How to measure fixed capacitance with multimeter
(1) Detection of fixed capacitance with a capacity above 0.01 pF Adjust the pointer multimeter to the R×10k ohm block, and perform ohm zero adjustment, then touch the two pins of the capacitor with the red and black pens of the multimeter respectively, and observe the pointer of the multimeter changes, as shown in Figure 1. If the pointer of the multimeter swings slightly to the right when the test lead is connected, and then returns to infinity, after changing the test lead, measure again, and the pointer also swings to the right and returns to infinity, then it can be judged that the capacitance is normal; , the pointer of the multimeter swings to the vicinity of "0", then it can be judged that the capacitor has been broken down or has a serious leakage; If the pointer does not swing, it can be judged that the capacitor is open.
(2) Detection of fixed capacitors with a capacity of less than 0.01 pF When detecting small capacitors below 10pF, because the capacitance is too small, use a multimeter to measure, and you can only check whether there is leakage, internal short circuit or breakdown phenomenon: use when measuring Multimeter R×10k block, connect the two test leads to the two pins of the capacitor randomly, the resistance should be infinite. If the measured resistance is zero, it can be determined that the capacitor is damaged by leakage or internal breakdown.
(3) To detect 10pF～0.01; tF fixed capacitance can adopt the following method. Adjust the multimeter to the R×10k gear, select two triodes 3DC6 (or 9013) with a value greater than 100 to form a composite tube, and its circuit schematic diagram is shown in Figure 2. Using the amplification effect of the composite tube, the charging current of the measured capacitor is amplified to increase the swing range of the pointer of the multimeter. Connect the capacitor to be measured between the base b and the collector c of the composite tube, and connect the red and black test leads of the multimeter to the emitter e and collector c of the composite tube respectively. If the pointer of the multimeter swings slightly and returns to infinity, the capacitor is normal; if the pointer does not move or cannot return to infinity, the capacitor is damaged. During the test operation, especially when measuring a small capacity capacitor, it is necessary to repeatedly exchange the two contact points of the measured capacitor pin to clearly see the swing of the pointer of the multimeter.
