| 摘要 |
PURPOSE:To inexpensively obtain a continuously variable feedback capacity by providing a feedback capacity variable means varying a feedback capacity for positive feedback with a level of a feedback signal to the limiter. CONSTITUTION:A variable resistor (feedback capacity variable means) 7 is adopted for an emitter resistor of an output transistor(TR) 4 and a feedback signal (a) being a signal resulting from attenuating a emitter output signal of the output TR 4 is outputted from a slider terminal of the variable resistor 7 to a feedback capacitor 2. Through the constitution above, a level of the feedback signal (a) is made variable, and then a feedback capacity CR for positive feedback from the emitter of the output TR 4 to a positive terminal of an operational amplifier 3 is made variable equivalently. Since the feedback capacity CR is varied continuously in this way, the feedback capacity CR is set to a value minimizing occurrence of black level inversion phenomenon. Furthermore, since the setting of the feedback capacity CR is adjusted by the position of the slider terminal of the variable resistor 7, the setting is vary easily implemented. |
