| 摘要 |
PURPOSE:To switch a connection of the inside of a circuit without changing a connection manually, by providing a logical circuit on the distributing board, in a subscriber's circuit which an be used by switching it to a loop starting system and a ground starting system. CONSTITUTION:In case when a subscriber's terminal 1 is a loop starting system, a setting terminal 23 for switching a starting system of this distributing board 2 is opened, and when a loop dial-tone switch HS1 is closed, a loop start monitoring relay A is operated, and a dial-tone is transmitted to an exchange control device. The exchange control device sends a control signal only when a call has been released, a G relay is operated by an output of an AND circuit AND, and a line A and a line B are cut off. In case of a ground starting system, earthing is given in advance to the terminal 23, the G relay is operated, and when a ground dial-tone switch HS2 is closed, a ground start monitoring relay D is operated, a dial-tone is transmitted to the exchange control device, a control signal is sent out and the G relay is operated by an output of an OR circuit OR1, and the line A and the line B are connected to a current supplying circuit 4. When a call is released, the control signal is eliminated.
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