Identifier: practicaltelepho00pool (find matches)
Title: The practical telephone handbook and guide to the telephonic exchange
Year: 1906 (1900s)
Authors: Poole, Joseph
Subjects: Telephone
Publisher: New York, Macmillan Co.
Contributing Library: Northeastern University, Snell Library
Digitizing Sponsor: Boston Library Consortium Member Libraries

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f register cc, bush of answering jacklj, sleeve of plug ap, contact v of combined speaking andringing key srk, register key contact, relay coil me to earth.The register cc lever remains in position until the contact v onsrk key is broken, so that only one call can be registered how-ever many times the key mk may be pressed, oc is a countercommon to a position which is operated at the same time. The Egner and Holmstrom Transmitter.—With this trans-mitter it is claimed that on long distance circuits on the Con-tinent of Europe, transmission results equal to twice thoseof any other transmitter have been obtained, and this claimappears to be to a large extent substantiated. A patent granted in 1908 (No. 6587) to the same persons was APPENDIX 575 connected with an arrangement of the granule cell of a trans-mitter which was to be made air-tight, and the air in the cellwas to be replaced by a better heat and electrical conductor,such as coal gas or other hydrocarbon gas, so that a stronger
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Fig. 518.—L. M. Ericssons C.B. System arranged for Measured Rate System current could be passed through the cell and the heat generatedbe rapidly dissipated. A later patent specification (No. 12,918 of 1909) describesmethods of stretching the diaphragms so as to ensure that thegreatest amplitude of vibration shall be at its centre, and alsoof so connecting subsidiary diaphragms for the granule cellsto the centre of the main diaphragm as to ensure a maximum 576 APPENDIX vibration in the microphone cell or cells. Fig. 519 showsone of the arrangements given, the fly nut on the top leftside being one of about 6 used to screw down a rimmededge of a round collar (shown only in section) on to aportion of the edge of the diaphragm which comes between thetwo edges of a recess in the circular frame. One of the micro-

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