| 摘要 |
PURPOSE:To elevate reliablity of a device by confirming at every 1 step of each sequence operation, and making shift to the next step, by means of a gate circuit for which a sequential counter is used. CONSTITUTION:When a call signal has come in from a telephone set A, the main wires L3, L4 of a telephone set C are closed through the monostable multivibrator N1 and the relay (a). Subsequently, the dial tone is detected by the PLL, and the terminal 2 of the counter V is made an H level. After that, an abbreviated telephone number is sent out to the main wires L3, L4 from the dual tone generator VI. When said send-out has been completed, the terminal 3 of the counter V is made an H level through the gate G5. In this way, the operation is shifted to the next step, confirming at every step of each sequence operation, and when the terminal 5 of the counter V has become an H level, the relay (b) and the amplifier III are operated, and the telephone sets A, B and D are connected. |
