3-Terminal Capacitor: A capacitor having a third terminal which connects to ground. A three terminal capacitor may be a through-hole with 3 leads or surface mount with 3 pads.
Read more on a 3 Terminal Capacitor.
4-Terminal Capacitor: A capacitor having four leads. An axial lead capacitor having both a positive and negative lead on each side of the capacitor. Note that both positive terminals are attached to the same plate of the capacitor and both negative terminals are attached to the same plate of the capacitor.
Tubular 4-Terminal Capacitor
Air Dielectric: A variable capacitor that uses air as its dielectric, only air separates the metal plates of the capacitor. Reference MIL-C-92 as an example of an air dielectric trimmer capacitor. A large panel mount variable capacitor is shown, but small Trimmer Capacitors are also possible.
Air Dielectric Capacitor
Aging: A term used to describe the negative, logarithmic capacitance change that takes place in ceramic capacitors with time [Shelf Life]. The more stable dielectrics have the lowest aging rates. The change in properties of a material with time. Class I capacitor do not age. There is a bit more data on the Capacitor Design Issues Page. Also see; Re-aging.
Capacitor Value Change with Time
Altitude: The vertical distance above sea level [or some other reference]. The maximum altitude of a circuit or capacitor needs to be accounted for during the design process. Refer to Capacitors at Altitude for more information.
Aluminum Electrolytic Capacitor: A polarized capacitor that uses Aluminum foil as the capacitor plates. The two conducting aluminum foils, one of which is coated with an insulating oxide layer, and a paper spacer soaked in electrolyte are rolled and placed inside a metal can. Electrolytic capacitors need to be installed in DC circuits such that the voltage applied to the leads always retain the same polarity; i.e. the positive pin always has a more positive potential than the negative side of the device. Aluminum electrolytic capacitors can also be manufactured for use in intermittent reversed voltage or a.c. applications by using two anode foils in place of one anode and one cathode foil. Refer to the Electrolytic Capacitor listing. [Manufacturers of Electrolytic Capacitors]
Aluminum Electrolytic Capacitor Diagram
Ambient temperature: Average or mean temperature of the medium (air, gas, liquid, etc.,) surrounding an object. For data sheet ratings the component specifications are provided for an ambient temperature of 250C.
Anode: Positive electrode of a capacitor. The electrode through which a direct current enters a discrete part of an electrical circuit. The longer lead of a polarized capacitor.
Arcover Voltage: The minimum voltage required to create an arc between electrodes separated by an insulation.
Array: A capacitor Array is a group of capacitors contained within the same package. In the case shown below four capacitors contained within an 8 pin Single In-Line Package [SIP]. A capacitor Array is similar to a capacitor network but do not connect to each other. An array contains capacitors which form no connections between any of the other components. Read more on capacitor networks [graphics and information].
Capacitor Array, 8-Pin SIP
Axial Leaded: Both leads of the component travel along the axis, one lead on either side of the component. An axial lead part is a through-hole component, as the leads of the device protrude through the Printed Wiring Board [PWB].