Capacitor

Introduction:

A capacitor is an electronic component used to store electrical energy. It serves the purpose of temporarily storing charge in a circuit. A capacitor consists of two conductors (usually metal plates) separated by a layer of insulating material (dielectric). When a voltage is applied across a capacitor, an equal amount but opposite sign of charge accumulates on the conductor.

How capacitors work:

Capacitors work on the basis of electric fields. When a capacitor charges, an electric field is stored in the dielectric between the conductors. When a capacitor discharges, the electric field energy stored in the dielectric is released.

Basic parameters of capacitor:

Capacity: The ability of a capacitor to store energy, measured in farads (F). Commonly used small units are microfarad (μF), picofarad (pF) and nanofarad (nF).
Operating voltage: The maximum voltage at which a capacitor can operate safely.
Equivalent series resistance (ESR): An ideal capacitor has no resistance, but actual capacitors have a certain internal resistance due to materials and construction.
Leakage Current: Even without an external circuit connection, a capacitor will still discharge itself due to the tiny resistance of the internal conductor.
Temperature coefficient: The property of a capacitor's capacitance that changes with temperature.

Common types of capacitors:

Capacitors can be divided into many types according to their dielectric type. Common ones are:

Ceramic capacitors: Use ceramic materials as the dielectric, are usually small in size, and are suitable for use in high-frequency circuits.
Electrolytic Capacitor: A polarized capacitor in which one conductor is a metal film (anode) and the other conductor (cathode) is usually an electrolyte. They have relatively large capacities and are often used for energy storage in low-frequency circuits.
Film capacitor: uses plastic film as the dielectric, has stable characteristics, and is suitable for high-precision circuit design.
Tantalum capacitor: Using metallic tantalum as anode material, it is widely used in portable electronic products due to its high stability and small size.

Applications of capacitors:

Filtering: In power supply circuits, capacitors can smooth the output voltage and reduce noise.
Coupling: Used in signal processing circuits to block DC and transmit AC signals.
Bypass: Placed near the IC to provide fast power and reduce transient disturbances on the power line.
Energy storage: In situations where a large amount of instantaneous energy is required, such as a camera flash, capacitors can quickly release electrical energy.
Timer: Combined with a resistor, it can form a delay circuit or oscillation circuit.

Safety Precautions:

Polarity: Electrolytic capacitors usually have polarity, and incorrect connection to the power supply can cause damage or explosion.
Voltage: Do not exceed the maximum operating voltage of the capacitor to avoid damaging the dielectric and causing a short circuit.
Discharge: Large-capacity capacitors should be discharged before handling them to avoid the risk of electric shock.