Identifier: electricalinstru00unitrich (find matches)
Title: Electrical instruments and telephones of the U.S. Signal corps
Year: 1911 (1910s)
Authors: United States. Army. Signal Corps
Subjects: Military telegraph -- United States Military telephone -- United States
Publisher: Washington, Govt. print. off.
Contributing Library: University of California Libraries
Digitizing Sponsor: MSN

View Book Page: Book Viewer
About This Book: Catalog Entry
View All Images: All Images From Book
Click here to view book online to see this illustration in context in a browseable online version of this book.

Text Appearing Before Image:
3 conductor cord Fig. 8.J.—Circuit, local battery desk set, Sumter type.LOCAL BATTERY DESK SET. In figure 85 is shown circuits of the local battery desk telephoneof the Sumter make, as furnished to the Signal Corps. The usualbridging circuit is used. The diagram shows the actual wiring as itis found in the instrument, and the various parts are shown correctlyplaced with respect to each other. 132 ELECTRICAL INSTRUMENTS U. S, SIGNAL CORPS. COMMON HATTERY TELEPHONE. Ill cer-cral it may be >aid that the parts used in the comiiioii battery^vall leK^piiones are similar to those used in the local battery. It will usually be found that the primary of the induction coilused in the common battery instruments is of h.igher resistance, andthat the ratio between the primary and secondary windings of theinduction coil are quite dilierent. A common battery wall telephoneof the Sumter make is shown in Hgure 80. A shows the wiring of r4V 9^
Text Appearing After Image:
THEORY B Ili;. sr>.— Iil-cnits. CDiniiuiii lialt-ry wall sol. Sinulcr typi the instrument and the parts with correct relation to each other, amiB a simplified circuit diagram of the instrument. The operation ofthe instrument is as follows: Assuming that the receiver is in place on the hook switch, theincoming ringing current will pass from the line L through the bells/>*. condenser f\ to the line Z, ringing the bells B. The hand receiverbeing removed from the hook switch, the contacts at // are closed. Inthis condition the battery from the central exchange passes from Lthrough the coarse-wire winding of the induction coil through theiraiismitter to the line L. Battery also passes from the bells B, sec- ELECTRICAL INSTRUMENTS U. S. SIGNAL CORPS. 133 ondary or fine-wire winding of the induction coil, receiver /?, trans-mitter 7, to the line L. The resistance of this second path is verymuch greater than that of the first path, so that the current flowingin this high resistance pa

Note About Images