| 摘要 |
PURPOSE:To make easy the maintenance and inspection of subscriber circuits, by displaying the state of off-hook during the off-hook of telephone sets, through the connection of a display circuit including the display elements in the output of a detection circuit detecting the off-hook of telephone sets. CONSTITUTION:To the output of a detecting circuit 4 which detects off-hook of a telephone set connected to a battery feed circuit 3 of a time sharing exchanger, a display circuit 6 including light emitting elements 7 as display elements is connected. If a subscriber is in off-hook, a battery current flows to the circuit 3 to activate the detecting circuit 4 and a detected output 8 is given to an interface circuit 5 and the display circuit 6. The circuit 6 is activated with the detected output 8 of the circuit 4 to illuminate the light emitting elements 7, allowing to display that the subscriber circuit is busy. In case of on-hook, no display circuit 6 is activated, thus the maintenance and inspection of the subscribe circuits can be made easy. |
