| 摘要 |
PURPOSE:To prevent the generation of a click noise, by connecting one-side terminals of resistances of a time constant circuit in common, and connecting the other-end terminals to a reference potential through a swith then changing the resistances and thus varying filter characteristics. CONSTITUTION:When a switch S is turned off, a transistor (TR) Q1 is also turned off, so the resistance for deciding on a time constant is only a resistance R1. When the switch S is turned on, the TRQ1 is turned on and the time constant is determined by resistances R1 and R2. At this time, one terminal of the resistance R2 is connected to the resistance R1 and the other terminal of the resistance R2 is applied with the same potential with the other terminal of the resistance R1, so that the potential of a signal line never varies. Therefore, when the noise reduction characteristics of a tape deck are changed over, the generation of a click noise by a filter circuit is prevented. |
