| 摘要 |
PURPOSE:To simplify a circuit on the night switching system of a telephone switchboard by omitting a specific relay which operates by the resetting of a night switching relay and by making a bothway-conflict preventive relay serve as the relay. CONSTITUTION:When night switching relay TL provided to night switching unit NTT-CH is switched to a night switching state, main wires L1 and L2 disconnected from main wires L1 and L2 are connected to the night attendant circuit via contact (tl) of this relay TL, and main-wire bothway trunk COBWT is connected to the power supply via the other contact (tl), so that signals will be received directly by the night reception board. In this case, the operation held by contact (b) of discrmination relay B is performed by using relay SP provided for the prevention of originating conflict so as to disallow the bothway trunk to reset relay TL of bothway trunk COBWT, and the trunk selector circuit is made into a call state in the same way as in the daytime by contact (sp) of this relay SP. |
