Miller, Kempster Blanchard, 1870-1933 · New York : McGraw publishing company · leaf 257
nce of potential from the earth by the batterv, 0,which finds circuit through the restoring coil, », of the annunciatorof that line to all the dififerent test-rings, ^, belonging to that lineat all of the sections of the board. If when the line is in that con-dition the tip of the test-plug, which… … test-ring are at the same potential. Silence will therefore indicate a free line. When, however, the line has been put into use by the insertionof a plug into the spring-jack thereof, the springs, b and h, are con- 236 AMERICAN TELEPHONE PRACTICE. nected by the contact-ring, i, carried on the plug,…
Telephone
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