Optical Scanners for Music Box Disks
By Jack Kane
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
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