On Thursday, November 10, 2016 at 12:29:19 PM UTC-8, Jon Elson wrote:
micky wrote:


So is this for real, or a kickstarter designed to cheat me out of my
hard-earned money?

http://www.avsforum.com/mag-lev-turntable/

Oh, boy! Did you see how HIGH they levitate the platter? Geez, I have
strong doubts it can be stable at that height. Also, the thing must have an
insanely strong external magnetic field.

Rogers Ritter published on a low-rumble magnetic suspension audio turntable back
in the seventies; he was using magnetic attraction, and some active feedback,
and was more interested in physics (gravity research) than audio. If these
folk have a patent, that's not what they're doing.

What puzzles me, is how there's enough reliable torque on the rotor.

Now, the only way I know one-sided levitation at low speeds can work is with
something that TOTALLY excludes flux lines, ie. a superconductor.

To levitate a light platter at low speeds, you could get use fixed
magnets and a 2-d conductor (pyrolitic graphite, doped, is light
and has conductivity better than copper). Levitation distances
of a few millimeters would work, after spin-up. No torque, though, if
that's the only trick used.

So, the only way this thing could work is with a spinning Halbach array .. or
massive high-field magnets underneath and a room temperature superconductor

Third possibility fixed magnets, spinning conductor. And smaller
gap than the pic shows.

Lots of info on the magnet-bearing subject:

https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19920018478.pdf