How to measure capacitance with a pointer multimeter?
1. Check the quality of electrolytic capacitors with a multimeter in the resistance range
The two leads of an electrolytic capacitor can be positive or negative. When checking its condition, for electrolytic capacitors with lower voltage resistance (6V or 10V), the resistance level should be set to R × 100 or R × 1K. Connect the red probe to the negative terminal of the capacitor and the black probe to the positive terminal. At this point, the multimeter pointer will swing and then return to zero or near zero. This type of electrolytic capacitor is good. The larger the capacity of an electrolytic capacitor, the longer the charging time, and the slower the pointer swings.
2. Use a multimeter to determine the positive and negative leads of an electrolytic capacitor
Some electrolytic capacitors with low voltage resistance can be judged based on their characteristics of low leakage current (high resistance value) when connected in the positive direction and high leakage current when connected in the reverse direction if the positive and negative lead markings are unclear. The specific method is to use red and black probes to contact the two leads of the capacitor, remember the magnitude of the leakage current (resistance value) (the resistance value indicated when the pointer swings back and stops), then short-circuit the positive and negative leads of the capacitor, swap the red and black probes, and then measure the leakage current. Judging based on the indication of low leakage current, the lead wire in contact with the black probe is the positive terminal of the electrolytic capacitor. This method is difficult to distinguish the polarity of electrolytic capacitors with low leakage current.
3. Check the variable capacitor with a multimeter
Variable capacitors have a set of fixed plates and a set of moving plates. Use the resistance range of a multimeter to check for any contact between the moving and fixed pieces. Connect the red and black probes to the moving and fixed pieces respectively, rotate the shaft handle, and if the pointer of the electric meter does not move, it indicates that there is no short circuit (contact) between the moving and fixed pieces; If the pointer swings, it indicates that there is a short circuit in the capacitor.
4. Roughly distinguish the quality of capacitors with a capacity of over 5000PF using a multimeter resistance range
The resistance range of a multimeter can roughly distinguish the quality of capacitors above 5000PF (capacitors below 5000PF can only be judged for internal breakdown). When checking, set the resistance range to the high range value, and place the two probes in contact with the two ends of the capacitor. At this point, the pointer quickly swings and then returns to its original position. Connect in reverse, and the swing amplitude is greater than the first time, and then returns to its original position. This type of capacitor is good.
The larger the capacity of a capacitor, the greater the swing of the meter pointer during measurement, and the longer the pointer recovery time. We can compare the capacity of two capacitors based on the magnitude of the meter pointer swing.
