Date: Wed Nov 22 11:38:29 2006

Author: Krishna Chowdary

Subject: Re: IFO 3000

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On 11/22/06, Cliff Bettis wrote:
>
> Does anyone know how this gadget works?
>
> http://scientificsonline.com/product.asp?pn=3036982&bhcd2=1164206070
>
>
>
There is a Hall effect sensor connected to an electromagnet. The "top" of
the globe has a permanent magnet. The Hall effect sensor measures the
magnetic field and is incorporated into a feedback system that adjusts the
current (magnitude and polarity) to the electromagnet. So it's an active
element servo feedback.

Here's a decent link (scroll to the bottom for a pretty good article
describing a little physics and more of the actual servo feedback mechanism
circuitry).

http://www.arttec.net/Levitation/


I agree that it is a cool attention getter. Unfortunately mine is a little
defective, and so any appreciable spin turns into a wobble turns into an up
and down oscillations that quickly gets the "north pole magnet" out of the
"sweet spot" and the globe crashes upward. But for just floating, mine
can't be beat!

--
regards
-Krishna

Krishna Chowdary
Department of Physics & Astronomy
Bucknell University

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On 11/22/06, Cliff Bettis wrote:








Does anyone know how this gadget
works?

http://scientificsonline.com/product.asp?pn=3036982&bhcd2=1164206070


There is a Hall effect sensor
connected to an electromagnet. The "top" of the globe has a
permanent magnet. The Hall effect sensor measures the magnetic
field and is incorporated into a feedback system that adjusts
the current (magnitude and polarity) to the electromagnet. So
it's an active element servo feedback.

Here's a decent link (scroll to the bottom for a pretty good article
describing a little physics and more of the actual servo feedback
mechanism circuitry).

http://www.arttec.net/Levitation/


I agree that it is a cool attention getter. Unfortunately mine is
a little defective, and so any appreciable spin turns into a wobble
turns into an up and down oscillations that quickly gets the "north
pole magnet" out of the "sweet spot" and the globe crashes
upward. But for just floating, mine can't be beat!
-- regards-KrishnaKrishna ChowdaryDepartment of Physics & AstronomyBucknell University


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