Polarized capacitors and non-polarized capacitors are the same in principle, and both store and release charges; the voltage on the electrode plate (here, the electromotive force accumulated by the charge is called voltage) cannot be abruptly changed.
The difference lies in the different media, different performance, different capacity, different structures, and different use environments and uses. Conversely, according to the needs of production practice, people have experimentally manufactured capacitors with various functions to meet the normal operation of various electrical appliances and the operation of new equipment. With the development of science and technology and the discovery of new materials, better and more diverse capacitors will continue to emerge.
1 Different media
What is the medium? To put it bluntly, it is the substance between the two plates of the capacitor. Most polar capacitors use electrolyte as the dielectric material. Generally, capacitors with the same volume have large polar capacitors. In addition, the polarized capacitors produced by different electrolyte materials and processes will have different capacities in the same volume. Then there is the close relationship between pressure resistance and the use of dielectric materials. There are also many non-polar capacitor dielectric materials, most of which use metal oxide films, polyester, etc. Due to the reversible or irreversible performance of the medium, the use environment of polar and non-polar capacitors is determined.
2 Different performance
Performance is the requirement for use, and maximum demand is the requirement for use. If a metal oxide film capacitor is used for filtering in the power supply part of a television, the capacitor capacity and withstand voltage required for filtering must be achieved. I'm afraid there can only be a power supply inside the case. Therefore, only polarized capacitors can be used for filtering, and polarized capacitors are irreversible. That is to say, the positive electrode must be connected to the high potential terminal, and the negative electrode must be connected to the low potential terminal. Generally, the electrolytic capacitor is above 1 microfarad for coupling, decoupling, and power supply filtering. Non-polar capacitors are mostly below 1 microfarad and participate in resonance, coupling, frequency selection, current limiting, etc. Of course, there are also large-capacity and high-withstand voltage, which are mostly used for reactive compensation of power, phase shift of motors, and shift of variable frequency power. There are many types of non-polar capacitors, which are not described in detail.
3 different capacity
As mentioned earlier, the capacitors of the same volume have different capacitances, which are not described in detail.
4 different structures
In principle, regardless of the tip discharge, any shape of capacitors can be used in the environment. Generally used electrolytic capacitors (with polar capacitors) are round, and square ones are rarely used. The shape of non-polar capacitors is ever-changing. Look like tube, deformed rectangle, sheet, square, round, combined square and round, etc. Of course, there are intangibles, which means distributed capacitance. The distributed capacitance must not be ignored in high-frequency and intermediate-frequency devices.
5 Use environment and purpose
In the repair of home appliances, all of the above may be encountered. If you want to understand something in simple terms, you have to figure it out by yourself. This is just a guide, please correct me.
Because of its internal materials and structure, polar capacitors (such as aluminum electrolytics) can be very large, but their high-frequency characteristics are not good, so they are suitable for power supply filtering and other applications. Polar capacitor-tantalum electrolytic, it is relatively expensive;
Non-polar capacitors are small in size, low in price, and good in high frequency characteristics, but they are not suitable for large capacity. Like ceramic capacitors, monolithic capacitors, and polyethylene (CBB) capacitors, ceramic capacitors are generally used in high-frequency filtering and oscillator circuits.
A magnetic capacitor is a capacitor that uses ceramic material as a meson and burns a silver layer on the surface as an electrode. The magnetic capacitor has stable performance. Loss and leakage are small, suitable for high frequency and high voltage circuits.
Generally speaking, the dielectric material between capacitors with large dielectric constant (such as ferroelectric ceramics, electrolyte) is suitable for making large-capacity and small-capacity capacitors, but the losses are also large. Small dielectric constants (such as ceramics) have low losses and are suitable for high frequency applications.
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