| 摘要 |
PURPOSE: An audio signal muting apparatus is provided to automatically mute an audio signal or cancel the mute of the audio signal at ON/OFF of AC power source of a set. CONSTITUTION: A first current limit resistance(201) is connected to an SMPS(Switching Mode Power Supply) power source(100). A second current limit resistance(202) is serially connected to the first current limit resistance. A base terminal is connected to the second current limit resistance. A collector terminal is connected to the audio output terminal. An emitter terminal is connected to the ground. A first PNP transistor(203) turns on at the moment when DC(Direct Current) power source is provided from the SMPS power source. The first PNP transistor mutes the audio signal.
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