I'm trying to see what is available in the market to "read" music box
discs -- I found a company which has a fiber optic photoelectric sensor.
I will need one amp and one fiber per track. The amplifiers are $119.00
and each fiber optic will be $40.00 to $77.00 depending on the required
fiber unit.  (yikes!)  A "gang" of readers could be placed side by side
in close proximity utilizing coaxial cabling.  The output of these
sensors will go to ground when a hole is detected.  This logic would
then have to feed into some low binary information that a device that
could convert it to MIDI.  Anyone in the digest have wisdom on pursuing
this?

Jack Kane

 [ Editor's Note:
 [
 [ Mark Fontana built a very inexpensive roll reader by stuffing
 [ light sensitive diodes into the holes of an old tracker bar.
 [ He said it worked pretty well except that some of the newer
 [ rolls were too translucent to block enough light.  This would
 [ not be a problem with a music box disk if it was back lighted.
 [
 [ If you accuracy, there's nothing that will compare with a CCD
 [ line scan camera.  You can either rotate the disk in front of
 [ the camera, or you can scan the disk from top to bottom and
 [ compute the angular rotation in software.
 [
 [ Robbie Rhodes has recently done some experiments with using
 [ a flatbed scanner to scan in "photos" of disks.  He's had
 [ some success.  Unfortuantely he's out of town for a while so
 [ he won't be able to comment right now.
 [
 [
 [ Another possibility is to build a mechanical reader, perhaps
 [ with Microswitches driving a Devtronix board.
 [
 [ Which of these techniques is appropriate for your application
 [ will be determined by how accurate the results are you want,
 [ and whether you want to do the conversion in real time.
 [
 [ Others who want to comment on this shouldn't be put off
 [ by my comments!
 [
 [ Jody