Roger Wiegand wrote in 060924 MMDigest:

> In thinking about the best way to add a MIDI interface to
> a keyed fairground organ, it seemed to me that one of the easiest,
> most transferable, and most sympathetic means would be to make
> a "mini-Vorsetzer" that would clamp on to the keyframe in place of
> the pressure bar and play the organ by operating the keys just as the
> book does, rather than by introducing additional plumbing downstream.

I think the "keyboard" that Roger wants to MIDIfy is the keyframe of
a book-playing organ, not a human keyboard.  The little "key" teeth are
very close together, and work backwards -- they're held down to keep
the note from playing, and letting one rise up sounds its note.

Roger's idea is good, but it would need a rather large magnet or
solenoid for each key.  These would work against springs that hold down
the keys -- each magnet would overcome the spring and let the key pop
up (assisted by the keyframe's own spring).  With the magnets spread
over several tiers (like player piano stack pneumatics), it should be
possible, though bulky and awkward to handle.

> This would keep the keyframe "exercised" (which I'm told is a good
> thing), and would be much simpler than other means of MIDI-fying
> a typical pressure-operated keyframe.

Yes -- a keyed frame must be blocked out of play with a slider switch
or pouch board, to keep it from "fighting" the MIDI-controlled valves.
And these valves must be capable of switching between pressure and
atmosphere, not just opening the tubing to atmosphere as with a keyless
or roll system.  Reisner-type pipe organ magnets can do that, but
they're not small or cheap compared to OSI/Peterson valves.

> How hard would it be to make the organ (or piano) an Ethernet network
> device with a wireless card so that it could be run off a remote
> laptop, perhaps displaying an electronic piano roll version of the
> music, a la Cakewalk?

Wireless MIDI links are probably used for live rock concert stage work,
but the display of moving notes would have to be on the laptop that is
driving the organ.  That might be an advantage -- people could watch
the "roll" from your shady tent at a hearing-safe distance, and not
have to stand at ground zero in front of the organ.

> On a related note, it seems that most MIDI systems I see use relatively
> archaic systems for data storage and transfer (like floppy disks or
> proprietary ROMs).

True enough.  Even the Palm Pilot I use requires a serial interface on
the parent PC, and those are going the way of floppy drives.  I've been
using the ittyMIDI Palm Pilot system to play my 31er Raffin crank
organ for about a year now.  Mine is the cheapest ($99) version with
no camera flash memory card, but there is still room for 100s of tunes
in the Palm's memory.  It's a great little system, and you can use the
Palm normally for phone numbers, date book, solitaire games, etc.

> As you can tell, I'm not an engineer (but I know there are many
> lurking here)!  :-) <<

You have the engineering problems and solutions pretty well pegged,
and are asking the right questions, so we engineering types will enjoy
working with you.

Mike Knudsen