Here is a list of 16 Capacitors categories. It encompasses a wide range including monolithic ceramic capacitors, tantalum capacitors, electric double layer capacitors, trimmer capacitors, etc. You can search for an overview, principle, and usage of each category, as well as find manufacturers and distributors.
A capacitor is an electronic component that can store and release electricity. It consists of an insulator sandwiched between two metal plates facing each other. When voltage is applied to the capacitor, charge is transferred, but because the two metal plates are separated by an insulator, the charge that has nowhere else to go is stored in the metal plate. This allows the capacitor to function like a charged battery.
Although often confused with batteries in terms of storage and discharge, batteries basically convert electrical energy via chemical reactions, whereas capacitors can directly store electric charge without such a conversion process, and thus can repeat extremely fast charge and discharge.
Capacitors can be incorporated into power supply circuits and repeatedly charged and discharged to buffer rapid voltage changes and provide stable voltage application.
Capacitors also have the characteristic of allowing high-frequency alternating currents to pass through them easily, which can be used to eliminate noise, cut DC components, and play other roles as a filter.
There are various types of capacitors, each with different characteristics.
Ceramic capacitors use ceramic as the dielectric and are characterized by high heat resistance and excellent frequency characteristics, making them suitable for use in digital circuits. Ceramic capacitors are mainly made of metal oxides such as titanium dioxide. They are small in size and have excellent heat resistance, but also have the disadvantage of being easily broken.
Electrolytic capacitors use an electrolyte made of aluminum or other metals. Two metal surfaces are oxidized by chemical reaction. The oxide film does not conduct electricity, so it is used as an insulator. It is characterized by high capacitance, but if the positive and negative values are mistaken, there is a risk of heat generation.
A film capacitor uses plastic film as the dielectric. They are suitable for audio equipment, etc., because their capacitance fluctuates little due to temperature changes and can be controlled with a high degree of accuracy. In the case of DC power supply, it maintains high insulation, but in AC power supply, impedance varies with frequency through current. It is often used as a noise suppressor.
While other capacitors have a fixed capacitance, a variable capacitor can achieve various capacitances with a single capacitor. It is suitable for tuning circuits of receivers such as radios. There are various types of variable capacitors, such as those whose capacitance can be continuously changed by turning a knob, and those whose capacitance can be switched between multiple fixed capacitors with a switch.
When a dry cell battery is connected to a capacitor, the electrons on the metal plate on the positive pole side move to the positive pole of the dry cell battery, so the metal plate is charged positively. When the voltage between the metal plates becomes the same as the voltage of the dry cell, the electrons stop moving and an electric charge is stored on the metal plates. This storage of electric charge is called a capacitor, and the storage of electric charge on a metal plate is called charging.
Until the charge is stored and the movement of electrons stops, an electric current flows for a moment. In other words, when a DC power source is connected to a capacitor, current flows only at first, and then it stops flowing. When the dry cell is removed in this state, a charge is stored in the metal plate.
The charge stored in the capacitor is called capacitance and is represented by the symbol C and the unit F (farad). Capacitance is proportional to the area of the metal plates and the inductance of the inductance between the metals. It is inversely proportional to the distance between the metal plates.
When AC is applied to a capacitor, it continues to charge and discharge repeatedly. In a DC power supply, the current stops when the storage is completed, but in AC, the current continues to flow continuously.
This does not mean that current is passing between the metal plates, but it is apparently flowing. And the faster the current changes direction (the higher the frequency), the easier it is for the current to flow.
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