| 摘要 |
PURPOSE:To prevent occurrence of the short ring of the telephone bell by increasing and decreasing gradually the current to the next code transmitter after the network control unit is actuated with the start signal sent from the central unit. CONSTITUTION:Terminal 51 of no-ringing network control unit 5 is connected to the telephone network, and terminal 58 is connected to the code transmitter each. With supply of the working power from terminal 51, all circuits 52-57 within unit 5 become active. And the start signal sent from the central unit is received at reception circuit 54, and then the necessary process is carried out through reception decision circuit 56. After this, switch circuit 57 is controlled to give switching to both terminal 58 and no-ringing connection circuit 55. Circuit 55 gives the slow connection between the rise and the fall of the power consumption level of the code unit. In such way, the occurrence can be prevented for the short ring phenomenon of the bell circuit caused by the sudden current change when the code unit is connected. |
