27 Sep
2004
27 Sep
'04
4:55 p.m.
On Mon, 2004-09-27 at 14:00, Dwight K. Elvey wrote:
You don't need the steering diodes if the lines
that provide the
terms don't cross talk to other coils. This is pure relay logic
and works with AC relays as well as DC. The diodes are only
needed when you share complex terms that use the same stack of
contact terms but would otherwise cross talk. The diodes allow
one to optimize the number of contacts used by sharing common
terms.
You're right, and while diodes would allow you to conjure up arbitrarily
complex terms of even relay logic, it's also true that solid state
diodes didn't exist back when relay calculators were The Latest Thing,
if these questions are leading to 'why didn't they...'
Though there's always selenium rectifiers, ugh. Besides being toxic,
huge, hot, they are slow and terrible forward/reverse ratio, though
likely faster than a relay. They've been around for a long time, I
wonder how good they' be as a relay signal diode (shudder).