Hi Phil, The typical 20-note organ turns at about 60 RPM. If you chose
a 1700 RPM motor, you'll need a 3-stage gear reduction. That's quite
a job unless you're hoping to use up all the gears in your junk drawer.

What you need is a low RPM gear motor. Places such as the Surplus
Center have a nice selection. Small motors from a car would work well
and you might try a motor from a 1/3-scale toy car. Bodine makes a
whole series of variable speed gear motors that would work but they're
sort of pricey.

If you use one of Bill Klinger's MIDI controller systems, you'll need
a source of 12 volts dc for the electronics so you might as well use
a 12-volt motor too.

Lastly, have you considered installing the MIDI system to control the
music and solenoid functions and just cranking the bellows yourself?
I don't know your application, but it works great for me so I can
participate in making the music.

Good luck with your project.

Craig Smith - from chilly western New York
By the way, I still have the precision flow meter system that you
designed about 20 years ago.

 [ See "Airflow and Leak Measurement Equipment," by Phil Dayson, at
 [ https://www.mmdigest.com/archives/Digests/199702/1997.02.05.08.html 
 [ https://www.mmdigest.com/archives/Digests/199904/1999.04.15.05.html 
 [
 [ Special effects designer Thaine Morris used a 24-vdc skateboard
 [ motor to power his 37-key Hofbauer Harmonipan street organ, visit
 [ https://youtu.be/fXpdLFWTg-U?t=76 -- Robbie