DIY Induction Stove

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About: We are a supplier of neodymium, rare earth magnets. We also love to conduct experiments with our magnets and build unique projects with them! We have several engineers on staff who are always thinking of new...

Can spinning magnets fry an egg? You bet they can! Let’s see how a simple array of magnets can generate eddy currents in a conductive frying pan, heating it up enough to cook an egg.

The setup is quite simple. Simply take a motor that can spin quickly and handle a decent amount of load (we used an old treadmill motor), bolt it to the underside of a table, mount a disc with the magnet array onto the shaft, and spin away! You'll also need some sort of tabletop to put the pan onto.

Materials used:

-1 motor w/ controls (we used an old treadmill motor)

-Wooden or plastic disc

-Several neodymium magnets

-Scrap wood

-Plexiglass/Lexan

-Solid aluminum or copper pan

Step 1: Creat Magnet Array

The first step is to create the magnet array on the spinning portion of the stove top. We found a large, wooden disc at a local craft store. This was perfect for our array of magnet.

We laid out a template for placing the magnets, to make sure they were spaced evenly. We planned on using 10 1.5" x 1/2" x 1/4" countersunk magnets. The K&J part number is BX884DCS.

The outer diameter of the magnet array was about 5.5"...we figured this would mimic a smaller stove burner.

Centering the template on the disc, we screwed the magnets in place, making sure to alternate the polarities. The alternating poles is what induces the eddy currents in the pan, creating heat!

Then we drilled out a center hole in the disc. This is where the nut would sit that screws onto the motor shaft.

Step 2: Mount Motor

The treadmill motor we found was perfect for this, because it came with a bracket that we could use to mount it. We drilled a hole through our table, and bolted the motor to the underside of the table.

We found it easier to flip the table over to mount the motor, so that we didn't have to hold it up while bolting it.

We fastened the electronics to a wooden board under the table, to keep them out of the way.

Also, we salvaged the controls for the treadmill motor and kept them hooked up so we could have variable speed control. We didn't have to do any additional wiring, just kept it as is!

You could use many different types of motors for this. We spun our disc at around 1600 RPM. The eddy currents create some resistance, so you'll need to choose a motor that can handle the additional load.

Step 3: Mount the Disc to Motor

This step is simple enough...mount the disc to the motor shaft. Our treadmill motor shaft has left-handed threads, so we had to go out and buy left-handed nuts. You might need a few washers to keep the disc from scraping against the table top.

Step 4: Create "stove Top"

You'll need something to keep the aluminum/copper pan very close to the spinning magnets, but without touching them. The closer the pan is, the stronger the eddy currents, the more heat that will be produced.

We used some scrap wood to get the right height and a 1/4" thick lexan sheet. The lexan was only about 1/16" away from the magnet surface, so in total the magnets were only 5/16" away from the pan.

Step 5: Testing and Troubleshooting

Check out the video to see the whole setup and the testing/troubleshooting we went through with the project.

Initially, we only used one layer of magnets with a large aluminum pan. However, we could only get this setup to reach about 120°F.

So we doubled up the magnets (20 total) and used a smaller, thicker aluminum pan. With this setup, we were able to get the pan up to around 212°F, which is boiling water temperature! It's max temperature topped off around 240°F, which is enough to fry an egg and slowly cook things, but not nearly as hot as a regular stove.

Step 6: Cook Away!

Ultimately, we were able to fry an egg with our DIY induction stove. We definitely won't be winning any design awards, but it was a fun way to demonstrate how eddy currents can create heat.

You can buy induction stoves for your home, but they work a bit differently. They don't use permanent magnets--they basically use AC current flowing through coils to heat up steel or cast iron pans. They are pretty neat, but you are limited to only using steel or cast iron pans.

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    68 Discussions

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    n5edd

    4 months ago on Step 2

    try cooking it with the paper plate. maybe the magnets will affect the egg directly.

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    jtechian

    4 months ago

    I like this project being a demonstration of eddy currents, but I saw you did miss a step. The magnets produced counter magnetic forces as eddy's but also repelling forces on the pan (noticed you had to hold the pan down) so adding a hold down bracket for the pan would have saved you there. Glad you had some fun, that's what matters most !

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    chronocide67

    6 months ago

    This has some interesting DIY off grid applications if one were to use a bicycle as the means to spin the magnets.

    2 replies
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    JohnC430chronocide67

    Reply 6 months ago

    yeah... who is going to pedal the bike? remember it is putting out Watts of power and u are going against that. the motor does not feel it but you will. 50 watts is a LOT for a person to pump.

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    Intensescroot

    6 months ago

    Aluminum isn't attracted by magnets and MY aluminum pans won't work on my induction stove...how does YOURS? That must be a bada** eddy currant!

