| 摘要 |
PURPOSE:To reduce a longitudinal noise by inserting a first transistor between input and output ends, inserting a detection circuit to detect voltage variations between input and output ends and providing a by-pass circuit thereto. CONSTITUTION:An electronic choke circuit 11 is connected between the power supply 2 and a load side circuit 3. The choke circuit 11 is equipped with a transistor(TR), constant voltage diodes ZD1 and ZD2, resistors R1 and R11 and a capacitor C. A detection circuit is constituted of the constant voltage diode ZD1, resistors R2 and R3, a TR 2 and resistor R4. Variations in voltage across terminals A and C are detected to control a TR 1 by the TR 2. Accordingly, the increase in voltage drop in the resistor R1 due to the increase in the current of the resistor R1 is offset by the decrease in voltage drop of the TR 1, so that the voltage drop between the terminals A and C is kept constant. While, a detection circuit constituted of resistance R6, a TR 3, the constant voltage diode ZD2, the TR 4 and so on controls the TR 3 and keeps the voltage drop between terminals B and D constant. |
