Electricity, magnetism, and electric telegraphy; by Lockwood Thomas Dixon 1848-

Author:Lockwood, Thomas Dixon, 1848- [from old catalog]
Language: eng
Format: epub
Tags: Electrical engineering, Telegraph
Publisher: New York, D. Van Nostrand
Published: 1883-03-25T05:00:00+00:00

Fig. 60.

In the figure line 1 is shown connected with its instruments by means of two plugs inserted between the upright bars and the discs; line 2 is similarly connected with its own instrument, and line 3, in addition to being connected with its instruments, is grounded by the insertion of a plug in the upper right-hand hole.

When such a switch is used for telephone service the horizontal bars are chiefly used as connecting strips between any two circuits, and in that case each line is attached to only one vertical strip, thence to instruments and ground.

Since the introduction of the telephone the importance of the switch-board has greatly increased, and many improvements have been invented, chiefly relating to the modes of connection and manipulation.

Digitized by VjOOQIC

200 ELECTEICITY, MAGNETISM, AND TELEGRAPHY.

186. Describe briefly other switches in use. Many small switches or circuit-changers are used for cut-outs, ground-switches, battery-switches, and kindred purposes. They are usually either plug or button switches.

The plug-switch is simply two or more brass plates with holes drilled between them, so that by the insertion of a metal plug any two or more plates, with the circuits attached to them, may be connected together. The byUon-switch^ as shown in Figure 70, consists of a lever. A, pivoted at one end to a screw, to which the main-circuit wire is attached, and of any required number of buttons, or contact-points, as B, G, each connected to a screw and branch wire below the base-board, and to any of which the lever may be swung, thus connecting the circuit to the branch

Fig. 70. . °j

required.

Several such levers may be connected together by an insulated cross-bar and worked by the same movement; these are called compound switches. Special forms of switch are also used in connection with telephones; these are popularly known by the names of secrecy and automatic switches. The first of these was devised on the baseless theory that every person would be on the lookout to listen to the conversation of others, and is designed to obviate such occurrences. It consists in devices whereby a telephoner, by turning a lever or a hook, opens or breaks the line in the direction in which he is not about to converse, and at the same time connects a temporary ground, completing the circuit through his telephone in the direction in which he does intend to converse.

The automatic switch is one in which the removal of the telephone changes the circuit from the alarm to the telephone, and is in general use. The principle is

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