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| 18 inch induction coil . In 1898, this example was used at the Needles Hotel, on the Isle of Wight whitch was one of the first two commercial stations in the UK . (Photo courtesyof the History of Science and Technology Museum m, Oxford,) |
The 18 inch induction coil is a step-up transformer. It has two windings - a primary of a few turns and a secondary of many turns. This is called the turns ratio. The windings have a soft iron core to concentrate the mahnetic field which also works the contact breaker or interrupter. The interrupter rapdily breaks the primary current from the battery , thus creating a a voltage in the secondary whose value is depemdent on the turns ratio of the transformer.Marconi used this equipment (80% more powerful than the 10 inch induction coil ) to generate high voltage. This caused ionization of the air between the two brass balls (spark gap) thus providing a path for the sparks to discharge to. The oscillations caused by this discharge excited the aerial and earth system into producing wireless waves.
Circa 1898
Width: 42 inches
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| 18 inch induction coil . In 1898, this example was used at the Needles Hotel, on the Isle of Wight whitch was one of the first two commercial stations in the UK . (Photo courtesyof the History of Science and Technology Museum m, Oxford,) |
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| This sample circuit shows the use of the 18 inch induction coil labeled as "I" on the diagram. Click on image to enlarge. |
Contributors and Credits:1) Lewis Bodkin [05bodkin555(at)gmail.com]
Mar 30//21