| 摘要 |
PURPOSE:To require no special manual switching action, by setting the switching means in the front stage of an amplifying device under the OFF state for a certain calling time. CONSTITUTION:With operation of the calling switch 101, the timer 104 and the calling device 102 start their operations at the operation moment of the switch. The timer 104 produces an output for a certain time from the moment of its operation to turn off the switch means 105. Accordingly, no voice signal is supplied to the amplifying device 103. On the other hand, the calling device 102 produces the call signal for the OFF period of the means 105. As a result, both the timer 104 and the means 105 block automatically the mixture of the voice signal or the like for a certain time when the switch 101 is operated. |
