| 摘要 |
PROBLEM TO BE SOLVED: To obtain a highly accurate DC power supply for detecting the variation range of a load voltage, based on a load current as the range as small as possible by neraly adding simple electronic components. SOLUTION: In a DC power supply circuit for pulse width control or the like, a small line drop detecting resistor 31 is inserted into the output line between the secondary side of an output transformer 11 as the power supply side, and an output terminal 29 as the output side, one end of a current dividing resistor 30 having sufficiently larger value than this resistor 31 is connected to the power supply side of this resistor 31, one end of a voltage dividing resistor 25 for reference voltage is connected to the output side of the resistor 31, and the other end of the current-dividing resistor 30 is connected to the connecting point of the voltage-dividing resistors 24 and 25. As a result, a load voltage V2 becomes a constant voltage, even if an output current I1 is changed, by setting Re, R1, R2, so as to provide the result that I1 (output current)×R1 (resistor 31)×Re (resistor 24)/R2 (resistor 30) =ΔV (line drop voltage).
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