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A sound-powered telephone circuit can be as simple as two handsets connected together with a pair of wires, which is defined as the "talk" portion of the circuit. Talk circuits can be realized over a pair of wires that are 50 km (30 miles) long. More complex circuits include magnetos, selector switches and bells to allow one user to select and ...
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.
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 payphone (alternative spelling: pay phone or pay telephone or public phone) is typically a coin-operated public telephone, often located in a telephone booth or in high-traffic public areas. Prepayment is required by inserting coins or telephone tokens , swiping a credit or debit card, or using a telephone card .
Part of the Russian–American Telegraph line bearing the single wire of an earth-return circuit, c. 1866. Earth-return telegraph is the system whereby the return path for the electric current of a telegraph circuit is provided by connection to the earth through an earth electrode. Using earth return saves a great deal of money on installation ...
Telephone hybrid transformer at the interface of the four-wire long-distance trunk and the two-wire local loop. Z B is the balance termination. NBOC is the network build-out capacitor, which is set to the average shunt capacitance through the telephone central office switch. Red arrows show relative current flow.
Amos Dolbear was born in Norwich, Connecticut, on November 10, 1837. [3] He was a graduate of Ohio Wesleyan University, in Delaware, Ohio.While a student there, he had made a "talking telegraph" and invented a receiver containing two features of the modern telephone: a permanent magnet and a metallic diaphragm that he made from a tintype.
Because over a poor quality connection the words "affirmative" and "negative" can be mistaken for one another (for example over a sound-powered telephone circuit), United States Navy instruction omits the use of either as prowords. [20] Sailors are instructed to instead use "yes" and "no".