| 摘要 |
PURPOSE:To reduce noise and to permit several tens of omnibus telephones to be connected to a line, by providing a switching circuit which separates respective omnibus telephone from the line at every omnibus telephone, and connects the line directly. CONSTITUTION:Change-over switches 2, 3, 5, and 6 are switched simultaneously by a maintenance engineer, and the omnibus telephone 14 is connected to an up and a down channels via a branch circuit. A signal from an input down channel is received by the telephone 14, and is relayed and sent to an output down channel. Also, an input up channel is connected to the telephone 14 via a terminal 4, the switch 5, a transformer 11, a mixer 8, and a terminal 1. Also, the output of the transformer 11 is connected to the output up channel via a mixer 12, a transformer 13, the switch 6, and the terminal 1. Therefore, the signal of the input up channel is received by the telephone 14, and is relayed and outputted to the output up channel. Furthermore, the transmission output of the telephone 14 is inputted to the mixers 9 and 12, and is sent to either the output up or down channel.
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