What should we pay attention to when measuring capacitance with a digital multimeter?

Use the resistor scale to select an appropriate measurement range based on the capacitance, and note that the film capacitor should be connected to the positive terminal of the capacitor when measuring the black DC ammeter.

① Estimate the size of microwave grade capacitor: You can use experience or reference to standard capacitors of the same capacity, and judge by the maximum swing of the meter needle. The capacitors used for reference do not need to have the same withstand voltage, as long as the capacity is the same. For example, if you estimate a 100μF/250V capacitor, you can use a 100μF/25V capacitor as a reference. As long as the maximum swing of their meter needles is the same, you can judge that the capacity is the same.

② Estimate the size of the picofarad capacitor: Use the R×10kΩ range, but it can only measure capacitors above 1000pF. For capacitors of 1000pF or slightly larger, as long as the needle shakes slightly, you can assume that the capacity is OK.

③ Measure whether the capacitor is leaking electricity: For capacitors above 1000 microfarads, first use the R×10Ω position to quickly charge it and basically estimate the capacitance, then change to the R×1kΩ position to continue measuring for a while. At this time, the needle should not go back, but should stop at or very close to ∞, otherwise it means there is leakage. For some timing execution or oscillation capacitors below tens of microfarads (such as the oscillation capacitor of the color TV power transformer), the leakage characteristics are very high. If there is a slight leakage, it cannot be used. At this time, after charging at the R×1kΩ position, change to the R×10kΩ position to continue accurate measurement. The needle should also stop at ∞ and not go back.