This unit was built in the late 1980s as an interesting project I did
with a couple of associates.  There were some that had an interest in
the project.  I was going to let them know where they could view the
project.  It is listed on YouTube as "optical / solenoid player piano
attachment for standard piano" and it can be viewed at

  https://www.youtube.com/watch?v=i9_ThkZyHhQ
 

It was very challenging but I think it works well.  I can provide the
other electronics involved if someone would like to know, or build one
for themselves.

Thank you,
Jerry Holmes