| 摘要 |
PURPOSE:To prevent the disturbance given to the circuit by the useless transmission caused by the malfunction due to the noise and at the same time increase the using field of the sound control, by providing the sensitivity switching circuit and the long-time time limiting circuit. CONSTITUTION:Both sensitivity switching circuit 7 and long-time time limiting circuit 8 are provided. And in case the input of a high level exceeding the high threshold level necessary for the control of the sound input is supplied like in case the talking is given toward microphone 1, the DC signal enough to drive transmission control circuit 4 is generated by amplifier 2 and rectifier 3. And transmitter 5 is actuated. In this case, circuit 7 gives an automatic switch to the threshold level of the sound input necessary to hole the sound control function to a low level (high- sensitivity state). At the same time, time limiting circuit 6 keeps circuit 4 under the transmission starting state in the case of interruption of the sound. And circuit 8 is actuated simultaneously to start circuit 7 so that the sensitivity may be reset to the state of a low sensitivity at the moment before start of the talking and after a time longer than circuit 6. |
