Larry Claus wrote in 010226 MMDigest, "I'm still stuck on deciding
about valves and solenoids. Money is a factor here ..."
In 010107 MMDigest I posted about "MIDIfying a Raffin 20-key Organ".
I bought the valves from Peterson Electro-Musical Products in the U.S.
-- they were USD 4 apiece for the smallest ones. They have quite
large valves also, I think up to about 2 inches pallet diameter.
In my organ, the air pressure tries to *open* the valves, which is
probably wrong for a calliope with its high pressure; there, you would
have to put them inside a wind chest, so that the pressure tries to
close them. If the pressure on the pallet is so high that the magnet
cannot open it, maybe you can put a second, small-pallet valve in
parallel which opens first and thus equalizes the pressure on both
sides of the big valve (similar designs are used in church organs).
Re the MIDI connection: my laptop PC also has no MIDI output. I
purchased a BiPort [connects to the parallel port] from Midiman. If
you use Win95 or Win98 or Win2000, a Midiman Portman/S ("S" for serial
port) also works and is less than half the price of the BiPort. The
BiPort feeds the MIDI signal into an MTP-3 by John Wale in England. A
parallel interface (with enough outputs) is, as far as I know, not much
cheaper than using real MIDI, and using MIDI has the advantage that you
can hook up your instrument to anything MIDI in this big world.
Hope that helps a bit.
Harald M. Mueller
[ A Tangley calliope may operate at pressure 2 pounds(force) per
[ square inch, or more. If the valve area is 0.25 sq. in. then the
[ solenoid must overcome 0.5 pound force, or 8 ounces force. The
[ valve travel is only 0.25 inch or maybe less. Paul Freiling made
[ small magnet valves to operate the pneumatic player action of his
[ calliope. See http://mmd.foxtail.com/Calliope/freiling.html
[ -- Robbie