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Telephone Line Indicator


Many ‘busy’ indicators for use in telephone systems present undesirable loading of the telephone line. Some circuits are very simple indeed to the extent of only loading the line when it is not in use. The downside is that a (usually green) LED lights when the line is not occupied. The author feels that a LED should flash when the line is actually in use by another extension and that the circuit should present a minimal load of the line.
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