The lower branch circuit, with two bells in parallel
A simplified call circuit is shown in figure 5-20. The
with each other and in series with one push button, is
upper branch circuit, with one bell and one push button
used to call two stations from one remote location.
in series with each other, is used to call a single station
from one remote location.
Note that the bells or signaling devices are
connected to the side of the lines bearing the negative
The center branch circuit, with two push buttons
designation EE. This arrangement is used on ac circuits
in parallel with each other and in series with the bell,
that have no polarity, but in which one side of the line
is used to call a single station from two remote
arbitrarily is designated as EE for convenience.
Figure 5-20.--Simple call-bell system.