Hi Piotr,  About 25 years ago we visited Paul Manganaro's shop and
home in Coopersburg, Pennsylvania.  One of the things Paul showed
us was his MIDI file transcription machine.  It was a large MIDI
keyboard and the player action from a piano.

The player was mounted upside down above the keyboard such that the
strikers of the player would contact the corresponding keys on the
keyboard.  Play a roll and the keyboard would play and record it in
MIDI.

Damn clever, I thought.  Why take the trouble to invent and build
new things when you can just combine useful existing things to get
the job done.

About 10 years earlier, I bought some pipes, chests and blowers from
a pipe organ.  My friend Jeff bought the rest of the organ, including
the console, and installed it in his dining room.

I built a 'contact bar' that mounted just behind the keys of my player
piano.  There was a wooden 'buss bar' that ran the full length of the
piano and 88 light springs, one mounted behind each key.  When the
back end of a key went up, it made the corresponding spring touch the
buss bar. Each spring was wired to one of the chest magnets and the
other leads of the magnets were connected to the power supply.

With the pipes in the basement and the basement door open, I could play
the piano in the family room and hear the organ play along with the
piano.  After a few years, I sold most of the pipes/chests so I gave
the buss bar to Jeff and he's been using it to play his part of the
organ ever since.

Regards,
Craig Smith