File:Bell telephone magazine (1922) (14569763749).jpg

Identifier: belltelephonemag11amerrich (find matches)
Title: Bell telephone magazine
Year: 1922 (1920s)
Authors: American Telephone and Telegraph Company American Telephone and Telegraph Company. Information Dept
Subjects: Telephone
Publisher: (New York, American Telephone and Telegraph Co., etc.)
Contributing Library: Prelinger Library
Digitizing Sponsor: Internet Archive

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e nextamplified many thousands of times by vacuum tube amplifyingsystems, the first elements of which are shown in the smallboxes adjacent to the large photoelectric cells, and these cur-rents when boosted to the magnitude of ordinary telephone cur-rents are ready to be sent over a proper communication channel. Going now for simplicity of discussion to the scanning meansused at the receiving end, let us examine Figure 9. Here wehave again a scanning disc with a spiral of holes with a smallrectangular aperture in front which exposes only one hole at atime. Behind this disc is a light source, which in this case isan electrical glow lamp containing neon gas at a low pressure;this gas, when excited by an electric current, causes a glow oflight to cover a flat plate electrode which is of the same sizeand shape as the aperture over the disc. In front of the discto the left is shown the observer, who looks through the holes inthe disc at the flat glowing area of the electrode. At any in- 136
Text Appearing After Image:
Fig. 8. Apparatus Used at the Sending End for Television.

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