The Role of Capacitors

    The basic function of capacitors is to charge and discharge, but many circuit phenomena extended by this basic charge and discharge function make capacitors have various uses, such as in electric motors, we use them to generate phase shift; In photography flash, it is used to generate high-energy instantaneous discharge, and so on; In electronic circuits, capacitors have a wide range of applications with different properties, and although they have distinct differences, their functions all come from charging and discharging. Here is a list of the functions of some capacitors:

    Coupling capacitance: The capacitance used in coupling circuits is called coupling capacitance, which is widely used in resistance capacitance coupling amplifiers and other capacitance coupling circuits to isolate direct current and AC.

    Filter capacitor: The capacitor used in the filter circuit is called a filter capacitor, which is used in power filtering and various filter circuits. The filter capacitor removes signals within a certain frequency band from the total signal.

    Decoupling capacitor, a capacitor used in a decoupling circuit called a decoupling capacitor, is used in the DC voltage supply circuit of a multi-stage amplifier. The decoupling capacitor eliminates harmful low-frequency interconnections between each stage of the amplifier.

    High frequency damping capacitor: The capacitor used in the high-frequency damping circuit is called the high-frequency damping capacitor. In the audio negative feedback amplifier, this capacitor circuit is used to eliminate the high-frequency self-excitation that may occur in the amplifier to eliminate high-frequency whistling.

    Resonant capacitor: The capacitor used in LC resonant circuits is called a resonant capacitor, which is required in both LC parallel and series resonant circuits.

    Bypass capacitor: The capacitor used in the bypass circuit is called a bypass capacitor. If a signal in a certain frequency band 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.

    Neutralizing capacitor: The capacitor used in a neutralizing circuit is called a neutralizing capacitor. In radio high-frequency and intermediate frequency amplifiers, as well as television high-frequency amplifiers, this neutralizing capacitor circuit is used to eliminate self-excitation.

    Timing capacitor: The capacitor used in a timing circuit is called a timing capacitor. In circuits that require time control through capacitor charging and discharging, a timing capacitor circuit is used, and the capacitor plays a role in controlling the size of the time constant.

    Integrating capacitor: The capacitor used in an integrating circuit is called an integrating capacitor. In the synchronous separation stage circuit of television field scanning, this integrated capacitor circuit is used to extract the field synchronization signal from the composite synchronization signal of the line field.

    Differential capacitor: The capacitor used in differential circuits is called a differential capacitor. In order to obtain the tip trigger signal in the trigger circuit, this differential capacitor circuit is used to obtain the tip pulse trigger signal from various (mainly rectangular pulse) signals.

    Compensation capacitor: The capacitor used in the compensation circuit is called a compensation capacitor. In the bass compensation circuit of the card holder, 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 capacitor: 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 slightly increase the positive half cycle amplitude of the signal through positive feedback.

    Frequency divider capacitor: The capacitor in the frequency divider circuit is called a frequency divider capacitor. In the speaker frequency divider circuit of the speaker, a frequency divider capacitor circuit is used to make the high-frequency speaker work in the high frequency range, the mid frequency speaker work in the mid frequency range, and the low-frequency speaker work in the low frequency range.

    Load capacitance: Refers to the effective external capacitance that, together with a quartz crystal resonator, determines the resonant frequency of the load. The commonly used standard values for load capacitors are 16pF, 2OpF, 3OpF, 5OpF, and 1OOpF. The load capacitance can be adjusted appropriately according to the specific situation, and by adjusting it, the working frequency of the resonator can generally be adjusted to the nominal value