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Capacitor

Capacitors are storage devices that store electrical energy on an electrode surface. Capacitors are one of the three basic electronic elements along with resistors and inductors that make up all passive electrical circuits. A capacitor is used to store electrical charge or electrical energy. A capacitor can also function as a filter by passing alternating current (AC) while blocking direct current (DC). Capacitors also can serve as a source of instantaneous released energy, or to prevent current and voltage transients across batteries. Electric circuits usually utilize a great number and various type of capacitors, especially the circuits associated with frequency domain signal or AC signals power supply device and filtering circuits. Typically, a capacitor comprises two electrode plates facing each other, with an insulating dielectric between the plates. Capacitors have two main types, fixed and variable. A fixed capacitor has a pre-defined capacitance that is fixed during manufacturing. Variable capacitors do not have their capacitance fixed during manufacturing. These capacitors are designed so that they afford a range of capacitance values. A variable capacitor, referred to as a varactor, is one type of circuit element commonly used in RF and microwave circuits which include voltage-variable tuned circuits, voltage controlled oscillators, phase shifters, frequency multipliers, etc. There're various types of capacitors devided by the materials they use. Such capacitors include aluminum electrolytic capacitors, tantalum electrolytic capacitors, plastic film capacitors, paper capacitors, and ceramic capacitors. They are obtained by enclosing capacitor elements in capacitor enclosures made of a metal such as aluminum, brass, tantalum, silver or nickel, or a synthetic resin such as phenol resin, polypropylene resin, polyethylene resin polyphenylene sulfide resin, or polysulfone resin; or by coating by molding such capacitor elements with a synthetic resin such as epoxy resin or polyester resin. Electrolytic capacitors generally have a structure such that an anode foil and a cathode foil are together spirally wound via a separator, and placed and sealed in a casing. Electrolytic capacitors that use tantalum, aluminum, or another metal with a valve action can attain a large capacity with a small size and are therefore widely used in common practice. A typical aluminum electrolytic capacitor comprises a capacitor element having a positive electrode foil and a negative electrode foil separated by a separator and wound to a roll, a driving liquid electrolyte permeated into the capacitor element, and a metal case accommodating the capacitor element. A thin-film capacitor generally has a structure wherein a lower electrode, a dielectric layer, and a upper electrode are deposited on a substrate. A ceramic capacitor includes a chip-shaped sintered body and a pair of electrodes formed at two opposite sides thereof. In case of a multi-layer ceramic capacitor, the sintered body is generally made of alternately laminated dielectric layers and internal electrodes. Ultracapacitors, also called supercapacitors or electrochemical capacitors, can store several hundred times more energy per unit weight (gravimetric energy density) and volume (volumetric energy density) than traditional electrolytic capacitors. Ultracapacitors are attractive for high-voltage applications.

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Aluminum electrolytic capacitor Aluminum electrolytic capacitor (1)

Chip capacitor Chip capacitor (0)

Electrolytic capacitor Electrolytic capacitor (0)

High voltage capacitor High voltage capacitor (1)

Multilayer ceramic capacitor Multilayer ceramic capacitor (2)

Plastic capacitor Plastic capacitor (0)

Surface mount capacitor Surface mount capacitor (0)

Tantalum capacitor Tantalum capacitor (0)

Thin film capacitor Thin film capacitor (0)

Ultracapacitor (supercapacitor) Ultracapacitor (supercapacitor) (0)

Varactor Varactor (0)

Variable capacitor Variable capacitor (0)


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