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Home > Mall Dynamic > The Structure, Principle And Function OF Capacitor
With the rapid development of electronic information technology, the upgrading rate of digital electronic products has become faster, and the sales volume of consumer electronic products and electronic equipment dominated by flat panel TV sets (LCD and PDP), notebooks, digital cameras and other commodities has increased steadily, which has promoted the improvement of the capacitor industry chain. Capacitors are one of the most widely used electronic components in electronic equipment, so they are widely used in straight separation, coupling, bypass, filtering, tuning control loop, energy conversion, control loop and other levels. So how does it work? What are the effects? The following will introduce you:
Capacitors are components that store electricity and electrical energy (potential energy). One conductor is surrounded by another conductor, or the electric field lines emitted by one conductor are all terminated in the other conductor's conduction system, called a capacitor. It is represented by the letter C. Definition 1: A capacitor, as the name suggests, is an 'electric container', a device that holds an electric charge. Name: capacitor. Capacitors are one of the most widely used electronic components in electronic equipment, which are widely used in circuit separation through alternating, coupling, bypass, filtering, tuning loop, energy conversion, control and so on. Definition 2: Capacitor, any two conductors (including wires) that are insulated from each other and closely separated form a capacitor.
The basic structure of a capacitor is two electrodes (metal plates) spaced against each other. A direct current voltage (V) is applied to two electrodes, and electrons are instantly concentrated on one electrode, which is negatively charged, and the other electrode, which is in a state of electron deficiency, is positively charged. This state persists after the DC voltage is removed. That is, an electric charge (Q) is accumulated between the two electrodes. A dielectric (ceramic, plastic film, etc.) is inserted between the electrodes, and the accumulated charge increases through the polarization of the dielectric. The indicator that indicates how much charge a capacitor stores is called capacitance (C)(referred to as capacity).
Electrical energy is stored by storing charge on the electrode, usually in conjunction with an inductor to form an LC oscillating circuit. The working principle of the capacitor is that the charge will be forced to move in the electric field, when there is a medium between the conductors, it prevents the charge from moving and causes the charge to accumulate on the conductor, resulting in the accumulation of charge storage.
A capacitor, like a battery, has two electrodes. Inside the capacitor, the two electrodes are connected to two metal plates separated by a dielectric. The dielectric can be air, paper, plastic, or any other substance that does not conduct electricity and prevents the two metal poles from coming into contact with each other.
A metal plate on the capacitor connected to the negative electrode of the battery will absorb the electrons produced by the battery. A metal plate on the capacitor connected to the positive electrode of the battery will release electrons to the battery. After the charge is complete, the capacitor has the same voltage as the battery (if the battery voltage is 1.5 volts, then the capacitor voltage is also 1.5 volts).
(1) Resonance: The capacitor used in the LC resonant circuit is called the resonant capacitor, and the capacitor circuit is required in the LC parallel and series resonant circuit.
(2) Coupling: The capacitor used in the coupling circuit is called the coupling capacitor, which is widely used in the resistance-capacitance coupling amplifier and other capacitive coupling circuits, and plays the role of separating the direct flow AC.
(3) Neutralization: capacitors used in neutralizing circuits are called neutralizing capacitors. In radio high frequency and intermediate frequency amplifiers and television high frequency amplifiers, this neutralizing capacitor circuit is used to eliminate self-excitation.
(4) Filter: the capacitor used in the filter circuit is called the filter capacitor, which is used in the power supply filter and various filter circuits, and the filter capacitor will remove the signal in a certain frequency band from the total signal.
(5) Integration: capacitors used in integrating circuits are called integrating capacitors. In the synchronous separation circuit of potential field scanning, the field synchronization signal can be extracted from the field complex synchronization signal by using this integrated capacitance circuit.
(6) Timing: The capacitor used in the timing circuit is called a timing capacitor. A timed capacitor circuit is used in a circuit that requires time control through capacitor charging and discharging, and the capacitor controls the size of the time constant.(7) Decoupling: The capacitor used in the decoupling circuit is called the decoupling capacitor, which is used in the DC voltage supply circuit of the multistage amplifier, and the decoupling capacitor eliminates the harmful low-frequency cross-connection between each stage amplifier.
(8) Bootstrap: The capacitor used in the bootstrap circuit is called the bootstrap capacitor, and 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 of positive feedback.
(9) Compensation: the capacitor used in the compensation circuit is called the compensation capacitor, in the bass compensation circuit of the cassette, the low-frequency compensation capacitor circuit is used to enhance the low-frequency signal in the playback signal, in addition, there are high-frequency compensation capacitor circuits.
(10) Differential: capacitors used in differential circuits are called differential capacitors. In order to obtain the peak trigger signal in the trigger circuit, this differential capacitance circuit is used to obtain the peak trigger signal from various kinds of (mainly rectangular pulse) signals.
(11) high-frequency vibration suppression: the capacitor used in the high-frequency vibration suppression circuit is called the high-frequency vibration suppression capacitor. In the audio negative feedback amplifier, in order to eliminate the high-frequency self-excitation that may occur in the vibration, this capacitor circuit is used to eliminate the high-frequency whistling that may occur in the amplifier.
(12) Frequency division: the capacitor in the frequency division circuit is called the frequency division capacitor, in the speaker frequency division circuit of the speaker, the frequency division capacitor circuit is used to make the high-frequency speaker work in the high frequency band, the medium frequency speaker works in the middle frequency band, and the low frequency speaker works in the low frequency band.
(13) Bypass: The capacitor used in the bypass circuit is called the bypass capacitor. If the signal in the circuit needs to be removed from the signal in a certain frequency band, the bypass capacitor circuit can be used. According to the different frequency of the signal removed, there are full-frequency domain (all AC signals) bypass capacitor circuits and high-frequency bypass capacitor circuits.
(14) Load capacitance: It refers to the effective external capacitance that determines the load resonance frequency together with the quartz crystal resonator. Common standard values for load capacitors are 16pF, 20pF, 30pF, 50pF and 100pF. The load capacitance can be adjusted appropriately according to the specific situation, and the working frequency of the resonator can be adjusted to the nominal value by adjusting it.
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