A remote control coil for a coin piano can be easily made from an old
style doorbell.  It will require some wiring modification so that the
bell will no longer reiterate, and it will require a 12 volt DC power
source of either batteries or a modern transformer.

When the above is accomplished, cut off the clapper of the bell, remove
the bell, and connect a string of fish line between the trip mechanism
and the stub where the clapper was removed.

I made one of these devices and it has worked perfectly for many years.

Bruce Clark