| 摘要 |
PURPOSE:To prevent the generation of a harsh sound by eliminating the distortion of an input signal waveform when a low frequency amplifying circuit is powered up, by applying a voltage to the bias circuit of the low frequency amplifying circuit without passing the voltage through a ripple filter circuit in a transient state. CONSTITUTION:A ripple filter circuit consists of a resistance R12, a capacitor C4, and a transistor (TR) Q3, and resistances R1-R4 and TRs Q1 and Q2 form a bias circuit. A TRQ4 is biased through a resistance R5 to amplify a signal inputted from an input terminal 1 through a capacitor C1. The TRQ4 is supplied with a power voltage from the TRQ3 through a load resistance R6, and a diode is connected in series between the collector and base of the TRQ3. When the circuit is powered up, diodes D1 and D2 are turned on until the circuit becomes steady, and thus the distortion of an input signal waveform is eliminated, thereby preventing the generation of a harsh sound. |
