Permanent Magnet: ON/OFF Mechanism...

[argona369]

>?Take a magnet, and ensure any protective metal coating is removed (e.g. most neodymiums have a metal layer over them).?

Not sure how toxic neo?s are, but they are toxic as far as I know.
And I was reading about ?don?t burn them? so
I would want to be careful about any sparking, around a ?bare neo?.
i would not want to handle them without gloves either.

[tao]

>?Take a magnet, and ensure any protective metal coating is removed (e.g. most neodymiums have a metal layer over them).?

Not sure how toxic neo?s are, but they are toxic as far as I know.
And I was reading about ?don?t burn them? so
I would want to be careful about any sparking, around a ?bare neo?.
i would not want to handle them without gloves either.

You can handle them with gloves, just don't try to machine them or let them ignite in anyway.

But, handling an uncoated neodynium is totally safe and non toxic, it only becomes toxic when ignited.

[Honk]

Seeing the first post in this thread has been removed I decided to have a hunt around and I think it went along these lines below:

**Quoted from another source**

on/off switch for permanent magnet

Ever considered whether it?s possible to turn a *permanent* magnet on/off at will ?

Well now you can, and those who are astute enough will realise how this can be used in motors, generators etc.

How is it done ? Simply apply a 180khz square wave current directly through the magnet at right angles to the magnetic field. Only a small current is required at a voltage of 12-20Volts.

Take a magnet, and ensure any protective metal coating is removed (e.g. most neodymiums have a metal layer over them). Then connect two wires, one to either side of the magnet at right angle to the direction of the magnetic field. Use conductive epoxy to do this. Then cover the whole magnet in an epoxy layer.

Then connect these wires to a simple square wave generator circuit, capable of going up to 250khz. At around 180khz you?ll notice the power of the magnet significantly reduced (to virtually zero).

An easy way to view this is to place another magnet in a tube, in such a way that it cannot rotate. With the other magnet with the wires attached oriented with North up. And the magnet in the tube oriented North DOWN. Place the tube on top of the other magnet. Thus the magnets repel.

As the tune your circuit up to 180khz you?ll be able to the see the repelled magnet lowering as the magnetic field diminishes. Switch off the current and the magnet in the tube leaps back up as it is repelled once again. The strength of the magnet does not appear to deteriorate even over many thousands of cycles.

Note I?m talking about a CURRENT being applied through the magnet NOT another magnetic field being applied at right angles using a coil or such like.

I removed the coating of a small Neo I got laying around but the magnet was just as conductive without the coating.
With coating the resistance from side to side was measured to 0R, without the coating the resistance was still 0R.
I don't believe the neo can be turned on/off by a square wave signal.

I also measured a ferrite magnet 4 times as big as the neo.
This resistance was approx 0.5 to 1.5 Megaohm depending on how hard pressure I put on the test pins.
If any magnet can be turned of it's a ferrite magnet.
I might try to do this at work during next week. I got access to a square wave generator capable of 0Hz to 800Khz
and putting out heavy currents as well. The square wave voltage can be adjusted between 5V to 40V.

[Honk]

I have now tested the so called ON/OFF mechanism on a ferrite magnet.
I'm sad to report that I did not notice any weakening of the magnetic field at 180KHz or any other frequency for that matter.
I tried voltages between 5-40V at 1Khz to 2Mhz (I tweaked our generator by swaping capacitors.)
The magnet had conductive tape onto it and I measured the resistance to approx 1Mohm.
Perhaps somebody else is lucky when trying this.  Personally I think the original idea is flawed.

[Thaelin]

   I have come to the conclusion of the same. I found no weakness in the field at all either. Best way to switch a magnet is like Jack does or Flynn does.

thaelin