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The Telegraph Sounder |
 | | Special sounders with higher resistance (and lower operating current) were also available for direct connection in the line in emergencies, and these were often mounted together with a key in a set, called a pocket relay, protected by a case. |
 | | It was common to mount the sounder in an open wooden enclosure on a jointed arm, so that it could be brought closer to the operator's ear, and even to wedge an empty Prince Albert can so that it touched the metal baseplate, to give it a distinctive voice, as well as for added amplification. |
 | | The sounder (to be precise, its relay) was connected to the desired circuit by means of a switchboard using brass plugs. |
| www.du.edu /~jcalvert/tel/sounder.htm (933 words) |
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