    6 replies
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    NiytOwlIntensescroot

    Reply 5 months ago

    By using spinning magnets, the OP is essentially creating a generator with the pan being the conductor in the magnetic field. So any conductive material will work, although better conductors with thicker cross sections will generate more heat. That's why the thicker aluminum pan got hotter. A thicker pan has more material exposed to the magnetic field, which will induce more current in the pan. Also, the faster the magnetic field fluctuates (more magnets or faster rotation), the more current, and therefore resistive heating. If this setup where to use a few pulleys to increase the rotational speed, the pan would get much hotter - limited only by the power of the motor. Not exactly practical, but definitely a good illustration of the principle.

    The commercial induction stoves require steel (ferrous material) because they are essentially set up as transformers with the steel in the pan forming the core. With no secondary winding, all the power goes into creating eddy currents in the core (the pan) producing resistive heat.

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    ClLylIntensescroot

    Reply 6 months ago

    The experiment seems to be the very basics of magnetic induction. Although aluminum isn't attracted or repelled by magnetics it can have a magnetic field indiced into it. So this build up and collapse could induce a small amount of heat with a regular magnet. When you quickly produce a small magnetic field and before that field collapses expose it to another opposite field then you can get effectively a higher amount of resistance to the passing magnetic field. That resistance in motion should equate to the amount if heat that can be dissipated. The flaw in this expeiment was the arrangements of the magnets. They only allow a small amount of magnetic induction (energy) to be put into the pan (but it was a fun experiment to read about). The Halback array configuration would have probably induced more energy BUT at some point if the magnetic field is stong enough it will try to grab the pan and rotate it, making Scrambled Eggs au Over the Kitchen! BUT seriously be careful because if strong enough it can actually throw the pan and injure someone or cause some damage. Some spin bikes use this for braking and resistance. Permanent magnet electric motors in experimental cars built by college students will also use this configuration. Look up the Halback Array and hopefully that will help understand more about magnetic induction. What's happening here really is since we don't allow the pan to rotate, the induce energy is basically turned into heat as though we are applying a brake and that heat should be proportional to the energy induced into the pan.

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    wobblerIntensescroot

    Reply 6 months ago

    Some apparently aluminium (and copper) pans do work, but in reality they have a core of a suitable magnetic metal layer embedded in the base. Similarly, not all stainless steel pans work because not all types of stainless steel are magnetic. You can test if something will work on an induction hob by seeing if a magnet sticks to out.On
    You can also buy a flat heating disk which you place on top of the induction hob which turns it in to a hot plate for using with non-magnetic or glass cookware although it's obviously easier just to buy induction capable pans.

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    JennyN33

    6 months ago

    Great video,thanks for sharing

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    DavidR165

    6 months ago

    Fascinating! I guess you have to put more energy into the motor than you get out as heat in the pan, so it wouldn't be an energy-saving measure. But I wonder if it would be possible with a wind or water-powered turbine to heat a pan this way? How fast was the motor spinning to get the heating effects that you experienced?

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    S0dyP0pDavidR165

    Reply 6 months ago

    I had almost the same thought, but picturing someone on a stationary bicycle with the induction setup as the resistance. But since I have Google, I now know that even cheap low-power hot plates are 500 watts and that pedaling pretty hard gives about 200-300 watts for a recreational cyclist. So probably not worth building that version unless you're really into frustration.
    A good wind and a ~$200 wind turbine, you could probably make this work. A fun back of the envelope exercise, which I'll leave to others to actually attempt.
    Nice inspring Instructable. Thanks!

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    DavidR165JohnC430

    Reply 6 months ago

    The idea of a water-turbine is good. For some reason it reminds me of how energy was first shown to be convertible between different forms by James Prescott Joule in the mid-1800's. He heated water by spinning a perforated paddle-wheel and showed that the mechanical energy put in matched the heat energy generated - If I remember my ancient Physics classes - which seem almost as long ago as the mid-1800's to me now :-)

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    JamesA41DavidR165

    Reply 6 months ago

    I was going to comment using a bike for pedal power and saw this and started thinking to make sure to use a flywheel to overcome the variability of the wind load... adding a large (maybe tire from a truck filled with cement) flywheel making sure to have a freewheel bike hub type connection for will help.

    Way cool instructable and I've never thought about before. Neat application and great to see a magnetic system.

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    Captain ColonDavidR165

    Reply 6 months ago

    If you're talking about actually driving the rotor directly from a turbine then you could probably do it with water power. I can't see wind working well due to constantly varying wind speed making it hard if not impossible to keep a steady temperature, but water should allow for some pretty precise control with a variable-speed belt drive. It'd be a lot more work to design and put together - can't remember the last time I saw a water wheel at my local scrap yard or yard sale - but it would certainly be impressive!