| 摘要 |
PURPOSE:To prevent the shock during the make of the power supply, by securing a quicker rise of the current for the bias circuit of the constant current source at the A-class amplifying stage of the 1st stage or between the stages of the amplifiers than the power source of the amplifier and thus ensuring a quick normal operation for the constant current source at the 1st stage or between the stages of the amplifier. CONSTITUTION:The time constant of the decoupling circuit is set sort for the bias circuit of the constant current source and set long for the 1st stage, between the stages and the output stage of the amplifier respectively. In other words, the potential at the point B rises up more quickly than that at the point A when the current is flowed with application of +VCC by satisfying T2(=C2R2) <<T1(=C1R1), where R1 and R2 show the resistance values of the resistors 27 and 31, C1 and C2 are the capacity of the capacitors 28 and 32, and T1 and T2 are the time constant. As the potential of the point B rises up, the current flows to the diodes 22 and 23 through the resistor 21. And thus the bias is given to the transistors 6 and 15 of the constant current source of the A-class amplifying stage at the 1st stage and between the stages of the amplifier. Then the potential of the point A rises up slowly after a sufficient operation of the transistors 6 and 15. And the potential fluctuation of the output terminal 20 rises up slowly based on the rise of the point A, thus producing no shock sound during the make of the power supply. |
