| 摘要 |
PURPOSE:To obtain a large amount of muting by providing an FET and a transistor connected in series and in parallel respectively to a signal source and applying a mute signal to the gate of the FET and the base of the transistor. CONSTITUTION:When muting a signal from a signal source 1, a mute signal of positive voltage is applied from a muting terminal 2 to the gate of an FET-F1 and the base of a transistor T1. Consequently the FET-F1 becomes cut-off and the transistor T1 becomes on-state. As it is considered that when the FET-F1 becomes cut-off, the impedance of the signal source becomes very high equivalently, the amount of muting due to the transistor T1 can be made large.
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