Resistance measurement circuit schematic diagram

Working principle: Add a certain current to the resistor RX under test through a constant current source, and then use a multimeter to measure the voltage at both ends of Rx. The measured voltage value is divided by the constant current flowing through the resistor under test Rx, and the resistance under test can be obtained. resistance value. Theoretically, the greater the current flowing through the resistor to be measured, the easier it is to accurately measure the resistance of the small-value resistor Rx. However, if the current is too large, it will cause serious heating of the constant current source and affect the stability of the current, resulting in the measured resistance. The value is inaccurate; second, the low-power resistor does not allow excessive current to flow through. For this purpose, this circuit uses LM317 (U1), resistors R1, R2, and potentiometer RP1 to form a simple 100mA constant current source.