Volume 1 — Simple Open-Circuit Telegraph Line
Reading edition
Simple Telegraph Line
By using the circuit shown in the sketch for short-distance telegraph lines, the extra switches and wiring found in many circuits are done away with. Closing either key will operate both sounders, and, as the resistance of the sounders is very high, the batteries do not run down for a long time.
Contributed by A. D. Stoddard, Clay Center, Kan.