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| | Telephone is a device for transmitting sound at large distances with the help of electric signals.
History
Non-electric “telephones”
Overall telephone is any mechanism which can transmit sound at large distances. Unlike electric devices based on electro-magnetic signals, first telephones were mechanical devices based on transmission of sound by using air or other physical means.
According to a letter to Peking Gazette, in 968, a Chinese inventor Kung–fu-wing created thumtsein which probably transmitted speech through pipes.
Pipes for holding conversations are used even today.
Known for centuries was also a rope telephone: when two diaphragms were tied with a cord or wire, transmitting sound from one end to the other by vibrations of cord but not through current.
This term has other meanings too. See Telephone (meanings).
That what we call now by telephone, is a fruition of the work done by many people. Documentary evidence says that one of the first successful electrical devices which through wires transmitted music tunes and distinct speech was created by Johann Philipp Reis in Germany in 1861.
The instrument had a transmitter of quaint design, power source – an electrochemical battery and dynamic speaker. Reis himself called the device designed by him a telephone. In the same year Antonio Meucci, an Italian immigrant in USA, demonstrated another device which also could transmit sound through wires and was named by him teletophone. Telephone, patented in 1876 by an American Alexander Bell was called, “speaking telegraph”. Bell’s handset was used both for transmission and receiving audio. Bell’s telephone did not have a bell. Calling was alerted at the other end, or the exchange operator, by whistling into the transmitter. Distance between these lines did not exceed more than 500meters.
In 1877, inventor Vaden applied telephone key which closed bell circuit (later key was replaced by a switch). In the same year a Petersburg branch of German company “Siemens and Galske” started manufacturing telephone instruments with two handsets – one for receiving and the other for transmission of speech.
In the next year, Russian electro-technician P.M. Golubitsky applied condenser in telephone instruments and developed first Russian telephone with interesting design. This comprised of several permanent magnets. In 1885, Golubitsky developed transmitters with a centralized system of power supply in telephone instruments.
Thomas Edison invented carbon granule transmitter which worked up to 1980 without any changes.
First commercial telephonic conversation between New York and London took place on 7 January 1927 through Trans- Atlantic telephone cable.
History of further developments in telephone includes: electric transmitter in place of carbon one, loud connection, tone dialing, digital volume compression. New technologies: IP-telephony, ISDN, DSL, cellular transmission and DECT. |
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