Another method to measure capacitance with pointer multimeter

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Another method to measure capacitance with pointer multimeter [Copy link]

Any type of pointer multimeter can calculate the capacitance of the capacitor based on the measurement results as long as the capacitor to be measured is connected in series with the test leads and then a known AC voltage is measured. The measurement range can cover the range of 15pF-0.1 uF.

In the formula, C is the capacitance of the capacitor being measured (uF), γ is the internal resistance of the AC voltage range of the multimeter (MΩ), V1 is the external AC 50Hz voltage (V), and V2 is the AC voltage measured after connecting the capacitor in series (V), that is, the reading value of the multimeter.

For example: a pointer multimeter has a 250V AC voltage range, an internal resistance of 1MΩ, a mains voltage of 215V, and a capacitor (with a withstand voltage of 400V) is connected in series to obtain an AC voltage of 93V. Substituting the above formula into the calculation, the capacitance of the capacitor is 1528pF. To verify whether this value is correct, a digital multimeter is used to measure the capacitance of the capacitor, which is actually 1510pF, with a small error.

Due to the current limiting effect of the multimeter's internal resistance, the current in the measuring circuit is very small and will not cause permanent damage to capacitors with lower voltage resistance.

Similarly, this method can be used to measure high resistance, and the calculation formula is:

For example: the internal resistance of a pointer multimeter in the 250V AC voltage range is 1MΩ, the mains voltage is 205V, and the voltage measured after connecting a resistor in series is 20V. Substituting it into the above formula, the resistance value of the resistor is calculated to be 9.25MΩ.