In electronic production, capacitors are an indispensable basic component. They are widely used in various circuits and play a variety of important roles. Capacitors, often referred to as "capacitors" and represented by the letter C, have a basic function of storing electric charge. There are many types of capacitors, but their common basic structure is that two pieces of metal (called plates) are separated by a substance (solid, gas, or liquid), which is called a medium. Capacitors are divided into two categories: fixed capacitors and variable capacitors according to whether their capacity is adjustable. Fixed capacitors are more common, such as electrolytic capacitors and ceramic capacitors.
The capacitance of a capacitor is expressed in farads (F), but due to the larger unit of farads, smaller units such as microfarads (μF), nanofarads (nF) and picofarads (pF) are more commonly used in practice. An important function of a capacitor is to allow alternating current to pass while blocking direct current. They are used in circuits to store and release charges and act as filters to smooth out pulsating signals. Small-capacity capacitors are often used in high-frequency circuits, such as radios, transmitters, and oscillators; while large-capacity capacitors are mostly used for filtering and storing charges.
Capacitors have a wide range of applications, especially electrolytic capacitors and ceramic capacitors. Generally speaking, capacitors with a capacity above 1μF are mostly electrolytic capacitors, while capacitors with a capacity below 1μF are mostly ceramic capacitors. The electrolytic capacitor has an aluminum shell, which is filled with electrolyte and has two positive and negative electrodes. Unlike other capacitors, their polarity cannot be connected incorrectly in the circuit.
Capacitors are widely used in electronic circuits. For example, capacitors are used in rectified power supplies to store electrical energy, which is then gradually released after the plug is unplugged, which is why the lights on some devices stay on for a while after power is removed. In HiFi sound systems, in order to ensure that the output voltage waveform is close to DC and has enough energy to be converted into strong audio output, large-capacity capacitors are often used for filtering.
In electronic circuit design, many factors need to be considered when selecting capacitors. The first is the voltage withstand capability of the capacitor. If the voltage across a capacitor exceeds its rated voltage, the capacitor may breakdown and be damaged. Electrolytic capacitors usually have multiple voltage levels, such as 6.3V, 10V, 16V, 25V, 50V, etc. Correct selection of capacitors suitable for circuit requirements not only helps ensure the safety of the circuit, but also improves the overall performance of the circuit.