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A telegraph operator at the sending end of the line would create the message by tapping on a switch called a telegraph key, which rapidly connects and breaks the circuit to a battery, sending pulses of current down the line. The telegraph sounder was used at the receiving end of the line to make the Morse code message audible.
In 1878, Jesse created his own company, J. H. Bunnell and Co. Jesse constantly developed telegraphic instruments. In 1868 he received a patent for telegraph repeater, [4] printing telegraph, [5] created different telegraph sounders [6] and improved telegraph switchboard. [2] [7] He is famous for his steel lever key, which was patented on 15 ...
It is a simple bar with a knob on top and an electrical contact underneath. When the bar is pressed down against spring tension, it makes a closed electric circuit. [4] Traditionally, American telegraph keys had flat topped knobs and narrow bars (frequently curved), while European telegraph keys had ball shaped knobs and thick bars.
Alexander Graham Bell was a professor of elocution at Boston University and tutor of deaf children. He had begun electrical experiments in Scotland in 1867 and, after emigrating to Boston from Canada, pursued research into a method of telegraphy that could transmit multiple messages over a single wire simultaneously, a so-called "harmonic telegraph".
When the key was pressed, it would connect a battery to the telegraph line, sending current down the wire. At the receiving office, the current pulses would operate a telegraph sounder, a device that would make a "click" sound when it received each pulse of current. The operator at the receiving station who knew Morse code would translate the ...
A simple development of the single-stroke bell was the sprung bell. This had previously been used, mechanically actuated, for servant-call bells in large houses. Instead of working a clapper, the electromagnet shook the whole bell, which was mounted on a flexible spiral spring.
The word telegraph (from Ancient Greek: τῆλε 'at a distance' and γράφειν 'to write') was coined by the French inventor of the semaphore telegraph, Claude Chappe, who also coined the word semaphore. [2] A telegraph is a device for transmitting and receiving messages over long distances, i.e., for telegraphy.
The circuit of a coherer receiver, that recorded the received code on a Morse paper tape recorder. Unlike modern AM radio stations that transmit a continuous radio frequency, whose amplitude (power) is modulated by an audio signal, the first radio transmitters transmitted information by wireless telegraphy (radiotelegraphy), the transmitter was turned on and off (on-off keying) to produce ...