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| Description |
A mechanical filter for a sound reproducing apparatus and its electrical equivalent circuit. |
|---|---|
| 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. |
 | The uploader or another editor requests that a local copy of this file be kept. This image or media file may be available on the Wikimedia Commons as File:Harrison mechanical filter.png. While the license of this file may be compliant with the Wikimedia Commons, an editor has requested that the local copy be kept too. This file does not meet CSD F8 and should not be tagged as a Commons duplicate. If you desire to nominate it for deletion, notify the tagging editor. |  |
File history
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| Date/Time | Thumbnail | Dimensions | User | Comment | |
|---|---|---|---|---|---|
| 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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