Electronic Engineering Dictionary

Excess-3 Code. Text is in review. For a functional diagram refer to the Excess-3 to Decimal Decoder Schematic.

Excitation Voltage. The supply voltage required to activate a circuit.

Exciting Current. The current that flows in the primary winding of a transformer when the secondary is open-circuited; it produces a magnetic flux field. Also called magnetizing current.

Exclusive OR. A function whose output is a 1 if one and only one of the input variables is a 1.

Exclusive-OR Gate. A gate that produces a logic 1 output when the inputs are different, but not when they are the same. Symbol and Truth Table below right. Standard Exclusive-OR gates include 7486, 74136, 741086 ICs. CMOS Exclusive-OR logic gates include 4030 and 4070 ICs. Glue Logic Vendors.

Exclusive-NOR Gate. A gate that produces a logic 0 output when the inputs are different, but not when they are the same. Symbol and Truth Table below right. Standard Exclusive-NOR gates include 74266 ICs. CMOS Exclusive-NOR logic gates include 4077 ICs. Glue Logic Vendors.

Expansion Slot. A card-edge style connector on a PC mother board which allows add-on cards to be plugged into the motherboard to add capability to the system. Interfaces currently being used on an expansion slot include the PCIe and PCI buses.

Expansion Card. A printed circuit board assembly that plugs into an expansion slot connector on a PC mother board which than expands the functionality of the personal computer.

Exponent. The numeral written in superscript (10²) which indicates the power to which the base is to be raised. Also refer to SI Prefixes.

Expression. A validated series of variables, constants, and functions that can be connected by operating symbols to describe a desired computation.

Externally Excited Meter. A term used to describe meters that get their power from the circuit to which they are connected.

Extremely High Frequency. The band of frequencies from 30 gigahertz to 300 gigahertz. Table of Frequency Bands

Extremely Low Frequency. The band of frequencies up to 300 hertz.

Extension Cord. A flexible power cord with an AC plug on one end that extends power out some distance and having one or more sockets on the far end.

AC Extension Cord

Extrinsic. A semiconductor in which impurities have been added to create certain charge carrier concentrations.

Eye Pattern. An oscilloscope display in which a pseudorandom digital data signal from a receiver is repetitively sampled and applied to the vertical input, while the data rate is used to trigger the horizontal sweep. The pattern that results from the superpositioning of ones and zeros in a data sequence, when the time base of the oscilloscope is synchronized to the bit rate clock.

Eye Diagram. A display on an oscilloscope or some other display that shows a repeating pattern over top one another so the variation in time of arrival can be ascertained. The resulting opening or the eye [shaded square] between the overlayed waveforms determines time between pulses, or the free space between transmitted pulses. See Intersymbol Interference.