Several tips for measuring capacitance with a multimeter
1. Direct detection with capacitor file
Some digital multimeters have the function of measuring capacitance, and their ranges are divided into five ranges: 2000p, 20n, 200n, 2μ and 20μ. When measuring, you can directly insert the two pins of the discharged capacitor into the Cx jack on the meter board. After selecting the appropriate range, you can read the display data.
000p gear is suitable for measuring capacitances less than 2000pF; 20n gear is suitable for measuring capacitances between 2000pF and 20nF; 200n gear is suitable for measuring capacitances between 20nF and 200nF; 2μ gear is suitable for measuring capacitances between 200nF and 2μF. capacitance; 20μ gear, suitable for measuring capacitance between 2μF and 20μF.
Experience has proven that some models of digital multimeters (such as DT890B+) have large errors when measuring small-capacity capacitors below 50pF, and have almost no reference value when measuring capacitances below 20pF. At this time, the series method can be used to measure small value capacitance. The method is: first find a capacitor of about 220pF, use a digital multimeter to measure its actual capacity C1, then connect the small capacitor to be measured in parallel with it to measure its total capacity C2, then the difference between the two (C1-C2) is The capacity of the small capacitor to be measured. This method is very accurate for measuring small capacitances of 1 to 20pF.
2. Use resistance level to detect
Practice has proved that the charging process of the capacitor can also be observed using a digital multimeter, which actually reflects the changes in the charging voltage in discrete digital quantities. Assuming that the measurement rate of the digital multimeter is n times/second, when observing the charging process of the capacitor, n independent and sequentially increasing readings can be seen every second. According to this display feature of the digital multimeter, the quality of the capacitor can be detected and the capacitance estimated. The following describes the method of using the resistance setting of a digital multimeter to detect capacitors, which is of great practical value for instruments that do not have a capacitance setting. This method is suitable for measuring large-capacity capacitors ranging from 0.1μF to several thousand microfarads.
