Homemade Electromagnetic Project

Thread Starter

clark.donaldson

Joined Aug 19, 2019
30
Hi there -
I am looking to do a "DIY" electromagnet project with a nephew. I ordered some 22AWG magnetic wire and a ferrite rod. I used a drill to wind the wire around the rod, back and forth, maybe a total of 300 winds.
Unfortunately, when I plug in each end to a battery - the battery gets very hot - and while the rod has some magnetic power, but it's fairly weak.
Are there any special measures someone should take when doing a project like this to maximize the results? Does it maybe just need more winds?

Thanks.
 

Ohmlandia

Joined Mar 2, 2020
32
Probably an iron bar would give better results; ferrite has quite a low permeability. That will not stop the battery getting hot though. You don't have enough resistance to set a reasonable amount of current being taken. Ohms Law applies! What is the resistance of the coil you have made? You probably need many many more turns of wire.
 

Thread Starter

clark.donaldson

Joined Aug 19, 2019
30
Probably an iron bar would give better results;
That's interesting. I know a lot of the online guides have suggested an iron nail - but I deferred because I wasn't sure how to tell if a nail was made of iron or some other material, at this point. Is there a fast way to check if a metal is comprised of iron?
 

djsfantasi

Joined Apr 11, 2010
6,362
How important is it for the winding to be "perfect" (no overlaps, even distribution, back and forth, etc)?
Not as important as the question Ohmlandia asked the the second post!

Get your VOM or DMM out and measure the ohms across your hand wound coil! What do you measure?

What battery are you using? Remember Ohms Law...

Amps = Battery Volts
divided by Ohms (coil)
 

DickCappels

Joined Aug 21, 2008
6,315
A suggestion about the hot batter: If you are using a battery that can provide high current, especially nickel–cadmium or alkaline switch to carbon-zinc. Also to minimize power lost in the battery, keep the voltage low -a single cell should do it.

Another approach is to increase the number of turns or use a smaller wire size.

The problem with ferrites is that they vary all over the map. The old steel or iron nail is more predictable. As Alec_t indicated, if you can pick the nail up with a magnet then the nail is a good candidate.
 

atferrari

Joined Jan 6, 2004
3,930
Hi there -
I am looking to do a "DIY" electromagnet project with a nephew. I ordered some 22AWG magnetic wire and a ferrite rod. I used a drill to wind the wire around the rod, back and forth, maybe a total of 300 winds.
Unfortunately, when I plug in each end to a battery - the battery gets very hot - and while the rod has some magnetic power, but it's fairly weak.
Are there any special measures someone should take when doing a project like this to maximize the results? Does it maybe just need more winds?

Thanks.
When you finally start doing your tests with the nail of choice (sure the cheapest in your drawers will work) do not be surprised that as you repeat them, the nail will be more or less magnetized. Been there.
 
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