| 摘要 |
PURPOSE:To allow easy setting of control current at an arbitrary value by connecting at least one diode and a linear resistor element in parallel and employing the abrupt variation of different voltage drop, caused by the variation of current flowing through the parallel circuit, as a control signal. CONSTITUTION:In a bridge circuit comprising at least a resistor R1 diodes D1, D2, and resistors R11, R12, the combined resistance of the diode D1 and the resistor R1 and that of the diode D2 and the resistor R2 are substantially equal to the resistances R1 and R2 for low circuit current and substantially equal to the equivalent resistances of the diodes D1 and D2 for high circuit current. Since the voltage drop caused by the combination or the diode D1 and the resistor R1 or the combination of the diode D2 and the resistor R2 makes an abrupt variation, a detection/control transistor TR1 is turned OFF when the base thereof is L and turned ON when the base is H. Consequently, a circuit connected with the transistor TR1 is operated in response to the ON/ OFF control signal. |
