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ebijma 2nd December 2004 08:14 PM

Tangential Arm Floating Magnets
Hello everybody,

Just had a idea.
Would it be possible to let a Tangential Arm Float on Magnets?
Just like a mono rail.
I think this must be possible.
Need some ideas and info on this.
Is this ever tried by anyone?

AuroraB 2nd December 2004 08:41 PM

Have never seen it, but have been pondering along these lines myself,,-- something like a Ladegaard with magnetic V-grooves...
Was thinking about an experiment, as I have a bunch of Nd magnets lying around.
With a strong field in the bottom permanent V and some lighter magnets floating atop...

I wonder though, if a contraption like this would affect the PU ??

LineSource 2nd December 2004 09:45 PM

NdFeB arcs
2 Attachment(s)
There are very strong NdFeB magnets that are arc shaped, polarized N/S on their curved faces. They can be used to assemble two concentric cylinders with opposing fields to produce a gap - one long magnetic cylinder on the bearing shaft, and short ring on the tone arm joint - you would have a frictionless bearing. BUT you would also have very strong magnetic fields near your cartridge, and hence would likely need some "C" shaped magnetic shielding around the bearing shaft.

One could also wrap a small coil of wire on the edge of the arm joint that could run a small DC current to create a linear motor for anti skating.

ebijma 3rd December 2004 09:15 AM

Re: NdFeB arcs

Originally posted by LineSource
One could also wrap a small coil of wire on the edge of the arm joint that could run a small DC current to create a linear motor for anti skating.
On a Tangential Arm?
Thats not needed.

Bill Fitzpatrick 3rd December 2004 05:31 PM

I'm sure there was a previous thread covering this topic.

ebijma 4th December 2004 03:58 PM

Here's an idea i found.

Looks funny this turntable.

martin clark 4th December 2004 07:28 PM

Nice idea, but you can't do it as proposed. Google for Earnshaw's theorem - stable levitation with permanent magnets is impossible without some other force providing stabilisation i.e tether, guide rail etc.

johnnyx 4th December 2004 08:31 PM

I saw a demonstration of magnetic levitation on TV which used servo controlled electromagnets suspended above permanent magnets. The feedback system corrected the tendancy to stick to one side or the other. I think they used a microcontroller, but a linear system may be possible. It's possible, but getting this to work would be a project-and-a-half in itself.:)

Nat Eddy 6th December 2004 07:37 PM

Two problems: the magnetic suspension would be inherently unstable as pointed out above, but even worse, it wouldn't be rigid enough -- the arm would be bouncy in all dimensions -- ack!

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