| 摘要 |
PURPOSE:To prevent noise in a minimum muting time without dispersion in the muting time, by using a Zener diode. CONSTITUTION:Signals pass from a terminal 15 to a terminal 17. A muting circuit consisting of a transistor (TR) 18 exists on the way, and when the TR turns on, the muting is executed. In applying the power supply, the voltage on the power line is gradually increased, the TR18 is turned on via a Zener diode 14 at a potential to attain the muting state. When the voltage further increases, since the voltage drop across a resistor 21 turns on a TR13, the TR18 is turned off and the muting is released. At the interruption of the power supply, the voltage of a capacitor 4 is gradually decreased, the TR13 is turned off to obtain the muting state. |
