JPS6225004Y2 - - Google Patents

Description

[Detailed Description of the Invention] This invention relates to a stereo audio device having an FM tuner, and particularly to a stereo/monaural mode switching circuit thereof.

When using a stereo integrated amplifier to play audio signals from a popular playback audio device that has only one playback output terminal, such as a monaural cassette recorder or record player, connect the playback output terminal to one of the left or right channels of the integrated amplifier. If you connect it to the AUX terminal of the AUX terminal, you will only get the playback sound from one speaker, so normally a connection cable with a fork-shaped end is used, and this connection cable connects the playback output terminal to the integrated amplifier. AUX
It is connected to each terminal. However, this connection cable must be prepared by the user, and the connection operation is troublesome.

Therefore, the purpose of this invention is to send the audio signal from a playback audio device that has only one playback output terminal to each of the right and left channels of the integrated amplifier by operating the FM stereo/mono switch. The object of the present invention is to provide stereo audio equipment that can input audio signals.

Hereinafter, embodiments of this invention will be described with reference to the accompanying drawings.

This stereo audio equipment uses antenna 1 to
FM stereo demodulation circuit 2 into which FM received waves are input
, an equalizer circuit 3 having a pair of AUX terminals 4 and 5 for left and right channels, and a low frequency amplifier connected to each output side of these circuits 2 and 3 via a pair of signal lines 7 and 8. A circuit 6 and an FM stereo/monaural mode changeover switch 9 are provided. This mode changeover switch 9 is a known sliding contact type two-circuit changeover switch. That is, one fixed contact a on the monaural side is connected to the demodulation circuit 2 described above, an intermediate contact b is connected to ground, and a fixed contact c on the stereo side is used for monaural display of the stereo/monaural display device 10. A power source + that supplies operating current to the anode sides of the light emitting diode 11 and the light emitting diode 12 for FM stereo display and to these light emitting diodes.
It is connected to B. On the other hand, the other fixed contact a' and intermediate contact b' on the monaural side are connected to each of the pair of signal lines 7 and 8 described above via bypass lines 13 and 14, and the other fixed contact a' and intermediate contact b' on the stereo side The fixed contact c' is floating on the circuit. Note that the cathode side of the light emitting diode 11 is connected to ground, and the cathode side of the light emitting diode 12 is connected to the FM stereo demodulation circuit 2 via a resistor.

A case where this stereo audio equipment reproduces an audio signal from a monaural type reproduction audio equipment 16 having only one output terminal will be described. When this audio reproduction device 16 is connected to, for example, the left channel AUX terminal 4 of the equalizer circuit 3, the audio signal appears on the left channel signal line 7 via the equalizer 3, but the mode selector switch 9 is set to the monaural side. In the illustrated state in which the signal is switched to , the signal also appears on the right channel signal line 8 via the bypass lines 13 and 14 and the movable contact 15. The audio signals appearing on the respective signal lines 7 and 8 in this way are amplified by the low frequency amplification circuit 6, and the amplified signals are used to send the left speaker 17 and the right speaker 1.
8 will be driven. In this case, since the stereo side fixed contact c of the mode switching circuit 9 is open, the operating current from the power supply +B flows to the light emitting diode 11, and the light emitted from the diode 11 produces a monaural display. Next, in the case of FM stereo, the mode changeover switch 9 is switched to the stereo side. Thereby, the FM signal received by the antenna 1 is supplied to the left and right speakers 17 and 18, respectively, via the FM stereo demodulation circuit 2 and the low frequency amplification circuit 6, as is well known. In this case, the monaural display light emitting diode 1
Since the anode side of 1 is grounded via fixed contacts b, c and movable contact 15, the monaural display is turned off, and instead, the operating current from power supply +B is FM stereo demodulated via the stereo display light emitting diode 12. Since the light flows to the circuit 2 side, stereo display is performed by lighting the light emitting diode 12.

As is clear from the description of the embodiments described above, according to this invention, when an audio signal from a monaural type reproduction audio equipment having only one reproduction output terminal is reproduced by a stereo audio equipment, an FM stereo/
Playback sound can be obtained from the left and right speakers by simply switching the monaural mode selector switch to the monaural side. In addition, as the mode selector switch is switched, monaural display or stereo display is selectively performed, so it is easy to know which mode the mode selector switch is in, which prevents erroneous operation. Prevented.

[Brief explanation of drawings]

The figure shows a circuit diagram of a stereo audio device based on this invention. In the figure, 2 is an FM stereo demodulation circuit, 3 is an equalizer, 4 and 5 are AUX terminals, 6 is a low frequency amplification circuit, 7 and 8 are signal lines, 9 is a mode selection switch, 10 is a stereo/monaural display device, 13,
14 is a bypass line.

Claims (1)

[Claims for Utility Model Registration] (1) An FM stereo demodulation circuit, an equalizer circuit having a pair of spare terminals, connected to each channel output terminal of these circuits via a pair of signal lines, and capable of transmitting each channel signal. a low frequency amplification circuit that amplifies and drives the left and right speakers;
Stereo audio equipment equipped with a mode changeover switch that changes the signal mode of an FM stereo demodulation circuit between stereo and monaural, and a display device that selectively displays stereo display and monaural display in relation to the operation of the changeover switch. , A short circuit including the mode changeover switch is provided between the pair of signal lines, and when the mode changeover switch is switched to the monaural side, the signal lines are short-circuited. Stereo audio equipment. (2) In claim (1) for utility model registration, the display device includes a light-emitting diode for monaural display, a light-emitting diode for stereo display, and a power source that supplies operating current to each of these light-emitting diodes, and What is a light emitting diode and a power supply?
A stereo audio device characterized in that the operating current is connected to one of the light emitting diodes in connection with the switching operation of the mode changeover switch.