In a cycle of alternating current, due to the positive and negative charge of the capacitor, the direction of the current flowing through the circuit is changed, but because of the repeated charge and discharge of the capacitor, there is always a current through the circuit, which is equivalent to the capacitor can let the alternating current through, which is the on-off characteristics of the capacitor. Features of capacitors:
1, it has charge and discharge characteristics and prevent direct current flow through, allowing AC current through the ability.
2, in the process of charging and discharging, the charge on the two plates has an accumulation process, that is, the voltage has a process of establishment, therefore, the voltage on the capacitor cannot be mutated. Capacitor charging: the two plates respectively have an equal amount of dissimilar charge, and the absolute value of each plate with electricity is called the capacitor with electricity. Discharge of a capacitor: the positive and negative charges at the two ends of a capacitor are neutralized by a wire. There is a brief current generation on the guide line during discharge.
3, capacitors are inversely proportional to frequency and capacity. That is, when the capacitive reactance is analyzed, the frequency and capacity of the signal must be contacted. 1. 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. 2, 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. 3, decoupling: the capacitor used in the decoupling circuit is called the 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 cross-connection between each stage amplifier.
4, 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.
5, resonance: the capacitor used in the LC resonant circuit is called the resonant capacitor, and the capacitor circuit is needed in the LC parallel and series resonant circuit.