File:Crystal radio advertisement.png

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Description
English: Photo of an American family in the 1920s listening to a crystal radio. From a 1922 advertisement for Freed-Eisemann radios in Radio World magazine. The small radio is on the table. Crystal sets work off the power received from radio waves, so they are not strong enough to power loudspeakers. Therefore the family members each wear earphones, the mother and father sharing a pair. Although this is obviously a professionally posed, promotional photo, it captures the excitement of the public at the first radio broadcasts, which were beginning about this time. Crystal sets like this were the most widely used type of radio until the 1920s, when they were slowly replaced by vacuum tube radios.
Français : Photo d'une famille américaine dans les années 1920 à l'écoute d'une radio à cristal. D'une publicité 1922 pour-Eisemann radios Libéré en radio mondiale magazine. Cette photo de promotion capturant l'émotion du public à l'écoute de la radio à cette époque. Le petit poste de radio à cristal est sur ​​la table, fonctionnant sans alimentation électrique, d’une très haute fidélité sonore et d’une étonnante musicalité (comparé au récepteur moderne superhétérodyne). Mais, la limite de détection du signal radioélectrique est imposée par le niveau absolu des signaux reçus utile au fonctionnement de l’écouteur ou du casque (car les signaux reçus ne sont pas assez forts pour un haut-parleur de puissance. ). Car seul le signal radioélectrique de la station radio écoutée fait fonctionner le récepteur à cristal. Par conséquent, les membres de la famille ont des écouteurs. La radio à cristal comme tel était le type de radio le plus largement utilisé jusqu'à ce que les années 1920, quand ils ont été progressivement remplacés par des radios à tubes sous vide.
Date
Source Downloaded 2010-02-27 from Alan Douglas (1995) Radio Manufacturers of the 1920s, Vol. 2, Sonoran Publishing, USA, ISBN 1886606005, p. 3 on Google Books. Source credits it to Radio World magazine, 1922.
Author Unknown authorUnknown author
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Public domain in USA - published in USA prior to 1923
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current17:22, 2 May 2021Thumbnail for version as of 17:22, 2 May 2021881 × 532 (274 KB)wikimediacommons>MaterialscientistFFT

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