| 摘要 |
PURPOSE:To prevent noise at application of power by adding a charging circuit to a negative feedback capacitor. CONSTITUTION:An emitter of a charging transistor(TR) 6 of the negative feedback capacitor 3 is connected to a power line, the base is connected to a high voltage side of a ripple rejection capacitor 7 and the collector is connected to a high voltage side of the negative feedback capacitor 3. Then the potential at a point wherein the base is connected is brought into a potential making the TR 6 turned off when the low frequency amplifier is made stable. The TR 6 at application of power supplies a collector current to the capacitor 3 while the capacitor 7 is charged, the base potential rises, the base-emitter voltage is reduced and the TR 6 is turned off, then the potential at an inverted input terminal B rises as soon as the potential at an input terminal A rises to change the potential at an output terminal C to the balanced potential from zero gradually. Thus, production of noise at application of power is prevented.
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