Introduction to capacitors | types and functions of capacitors

Paper dielectric power Capacity
Use two pieces of metal foil as the electrode, clip in the extremely thin capacitor paper, roll into a cylindrical or flat cylindrical core, and then seal in the metal shell or insulation material (such as fire paint, ceramics, glass glaze, etc.) made in the shell. It features a small volume and a large capacity. However, the inherent inductance and loss are both relatively large and suitable for low frequencies.
Mica Capacitor
Use metal foil or spray the silver layer on the masterbatch to make the electrode plate. After the plate and the mica layer are laminated, die-casting is made in the powder or sealing in epoxy resin. It features low dielectric loss, large insulation resistance, and small temperature coefficient, and is suitable for high-frequency circuits.

Ceramic Capacitor
Use Ceramic as media, spray silver layer on both sides of the ceramic matrix, and then burn silver film as plate. It is characterized by small size, good heat resistance, low loss, high insulation resistance, but small capacity, suitable for high frequency circuits.
The capacity of the capacitor is large, but the loss and temperature coefficient are large. It is suitable for low frequency circuits.

Film Capacitor
The structure is the same as the paper medium capacitor. The medium is polyester or polystyrene. Polyester Film Capacitor, high dielectric constant, small size, large capacity, good stability, suitable for bypass capacitor.
Polystyrene film capacitor, low dielectric loss, high insulation resistance, but high temperature coefficient, can be used in high frequency circuit.

Metallic Paper Capacitor
The structure is basically the same as that of the paper capacitor. It is covered with a metal film on the capacitor paper to replace the metal foil. It is small in size and large in capacity and is generally used in low frequency circuits.

Oil dip paper medium Capacitor
It dipped the paper medium capacitor in specially processed oil to enhance its pressure resistance. It features a large capacity, high voltage, but large size.

Aluminum electrolysis capacitor
It is made of an aluminum cylinder as the negative electrode, which is equipped with a liquid electrolyte and inserted into a curved aluminum band as the positive electrode. It also requires DC voltage processing to form an oxide film on the positive pole as the medium. It features high capacity, high leakage, poor stability, positive and negative performance, and is suitable for power supply filtering or low frequency circuits. During use, do not reverse the positive and negative interfaces.

Electrolytic capacitors of Ta AND Nb
It is used as the positive electrode with metallic Ta or Nb. It is used as the negative electrode with dilute sulfuric acid and the oxide film generated on the surface of Ta or Nb as the medium. It features small size, large capacity, stable performance, long life, large insulation resistance, and good temperature characteristics. Used in devices with high requirements.

Semi-Variable Capacitor
It is also called a fine-tuning capacitor. It is made of two or two pieces of Small Metallic shrapnel with medium in the middle. Change the distance or area between two slices during adjustment. The media includes air, ceramics, mica, and film.

Variable Capacitance
It is composed of a group of fixed and a group of dynamic parts. Its capacity can change continuously with the rotation of the dynamic part. The two sets of variable capacitors are mounted together for coaxial rotation, which is called dual-connection. The variable capacitor has two kinds of media: Air and polystyrene. The variable capacitance of the air medium is large in size and has low loss. It is used in electronic tube radio. The Polystyrene medium variable capacitor is made into a sealed type, which is small in size and used in transistor radio.

NPO (COG): it has the most stable electrical performance and basically does not change the surface of temperature, voltage and time. It is suitable for high-frequency circuits with high stability requirements;
X7R (2x1): The electrical performance is relatively stable, and the changes in temperature, voltage, and time are not significant, this method is applicable to direct separation, coupling, bypass, and frequency identification circuits with low requirements on capacity stability. Because X7R is a strong electrical medium, it can generate capacitors with larger capacity than NPO medium;
Y5V (2f4) (z5u): it has a low dielectric constant and is often used in the production of large capacity capacitor products with a higher nominal capacity, but its capacity stability is less than X7R, capacity and loss are sensitive to temperature, voltage, and other test conditions.

