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A sound-powered telephone is a communication device that allows users to talk to each other with the use of a handset, similar to a conventional telephone, but without the use of external power. This technology has been used since at least 1944 [ 1 ] for both routine and emergency communication on ships to allow communication between key ...
The first field telephones had a battery to power the voice transmission, a hand-cranked generator to signal another field telephone or a manually-operated telephone exchange, and an electromagnetic ringer which sounded when current from a remote generator arrived. This technology was used from the 1910s to the 1980s.
Stromberg-Carlson produced several unique switching systems, including: XY, a "flat motion" switch logically similar to Strowger switching.The "XY Selector" was not invented by SC, but licensed from L.M. Ericsson of Sweden in the late 1940s and re-engineered for U.S. switching applications (Ericsson used it for PABX and a very small Rural Exchange application).
A sound-powered telephone is a telephone which transmits voice communication by wire, powered by the energy of the sound waves of the operator speaking. Principle of operation A moving-coil microphone converts the sound waves into an electrical signal, which is then converted back into sound waves at the receiver's end.
A telephone magneto is a hand-cranked electrical generator that uses permanent magnets to produce alternating current from a rotating armature. In early telegraphy , magnetos were used to power instruments, while in telephony they were used to generate electrical current to drive electromechanical ringers in telephone sets and activate signals ...
A sign in the US restricting cell phone use to certain times of day (no cell phone use between 7:30–9:00 am and 2:00–4:15 pm) (from Mobile phone) Image 42 The LG Prada with a large capacitive touchscreen introduced in 2006 (from Smartphone )
A typical volume of Bell System Practices from the 1970s. The Bell System Practices (BSPs) is a compilation of technical publications which describes the best methods of engineering, constructing, installing, and maintaining the telephone plant of the Bell System under direction of AT&T and Bell Telephone Laboratories. [1]
Siemens & Halske AG (or Siemens-Halske) was a German electrical engineering company that later became part of Siemens. It was founded on 12 October 1847 as Telegraphen-Bauanstalt von Siemens & Halske by Werner von Siemens and Johann Georg Halske .