The Blake Transmitter (1833)
used a carbon and platinum resistance element.
Carl F.Gauss and Ernst H. Weber (1834)
The telegraph was the first step to making electrical signals travel from one device to another.
Speaking telegraph (1844)
Innocenzo Vincenzo Bartolomeo Luigi Carlo Manzetti
Transmitting the vibrations of the human voice by electrical means over a telegraph wire. He has lately made improvements in his method of transmission, by which he dispenses with the use of the battery, and substitutes the magneto-electric plan of producing the current. Reis telephone (1861)
Johann Philipp Reis
A transmitter, the companion piece for his telephone receiver.
The First Telephone (1876)
Alexander Graham Bell
You place the earpiece to your ear and speak into the microphone attached to the box on the wall. Later models had a little generator handle which you would turn to call the exchange or ring 'off' when you hang up.
The Carbon Microphone(1878)
David Edward Hughes
Carbon is a resistor, meaning it conducts electricity, but not very well. A current runs from one plate through the carbon to the other plate. The carbon molecules normally resist it somewhat, lowering the power flow. When a sound wave pushes down on the top plate, however, it squeezes the carbon molecules more tightly between the two plates. This increases their conductivity, creating more electric current. As the plate moves up and down with the sound wave, the current increases and decreases, creating an electric wave in the shape of the sound wave.
Tapered Shaft Oil-can Candlestick (1900)
The candlestick telephones were connected to a bell box that was mounted on a nearby wall. Later models included a dial on the base of the transmitter.
Digit Potbelly Dial Candlestick
Almon Brown Strowger (1905)
It was the same as the Oil-can Candle Stick but it has a dial on it.
Transcontinental Call Telephone (1915)...
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