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(disclaimer: bit of an electronics newbie here)

I have a bunch of little magnet ball-bearings that I was playing around with the other day. I formed them into a strand, then fixed both ends leaving a small gap in the middle of the "string" allowing it to vibrate when plucked:

horizontal strand of magnetic balls

My ultimate goal is to be able to pluck this strand like a string and be able to convert the subtle (I would presume) changes in the magnetic field as the string oscillates into an analogous oscillation in voltage/current which I can supply to an arduino where weird sounds shall be produced.

This question about making a magnetic field sensor was helpful and pointed me to the Allegro A1301 IC and the Hall effect, which might be what I'm looking for but I suspect won't work for me here.

I also wondered whether I could use inductance here in a way similar but sort of opposite to the inductive phone tap here.

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    \$\begingroup\$ Very cool idea. \$\endgroup\$ – Ben Voigt Feb 22 '12 at 19:06
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Yes, you will be able to use a coil to produce a varying voltage which you can then amplify and input to a microcontroller. While it would be possible to provide a coil that produced signals at a level suitable for direct input to a uC ADC, in most cases you will end up with very small signals which need to be amplified.

Use of a linear hall cell is liable to be easier overall.

The A1301 is a good choice. Not in stock at Digikey.

Digikey do have this Honeywell SS39ET Hall sensor that looks good.
$1.44/1 in stock

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  • \$\begingroup\$ Thanks, Russell! I guess I'll have to just play around with it and see if one of these ICs will do the trick. \$\endgroup\$ – jberryman Feb 22 '12 at 14:46

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