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.