"Bay78" wrote in message
news:56544523-f591-4351...@googlegroups.com...
The German board is the only one that fixes the direct driving of the switch
matrix problem.
You can use everyday slotted opto switches on these boards due to using
external driver circuitry for the switch matrix rather than the optical
switch. A much, MUCH better design.
The other clock boards must use high current drive optos with low voltage
drop....custom ordered parts. If the opto dies (and it will) then there is
only one source for these.
Ed