| 摘要 |
PURPOSE:To avoid the interruption of communication current between the relay board and the communication path switch, by transmitting the push button signal having suitable amplitude to the relay board as side tone, in transmitting the push button signal from the push button signal generation circuit. CONSTITUTION:When the relay board 2 performs the push button signal transmission request, the control circuit 1 delivers the push button signal to the push button signal generating circuit 4 and the brake contact 12 of the relay is made open. As a result, the push button signal is delivered to the communication path switch 5 and the attenuated push button signal is delivered to the relay board 2 via the resistor 13. The contact 12 operated only at the delivery of the push button signal. Accordingly, while the push button signal is not delivered, the connection between the relay board 2 and the switch 5 is made, then communication is not made impossible between the operator telephone circuit and the communication path switch 5 of the relay board 2. |
