Creating an Electromagnet for Attracting Copper, Aluminum and Non-Ferrous Metals

Thread Starter

ElectromagneticsArt

Joined Apr 1, 2019
2
Hello,

I am trying to create an electromagnet to attract a small disk of copper, 1/2" in diameter. The concept was first outlined by Leonard Crow in his book (attached), and was demonstrated by a particular YouTube channel:


I would like to create the same magnet. I am familiar with the concept of magnetics, in terms of magnet construction, number of coils, core material etc. However, I am having difficulty designing the circuit to do my testing.

In the video, the author uses a power supply and a ZVS driver board, which he connects to the opposite ends of the coil. What would be the best way to create a simple circuit to prove this magnet concept?

Would it be enough to simply get an AC power supply, and run 9 or 12V through a small coil? Do I need a specific circuit, such as the ZVC driver or an arduino? If possible, I'd like a convenient single piece of equipment that I can order off of Amazon, as opposed to making it myself. All I'd need to do is attach alligator clips to the device and to my coil.

Thank you!
 

Attachments

AlbertHall

Joined Jun 4, 2014
8,302
It looks to me more like the copper disks shield the centre from the field produced by the coil. The copper foil is repelled from the coil. If the foil is nearer the outside it is repelled outward, if it is nearer the centre it is repelled inward.

No attraction of non-ferrous metal here.
 

Alec_t

Joined Sep 17, 2013
10,350
For generating a force on non-ferrous metal, the metal would need to be moving relative to the coil-produced magnetic field so that eddy currents could be created in it. Have a read of this article, for example.
 
Last edited:

Yaakov

Joined Jan 27, 2019
1,532
To start, this is not really an electromagnet for attracting non-ferrous metals. It is an electromagnet that induces eddy currents into non-ferrous metals and uses them to keep the object in the field.

Second, it would require AC, and quite a lot of current.

This might be instructive, it's a very interesting lecture:

 

Thread Starter

ElectromagneticsArt

Joined Apr 1, 2019
2
That is the absolute best demonstration and explanation of eddy currents that I have ever seen, thank you very much!

To induce such eddy currents in a piece of copper, for example, is there a specific power supply or frequency that would work best? Or simply any standard 60 Hz 12V supply, given that I have ample current?

All devices I could find on Amazon only do AC to DC, and wouldn't work for my application. Where I can plug it into a standard 120V 60Hz outlet, and get an output of 15V, 3 Amps, at 60 Hz (for example).

What would you recommend?
 

xox

Joined Sep 8, 2017
351
That is the absolute best demonstration and explanation of eddy currents that I have ever seen, thank you very much!

To induce such eddy currents in a piece of copper, for example, is there a specific power supply or frequency that would work best? Or simply any standard 60 Hz 12V supply, given that I have ample current?

All devices I could find on Amazon only do AC to DC, and wouldn't work for my application. Where I can plug it into a standard 120V 60Hz outlet, and get an output of 15V, 3 Amps, at 60 Hz (for example).

What would you recommend?
Just a beginner myself but I would think a simple 8:1 or 10:1 transformers connected to mains should work fine. It would need to be pretty beefy though to handle 3 amps. Just a guess of course, you should probably wait for the experts to weigh in before making any rash purchases. :D
 

wayneh

Joined Sep 9, 2010
16,102
I agree, just search for a transformer AC-AC adapter with the specs you need. I say AC adapter because you want a transformer that’s ok to connect to mains. That won’t be true of every transformer.
 
  • Like
Reactions: xox

Glenn Holland

Joined Dec 26, 2014
649
A nonmagnetic metal cannot be attracted to a magnet of any type.

However a nonmagnetic metal can be repelled from an electromagnet powered by AC current.This is commonly used in scrap metal recycling plants to sort ferrous and nonferrous metals.
 

Wendy

Joined Mar 24, 2008
21,847
A nonmagnetic metal cannot be attracted to a magnet of any type.

However a nonmagnetic metal can be repelled from an electromagnet powered by AC current.This is commonly used in scrap metal recycling plants to sort ferrous and nonferrous metals.
Actually you are incorrect. Professional rigs do it by using intense AC EMF field This creates eddy currents in the nonferrous materials which in turn generate a magnetic fields of their own. The AC electromagnet couple to the induced magnetic fields . Fascinating stuff really. Recycle shops routinely use this kind of EM. I imagine the copper and aluminum get quite hot in the process. It is also a way to separate materials.

It has been done commercially for quite some time.
 
Last edited:
Top