Two simple methods to measure capacitance with a multimeter

Multimeter is one of the most frequently used electronic components in electronics, but many people do not know how to detect capacitance. Here are some methods to test capacitance with a multimeter. Capacitor is one of the most commonly used electronic components. The universal symbol of capacitor is "C". Capacitor is mainly composed of metal electrode, dielectric layer and electrode lead, and the two electrodes are insulated from each other. Therefore, it has the basic performance of "blocking DC and passing AC".

How to use the resistance range of a multimeter to measure capacitance

Practice has proved that the charging process of capacitors can also be observed using a digital multimeter, which actually reflects the change of charging voltage with discrete digital quantities. Assuming the measurement rate of the digital multimeter is n times/second, when observing the charging process of the capacitor, n independent and 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 size of the capacitance can be estimated. The following is a method of using the resistance range of a digital multimeter to detect capacitors, which is very practical for instruments that do not have a capacitance range. This method is suitable for measuring large-capacity capacitors from 0.1μF to several thousand microfarads.

Set the digital multimeter to the appropriate resistance range, and touch the red and black test leads to the two poles of the capacitor Cx to be tested. The displayed value will gradually increase from "000" until the overflow symbol "1" is displayed. If it always displays "000", it means that the capacitor is short-circuited; if it always displays overflow, it may be that the internal poles of the capacitor are open-circuited, or the selected resistance range is inappropriate. When checking electrolytic capacitors, it is necessary to pay attention to the red test lead (with positive charge) connected to the positive pole of the capacitor and the black test lead connected to the negative pole of the capacitor.

How to use the capacitance range of a multimeter to measure capacitance

Some digital multimeters have the function of measuring capacitance, and their ranges are divided into five gears: 2000p, 20n, 200n, 2μ and 20μ. When measuring, the two pins of the discharged capacitor can be directly inserted into the Cx jack on the meter board, and the displayed data can be read after selecting the appropriate range. The 2000p gear is suitable for measuring capacitance less than 2000pF; the 20n gear is suitable for measuring capacitance between 2000pF and 20nF; the 200n gear is suitable for measuring capacitance between 20nF and 200nF; the 2μ gear is suitable for measuring capacitance between 200nF and 2μF; the 20μ gear is suitable for measuring capacitance between 2μF and 20μF.
Experience has shown that some models of digital multimeters (such as DT890B+) have large errors when measuring small-capacity capacitors below 50pF, and there is almost no reference value for measuring capacitance 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 tested in parallel with it to measure its total capacity C2, and the difference between the two (C1-C2) is the capacity of the small capacitor to be tested. This method is very accurate for measuring small-capacity capacitors of 1 to 20pF.