MMD > Archives > April 1997 > 1997.04.17 > 10Prev  Next


Transcribing Music Box to Midi
By Pete Woodworth

Hi, all.  In MMDigest 97.04.16, Beatrice Robertson wrote:
> And Larry, there's another project for you.  You would sure be a hit in
> MBSI if you made an adjustable microswitch mechanism that could be made
> to fit many music box comb layouts!  That would be a standing-room-only
> workshop for a convention!

To which Robbie responded:
>[ Perhaps a strip of tiny music-wire or brass contacts could be fitted
>[ to the comb to make an electric connection as the tine is plucked.
>[ The circuit boards to make Midi signals, and the record/play programs,
>[ are readily available now.

I would suggest a non-contact version, first. I believe I have seen some
very tiny Hall-effect sensors, which are extremely sensitive to magnetic
change, arrayed in a line. As a crude example, consider the individual
string pickups on an electric guitar: a coil of wire, surrounded by the
poles of a permanent magnet. The (non-magnetized) string vibration
induces magnetomotive force in the coils; the result being rock-and-roll.
Alternately, how about individual Hall-effect sensors mounted above the
teeth of the comb? I would love to see the resulting waveform on a
'scope.

What about photo diodes? These are available tiny, also. To increase
contrast, just dip or spray the cylinder with flat-black paint, and paint
the pins white. If you use Rust-o-leum, it would also reduce corrosion.

Just kidding, Beatrice!

Pete Woodworth
Wearing flame-proof undies.


(Message sent Thu 17 Apr 1997, 19:04:17 GMT, from time zone GMT-0700.)

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