Laurent Coray wrote:

> Andy Taylor's suggestion, "Maybe it could read the roll with wire
> brushes like the old Mills Violano machines", is interesting, but I
> wonder if this pickup system would be reliable enough.

The IBM card readers used from 1934 to 1965 used wire contacts to read
holes punched in cards. They worked forever and never wore out. I was in
Mexico recently and saw one still in use, running an automata display.

Also, the San Antonio Municipal Auditorium had a large theatre organ
built by M. P. Moller of Hagerstown, Maryland, that played from perforated
rolls read by wire contacts. It lasted for about 30 years until the
building burned to the ground.

On the surface one would assume that reading light with a photo-diode
array would be most reliable, but if have a MIDI box that reads switch
closure, I see nothing wrong with reading with mechanical electrical
contacts. I would try phosphor bronze strips coated with tin. That should
work for a long long time.

I once made a carillon reader with paper rolls pulled by a surplus
variable speed Bodine motor. The holes were punched with a slightly
modified office paper punch. The contacts were nickel plated hard copper.
The contacts operated automobile horn relays which supplied voltage for
the clapper solenoids. The thing worked for 10 years until it was
replaced by a commercial electronic program (pre-MIDI).

Bill Finch