. American telephone practice . ew, as secured to the rear end of the piece, a, is the line spring, MAGNETO SWITCH-BOARD FOR SMALL EXCHANGES. 179 c, formed with a rearwardly projecting tongue, to which the wire, /,leading from the line is soldered. The forward end of the spring, c,rests normally against the pin, p, carried by, but insulated from,the base, a. A wire, g, leads from this pin, and through the coilof the line annunciator or drop to ground. When the plug is in-serted in the jack its conducting tip makes contact with the tip of theline spring and at the same time forces
. American telephone practice . ew, as secured to the rear end of the piece, a, is the line spring, MAGNETO SWITCH-BOARD FOR SMALL EXCHANGES. 179 c, formed with a rearwardly projecting tongue, to which the wire, /,leading from the line is soldered. The forward end of the spring, c,rests normally against the pin, p, carried by, but insulated from,the base, a. A wire, g, leads from this pin, and through the coilof the line annunciator or drop to ground. When the plug is in-serted in the jack its conducting tip makes contact with the tip of theline spring and at the same time forces it out of engagement withthe pin,./>. Normally, therefore, the line wire is connected to theground through the wire, /, spring, c, pin, p, wire, g, and line-dropto the ground connection. When the plug is inserted in the jack,however, the line is disconnected from the branch leading throughthe drop, but is connected through the medium of the plug to theflexible cord. Fig. 157 shows a common form of switch-board drop. The pur-. FIG. 157.—SWITCH-BOARD DROP. pose of the drop is to attract the attention of the operator wheneverany subscriber wishes a connection. The coil of the electromagnetis mounted on the back of the front plate, c, of the switch-board, asshown. To the armature, a, pivoted at its upper end, is attached arod, b, passing forward through a hole in the front plate and pro-vided with a hook on its forward end, adapted to engage the upperportion of a pivoted drop-shutter, s, and to hold it in its raised posi-tion. The attraction of the armature due to a current passingthrough the coil causes the hook to rise, thus releasing the shutter,which falls to a horizontal position and displays to the operator thenumber by which that line is designated. In order to attract the attention of the operator at night or atsuch times as she may not be in sight of the board, a night-alarmattachment is provided on each drop, which serves to close the cir- 180 AMERICAN TELEPHONE PRAC
Size: 1651px × 1514px
Photo credit: © Reading Room 2020 / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., boo, bookcentury1900, bookdecade1900, bookidamericantelepho00mill
