How to measure capacitance with a multimeter using the resistance range
Practice has proven that using a digital multimeter can also observe the charging process of capacitors, which actually reflects the changes in charging voltage in discrete digital quantities. If the measurement rate of a digital multimeter is n times per second, then during the process of observing the charging of a capacitor, n independent and sequentially increasing readings can be seen every second. Based on the display feature of a digital multimeter, it is possible to detect the quality of capacitors and estimate the size of their capacitance. The following is a method of using a digital multimeter to detect capacitors in the resistance range, which is of practical value for instruments that have not set the capacitance range. This method is suitable for measuring large capacity capacitors ranging from 0.1 μ F to several thousand microfarads.
Set the digital multimeter to the appropriate resistance range, with the red and black probes respectively touching the two poles of the tested capacitor Cx. At this point, the displayed value will gradually increase from "000" until the overflow symbol "1" is displayed. If "000" is consistently displayed, it indicates an internal short circuit in the capacitor; If overflow is consistently displayed, it may be due to an open circuit between the internal poles of the capacitor, or it may be due to an inappropriate resistance level selected. When checking electrolytic capacitors, it is important to note that the red probe (positively charged) should be connected to the positive terminal of the capacitor, and the black probe should be connected to the negative terminal of the capacitor.
The effective value of a multimeter usually refers to one of the following three situations:
1. The method of calibrating the average value, also known as the corrected average value or the rectified average value calibrated to the effective value, is based on the principle of converting an AC signal into a DC signal through rectification and integration circuits, and then multiplying it by a coefficient according to the characteristics of a sine wave. For a sine wave, the result of multiplying by this coefficient is equal to the effective value of the sine wave. Therefore, this method is limited to sine wave testing only.
2. Peak detection method obtains the peak value of an AC signal through a peak detection circuit, and then multiplies it by a coefficient based on the characteristics of a sine wave. For a sine wave, the result of multiplying by this coefficient is equal to the effective value of the sine wave. Therefore, this method is limited to sine wave testing only.
3. The true effective value method uses a true effective value circuit to convert AC signals into DC signals before measurement. This method is applicable for testing the true effective value of any waveform.
