Electronic Levitron...How the heck does this thing work?

[Pirate88179]

https://www.youtube.com/watch?v=W6SSY7ABJkw


Check this thing out.  I know it has been out for a while, and a guy had one at work last year on his desk.  It is amazing and, I would like to make one as it costs about $100 US to buy.  The video above says it all.  It even works sideways!

To me, this is the opposite of the kind of devices that TK, Lidmotor and others have built where something hangs in space using light sensors.
I am guessing that there is only about $10-$20 worth of parts in this thing.  I just think it would be really cool to make one.

TK suggested searching for their patent to see what that says.  This is a good idea and I will look for it.

Bill

PS  It also rotates the levitating disk as well as adjusts for any added weight differential.  Amazing!

PPS:  I found this while searching: US patent number 2007/0170798A1.  I will pull it up to see what it says.

[Pirate88179]

I found this:

http://www.google.com/patents/US20070170798

Very interesting to read.  I am just getting started with it.

Bill

[TinselKoala]

I haven't read the patent yet but here's what I think.

The black disc contains a big ring magnet polarized on the faces, and a couple smaller magnets around the edge of the ring, but facing sideways.  The base contains a big coil facing up/down, and a few smaller coils around the edges. The big coil is switched in polarity, rather then being just turned off and on as in my levitation system. The opposite switching polarities of the big coil act on both poles of the ring magnet to "lock" it into position, whereas in the usual system like mine, the levitated object is not locked but rather balanced between gravity pulling it down, and magnetism pulling it up. It's always falling slightly when the coil is off and rising slightly when the coil is on. But in the Levitron, gravity doesn't play a role, the thing is first attracted-repelled by one polarity of the coil acting against the faces of the ring magnet and then attracted-repelled oppositely by the other polarity of the coil. So it's "locked" in position. The rotation and perhaps lateral stabilization come from the side-facing magnets in the black disc, the rotation coming from being slowly attracted or repelled by the smaller coils around the outside of the big coil in the base, in ordinary "pulse motor" fashion. This locking in position, regardless of direction of gravity, can be seen in my demonstration of what I call the "Nikolayev trailer hitch", where a ring magnet and a cylinder magnet are kept in that relationship, and the cylinder is prevented from flipping over by being inside a central tube. In the Levitron the black levitating disc doesn't flip over because the polarity of the coil is flipping over instead.  The spacing is probably maintained by photodetectors and UV or IR LEDs, and the visible LEDs are there to tell the operator when the disk is in the correct position for the sensing system to take over. 
That's my guess.

Now I suppose I should read the patent.

(There is another really cool levitation system that works by having most of the weight of the levitated object taken up by a strong Permanent Magnet in the top of the assembly, and the electromagnet coil is wrapped around the PM. The strength of the overall field of the PM/coil is regulated in the usual way by sensing shadow  edge or by Hall sensor, and it takes very little current in the coil to maintain the levitation. If the power goes off, the levitated object doesn't drop like it does in the usual system like mine, but rather is pulled UP to the permanent magnet in the top part of the device. It also will "self start" from this position when the power is turned on, it doesn't need any intervention from the operator to get things in the right position. This system is much more efficient than the usual one since it takes so little current to regulate the field of the PM that is supporting the weight of the object.)


ETA: now I've read the patent. I almost guessed it! It looks like sort of a combination of what I guessed and the other system mentioned above, partially permanent magnets and partially coils modulating the field of the PMs.But I had the base and disc PM configurations reversed, apparently, from what's in the patent.

Good find Bill, thanks!

[pavqw]

Yes, there are few strong permanent magnets and with sensor usage it just balances the object all the time with weak electromagnets.

[FatBird]

Click on this Link to see the Patent in a PDF format that's easier to read.

http://www.pat2pdf.org/patents/pat20070170798.pdf
                                                                               .