How to Use a Multimeter to Measure Capacitance

Multimeter, also known as multiplex meter, multimeter, three-purpose meter, multimeter, etc., is an indispensable measuring instrument in power electronics and other departments. Through the multimeter, physical parameters such as current and resistance in the circuit can be detected. Generally, the main purpose is to measure voltage, current and resistance. Multimeters are divided into analog multimeters and digital multimeters according to their display modes. It is a multi-functional, multi-range measuring instrument. Generally, a multimeter can measure DC current, DC voltage, AC current, AC voltage, resistance and audio level, etc.

When comparing a capacitance meter and a multimeter, it's important to understand their specific functions and capabilities, as well as how they differ in terms of usage and precision in measuring capacitance.

Capacitance Meter vs Multimeter

Capacitance Meter

A capacitance meter is specifically designed to measure the capacitance of electronic components. This specialization generally allows for greater accuracy and sensitivity in capacitance measurements. It typically measures only capacitance, though some advanced models might include other features like leakage testing, equivalent series resistance (ESR), and inductance measurements. Ideal for tasks that require detailed analysis of capacitors or other components where capacitance is a critical parameter. It is particularly useful in electronic circuit design and testing.

Multimeter

A multimeter is a versatile tool that can measure voltage, current, resistance, and often capacitance, among other parameters. This makes it a more general-purpose tool compared to a capacitance meter. While many multimeters can measure capacitance, they are generally not as accurate or sensitive as dedicated capacitance meters, especially for very small or very large values. For general electrical and electronic troubleshooting, a multimeter is more practical as it reduces the need to carry multiple specialized instruments.

Key Differences

• Precision and Range: Capacitance meters are typically more precise when measuring capacitance, especially in the extremes of the measurement range. Multimeters, while capable, may not offer the same level of precision or range for capacitance.
• Functionality vs. Specialization: The choice between these tools often comes down to the need for specialized measurement (capacitance meter) versus the need for multiple types of measurements (multimeter).

How to test capacitance with a multimeter

1. Multimeter capacitance range measures capacitance

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.

Extended reading: Capacitance farads and picofarads conversion

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. Multimeter resistance range measuring capacitance

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.

Set the digital multimeter to the appropriate resistance level, and the red test lead and the black test lead touch the two poles of the capacitor Cx under test respectively. At this time, the displayed value will gradually increase from "000" until the overflow symbol "1" is displayed. If it always displays "000", it means there is a short circuit inside the capacitor; if it always displays overflow, it may be that the internal electrodes of the capacitor are open circuited, or it may be that the selected resistance level is inappropriate. When checking the electrolytic capacitor, please note that the red test lead (positively charged) is connected to the positive electrode of the capacitor, and the black test lead is connected to the negative electrode of the capacitor.

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3.Multimeter voltage range measuring capacitance

Measuring with the voltage range is actually an indirect measurement method. This measurement method is the most accurate measurement method. Set the multimeter to the DC current setting, connect the red and black test leads to the capacitor, charge the capacitor and use the formula to calculate the capacitance. There are many ways to measure capacitance with a multimeter. The measurement principle is to use the change in the indication on the multimeter to measure the size of the capacitor as the amount of electricity charged increases during the charging process of the capacitor. . The multimeter is a precision instrument, but you should also pay attention to some things when using it. For example, the red and black test leads cannot be connected incorrectly, and the power and voltage levels must not be misaligned to avoid damage to the instrument.

Measure-Things to note

The power must be cut off and discharged before measurement. The method of discharging is to find a metal object such as a screwdriver, hold the exposed metal part on the insulating handle and place it on the two legs of the capacitor being measured. Use a digital multimeter to measure the capacitance. Find the correct capacitor block and then plug the two pins of the capacitor into the capacitance measurement socket after the capacitor is discharged. When the changing reading on the LCD screen stabilizes, the actual value is the capacity of the capacitor on the side.