Magnetic Levitation Anamoly Needs Your Explanation 1

[Auburnate]

I have a short video of a magnetic levitator I built and am trying to explain a curious effect.

http://www.youtube.com/watch?v=fWRJL3Nbb-0

Notice the washer oscillating side to side without touching anything? Can someone please explain what this can be attributed to?


Theory 1. Flux density: If the return path for the flux is biased in one direction (i.e., through the
back of the visible setup), then the washer tends to rotate so as to minimize
the path length in air.

Theory 2. Irregularities in the surface of the washer cause the sensors to see it in different spots, causing it to oscillate like a limit cycle.

Theory 3. Video is faked. Change career to film editor immediately.


Thanks,

Nathan

Short explanation of operation:

When a current passes through a wire, a small magnetic field is generated. When that wire is coiled around a ferromagnetic core, a very strong magnetic field is created. This magnetic field provides the lifting force to cause ferric metal objects (e.g. a steel ball) to rise towards the electromagnet. The IR diode and IR phototransistor measure the location of the ball. With the essential phase lead circuitry, a control signal is generated that drives a power transistor. The power transistor turns on or off the electromagnet. The timing of when to turn off or on the electromagnet causes the ball to rise and fall so fast as to appear to be levitating. Just before the ball is outside the controlling distance of the electromagnet, the current is sent through the coil and the ball is pulled back up.

 

[jimkirk]

It's called a Foucault Pendulum, by the way.

 

[MustUnify]

I've been watching, I have to admint. However, it seems to me like there are so many possible explanations (most of which can be proven true or false if someone wants to take the time!) that the question has sunk into the realm of engineering trivia.. zzzzz