In the DC circuit, the capacitor is equivalent to open circuit. A capacitor is a device that can store charge and is one of the most commonly used electronic components. This comes from the structure of the capacitor. The simplest capacitor is made up of plates at both ends and an intermediate dielectric (including air). When energized, the plates are energized to form a voltage (potential difference), but the entire capacitor is non-conductive due to the middle insulating material. However, this is the case without exceeding the critical voltage of the capacitor (breakdown voltage). We know that any material is relatively insulated, when the voltage across the material increases to a certain extent, the material can be conductive, we call this voltage breakdown voltage. Capacitance is no exception, the capacitor is breakdown, it is not an insulator. However, in the secondary stage, such a voltage is not seen in the circuit, so they are below the breakdown voltage work, can be seen as an insulator. However, in the AC circuit, because the current direction is a function of time as a function of change. The capacitor charging and discharging process is time, this time, the formation of a change in the electric field between the plates, and the electric field is also a function of time. In fact, the current is passed between the capacitors in the form of an electric field. The role of the capacitor ● Coupling The coupling capacitor used in the coupling circuit is called the coupling capacitor, which is used extensively in RC-coupled amplifiers and other capacitive coupling circuits to act as DC-blocking AC
● Filtering The capacitor used in the filter circuit is called the filter capacitor. This capacitor circuit is used in the power supply filter and various filter circuits. The filter capacitor removes the signals in a certain frequency band from the total signal. 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 multistage amplifier, and the decoupling capacitor eliminates the harmful low-frequency crossover between each stage of the amplifier. ● High-frequency anti-vibration high-frequency anti-vibration circuit used in the capacitance called high-frequency anti-vibration capacitors, audio negative feedback amplifier, in order to shake off the possible high-frequency self-excitation, the use of this capacitor circuit to eliminate The amplifier may appear high-frequency whistling. ● Resonance The capacitor used in the LC resonant circuit is referred to as the resonant capacitor, which is required in both LC shunt and series resonant circuits
● Bypass The capacitor used in the bypass circuit is called the bypass capacitor. If the circuit needs to remove a certain frequency band from the signal, bypass capacitor circuit can be used. Depending on the frequency of the signal removed, there is a full frequency band (All AC signals) bypass capacitor circuit and high-frequency bypass capacitor circuit
● Neutralization The capacitor used in the neutralization circuit is called the neutralization capacitor. In the radio frequency and IF amplifier, TV high-frequency amplifier, the use of such capacitors and neutralization circuit to eliminate self-excited. ● Timing The capacitor used in the timing circuit is called the timing capacitor. In the need to charge through the capacitor, the time-controlled discharge circuit used in the timing capacitor circuit, the capacitor control the size of the role of time constant. ● Integration The capacitor used in the integration circuit is called the integration capacitor. In the potential separation field scanning synchronous separation circuit, the use of such integrated circuit capacitance can be extracted from the vertical sync signal field sync signal
● Differential The capacitor used in the differential circuit is called a differential capacitor. In the flip-flop circuit in order to obtain the spire trigger signal, this differential capacitor circuit is used to derive the spire trigger signal from various (mainly rectangular) signals. ● Compensation The capacitor used in the compensation circuit is called the compensation capacitor. In the bass compensation circuit of the deck, 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. ● Bootstrap The capacitor used in the bootstrap circuit is referred to as a bootstrap capacitor. The common 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 by positive feedback. ● Frequency Divide The capacitor in the frequency divider circuit is called the frequency divider capacitor. In the speaker frequency divider circuit of the speaker, the frequency divider capacitor circuit is used to make the high-frequency loudspeaker work in the high frequency range. The intermediate frequency loudspeaker works in the medium frequency range and the low frequency The speaker works in the low frequency range
● Load capacitance refers to the crystal resonator with the resonant load to determine the effective external capacitor capacitance. Commonly used load capacitance standard values ??are 16pF, 20pF, 30pF, 50pF and 100pF. Load capacitance can be adjusted according to the specific circumstances, by adjusting the resonator can be adjusted to the nominal operating frequency.