5 Points of the Capacitor You Should Know

Capacitor is an electronic component that hold and release electric charges in circuits. It consists of two conductors close to each other with a non-conductive insulating medium in between them. When a voltage is applied to, the capacitor will store electric charges. The capacitance of a capacitor is numerically equal to the ratio of the amount of charge on one conductive plate to the voltage between the two plates. The basic unit of capacitance is farad (F). In circuit diagrams, the letter C is usually used to represent capacitor components.

What is A Capacitor Mainly Used For?

1. Coupling: The capacitor used in the coupling circuit is called the coupling capacitor. This capacitor circuit is widely used in the RC coupling amplifier and other capacitor coupling circuits to block DC and pass AC.

2. Filtering: The capacitor used in the filter circuit is called the filter capacitor. This capacitor circuit is used in power supply filtering and various filter circuits. This kind of capacitor removes the signal within a certain frequency band from the total signal.

3. Decoupling: The capacitor used in the decoupling circuit is called the decoupling capacitor. This capacitor circuit is used in the DC voltage supply circuit of the multi-stage amplifier. The decoupling capacitor eliminates the harmful low-frequency connection between each stage of the amplifier.

4. High-frequency vibration elimination: The capacitor used in the high-frequency vibration elimination circuit is called a high-frequency vibration elimination capacitor. In the audio negative feedback amplifier, in order to eliminate the high-frequency self-excitation, this capacitor circuit is used to eliminate the high-frequency howling that may occur in the amplifier.

5. Resonance: The capacitor used in the LC resonant circuit is called a resonant capacitor. This capacitor circuit is required in both LC parallel and series resonant circuits.

6. Bypass: The capacitor used in the bypass circuit is called a bypass capacitor. If a certain frequency band of the signal needs to be removed from the signal in the circuit, a bypass capacitor circuit can be used. Depending on the frequency of the removed signal, there are full-frequency domain (all AC signals) bypass capacitor circuits and high-frequency bypass capacitor circuits.

7. Neutralization: The capacitor used in the neutralization circuit is called the neutralization capacitor. In the radio high-frequency and intermediate-frequency amplifiers, and the television high-frequency amplifiers, this neutralization capacitor circuit is used to eliminate self-excitation.

8. Timing: The capacitor used in the timing circuit is called the timing capacitor. The timing capacitor circuit is used in the circuit that needs to control the time by charging and discharging the capacitor, and the capacitor plays the role of controlling the time constant.

9. Integration: The capacitor used in the integration circuit is called the integration capacitor. In the synchronous separation circuit of the potential field scanning, this integration capacitor circuit is used to extract the field synchronization signal from the field composite synchronization signal.

10. Differentiation: The capacitor used in the differential circuit is called a differential capacitor. In the trigger circuit, in order to obtain a peak trigger signal, this differential capacitor circuit is used to obtain a peak pulse trigger signal from various types of (mainly rectangular pulse) signals.

11. Compensation: The capacitor used in the compensation circuit is called a compensation capacitor. In the bass compensation circuits, this low-frequency compensation capacitor circuit is used to enhance the low-frequency signal in the playback signal. In addition, there is a high-frequency compensation capacitor circuit.

12. Bootstrap: The capacitor used in the bootstrap circuit is called a bootstrap capacitor. The commonly used OTL power amplifier output stage circuit uses this bootstrap capacitor circuit to increase the positive half-cycle amplitude of the signal by a small amount through positive feedback.

13. Frequency division: The capacitor in the frequency division circuit is called the frequency division capacitor. In the speaker frequency division circuit of the sound box, the frequency division capacitor circuit is used to make the high-frequency speaker work in the high frequency band, the medium-frequency speaker work in the medium frequency band, and the low-frequency speaker work in the low frequency band. Where Load capacitance refers to the effective external capacitance that determines the load resonant frequency together with the quartz crystal resonator. The commonly used standard values of load capacitance are 16pF, 20pF, 30pF, 50pF and 100pF. The load capacitance can be appropriately adjusted according to the specific situation. Through adjustment, the operating frequency of the resonator can generally be adjusted to the nominal value.

How to Name a Capacitor?

For any capacitor naming, you need to consider the following aspects:

1. Capacitance Value: The capacitance value of a capacitor is denoted in farads (F) or microfarads (μF), nanofarads (nF), or picofarads (pF) for smaller values. This value indicates the amount of charge the capacitor can store.

2. Tolerance: Capacitors have a tolerance that indicates how closely the actual capacitance value matches the stated capacitance value. Tolerance is usually represented by a percentage, such as ±5% or ±10%.

3. Voltage Rating: This parameter specifies the maximum voltage that can be applied to the capacitor without causing damage. It is usually expressed in volts (V) or kilovolts (kV).

4. Temperature Coefficient: Some capacitors list a temperature coefficient, which indicates how the capacitance value changes with temperature variations. Common codes include NPO, X7R, and Y5V for ceramic capacitors.

5. Dielectric Material: The dielectric material used in the capacitor is sometimes specified in the nomenclature. Different dielectric materials have varying properties such as temperature stability, dielectric constant, and leakage current characteristics.

6. Voltage Polarity: For polarized capacitors like electrolytic capacitors, the polarity of the capacitor (positive and negative terminals) is essential and should be observed. Incorrect polarity can cause the capacitor to fail.

7. Physical Size and Package: Capacitors come in various sizes and packages, which can sometimes be indicated in the nomenclature, especially for surface-mount capacitors.

8. Manufacturer's Part Number: Capacitors may also include a manufacturer-specific part number or series identification as part of the nomenclature.

How to calculate the Capacitance of a Capacitor?

