak gear-box to make both DC motors spin at the same rate.

I Have A Question. In Order To Create The Invisible Gear Like This, Do We Need A Conductive Metal (Like The Aluminium Flywheel Shown In The Video) Or It Will Work With Any Metal? And Also Please Make More Videos Of Magnetic Experiments.

As an Engineer I can tell you that invisible gears are difficult to make. Gears are made with Gear Hobs, and depending on the Pressure Angle and Pitch each Hob is made special and precise. The problem comes in when cutting the invisible gear material, zeroing an invisible Gear Hob is difficult at best. And advancing the Invisible Dividing head the proper amount is extremely hard when you cannot see the tool, the Divider, or the gear material. That is why they cost so much. But they do run quietly with very little gear backlash.

And that's how we can make hot coffee with a coin. Great content here!

It wouldn't be an Action Lab video without an ”Ouch!".

Super cool. You are so skilled and knowledgable

The BEST sound ever; Teacher’s surprise when that quarter spins Wow that’s cool! *is this sort of how induction cooktops work? There’s got to be something else going on, or pots would be flying off the surface

Your a genius, thanks🎉 Your Really coming together

This man really grabbed a coin that he boiled water off of while it was still heated. Bravo and props for leaving it in

This is the kind of thing I'm interested in so I love it! Thank you for this one 👍

In an automobile internship contest, I had presented a similar idea of having synchromesh replaced with neodymium magnets and aluminium gears inside a transmission. One of the panelists was like "eddy currents? We don't want sparks and fire inside a transmission!" Lol.

Watch me boil water on this quarter; then he grabs it with bare fingers. That was an Electro Boom moment. 😂🤣

two facts about what you said: 1) Cody's lab made a video melting a bullet with magnets 2) I have a pan that is barely balanced on it's edge, so when it's putted on an induction cooker, it will tilt, the cooker will turn off (because it doesn't detect it) so the pan falls down and repeat

I really like your videos! They are very entertaining and educative

So can we say that the power the disk received in angular momentum to spin is pretty much equivalent to the heat energy received if kept from spinning?

I have seen slip clutches on big industrial drives that had magnets on both wheels but not something that was "geared" like this. Cool idea. Using eddy currents you can have a loosely coupled and geared slip drive (consumer air fan) and with magnets on both wheels you can do the same with nearly no slip (Industrial or automotive transmission?). Particularly useful since the slip can be modulated like an automotive clutch.

I love this kind of invention 😮

This man is always blowing my mind

this is my favorite video so far

That was a good one!!! Really cool and fun to learn!!!

Another great video. It would be interesting to quantitate torque vs distance or composition of flywheel or field strength or angular velocity of the rotating magnets (so many variables to play with!

Thanks sir👍😁 now you give me a new idea , keep it up sir 🙏🏻👍😊

Love this bro, counter rotating field generator two plates of fr5 with directionally patterned 2”copper strap 6’ and 8’ natural green g10 discs with the copper strap in an accelerating electrode pattern. The lower disc is sucking up air, the upper 8’ disk is shooting it out. Mount this in an aluminum skirt with mesh under the aluminum charged negative as a target for the radiation to flow through and run down the skirt or hull of the craft, now mount yourself a chair and fly!!! In your homopolar aerodyne compliments of electro gravitational potentials P2

Kid: *I want a Beyblade.* Mom: *We already have a beyblade.* The Beyblade: 2:19

Very recent, nice experiment!!

It'd be cool to see these stacked

Wow I was just talking about trying this. Thanks for this. My idea was a little more complicated.

I love your demo. They awesome. You make science cool.

This is how the Hacksmith Industries Hoverboard works.

Your channel is great, thank you for the content!

It would be interesting to see the heat formed from the eddy currents with a thermal camera!

A company called Magnadrive tried to commercialize this for actual gearing on motors. Shafts did not require perfect alignment, bearings didn't wear out, and it was quieter and more controllable for speed. Unfortunately, they could not manufacture them in volume for these specialized needs.

Totally awesome!!! When are you going to do a Foucault's Pendulum?

Arguably that's like how the motor itself works, just in reverse.

You constantly surprise me with your topics. The way you demonstrate and describe the physics is so familiar, so easy to understand. I want my grandkids to learn physics from you… when I have grandkids.

"Look at how the coin is so hot that it can cook water!" **Picks it up** 👁👄👁

Really neat phenomenon awesome videos. The aluminum flywheel? Just a touch off center :) tip: never un-chuck work from lathe until done.

i love your videos they're so entertaining to watch.

You can also use a similar setup to make gears of a specific ratio. I made a video about this if you're interested.

Interesting was that it was turning the same way as the magnet wheel, regardless the position of the two wheels. I was expecting that it would act like like a gear and if it was just the edges "touching", it would turn the other way. Interesting.

This idea has been used for over 50 years for aquarium filter pumps

I'd like to see whether this actually gears up, ie higher torque at lower rpm, and whether it is more efficient than a transmission. I can see this benefitting a boat propellor

Ulternate title: how i made a wireless fan

I think control rods in nuclear reactors are spun and screwed in and out using an external spinning magnet, that way it can be sealed and is safer

Just curious, where do you get ideas to try these cool experiments.

This guys nailed it

A clutch that will never get burned

Sir can you please start a channel to discuss the basics and complex phenomenos of physics..for understanding ❤️❤️..love your videos bro

now i understand why it is recomended not to put too much weight on a ceiling fan, the heating up will damage it

time in this channel passes faster than in real-world your channel itself is an example of a frame of respect.

You have better knowledge than many professors around the world! I love your ideas!

That's exactly how the magnetic casting brakes in fishing reels work

Eddy current clutch used in diesel locomotives to rotate the radiator fans.