Items related to Practical telephone handbook and guide to the telephone...
This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1891 Excerpt: ... it is laid on prong B, carried in an ebonite bush, A, let into Fig. 125.--Scale J. the switch-table. Its weight presses down the spring c from a platinum contact on the brass plate D; c and D form part of the primary circuit of the transmitter. An ingenious plan for the same purpose, called Gray's Contact Breaker, is shown in Fig. 126. The receiver is Fig. 126.--Scale J. furnished with three terminals, ABC. Under A is fastened the flat spring D. From B a wire extends to a contact plate, F. The connections to the transmitter are shown in the figures, and it will be seen that the connection to B is common to both the secondary and primary circuits. The operator, in taking up the instrument, closes the primary circuit by pressing D against F. An objection to this form is that the flexible tinsel telephone cord is introduced into the primary circuit, the resistance of which is rather high, and gets higher with use. The operator has always to grasp the instrument in the same manner, and she is always in circuit with the secondary circuit, which is objectionable during lightning storms. In addition to the above arrangements, it is desirable to provide a two-way switch in the primary circuit, joined up to two cells, so that the operator may, by movingover the switch now and then during the day, change the working cell. The connections for this are shown in Fig. 126. Domestic Switch-boards.--Fig. 127 shows an instrument made by the Western Electric Company, designed for the joining up by telephones of a number of rooms in the same or adjoining buildings, so that a person at any one station may ring and speak to any other one without the aid of an ordinary switch-board and operator. To accomplish this an instrument like Fig. 127, which comprises switch-bell, microp...
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About the Author:
Poole, CERN, Geneva.
"About this title" may belong to another edition of this title.
- PublisherRarebooksclub.com
- Publication date2012
- ISBN 10 113020717X
- ISBN 13 9781130207170
- BindingPaperback
- Number of pages52
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