File:Harrison mechanical filter.png
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Description |
A mechanical filter for a sound reproducing apparatus and its electrical equivalent circuit. |
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Source |
US patent US1730425 |
Date |
8th October 1929 |
Author |
H. C. Harrison. Cropped and white space cleanup by SpinningSpark |
Permission (Reusing this file) |
See below.
|
Licensing[edit]
The text and illustrations of US patents are in the public domain in the United States unless the patent text contains a specific notice that portions are copyrighted.[1][2][3]
The original patent contains no such notice, so its contents are in the public domain in the United States. |
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current | 21:47, 18 November 2009 | 820 × 688 (60 KB) | Spinningspark (talk | contribs) | {{Information |Description=A mechanical filter for a sound recording apparatus and its electrical equivalent circuit |Source=US patent US1730425 |Date=8th October 1929 |Author=H. C. Harrison. Cropped and white space cleanup by ~~~ |other_versions= }} == |
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- File:Harrison mechanical filter.png from Commons
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