Name: aluminum electrolysis capacitor _ Anzmm)
Symbol: Bnnjkc
Capacity: 0. 47 -- zhangu@ Q ^} BM
Rated voltage: 6. 3--450v W) * JF"
Main features: small size, large capacity, large loss, and large leakage ! Y5rbdy
Applications: Power Supply filtering, low frequency coupling, decoupling, bypass, etc. D 4Z | gnqw
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Name: But electrolytic capacitor (CA) Nb electrolytic capacitor (CN) CV 'W = K +
Symbol: W <_ 87
Capacity: 0. 1 -- 1000uSLM @ Q
Rated voltage: 6. 3--125v + Jm9'
Main features: Loss and leakage less than aluminum electrolysis capacitor {NZ <T6/7
Application: replace aluminum electrolysis capacitor in High-requirement circuits M [BFS = 9O
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Name: Air Medium Variable Capacitor 'Nv70jbo
Symbol: Aj98do56
Variable Power Capacity: 100 -- 1500 PGDB '0c
Main Features: Low Loss and high efficiency. Linear, linear wavelength, linear frequency, and logarithm can be made as required. W ~ M67wawf
Applications: Electronic Instruments, broadcast and television devices, etc. ! E; m8seh |
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Name: variable film Capacitor \ M = l: Z
Symbol: ! 8 xdf
Variable Power Capacity: 15 -- 550 p Hzhpwogi9
Main features: small size, light weight, and greater loss than air medium-Lt7} K' ^ x
Applications: communications, broadcast receivers, etc. Orvu5wk =
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Name: Thin Film Media fine-tuning Capacitor C] d eu //]
Symbol: 1 ow & EU!
Variable Power Capacity: 1 -- 29 p Kjdk ['&
Main features: large loss and small size Crcnn)} # C'
Applications: recorders, Electronic Instruments, and other circuits for Circuit CompensationV Ta') E
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Name: ceramic fine-tuning Capacitor W 8 ^, W
Symbol: 6vm V-S
Variable Power Capacity: 0. 3 -- 22 p C4n + C2R
Main Features: Low Loss and small size 4 \ "M % 3
Application: high-frequency oscillation loop of precision Tuning ? W vjdq
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The biggest drawback of the Dushi capacitor is that the temperature coefficient is very high, so it is unbearable to make the stable drift of the oscillator. We made a 555 oscillator, And the capacitor was just next to 7805. after starting the system, we used the oscilloscope to view the frequency, it changes slowly. Later, it is much better to change to a polyester capacitor. ! | E) ", Q ~)
Unique-rock capacitor features: J \ | C + SV
Large Capacity, small size, high availability, stable electrical capacity, high temperature and humidity resistance, etc. T @! * LFN
Application Scope: W k = aaz
It is widely used in electronic precision instruments. Various small electronic devices are used for resonance, coupling, filtering, and bypass. Rmypxhlq
Capacity range:0 dchr & Z (
0.5pf -- 1 UF Q6o9) E ~ -O
Voltage: twice the rated voltage. ? | 'K4
It is also called multilayer porcelain dielectric capacitor, which has two types: Type 1 + Azi38m8p
Performance is good, but the capacity is small, generally less than 0. 2u, the other is ] F1 PT :'
Type II, large capacity, but moderate performance. *: Gzb #9
Name: Mica capacitor (CY) 7 & ', 1 # v. T $
Symbol: G ~ Quu V _*
Capacity: 10 p -- 0. 1u <B {[f da
Rated voltage: 100 V -- 7kv 3A @ vd3 \ CC
Main features: high stability, high availability, low temperature coefficient X) E % = ~ ++
Applications: high-frequency oscillation, pulse, and other circuits with high requirements _ 'A + jqq (
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Name: high-frequency porcelain dielectric capacitor (cc) Jqobh * qqmm
Symbol: U} km> S0 #
Capacity: 1 -- 6800 P H "U {L
Rated voltage: 63--500v "Ut? "Ba
Main Features: Low High-frequency loss and good stability {Lm K! S |
Application: High-Frequency Circuit Y' xlo \,
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Name: Low Frequency porcelain dielectric capacitor (CT) Or +! # DW
Symbol:5 N | 6R
Capacity: 10 p -- 4. 7u T :) e_ukr>
Rated voltage: 50v--100v D5! 6bo0x
Major Features: small size, low price, high loss, poor stability K, ^! E9x *
Application: Low-requirement Low-Frequency Circuit _ FZ; \ m3 \
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Name: glass glaze capacitor (CI) |, './{RFP
Symbol:C0't & R]
Capacity: 10 p -- 0. 1u G, ot0' t
Rated voltage: 63--400v Fr? Cbqxt <
Main features: good stability, low loss, high temperature resistance (200 degrees) X1/$ JS;
Applications: pulse, coupling, bypass, and other circuits Ricm % _ G $ s
Name: polyester capacitor (CL) A? S:. A $ <
Symbol: } Qh0! Yi %
Capacity: 40 p -- 4u K % m = UG
Rated voltage: 63--630v Ze4zj ": ax
Main features: small size, large capacity, heat resistance and humidity resistance, poor stability M7g52 I (
Application: Low-Frequency Circuits with low requirements for stability and loss 1q + Nu?
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Name: Polystyrene capacitor (CB) V & _ su = @ f2h
Symbol: Sltdyvj =
Capacity: 10 p -- 1u N3] jzylib
Rated voltage: 100v--30kv "| PDM.; ^
Main features: stability, low loss, and large size E4 + v U #
Application: circuits with high requirements on stability and loss O9h] m
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Name: Polypropylene Capacitor (CBB) Riq $"
Symbol: 4 'o + 5!> {^
Capacity: 1000 p -- 10uVe HR
Rated voltage: 63--2000v Iyrl2 [g} m
Main features: the performance is similar to that of polystyrene, but the size is small, and the stability is slightly lower. Z \ piuw
Application: replace most of the polybenzene or mica capacitors for High-requirement circuits

Iii. Functions of capacitors

1. Isolating DC: The function is to prevent the DC from passing through and let the AC pass through.

2. Bypass (decoupling): provides low-impedance paths for some parallel components in the AC circuit.

3. Coupling: As a connection between two circuits, the AC signal can pass through and be transmitted to the next level circuit.

4. filter: This is very important for DIY. the capacitors on the video card are basically used for this purpose.

5. Temperature Compensation: to improve the stability of the circuit, compensate for the effect of insufficient adaptability of other components to the temperature.

6. Timing: The capacitor is used with the resistor to determine the time constant of the circuit.

7. tuning: system tuning of frequency-related circuits, such as mobile phones, radios, and televisions.

8. rectification: enable or disable the half-closed conductor switch element at a predetermined time.

9. Energy Storage: used to store power and release it when necessary. For example, camera flash and heating equipment. (Currently, the energy storage level of some capacitors is close to that of a lithium battery. The energy stored by one capacitor can be used by a mobile phone for one day.