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In 1826, Poggendorff developed the mirror galvanometer, a device for detecting electric currents. He had an extraordinary memory, well stored with scientific knowledge, both modern and historical, a cool and impartial judgment, and a strong preference for facts as against theory of the speculative kind.
A mirror galvanometer is an ammeter that indicates it has sensed an electric current by deflecting a light beam with a mirror. The beam of light projected on a scale acts as a long massless pointer. In 1826, Johann Christian Poggendorff developed the mirror galvanometer for detecting electric currents. The apparatus is also known as a spot ...
Unlike the Phonofilm and Movietone systems in which the audio modulated the intensity of a recording lamp which exposed the soundtrack, thus creating a variable-density track, the GE system employed a fast-acting mirror galvanometer to create a variable-area soundtrack. A number of demonstrations of this system, now known as Photophone, were ...
The mirror galvanometer proved yet another point of contention. Whitehouse wanted to work the cable with a very different scheme, [43] driving it with a massive high-voltage induction coil producing several thousand volts, so enough current would be available to drive standard electromechanical printing telegraphs used on inland telegraphs. [44]
An early D'Arsonval galvanometer showing magnet and rotating coil. A galvanometer is an electromechanical measuring instrument for electric current.Early galvanometers were uncalibrated, but improved versions, called ammeters, were calibrated and could measure the flow of current more precisely.
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Leopoldo Nobili, born on 5 July 1784 [1] in Trassilico and died on 22 August 1835 [1] in Florence, was an Italian physicist who invented a number of instruments critical to investigating thermodynamics and electrochemistry.
The disadvantage of the mirror galvanometer was that it required two operators, one with a steady eye to read and call off the signal, the other to write down the characters received. [3] Its use spread to ordinary telegraph lines and radiotelegraphy radio receivers. A major advantage of the syphon recorder was that no operator has to monitor ...