The capacitor is made up of two electrodes and a dielectric material therebetween. A dielectric material is a dielectric that, when placed in an electric field between two parallel plates with an equal amount of anisotropic charge, is polarized on the surface of the medium due to polarization, so that the polarization bound to the plate A corresponding increase in charge to maintain the potential difference between the plates unchanged.
All the insulators are collectively referred to as dielectrics, or substances whose internal structures are altered by external shovels and which in turn affect the external electric field. There is a key point to be clear: whether the DC environment or the exchange environment, the ideal capacitor inside will not have any charge (current) through, but the charge balance of the two plates have changed, resulting in the electric field.
Capacitance resistance formula Cx = 2πfc. Capacitance is the overall resistance of the capacitor to AC. Where: 2π is a constant, about equal to 6.28. F is the frequency of the alternating current, and c is the capacitance. From the type can be seen: a capacitor on the AC resistance and AC frequency, the capacitance of the capacity, that is, the higher the frequency of AC, the greater the capacity of the capacitor, the smaller the resistance of the AC. On the contrary, the greater the resistance to AC.
From this formula, we can also form a concept: the basic nature of the capacitor is through the AC, DC isolation. In the capacitor capacity of a certain case, the higher the frequency of AC, the more easily through the capacitor. This is how the FM bypass capacitor works.
Capacitance of the important indicators
Capacity: The capacity of a capacitor, or the capacity of a charge. The basic unit of capacity for the Farah (F), but we are common in the motherboard microfarads (μF), skin method (pF) and other units (conversion relationship is a Farah = 1000000 micro-law, 1 micro-law = 1000000 picofarads). Capacity is directly marked out, such as GSC4700μF, in general, the index is the bigger the better.
Pressure value: It refers to the rated temperature range of the capacitor can work reliably for a long time the maximum DC voltage or the maximum AC voltage RMS, different capacitors with different voltage values, mostly between 6.3V ~ 16V.
Temperature value: temperature resistance value that can withstand the maximum operating temperature of the capacitor. General capacitor temperature is 85 ℃ or 105 ℃, and CPU power supply circuit next to the capacitor temperature value of more than 105 ℃.
Other indicators: Some capacitors also have a gold strip line, printed with a large hollow "I" letters, it said the capacitor belongs to LOWESR low loss capacitors. Some capacitors will also mark the ESR (equivalent resistance) value, ESR lower, the smaller the loss, the greater the output current, low ESR capacitor quality are good.
Capacitor Selection
In the computer, the capacitance is divided into Taiwan and Japan are two kinds of Japanese brands: NICHICON, RUBICON, Ruby (Ruby), KZG, SANYO (Sanyo), PANASONIC (Panasonic), NIPPON, FUJITSU (Fujitsu) Brand: TAICON, G-LUXCON, TEAPO, CAPXON, OST, GSC, RLS, and so on.
Generally speaking, the Japanese capacitor performance is better, in the pressure, temperature, life and other aspects of capacitance than the Taiwan Department of excellent, early capacitor "explosion pulp" event, nor in the Japanese capacitor, so if you want to choose a Overclocking, stability of the motherboard, take a look at the motherboard capacitor. Although the performance of the Taiwan-based capacitor is relatively poor, but if the motherboard PCB design, copper foil alignment are more standardized, then the general will not be in use in any problem Moreover, the use of Taiwan-based motherboard overclocking capacitor is not necessarily bad.
Motherboard capacitive capacity are generally marked directly, Intel requires CPU power supply circuit filter capacitor single capacity of at least 1000μF or more, and now the capacitance of more than 2000μF ~ 4000μF between the part of the motherboard with a capacity of 5000μF capacitor, memory Capacitance around the tank in 1000μF ~ 1500μF more between the smaller capacity of the capacitor is very difficult to provide to the CPU, the memory to a sufficient pure current, some older motherboards after the incompatibility of the CPU upgrade is actually derived from this.
Temperature value on the other hand also shows the quality of the capacitor, the motherboard temperature resistance of the capacitor value of more than 105 ℃, and if your motherboard capacitor temperature is 85 ℃, it is mostly manufacturers to save material results, low The voltage value of the capacitor in use no problem, but when the CPU in the overclocking state occurs when the "explosion pulp" the probability will be relatively large.
Capacitance error: the larger the better capacitance
Generally speaking, the larger the better capacitance, but this is not absolute, high-capacity capacitor is not easy to filter out high-frequency interference signal, and a number of small-capacity capacitor parallel capacitor than a single large-capacity more effective and more stable. Moreover, this and the motherboard of the alignment, there is a certain relationship, but if your motherboard is full of 100μF around the small capacitors, motherboard quality is not much better.