Relay Bells.
Bells connected by relay connection to a main line for acoustic
telegraphy. A stroke on one bell indicates a dot and on the other a
dash. The system is now nearly extinct.
Relay, Box-sounding.
A relay which is surrounded by or mounted on a resonator or wooden box
of such proportions and size as to reinforce the sound. This enables a
relay to act as a sounder, its weak sounds being virtually magnified so
as to be audible.
Relay Connection.
A connection used in telegraphy, including a local battery, with a short
circuit normally open, but closed by a switch and a sounder or other
appliance. The latter is made very sensitive so as to be worked by a
feeble current, and is connected to the main line. A very slight current
closes the switch and the local battery comes into operation to work a
sounder, etc. When the current ceases on the main line the switch opens
and throws the local battery out of action. The switch is termed a
relay, q. v. A long main line may thus produce strong effects at distant
stations, the intensity of action depending on the local battery.
Fig. 288. RELAY OR LOCAL CIRCUIT.
Relay, Differential.
A relay containing two coils wound differentially, and of the same
number of turns and resistance. If two equal currents pass through the
coils they counteract each other and no action takes place. If there is
a difference in the currents the relay acts as one coil preponderates.
The coils may be wound for uneven currents with different resistance and
number of turns.
Relay, Microphone.
A relay connection applied to a telephone circuit. It consists of a
microphone mounted in front of the diaphragm of a telephone receiver. In
circuit with the microphone is a battery and second telephone receiver.
The microphone is supposed to intensify the sounds of the first
telephone.