Features and Applications
Capacitors have various characteristics that make them widely used in circuits:
Charge and discharge characteristics: Capacitors can charge and discharge instantly, which makes them widely used in circuits that require fast response, such as camera flashlights, emergency backup power supplies, etc.
Communication passability: DC current does not pass through capacitors, but AC current does. This characteristic enables capacitors to play an important role in circuits such as filtering, coupling, and bypass.
Frequency characteristics: The blocking effect (capacitance) of capacitors on AC power is related to frequency. The higher the frequency, the smaller the capacitance and the easier it is to pass through. Therefore, capacitors are widely used in high-frequency circuits.
Types and structures
There are many types of capacitors, which can be divided into electrolytic capacitors, ceramic capacitors, polyester capacitors, polypropylene capacitors, etc. according to the different dielectric materials. Different types of capacitors have their own characteristics in structure, performance, and application:
Electrolytic capacitor: Using aluminum or other metals as the anode, an oxide film is formed on the surface of the anode as the dielectric, and the electrolyte serves as the cathode. Its characteristics are large capacity, but large leakage, large error, and poor stability of components. Commonly used as a communication bypass and Dharma wave.
Ceramic capacitors: electrodes are made by spraying silver layers on both sides of a ceramic substrate using ceramic as the dielectric. It has the advantages of small size, high temperature resistance, and low loss. Commonly used in high-frequency circuits.
Polyester capacitor: a non-polar capacitor made of polyester film as the dielectric. It has the advantages of positive temperature coefficient, temperature resistance, pressure resistance, moisture resistance, and low price. Commonly used in mid to low frequency circuits.
Polypropylene capacitor: a non-polar capacitor made of polypropylene film as the dielectric. Large capacity, low loss, consistent performance, and good insulation. Usually used as a starting capacitor in electric motors or low to medium frequency electronic circuits.