| 摘要 |
PURPOSE:To realize the changeover between a built-in speaker and a stereo earphone with simple configuration. CONSTITUTION:Speaker earphone changeover switches 17A, 17B and a switching element Q11 controlling the operation mode of a stereo demodulation circuit 13 are provided to the receiver. A DC voltage obtained at an output terminal T4R of an audio amplifier 14R when the switches 17A, 17B are turned on is fed to the switching element Q11 via the switch 17A to allow the stereo demodulation circuit 13 to perform a monaural operation. Furthermore, an output of an audio amplifier 14L is fed to a speaker 15. With the switches 17A, 17B turned off, the supply of the DC voltage obtained at the output terminal T4R of the audio amplifier 14R to the switching element Q11 is turned off to allow the stereo demodulation circuit 13 to perform a stereo demodulation operation. Furthermore, outputs from the audio amplifiers 14L, 14R are fed to a stereo earphone jack 16 and the supply of the signal to the speaker 15 is turned off. |
