The article by Willy van der Reijden is an excellent example of
"thinking outside the box", to wit:

> These relays, in turn, lift the primary valves of the stack by
> a short piece of stiff copper wire, soldered to the moving armature
> of the relays.

What a simple idea!  While most of us have been struggling with compact
and reliable ways to control the air in the primary lines from the
tracker bar, Willy has bypassed this and gone straight to the primary
valves.  Just lift the valves, never mind the pouches.

My Raffin crank organ has valve guides protruding through a Masonite
[hard pressed wood] board on the bottom.  If I could mount relays or
solenoids under these to push up on these guides, I could play the
organ directly.  The magnets and armatures wouldn't need to be larger
than a pipe organ valve such as Peterson's.

One consideration: in my organ, since the pouches operate from chest
pressure, not vacuum, an operated pouch pulls the valve up, rather
than pushes it, and to push up a valve guide means pushing against the
pouch pressure.  That means extra force is required by the magnet, and
it may also wear on the pouch over time.  But it's worth thinking
about.  Thanks, Willy!

Mike Knudsen

 [ See the photos of Willy's MIDI-controlled Frati-Hymnia orchestrion
 [ at http://mmd.foxtail.com/Tech/   "MIDI Control"  -- Robbie