(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.

  • 1
    \$\begingroup\$ Very cool idea. \$\endgroup\$
    – Ben Voigt
    Commented Feb 22, 2012 at 19:06

1 Answer 1


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

  • \$\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
    Commented Feb 22, 2012 at 14:46

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.