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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).
The W48 is the successor of the pre-war Modell 36 and the W38, with only a few modifications.The principle design features were based on the "classic" W28, the first widely distributed desktop telephone developed by the Siemens & Halske company and built in license for the German Reichspost from 1928 by several manufacturers.
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 )
12 November 1877: The first commercial telephone company enters telephone business in Friedrichsberg close to Berlin [26] using the Siemens pipe as ringer and telephone devices built by Siemens. 1877: The first experimental Telephone Exchange is established in Boston. 1877: First long-distance telephone line
The telegraph keys or telephone dial creates trains of on-off current pulses corresponding to the digits 1–9, and 0 (which sends 10 pulses). This equipment originally consisted of two telegraph keys engaged by knife switches, and evolved into the rotary dial telephone. The central office switching equipment has a two-motion stepping switch. A ...
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 ...