| 摘要 |
PURPOSE:To supply power only with a two-wire transmission line by controlling the 1st variable impedance element inserted in series with the transmission line and the 2nd variable impedance connected in parallel with a load based on a separate reference voltage. CONSTITUTION:A control circuit comprising resistors R1, R2 and a differential amplifier A1 controls the impedance of a transistor (TR)Q1 in the direction making a line voltage VL constant in response to a voltage V1 based on a reference voltage Vr1. A control circuit comprising resistors R4, R5 and a differential amplifier A2 controls the impedance of a TRQ2 in a direction making the value of a current Ic flowing to a resistor R3 constant in response to a voltage V2 based on a reference voltage Vr2. A terminal voltage Vs across the resistor Rs is converted into a digital signal by an analog-digital converter A/D1 and the signal is given to an arithmetic circuit OP as a setting value. |
