| 摘要 |
PURPOSE:To automatically select an input signal, by connecting a comparator to the output of an interlocking variable rheostat where the main and subsignals are input, and controlling switching circuit with this output. CONSTITUTION:Main and subsignals are input to input terminals 21, 22 of an interlocking variable rheostat 23. At the output terminal which is controlled reverse to the same directional operation of the variable rheostat 23, a comparator 30 detecting the output difference is connected. Further, when a switch 32 is opened, the switching circuit 31 is in short circuit if the output difference between the sliders d1 and d2 rised to a given level or more, and a signal greater between the main and subsignals is fed to the input terminal of the amplifiers 26, 27, and either one signal is reproduced from speakers 28, 29 at the same time. |
