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Home > Mall Dynamic > Comprehensive Explanation OF Capacitors
Along with the electronic information technology change rapidly, digital electronic product updates faster and faster, with the flat-panel TV (LCD and PDP) products, notebook computer, digital cameras and other consumer electronic products production and sales continued to grow, driven by growth in the capacitor industry. In this article we will learn something about capacitors including what capacitor is; the features of the capacitor, capacitor function; capacitor types; classification; capacitor formula; charging and discharging and etc.
What are capacitors? The capacity to hold the charge is called usually the capacitance, we use the letter C to express it. Definition 1: The capacitor, as its name implies, is a 'container for electricity, a device that holds a charge. Capacitors are widely used in electronic devices, which are widely used in electronic devices. They are widely used in direct circuit switching, coupling, bypass, filtering, tuning loop, energy conversion, control and so on. Definition 2: A capacitor can be made up of two insulated and closely spaced conductors(Including wires).
About capacitance: The capacitance is different from the capacitor. The capacitance is the basic physical quantity, the symbol C, the unit is F (Fala).
Formula: The special formula of the general formula C=Q/U parallel plate capacitor: the electric field strength between the plates E=U/d, the capacitor's capacitive determinant C= S/4 PI KD
Along with the electronic information technology change rapidly, digital electronic product updates faster and faster, with the flat-panel TV (LCD and PDP) products, notebook computer, digital cameras and other consumer electronic products production and sales continued to grow, driven by growth in the capacitor industry.
Capacitors are composed of a layer of insulating dielectric between two metal electrodes. When a voltage is added between the two metal electrodes, the charge is stored on the electrode, therefore, the capacitor is an energy storage element. Any two conductors, which are insulated from each other and close to each other, make up a capacitor. The parallel plate capacitor consists of the pole plate and the dielectric of the capacitor. It has the following features:
1. It has the capacity of charging and discharging characteristics and preventing the passing of DC current, allowing the passing of AC current.
2. In the process of charging and discharging, the charge on the two plates has a process of accumulation, that is, the voltage has a process of establishment. Therefore, the voltage on the capacitor can not be mutated.
Capacitor Charging: two plates have equal different kinds of charge respectively, the absolute value of the charge of each plate is called the charge of the capacitor.
Capacitor discharging: the positive and negative charge of the two poles of the capacitor is balanced out through the conductor. There is a short current on the wire during the discharge.
3. The Capacitance of capacitor is inversely proportional to the frequency and capacity of the capacitor. So we say that analyzing capacitance size need to know the frequency and capacitance size of the signal.
4. The capacitance formula of a parallel plate capacitor
Dielectric constant vacuum epsilon r=1, K as a static electric constant, S as two-plate positive pair area, D for two plate distance.
Attention: the electric field in the parallel plate capacitor is a uniform electric field
In a DC circuit, the capacitor is equivalent to a circuit breaker. The capacitor is a kind of element that can store the charge, as well as one of the most commonly used electronic components.
circuit symbol for capacitor
This has to be said from the structure of the capacitor. The simplest capacitor is made up of polar plates at both ends and dielectric (including air) in the middle. After electrifying, charged plate forming voltage (potential difference), but, due to the middle insulating material, so the capacitor is not conductive. However, this situation is under the condition that the critical voltage(breakdown voltage) of the capacitor is not exceeded. As we all know that any substance is relatively insulated. When the voltage at both ends of the material is increased to a certain extent, the matter can conduct electricity. We call this voltage breakdown voltage.
The capacitance is no exception, and when the capacitor is knocked out, it is not an insulator. But in the middle school stage, such voltage is not seen in the circuit, so it works below the breakdown voltage and can be seen as an insulator.
However, in the DC circuit, the direction of the current is changed with time to a certain degree of function. But the process of charging and discharging is time. At this time, the electric field which also a function of time is formed between the poles. Actually, the current pass by capacitors in the form of an electric field. The capacitor’s function is as follows:
1. Coupling: the capacitance used in the coupling circuit is called the coupling capacitance, which is widely used in the resistance-capacitance coupled amplifier and other capacitive coupling circuits, and it acts as a direct flow and alternating current.
2. Filtering: the capacitor used in the filter circuit is called the filter capacitor. In the power filter and various filter circuits, the capacitor circuit is used. The filter capacitor removes the signal from the total signal in a certain frequency band.
3. Decoupling: the capacitor used in the decoupling circuit is called a decoupling capacitor. The capacitor circuit is used in the DC voltage supply circuit of the multistage amplifier, and the decoupling capacitor eliminates the harmful low-frequency interconnection between the amplifiers.
4. High-frequency vibration elimination: capacitance used in high-frequency damping circuit is called high-frequency damping capacitor. In the audio negative feedback amplifier, in order to eliminate high-frequency self-excitation, we use this capacitance circuit to eliminate the possible high-frequency whistle of the amplifier.
5. Resonance: the capacitor used in the LC resonant circuit is called the resonant capacitance, and this capacitance circuit is required in both LC parallel and series resonant circuits.
6. Bypass: capacitor used in bypass circuit called the bypass capacitor in the circuit, if you need to remove the signal of a certain frequency from the signal, you can use a bypass capacitor circuit according to the signal frequency, a frequency domain (all AC signal) bypass capacitor circuit and a high-frequency bypass capacitor circuit.
7. Neutralization: the capacitor used in the neutralization circuit is called neutralization capacitance. In radiofrequency and medium frequency amplifiers, high-frequency amplifiers in TV sets, this neutralization capacitor circuit is used to eliminate self-excitation.
8. Timing: the capacitor used in the timing circuit is called the timing capacitance. The use of a timing capacitance circuit in a circuit that needs to charge and discharge the time by capacitor charging and discharging, and the function of the capacitor to control the time constant size.
9. Integral: the capacitor used in an integrated circuit is called an integral capacitor. In the synchronous separation circuit of the potential field scanning, the field synchronous signal can be taken out of the field compound synchronous signal by using this integral capacitor circuit.
10. Differential: a capacitor used in a differential circuit is called a differential capacitance. In order to get spike trigger signal in trigger circuit, we use this differential capacitance circuit to get spike pulse triggering signal from all kinds of (mainly rectangular pulse) signals.
11. Compensation: compensation capacitors used in the circuit are called the compensation capacitor, the compensation circuit card in the bass, the low-frequency compensation capacitor circuit, in order to improve the low-frequency signal, a playback signal in addition to this, there is a high-frequency compensation capacitor circuit.
12. Bootstrap: the capacitor used in bootstrapping circuit is called the bootstrap capacitor. The output circuit of the OTL power amplifier usually uses this bootstrap capacitor circuit to enhance the positive half-width of the signal by positive feedback.
13. Frequency division: the capacitor in the frequency divider
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