DIY/ school projects

[Medoria]

Would it be possible to convert a “broken” induction stove top into a electromagnet? If so how ? By broken I mean the glass top is damaged/ cracked but no other components apear to be damaged. 

Edited October 12, 2019 by Medoria

[studiot]

10 minutes ago, Medoria said:

Would it be possible to convert a “broken” induction stove top into a electromagnet? If so how ? By broken I mean the glass top is damaged/ cracked but no other components apear to be damaged. 

Well it's a good thought, but will probably turn out differently than you expect.

Induction hobs are ac devices so the mag field generated is alternating or oscillating.

Ordinary electromagnets are dc.

Here are a couple of picture from google.

 

700 × 601

 

250 × 184

 

These show the flat spiral winding of the coils and the resultant field with its harmonics.

 

Have a think about what this means talk to your teacher and come back to us if you want more advice.

[Medoria]

16 hours ago, studiot said:

Well it's a good thought, but will probably turn out differently than you expect.

Induction hobs are ac devices so the mag field generated is alternating or oscillating.

Ordinary electromagnets are dc.

Here are a couple of picture from google.

 

700 × 601

 

250 × 184

 

These show the flat spiral winding of the coils and the resultant field with its harmonics.

 

Have a think about what this means talk to your teacher and come back to us if you want more advice.

Thanks for the help, I’ll see what my teachers suggest

[Medoria]

20 hours ago, studiot said:

Well it's a good thought, but will probably turn out differently than you expect.

Induction hobs are ac devices so the mag field generated is alternating or oscillating.

Ordinary electromagnets are dc.

Here are a couple of picture from google.

 

700 × 601

 

250 × 184

 

These show the flat spiral winding of the coils and the resultant field with its harmonics.

 

Have a think about what this means talk to your teacher and come back to us if you want more advice.

What if I used an inverter to change it from ac to dc voltage ... would that then work ? 
On another note could I detach the existing coil and re-wrap it to form a more typical coil for electromagnets ??

[studiot]

The point of school science projects is to find out what you can and can't do.

It is not like woodwork where the object is to show you can accurately cut a piece of wood to a certain shape and size, and this is a measure of your success.

 

So the point of the ac v dc is that the generated magnetic field will be different.

Can you think why?

So do you really want an inverter to convert dc to ac ?

And where would you get mains voltage dc at that power level?

 

Rewinding coils is a serious undertaking.

It can be done but there are many opportunities for failure along the way.

And what would you achieve by rewinding?

 

Yes I'm very happy to discuss your ideas and try to make you think.
So don't get the idea I'm being negative or avoiding the issue.

I'd hoped your teacher would also perform this function, which is why I suggested talking to him/her.

[Enthalpy]

From a pan on an induction stove,  you feel a faint force, so it is an electromagnet, but a bad one.

DC won't improve much over AC. The huge air gap limits the induction, and the small section of the magnetic path too. See the black ferrite parts below the coil? They operate around 0.3T in the radial direction, so once the flux spreads over a pan, in the order of 20mT remain. 2µT from the Web image is nonsense, stoves would use no ferrite for that.

A rectifier would make use of the stove's electronics, but I consider this a bad idea. The electronics is designed to operate on its inductive load. It may very well be destroyed if no inductance limits the current. Anyway, the induction and the force won't improve as the ferrites are already as small as possible, hence near saturation for such frequencies.

Better proposal:

Take a used transformer to make an electromagnet. Remove the I laminations, keep the E laminations and the coils. This gives you >1.5T over an interesting contact area. The E laminations are rectified flat, so you'll get a good contact with the part to attract and a good induction. A 100W transformer makes a huge force.

Measure the DC resistance of the considered winding, deduce some reasonable operating voltage and current. Some watts suffice.

As a power source, you can use a used computer power supply. They provide 3.3V, 5V, and very strong 12V for little money. Short the ATX start pins so the supply starts.