Hello again.  Anyone that is building or contemplating a roll reader
needs to know about the ittyMIDI.com 'Discreet Encoder' board.  This
little gem will scan an array of switch closures and convert it into
MIDI code.  All of the details are available via the ittyMIDI.com
web site.

I just completed a reader that uses instrumentation vacuum switches.
This apparatus is just a roll frame with motor and tracker servo,
tracker bar, breeze box, motor regulator, and a 7 x 16 array of
switches.  The cross points (with blocking diodes) are wired directly
into a 34-pin connector.  Out the other side is a MIDI port that
outputs a MIDI signal for the appropriate switch closure.  Quite simple,
and it works very well, and the encoder board costs less than $100!

There have been a number of postings recently on the ittyMIDI player,
and this is a nice gadget also.  These people provide superb support
and very politely answer pretty dumb questions!

Larry Emmons

 [ Visit http://www.ittymidi.com/product_a0007.asp  -- Robbie