| 摘要 |
PURPOSE:To make the handling easy, by preventing the sound output from being outputted to a speaker, even if a plug is plugged in any jack of plural stereo headphone jacks. CONSTITUTION:When plugs are not inserted to the 1st and the 2nd headphone jacks 12L, 12R, the sound output of amplifiers 10L, 10R are given to ground through speakers 11L, 11R respectively. When the plug is inserted to the jack 12L only, the sound output of the left amplifier 10L is given to ground through a resistor R1, a terminal 3, a left speaker of a headphone and a terminal 7. Since a switch between the terminals 1 and 2 is opened, no sound output is given to the left speaker 11L. This is the same as the right amplifier 10R. When the plug is inserted to the jack 12R only, this is the case for the said jack 12L. When no plug is inserted to both the jacks, the sound output of the left amplifier 10L is outputted to the left headphone but no sound output is obtained from the speaker 11L, since the terminals 1, 2 and 1', 2' are opened. This is the same for the sound output of the right amplifier 10R. |
