| 摘要 |
PURPOSE:To use selectively plural microphones by providing a means for displaying the operating state of the microphones and for disabling the use of other microphones when one microphone is in use. CONSTITUTION:When both press-to-talk switches 11, 21 are not operatied, lamps 60, 70 are lighted. When a crew operates the switch 11 in this state, a relay driving circuit 43 generates a driving signal and a relay 41 is operated, then the normally open switch 41b is closed. Thus, when the microphone 10 is usable and the lamp 70 is extinguished by a signal from a logical element 31. Even when other crew operates the switch 21, since a logical element 32 is not operated by a signal from the logical element 31, a normally open switch 42b is not closed. Thus, the transmission is disabled even if a voice is inputted from the microphone 20. |
