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So, this project of mine is one of many reasons why I haven't been around much for a while... I did it for Physics E&M this term, which along with other things is what has been eating up all of my time.

This, however, I thought some of you here might find interesting.

http://www.youtube.com/watch?v=f3EIhbg5LNw

*reminds self to check this out*

I took Phys E&M last year--- will check it out when I get home.

(it had better have magnets and circuits!)

Woah, it's floating!

That is far more impressive than me making the magnetized silverware stick together at the restautant. Is that essentially the same technology that maglev trains use?

This reminds me of those magnetic pens, that would levitate over a base, but this project is many magnitudes more impressive than those things ever were. That was really fun to watch, thanks for sharing Howlitzer.

That's bloody cool, even if it's unstable and only works for a second or two. That's a second or two of making a battery levitate, and I'm sure there's a way to use this to do something cool and futuristic.

That is so neat!

Try something other than a battery, but of the same weight. I think what's happening is that the battery's contents or case is messing with the G/EMF* balance, and that's why it drops.

Something spherical would work best, because then there would be no secondary magnetizing of the levitated object. Think a ball from a bearing; it wouldn't be as cool looking, but it would float longer. And no soft iron, either; that stuff magnetizes in a heartbeat and then you'd have the same problem you have now. Anything long and narrow will magnetize over time in the intense field you're generating.

Anyway, that is one neat experiment!

*Gravity vs. Electromagnetic force. You're making a temporary magnet out of the battery shell and messing up the force balance.

actually it's not that strong a magnet, despite how large the coil is. The battery magnetizing wasn't the problem, our problem in getting it to work properly was that the primary adjustment was a 20 turn, 50 kohm resistor....and the tolerance once you get it into that sweet-spot is about 1 degree....so looking at it wrong would throw it out of whack. BREATHING on it wrong would throw it out of whack due to the conductivity of the moisture in your breath. We needed a finer adjustment, which we didn't have time or the means to get then.

Also using something spherical for some reason works worse than the cylindrical battery shape. The stabilization works in 1 dimension, it only senses when the object is or isn't in the path of the LED, and by how much....but interprets that as simple up-down. Any left-right motion leads to instability for this very reason, since it interprets that as up-down. The cylindrical shape of the battery seems to stabilize it more in terms of left-right motion since it's "hanging" the long way from the magnetic field....whereas a spherical object would be free to wobble any way it wants.

very very cool i mite look into makeing one these!

Wow. I wouldnt even know where to start if I wanted to make one of those. Nice job!

You should use the device to levitate a 20-sided dice. If you did this, you would get massive nerd points.

The reason I suggested something spherical is simply because a sphere won't show drift as seriously as other shapes.
And why not use a second .5 - 2.5 k ohm in series to fine-tune the thing. Set it one turn low on the big one, then use the smaller wirewound as a fine-tuning resistor. That way, you have the effect of one turn of the wirewound (2.5K ohm) in a fully adjustable second resistor. Think "Squelch" as a reference.

Anyway, that is a neat experiment you're doing.

Well, we were considering using a second, smaller variable resistor for exactly that purpose, but the ECE department at my school was fresh out of them. We did eventually get one, but the project had been dismantled by that time. I have yet to reassemble the circuit on my own breadboard.