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Capacitor

Type 1 of capacitors: aluminum electrolytic capacitors

It is made of an aluminum cylinder as the negative electrode, which contains a liquid electrolyte, and a bent aluminum strip is inserted into the positive electrode. It also needs to be treated with DC voltage to form an oxide film on the positive plate as a medium. It is characterized by large capacity, but large leakage, poor stability, positive and negative polarity, and is suitable for power supply filtering or low-frequency circuits. When using, do not reverse the positive and negative poles.

 

Type 2 of capacitors: film capacitors

The structure is the same as that of the paper capacitor, and the medium is polyester or polystyrene. Polyester film capacitors have high dielectric constant, small size, large capacity and good stability, and are suitable for bypass capacitors.

Polystyrene film capacitors have low dielectric loss and high insulation resistance, but have a large temperature coefficient and can be used in high-frequency circuits.

 

Three types of capacitors: metallized paper capacitors

The structure is basically the same as that of the paper capacitor. It is a layer of metal film on the capacitor paper to replace the metal foil, small size, large capacity, generally used in low-frequency circuits.

 

Type 4 of capacitors: oil-impregnated paper capacitors

It is a paper capacitor immersed in a specially treated oil, which can enhance its pressure resistance. It is characterized by large capacitance, high voltage resistance, but large volume.

 

Type 5 of Capacitors: Variable Capacitors

It consists of a set of fixed pieces and a set of moving pieces, and its capacity can be continuously changed with the rotation of the moving pieces. Putting two sets of variable capacitors together and rotating them coaxially is called double connection. There are two types of media for variable capacitors: air and polystyrene. Air dielectric variable capacitors are large in size and low in loss, and are mostly used in tube radios. Polystyrene dielectric variable capacitors are sealed and small in size, and are mostly used in transistor radios.

 

Type 6 of capacitors: tantalum, niobium electrolytic capacitors

It is made of metal tantalum or niobium as the positive electrode, diluted sulfuric acid as the negative electrode, and the oxide film formed on the surface of tantalum or niobium as the medium. It is characterized by small size, large capacity, stable performance, long life, high insulation resistance and good temperature characteristics. Used in demanding equipment.

 

Type 7 of Capacitors: Semi-Variable Capacitors

Also called trimmer capacitors. It is made of two or two sets of small metal shrapnel with a medium sandwiched between them. When adjusting, change the distance or area between the two pieces. Its medium is air, ceramics, mica, thin film and so on.

 

Type 8 of capacitors: paper capacitors

Two pieces of metal foil are used as electrodes, which are sandwiched in extremely thin capacitor paper, rolled into a cylindrical or flat cylindrical core, and then sealed in a metal shell or insulating material (such as varnish, ceramics, glass glaze, etc.) shell. It is characterized by a smaller volume and a larger capacity. However, the inherent inductance and loss are relatively large, and it is more suitable for low frequency.

 

Type 9 of capacitors: mica capacitors

The electrode plate is made of metal foil or sprayed with silver layer on mica sheet. After the electrode plate and mica are laminated layer by layer, they are die-cast in bakelite powder or sealed in epoxy resin. It is characterized by low dielectric loss, large insulation resistance and small temperature coefficient, and is suitable for high-frequency circuits.

 

Type ten of capacitors: ceramic capacitors

Use ceramics as the medium, spray silver layers on both sides of the ceramic substrate, and then sinter the silver film to make the plates. It is characterized by small size, good heat resistance, low loss, high insulation resistance, but small capacity, suitable for high-frequency circuits.

Ferroelectric ceramic capacitors have larger capacity, but larger loss and temperature coefficient, and are suitable for use in low-frequency circuits.