Greetings,  I am designing a circuit to interface my E-Roll Player
valve units to the real world for use where it is not desired to use
MIDI to control them.  This might be the case in the interfacing of
a pneumatic piano to a theatre organ, for example.  The circuit will
do signal level shifting and inversion if necessary.

I am also slightly concerned with contact bounce.  I have demonstrated
that the circuit works fine without debouncing if I use a small PC
board relay to simulate the contacts in the organ.  However, I have no
idea if the characteristics of these two different types of contacts
are similar.  I also do not know what signals are typically used in
a theatre (or other electrically signaled) organ.

My circuit will work with switching of either the - or + lead of the
organ power supply and the other side of the supply common to all
switches.  It will work with any DC voltage from 5 to 24 volts.  Wide
swings in the DC voltage would not be good.  I have heard rumors that
certain organs used unfiltered supplies to reduce contact wear but have
no idea if this is true or not.

I would to hear from someone who knows the details of organ switching
methods and can answer these and possibly other questions.

Best regards,
Spencer Chase
Laytonville, Calif.
http://www.spencerserolls.com/