| 摘要 |
PURPOSE:To make it possible to call at a remote area where it is unable to call by a general telephone facility because of its long distance for calling by allowing an output current from a power source to be a signal current for calling after rectifying its current to an external lead wire side on the one hand, by rectifying a signal current transmitted from other equipment which is inputted by the external lead wire to other direction than a power source on the other hand. CONSTITUTION:On the occasion of calling a telephone A side from a telephone B side, once a sequential button switch B is pressed to call an other part, a power source of current 2a flows to an external lead 1a as a calling signal current. The signal current coming from a power source 2a flows only to a direction of the external lead wire 1a but doesn't flow to a side of alarm 5a consisting of buzzer-BZ. The signal current flowed to the external lead wire 1a flows to the telephone B side through a cable W and is inputted by the external lead wire 1b of calling device 11b which is combined to the telephone B. The signal coming from 11a inputted doesn't flow to the power source 2b direction but flows only to the alarm 5b direction to operate this alarm 5b.
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