At 12:00 -0700 7/9/10, john CARMONNE wrote:
> For fear of sounding dumb. Just what does a person do with the  magnets? 
> Where are they in the drive.

One of the reasons for really small disks is that magnets made with rare-earth 
elements - Neodymium and Lanthanum in particular - can be much stronger than 
Alnico, soft iron, or ferrites of the past. I believe the alloy of choice for 
disks these days is Neodymium-Cobalt-Boron.

The magnets react with electric current in a coil of wire on the read/write 
head for positioning along the radius of the disks. It's a lot like a voice 
coil in a speaker. There is a pivot point near a corner and the magnets will be 
just inside of that.

Those rare earth elements are also finding use in the likes of a Toyota Prius 
motor/generator in larger quantities.

A very real financial problem is showing up in that China is pretty much the 
only supplier of rare earth elements these days. It will require something like 
another gold rush to get the US of A up to snuff and I donno about other 
countries.
-- 

--> From the U S of A, the only socialist country that refuses to admit it. <--

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