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The volt-ampere (SI symbol: VA, [1] sometimes V⋅A or V A) is the unit of measurement for apparent power in an electrical circuit. It is the product of the root mean square voltage (in volts) and the root mean square current (in amperes). [2] Volt-amperes are usually used for analyzing alternating current (AC) circuits.
In the power systems analysis field of electrical engineering, a per-unit system is the expression of system quantities as fractions of a defined base unit quantity. . Calculations are simplified because quantities expressed as per-unit do not change when they are referred from one side of a transformer to t
Normally this then goes to discrimination circuits or a multi channel analyzer. Further applications are in the readout circuitry of CCD imagers and flat-panel X-ray detector arrays. The amplifier is able to convert the very small charge stored within an in-pixel capacitor to a voltage level that can be easily processed.
A boost converter or step-up converter is a DC-to-DC converter that increases voltage, while decreasing current, from its input to its output . It is a class of switched-mode power supply (SMPS) containing at least two semiconductors, a diode and a transistor , and at least one energy storage element: a capacitor , inductor , or the two in ...
Some log amps may mirror negative input with positive input (even though the mathematical log function is only defined for positive numbers), and some may use electric current as input instead of voltage. Log amplifier circuits designed with operational amplifiers (opamps) use the exponential current–voltage relationship of a p–n junction ...
DC-to-DC converters are used in portable electronic devices such as cellular phones and laptop computers, which are supplied with power from batteries primarily. Such electronic devices often contain several sub-circuits, each with its own voltage level requirement different from that supplied by the battery or an external supply (sometimes higher or lower than the supply voltage).
One voltage cycle of a three-phase system, labeled 0 to 360° (2π radians) along the time axis. The plotted line represents the variation of instantaneous voltage (or current) with respect to time. This cycle repeats with a frequency that depends on the power system.
In electronics, it is common to refer to a circuit that is powered by a DC voltage source such as a battery or the output of a DC power supply as a DC circuit even though what is meant is that the circuit is DC powered. In a DC circuit, a power source (e.g. a battery, capacitor, etc.) has a positive and negative terminal, and likewise, the load ...