Telegraphone

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Telegraphone by Valdemar Poulsen (1898)
Wire telephonograph from Mix & Genest AG , Berlin (1900)
The improved apparatus with a steel band on spools

The telegraphone was an invention of the Danish electrical engineer Valdemar Poulsen in 1898 ; it is the first functional device to record speech and sound with the help of electromagnetic induction . A steel piano wire that was wound on a roller was used as the carrier medium, later a steel band that ran between two spools.

Valdemar Poulsen initially called the device the telephonograph . The French engineer Jules Ernest Othon Kumberg also used this term, which is made up of telephone and phonograph , for his invention, an early forerunner of the answering machine . Like Kumberg, Poulsen pursued the idea of ​​finding a technical solution to the problem that a caller could not leave a message if the person called could not be reached immediately. Kumberg used the usual technique of recording onto a wax cylinder, known by Thomas Alva Edison since 1888. Poulson relied on a new method and therefore not only concentrated on the answering machine, but soon considered all possible uses for his devices for sound recording.

In quick succession, Poulsen applied for a patent, first in Denmark and then in the German Empire , and then in numerous other countries. A few years earlier, Oberlin Smith from the United States had already had a comparable idea, but had not constructed a functioning device and had not applied for a patent at this point.

The version of the first telegraphone, improved with the support of the German telephone manufacturer Mix & Genest , received a Grand Prix when Poulsen first presented it to the public in the Palais de l'Electricité at the Paris World's Fair in 1900 . Wilhelm Exner , the General Commissioner of the Austrian Department for Paris immediately acquired a copy on behalf of the Austro-Hungarian Ministry of Commerce. A year later, the device was exhibited with other Austrian acquisitions for four weeks in the Gustav Pisko art salon in Vienna . On 12 October 1901 the opening night of the exhibition, it also became the emperor of Austria-Hungary Franz Joseph I. demonstrated. Poulsen had traveled from Copenhagen and was assisted in the presentation by two representatives from Siemens & Halske , whose company had meanwhile acquired the production rights for the German Empire, Austria-Hungary and the Russian Empire . During this demonstration, an approximately 24-second long recording was made with the voice of the emperor, which is today the oldest magnetic sound recording that has survived.

With the telegraphone, Poulsen carried an electromagnet parallel to the axis of a roller wound like a thread with a long wire, the poles of the magnet encompassing the individual wire windings. The speech currents emanating from a microphone were fed to the coil of the electromagnet, between whose poles the steel wire passed at high speed. The speech currents magnetized the wire from both sides and recorded a pattern of field lines along the running direction corresponding to the speech currents. If, after the end of the recording, the same wire was passed past the electromagnet in the same direction and connected to a telephone receiver , the magnetic recording affected the voltage of the coil, causing the diaphragm in the receiver to vibrate, producing a sound corresponding to the recorded sound waves generated. This reproduction could be repeated as often as required without any wear and tear. Conversations that came over a line from a great distance could also be recorded with it. A strong magnet or electromagnet was passed over the wire to erase the recording.

There was also a variant in the form of a gramophone in which a steel disc 13 cm in diameter and 0.5 cm thick was used for recording.

Although an improved model could record up to 30 minutes at a time with a steel wire running speed of 2.13 m per second, demand was limited. Another source speaks of 6000 m of wire, which is sufficient for a conversation of 40 minutes (corresponding to 2.5 m per second). In addition to the recording quality, which was clouded by a background noise, the low volume was a particular problem. The technical principle was therefore only taken up again twenty years later with the availability of the first audio amplifiers in the wire and steel tape recorders from Marconi's Wireless Telegraph Company and C. Lorenz .

See also

Web links

Commons : Telegraphon  - collection of pictures, videos and audio files

Individual evidence

  1. ^ The Telephonograph . In: New Science , Vol 12, No. 308, 23 November 1900, p. 812 f.
  2. ↑ Eric D. Daniel, C. Denis Mee, Mark H. Clark: Magnetic Recording - The First 100 Years , IEEE Press, New York 1999, ISBN 0-7803-4709-9 . P. 15.
    ( limited preview in Google Book search)
  3. ↑ Procedure for receiving and temporarily storing messages, signals or the like , German Imperial Patent No. 109569 of December 10, 1898
  4. ↑ cf. Method of recording and reproducing sounds or signals , U.S. Patent No. 661,619 of November 13, 1900. In: freepatentsonline.com, accessed November 7, 2015
  5. ^ JH West: The Poulsen telephonograph . In: Prometheus No. 567, Berlin 1900, pp. 743f.
  6. ↑ a b c Telegraphōn (lexicon entry). In: Meyers Großes Konversations-Lexikon. 6th edition, Bibliographisches Institut, Leipzig / Vienna 1905-1909. 1909, Retrieved July 4, 2018 .
  7. ^ Valdemar Poulsen , In: Encyclopædia Britannica Online, accessed November 6, 2015