How Can I Measure the Strength of a Magnet for Building a Larger Levitron?

[Demonis]

I was puzzling the Levitron today, and was trying to figure out what the magnets involved strength was, on the off chance that I may build a larger one for kicks.

However, after some moderate googling, it doesn't seem like figuring out the strength of a magnet is a quick or 'easy' task. Being that I don't own a Levitron to take measurements myself, but would likely buy one if there is a cheap and effective way to get those measurements, could someone point me in the right direction?

To clarify, I just need to know how to measure the strength of a permanent magnet to build a larger than average levitron. :D

 

[Bob S]

I have been measuring magnets for a very long time, and never have found a satisfactory measurement tool. Presently, the Hall Effect probe seems to be the most useful. You can buy Hall Effect ICs cheaply, and put them on your own opamp, or buy calibrated probes. A long time ago, we used rotating coil probes on the end of synchronous motors, or flip coils (with integrating amplifiers). The most precise (a few parts per million) is proton nuclear magnetic resonance.

 

[Demonis]

Is that the same method magnet manufacturers use to test the strength of their magnets? It also depends on the shape of the magnet doesn't it? Depending how the field is shaped rather.

 

[Bob S]

Is that the same method magnet manufacturers use to test the strength of their magnets? It also depends on the shape of the magnet doesn't it? Depending how the field is shaped rather.

Manufactures probably all use Hall Effect probes for 1% type measurements. The Hall element is perhaps 0.25 mm in size, and the measurement can be made in any shape magnetic field. For 1 ppm measurements in uniform fields, manufacturers and laboratories rely on proton nuclear magnetic resonance.

 

[Demonis]

So with something as precise as the Levitron is, relying on both magnet strengths, weights, and distances all being in perfect balance, would I be able to actually get good enough measurments to duplicate it on a larger scale without having extremely precise instruments?

I'm on a tight budget hehe!

 

[Bob S]

Hi-
If you have someone who can build simple op-amp circuits, then get Allegro Hall Effect sensor part #
http://www.allegromicro.com/en/Products/Part_Numbers/1381/1381.pdf
at digikey.com:
http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=A1381EUA-T-ND
Their unit cost is about $1.37 each.

[Added] Get the 3 pin SIP package (suffix UA)
Bob S