The practical telephone handbook and guide to the telephonic exchange (1906)
Poole, Joseph · New York, Macmillan Co. · leaf 301
Fig. 279 required, it is necessary to make the bell branch to earth,of a very high resistance, so that the current passing throughis insufficient to operate the line relay, for which reason thebells are wound to about 2500 ohms, and a resistance coil offrom 5000 to 20,000 ohms is added to the…
Telephone
Internet Archive · Northeastern University Library · Public Domain Mark 1.0. Free to use for anything.
