File:Foxhole radio from WW2.jpg

Foxhole_radio_from_WW2.jpg (529 × 487 像素,檔案大小:88 KB,MIME 類型:image/jpeg


摘要

描述
English: A "foxhole radio" receiver from World War 2. Not allowed powered radio receivers, which could give away their position to the enemy by the signal radiated by their local oscillator, American soldiers in World War 2 constructed their own homemade "crystal" radios so they could listen to news and music. The tuning coil (cylinder) was attached to a long wire antenna and ground. For a detector, this used a graphite pencil lead attached to the point of a safety pin, pressing against a "blue" steel razor blade. The graphite point touching the semiconducting oxide coating of the razor blade formed a crude point contact semiconductor diode which rectified the radio signal from the coil, extracting the audio signal from the radio frequency carrier wave, which was listened to with the earphones. The operator dragged the pencil lead across on the razor blade's surface until a sensitive spot was found and the station was heard, which required a lot of patience. The source says this foxhole radio belonged to Leutenant M. L. Rupert and was used on the Italian front.
日期
來源 Retrieved February 10, 2010 from John W. Campbell Jr., "Radio detectors and how they work" in Popular Science magazine, Popular Science Publishing Co., New York, Vol. 145, No. 4, October 1944, p. 209 on Google Books
作者 John W. Campbell Jr.
授權許可
(重用此檔案)
This 1944 issue of Popular Science magazine would have the copyright renewed in 1972. Online page scans of the Catalog of Copyright Entries, published by the US Copyright Office can be found here. Search of the Renewals for Periodicals for 1971, 1972, and 1973 show no renewal entries for Popular Science. Therefore the copyright was not renewed and it is in the public domain.

授權條款

Public domain
本作品在美國屬於公有領域,是因為該作品是在1929與1963年之間出版,沒有在該作品增加著作權聲明,且沒有進行著作權更新。除非此作品之作者已經過世一段時間,並達到公有領域所要求的條件,這類美國作品在其他不適用較短期限法則的國家或地區屬於有著作權狀態,如加拿大(作者過世後70年)、中國大陸(作者過世後50年,港澳除外)、德國(作者過世後70年)、墨西哥(作者過世後100年)、瑞士(作者過世後70年)與其他已簽署個別協議的國家。更多資訊請參考Commons:Hirtle chart

العربية  Deutsch  English  español  français  galego  italiano  日本語  한국어  македонски  português  português do Brasil  русский  sicilianu  slovenščina  українська  简体中文  繁體中文  +/−

Flag of the United States
Flag of the United States

說明

添加單行說明來描述出檔案所代表的內容
Foxhole radio from World War 2

在此檔案描寫的項目

描繪內容

多媒體型式 繁體中文 (已轉換拼寫)

image/jpeg

檔案歷史

點選日期/時間以檢視該時間的檔案版本。

日期/時間縮⁠圖尺寸用戶備⁠註
目前2015年6月3日 (三) 07:26於 2015年6月3日 (三) 07:26 版本的縮圖529 × 487(88 KB)ChetvornoUser created page with UploadWizard

下列頁面有用到此檔案:

全域檔案使用狀況

以下其他 wiki 使用了這個檔案: