Permanent Magnet: ON/OFF Mechanism...

[gn0stik]

What prevents this from de-guassing the magnet?

I don't know, I hope to find out soon though.

[longwolf]

Hi Jack,
(Remember when saying that could get you thrown in jail   )

I asked because I've de-magnitized tools by exposing them to an alternating current.
I'm not knocking the idea, I'm trying to understand why it doesn't effect your switched magnets.

[Light]

That's rite, JackH.
Here's parts of one of projects.
After a while this tiny, but powerful neodium magnet (in the middle) created a 'hole' in ceramic ring magnet (marked yellow, reversed polarity), which easily can be located by other ceramic magnet.
As well bad for magnets is heat and vibration, 'abuse', like Jack said.

[longwolf]

Hello longwolf,

""I've de-magnitized tools by exposing them to an alternating current""

I don't know, but maybe that is why you never see permanent magnets in an ac motor.    Yes ac will de-magnitize a permanet magnet, that is called abuse to the magnet.

Could be

Can you answer me one thing?  How can a permanent magnet last in a DC motor for so long?   Maybe because it is pulse DC and never goes totally against the permanent magnets poles.

I'm not sure, but as long as the applied field only attracted the magnets, there wouldn't be a problem as it would keep the magnetic domains aligned.

One thing you may want to know.  You can put a pare of permanent magnets along side of each other, in reverse polarity.  The magnets will still never go dead as long as both magnets contain the same power and you don't hammer on them.

I don't remember where I read it, but there's as site that sells neos.
They have a page about caring for magnets and it warned against storing them with like poles facing each other.
Which would also explain why PMM's that work on repulsion tend to kill the magnets.
(Perhaps those motors had vibration problems, as you mentioned)

Of course you're the man with a working proto type of the switch and if it isn't degaussing your magnets, then that's terrific!
Can't wait to learn more about it

[Esa Maunu]

This kind of change in magnets properties by a pulsed DC current can be current induced switching between opposite static magnetic spin directions,and happens through temporary DC current induced precession.You have a square wave DC pulses at frequency around 180 kHz.

Esa