File:Callans 1863 induction coil.jpg
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Callans_1863_induction_coil.jpg (753 × 404 pixels, file size: 42 KB, MIME type: image/jpeg)
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| Description |
English: Photo of an early induction coil, built by Irish clergyman Nicholas J. Callan in 1863 at Maynooth College. This was his largest coil, finished just before his death, one of the largest in the world at the time. The iron core was 43 inches (109 cm) long. The secondary windings were 21 inches (53 cm) in diameter and consisted of 150,000 feet of 34 gauge iron wire They were made in 3 separate pancake shaped rings separated by air gaps, so wires carrying large voltage differences would not lie adjacent to each other, reducing the risk of insulation breakdown and arcover. He probably intended to add more secondary windings. At the left end is a vibrating mercury 'contact breaker' in the primary circuit, actuated by the magnetic field in the primary, which interrupted the primary current. When powered by 4 'iron cell' battery cells, it could produce 15 inch (38 cm) sparks, corresponding roughly to a potential of 210,000 volts. Alterations to image: removed caption, which read: "Dr. Callan's large induction coil, completed in 1863, still preserved at Maynooth College". |
| Date | |
| Source | Downloaded from John Ambrose Fleming (1892) The Alternate Current Transformer in Theory and Practice, Vol.2, The Electrician Publishing Co., New York, p.20, fig.32 on Google Books |
| Author | John Ambrose Fleming |
| Permission (Reusing this file) |
Public domain in the US - published in the US prior to 1923 |
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This media file is in the public domain in the United States. This applies to U.S. works where the copyright has expired, often because its first publication occurred prior to January 1, 1929, and if not then due to lack of notice or renewal. See this page for further explanation.
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This image might not be in the public domain outside of the United States; this especially applies in the countries and areas that do not apply the rule of the shorter term for US works, such as Canada, Mainland China (not Hong Kong or Macao), Germany, Mexico, and Switzerland. The creator and year of publication are essential information and must be provided. See Wikipedia:Public domain and Wikipedia:Copyrights for more details.
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| Date/Time | Thumbnail | Dimensions | User | Comment | |
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| current | 17:26, 12 May 2008 | | 753 × 404 (42 KB) | Chetvorno (talk | contribs) | {{Information |Description=Photo of one of the first induction coils, built by British clergyman Nicholas J. Callan in 1863 and still preserved at Maynooth College. About 43 inches long. It could produce 15 inch sparks, corresponding roughly to a voltage |
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