Welcome to the official website of Zhizhong Electronics Co., Ltd.Company focus: Ceramic Capacitor, Monolithic capacitor

　　The common marking method for capacitors is direct marking. The commonly used units are pF and μF, which are easy to recognize. However, some small-capacity capacitors use the digital labeling method, which usually has three digits. The first and second digits are valid digits, and the third digit is a multiple, which means how many zeros should be followed. For example: 343 means 34000pF. In addition, if the third digit is 9, it means 10-1 instead of 10 to the 9th power. For example: 479 means 4.7pF.
　　When replacing medium and high voltage ceramic capacitors, it should be noted that the withstand voltage value of the capacitor is generally not lower than the withstand voltage requirement of the original capacitor. In circuits with stricter requirements, the capacity generally does not exceed ±20% of the original capacity. In circuits with less stringent requirements, such as bypass circuits, it is generally required to be no less than 1/2 of the original capacitance and no more than 2 to 6 times the original capacitance.
　　1 Detection of fixed capacitors
　　 A to detect small capacitances below 10pF?? Because the capacity of fixed capacitors below 10pF is too small, measuring with a multimeter can only qualitatively check whether there is leakage, internal short circuit or breakdown. When measuring medium and high voltage ceramic capacitors, you can choose a multimeter R×10k block, and use two meter pens to connect the two pins of the capacitor at will, and the resistance should be infinite. If the measured resistance value (the pointer swings to the right) is zero, it means that the capacitor is damaged by leakage or internal breakdown.
　　B Detect whether the fixed medium and high voltage ceramic capacitors of 10PF～0.01μF are charged, and then judge whether it is good or bad. The multimeter selects R×1k block. The β value of the two transistors is above 100, and the penetration current is more? You can choose 3DG6 and other types of silicon transistors to form a composite tube. The red and black test leads of the multimeter are respectively connected to the emitter e and collector c of the composite tube. Due to the amplification effect of the composite triode, the charge and discharge process of the capacitor under test is amplified, and the amplitude of the pointer of the multimeter is enlarged, which is convenient for observation. It should be noted that during the test operation of medium and high voltage ceramic capacitors, especially when measuring smaller capacity capacitors, it is necessary to repeatedly exchange the contact points A and B of the tested capacitor pin to clearly see the swing of the multimeter pointer.
C? For fixed capacitors above 0.01μF, the R×10k block of a multimeter can be used to directly test whether the medium and high voltage ceramic capacitors have charging process and whether there is internal short circuit or leakage, and the capacity of the capacitor can be estimated according to the magnitude of the pointer swing to the right .