| 摘要 |
PURPOSE:To prevent the shock sound at a power supply time to shorten the stabilizing time for circuit operation by selecting a bias resistance value so that the bias voltage may become over the voltage between the base and the emitter of a trnasistor for preventing the shock sound just after power supply. CONSTITUTION:When resistance R3 is so selected that the voltage drop of bias resistance R3 may become over the voltage between the base and the emitter of transistor TrQ7 just after supplying power Vcc, TrQ7 is operated, and the current is next flowed to diode D1 to charge capacitor C2 through TrQ4 and Q6 instantaneously and increase the base potential of TrQ2; howver, the base potential is clamped by diode D2 to shorten the circuit operation time. Meanwhile, the base potential of TrQ1 and Q2 is held at the same potential by diode D2 when TrQ6 is operating; and the base potential of TrQ2 is prevented from overshoot to make the displacement of DC output voltage Vp smooth. As a result, the shock sound at a power supply time can be prevented, and the stabilizing time for circuit operation can be shortened. |
