Cubus said:
Reading about electrical inventions back when Edison ruled
I often see the polarised relay mentioned. What characterizes
this relay?
I believe a "polarised" relay has a permanent magnet in the "magnetic
circuit" which makes the armature move in one direction if the net coil
current is positive and the other direction if the net coild current is
negative. It could be operated to act as a "center off" relay or to simply
operate for current only in one direction. There was a significant air gap
in the magnetic circuit in all permitted positions of the armature to keep
the relay from "latching up."
Edison made his first money in making arrangements for making a single
telegraph wire carry traffic in both directions at the same time and for the
line to carry more than one message at a time.
