| 摘要 |
PURPOSE:To stop sweeping when the tuner is turned to a radio wave of a wireless microphone in the standby state by providing a reception detecting circuit and a sound signal detection circuit. CONSTITUTION:When switch 10 is changed over and terminals 11, 13 are connected, a sound signal transmitted from an FM detection circuit 5 is converted into a DC voltage by a level detection circuit 6, amplified and inverted and inputted to an AND circuit 9. On the other hand, a reception detection signal extracted via an intermediate frequency amplifier circuit 2 is inputted to one input of the AND circuit 9. Since the AND circuit 9 outputs a high level signal when the tuner is turned to a radio wave of non-modulation, it is detected by a tuning control IC14 to stop the sweep of the frequency. When the switch 10 is thrown to the position of the terminal 13, the sweep is stopped in tuning with the non-modulation radio wave, that is, the radio wave of a wireless microphone in the standby state.
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