capacitor (redirected from Goldcap)

capacitor or condenser, device for the storage of electric charge. Simple capacitors consist of two plates made of an electrically conducting material (e.g., a metal) and separated by a nonconducting material or dielectric (e.g., glass, paraffin, mica, oil, paper, tantalum, or air). The Leyden jar is a simple capacitor. If an electrical potential (voltage) is applied to the plates of a capacitor (e.g., by connecting one plate to the positive and the other to the negative terminal of a storage battery), the plates will become charged, one positively and one negatively. If the externally applied voltage is then removed, the plates of the capacitor remain charged, and the presence of the electric charge induces an electrical potential between the plates. This phenomenon is called electrostatic induction. The capacity of the device for storing electric charge (i.e., its capacitance) can be increased by increasing the area of the plates, by decreasing their separation, or by changing the dielectric. The dielectric constant of a particular dielectric is the measure of the dielectric's unit capacitance. It describes the ratio of the capacitance of a dielectric-filled capacitor to a capacitor of the same size with a vacuum between the plates. Capacitors are used in many electrical and electronic devices. The main capacitor classifications are non-polarized (used for AC circuits) and polarized (used for DC circuits). Capacitors can also be classified as fixed or variable. One type of variable capacitor, formerly used in radio and television tuning circuits, consisted of two sets of semicircular plates, one fixed and the other mounted on a movable shaft. By rotating the shaft the area of overlap of the two plates increases or decreases, thus increasing or decreasing the capacitance. These devices have largely been replaced by frequency synthesizers and a special type of solid-state diode, known as a varactor, whose capacitance changes with the reverse-biased voltage across it.

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An electronic component that stores an electric charge and releases it when required. It comes in a huge variety of sizes and types for use in regulating power as well as for conditioning, smoothing and isolating signals. Capacitors are made from many different materials, and virtually every electrical and electronic system uses them.

Somewhat Like a Battery
Capacitors act like tiny storage batteries that charge and discharge rapidly. Made of two plates separated by a thin insulator or sometimes air, when one plate is charged negative and the other positive, a charge builds up and remains after the current is removed. When power is required, the circuit is switched to conduct current between the plates, and the charge is released. See ultracapacitor.

Many Applications
Big capacitors are used in computer power supplies. Tiny discrete ceramic and tantalum capacitors are built on the outside of the chip package or surround the chip on the motherboard. In signal processing, a capacitor and resistor smooth the spikes and sharp edges from a signal. In DRAM chips, capacitors are microscopic cells that hold the 0s and 1s (bits). Logic circuits, which are mostly transistors and resistors, may also contain capacitors. See tantalum capacitor and ferroelectric capacitor.

Capacitors

Silver Batteries

Looking like "silver cans," and acting like miniature storage batteries, capacitors are found on countless circuit boards such as this high-end display adapter. Wired between the power and ground planes, they quickly charge up when the computer is turned on. When more transistors switch simultaneously because the application demands extra processing, they are made to release their charge. (Image courtesy of NVIDIA Corporation.)

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(electronics)

capacitor - An electronic device that can store electrical charge. The charge stored Q in Coulombs is related to the capacitance C in Farads and the voltage V across the capacitor in Volts by Q = CV. The basis of a dynamic RAM cell is a capacitor. They are also used for power-supply smoothing (or "decoupling"). This is especially important in digital circuits where a digital device switching between states causes a sudden demand for current. Without sufficient local power supply decoupling, this current "spike" cannot be supplied directly from the power supply due to the inductance of the connectors and so will cause a sharp drop in the power supply voltage near the switching device. This can cause other devices to malfunction resulting in hard to trace glitches.