Calculating the capacitance value of a capacitor can be done using the formula that describes the relationship between the physical characteristics of the capacitor and its capacitance. The basic formula for capacitance (C) is:

C = εA/d

Where:

C is the capacitance in farads (F),

ε is the permittivity of the dielectric material between the plates (ε0εr), where ε0 is the permittivity of free space (approximately 8.854×10 ?12 F/m) and εr is the relative permittivity (dielectric constant) of the material,

A is the area of one of the plates in square meters (m2),

d is the distance between the plates in meters (m).

Here's how to calculate the capacitance step by step:

Determine the dielectric constant (εr): Look up the dielectric constant for the material used as the dielectric in your capacitor. This value is specific to the material and can vary widely.

Calculate the permittivity (ε): Multiply the dielectric constant by the permittivity of free space (ε0) to get the permittivity of the dielectric material.

Measure the area (A): Determine the surface area of one of the plates. If the plates are circular, square, or rectangular, you can calculate the area using the appropriate formula. For example, for a circle, A =πr2, where r is the radius of the circle.

Measure the distance (d): Measure the distance between the two plates of the capacitor. This is typically the thickness of the dielectric material.

Calculate the capacitance (C): Plug the values into the formula and solve for C.

This formula assumes that the plates are flat, parallel, and that the electric field is uniform between the plates. For more complex geometries or if the capacitor is not of the parallel-plate variety, different formulas or numerical methods may be required.

For practical purposes, most capacitors are manufactured with known capacitance values, which are often printed directly on the component or specified in the datasheet provided by the manufacturer. If you're trying to determine the capacitance of an existing capacitor without these details, just use a multimeter or an LCR meter to measure the capacitance directly.

What is the most common type of capacitor?

Commonly used capacitor types:

The most commonly used capacitor is the fixed capacitor. It can be divided into non-polar capacitors and polar capacitors. For non-polar capacitors, there is no restriction on the polarity of the voltage applied to the capacitor terminals, that is, it does not matter which terminal is positive. As long as it is a non-polar capacitor, a voltage rising and falling from zero potential can be applied, so it can be used directly even in AC circuits.

The mainstream of non-polar capacitors is ceramic capacitors and film capacitors, and there are also mica capacitors, paper capacitors, and air capacitors. Polar capacitors are capacitors that determine one of the two terminals as positive. If the polarity is wrong when use, the capacitor will malfunction. Therefore, it must be used under DC voltage or voltage that changes only on the positive side. However, the advantage of polar capacitors is that they are small in size.

Examples of several common types:

1) Aluminum electrolytic capacitor

Features:

Large size, large capacity, moderate voltage resistance, polarity, high ESR (internal resistance)

Used for energy storage, low price

Disadvantages: overvoltage failure, reverse breakdown, open circuit failure, leakage failure

2) Tantalum capacitor

Features:

Small size, large capacity, polarity, moderate ESR, wide temperature operation, moderate price, good stability, good high-frequency characteristics

Disadvantages: weak voltage resistance and current capacity, may catch fire when the capacitor fails

Suggestion: when selecting a capacitor, the voltage resistance value should be selected according to 2-2.5 times the working voltage

3) Ceramic capacitor

Features:

Small size, small capacity, high voltage resistance, non-polarity, low ESR, good high-frequency characteristics, moderate price

Disadvantages: overvoltage failure, welding deformation, unstable temperature characteristics

What are the world-famous manufacturers of capacitors?

There are several well-known and reputable capacitor manufacturers known for producing high-quality capacitors for a wide range of electronic applications. Some of the world-famous capacitor manufacturers include:

1. Murata

Murata Manufacturing Co., Ltd. is a Japanese company known for producing a wide variety of electronic components, including capacitors. They offer ceramic, polymer, aluminum electrolytic, and film capacitors.

2. TDK Corporation

TDK is a leading manufacturer of electronic components, including ceramic, aluminum electrolytic, film, and tantalum capacitors. They are known for their high-quality and innovative capacitor technologies.

3. AVX Corporation

AVX, a part of the Kyocera Group, is a manufacturer of a broad range of passive electronic components, including ceramic, tantalum, film, and electrolytic capacitors. They are recognized for their reliability and performance.

4. KEMET Corporation

KEMET is a global supplier of electronic components, specializing in capacitors, including tantalum, ceramic, aluminum electrolytic, and film capacitors. They are known for their quality and wide range of capacitor products.

5. Vishay Intertechnology

Vishay is a prominent manufacturer of electronic components, offering a variety of capacitors, including ceramic, film, aluminum electrolytic, and tantalum capacitors. They are known for their technological advancements and high-performance capacitors.

6. Nichicon Corporation

Nichicon is a Japanese manufacturer specializing in aluminum electrolytic and film capacitors. They are recognized for their high-quality capacitors used in various industrial, automotive, and consumer electronics applications.

7. Panasonic Corporation

Panasonic is a well-known electronics company that manufactures a wide range of electronic components, including aluminum electrolytic, film, ceramic, and tantalum capacitors. They are known for their reliability and innovation in capacitor technology.

8. Samsung Electro-Mechanics

As part of the Samsung Group, this company manufactures various electronic components, including multilayer ceramic capacitors (MLCCs).

9. Würth Elektroni

Based in Germany, Würth Elektronik is known for its wide range of electronic components, including various types of capacitors.

10. LITE-ON Technology Corporation

Liton, a Taiwanese company, specializes in aluminum electrolytic capacitors. LITEON primarily manufactures consumer electronics, including LEDs, semiconductors, computer chassis, monitors, motherboards, optical disc drives, and other electronic components.

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