ملف:Woman tuning radio 1923.jpg

الملف الأصلي(1٬060 × 1٬457 بكسل حجم الملف: 244 كيلوبايت، نوع MIME: image/jpeg)

وصف قصير

⧼wm-license-information-description⧽
English: Woman tuning early radio, from 1923 radio magazine. Broadcasting had just begun in 1920 and vacuum tube radio receivers like this had just come on the market.. They ran off batteries, usually a 3-6V storage battery to power the vacuum tubes' filaments and a 30-90V "B" battery to provide the plate voltage. This woman kept forgetting to turn off the set, running the battery down, so she has wired a small indicator lamp (on top of radio) in the filament circuit to remind her. The early vacuum tubes could not produce much audio power, so early radios used horn loudspeakers, like the one on top of the set. The horn coupled sound from the speaker's diaphragm to the outside air better, and so could produce 10 times (10 dB) more sound power from a given audio signal than a cone speaker.

Caption: A fair fan's idea that saves a lot of worry when she shuts off for the evening. Miss Margie O'Neil found that she sometimes went to her downy and forgot to turn the current off her Magnavox, with the result that her battery was run down the next morning. So she placed a small 6V lamp in series with the battery line, which warns her to "turn off".

Alterations to image: Removed aliasing artifacts (crosshatched lines) introduced when the original halftone photo was scanned, using Gimp FFT filter.
⧼wm-license-information-date⧽ 1923
⧼wm-license-information-source⧽ Retrieved March 1, 2014 from Radio World, Hennessey Radio Publications Corp., New York, Vol. 2, No. 26, March 24, 1923, p. 17 on Google Books
⧼wm-license-information-author⧽ Credited to Kadel and Herbert
⧼wm-license-information-permission⧽
(⧼wm-license-information-permission-reusing-text⧽)

This 1923 issue of Radio World magazine would have the copyright renewed in 1951. Online page scans of the Catalog of Copyright Entries, published by the US Copyright Office can be found here. [1] Search of the Renewals for Periodicals for 1950, 1951 and 1952 show no renewal entries for Radio World. Therefore the magazine's copyright was not renewed and it is in the public domain.

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قالب:PD-US-not renewed

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02:01، 3 نوفمبر 2023
تصغير للنسخة بتاريخ 02:01، 3 نوفمبر 20231٬060 × 1٬457 (244 كيلوبايت)Pastakhov (نقاش | مساهمات)Upload https://upload.wikimedia.org/wikipedia/commons/a/a6/Woman_tuning_radio_1923.jpg

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