| 摘要 |
PURPOSE:To prevent transistors in a negative feedback circuit from being saturated, by inhibiting the output signal of an amplifier from rising or falling unnecessarily by connecting the output of the amplifier to a bias voltage source via diode. CONSTITUTION:The output of amplifier 1 is connected to the bias power source via diode 23 and bias terminal 24. If the output of amplifier 1 reaches a voltage high enought to saturate transistor Tr2, diode 23 turns on and the output of the amplifier never rises above a constant voltage. Thus, the saturation of Tr2 is prevented and Tr2 and the amplifier constitute a negative feedback circuit, so that when the output of amplifier 1 falls in a normal state, diode 23 turns off. Namely, diode 23 turns on only when Tr2 is almost saturated in electric power feed, etc., and turns off when the negative feedback circuit is in normal operation with the power source stable. |
