Hi Mike.  Vern Jones also uses the power MOSFETs in his Sound Research
products, as I plan to.  Smaller 1/2-ampere MOSFETs are employed in the
Octet products to drive high-current organ magnets.

But worst-case total current consumption can be higher than you imagine.
The Unaphone can also operate in single-strike mode, and a music roll
player is likely to be controlling it.  You know what occurs when a
music roll snaps or doesn't rewind -- the tracker bar is completely
exposed and all the notes play at once.

I don't want any transistors to melt when all the Unaphone magnets turn
on and stay on, so the whole system, including the MIDI converter unit,
must withstand operation of all striker magnets at once, until the
system circuit breaker pops and disconnects the battery.  (Pneumatic
systems sure are nice; they don't have these silly problems!)

Robbie Rhodes