Engineering Dictionary of Electronic Terms
"A" "B" "C", "D", "E", "F", "G", "H", "I", "J", "K", "L", "M",
"N", "O", "P", "Q", "R", "S", "T", "U", "V", "W", "X", "Y", "Z"

"R" to "Rad", "Rai" to "Rea", "Rec" to "Relat",
"Relay" to "Resol", "Reson" to "Rh", "Ri" to "Rm", "Ro" to "Rz"

RAID. See Redundant Array of Inexpensive Disks.

Rail Splitter. An integrated circuit that provides a precision virtual ground whose output voltage is always equal to one-half the input voltage. Vo = Vi/2. A TLE2426 IC.

Rail-to-Rail. An active circuit that switches within a few tenth of a volt to the supply rails [Vcc, Vdd].

Rainproof. So constructed, projected, or treated as to prevent rain from interfering with the successful operation of the apparatus under specified test conditions.

Raintight. So constructed or protected that exposure to a beating rain will not result in the entrance of water.

Raised-Cosine Filter. A type of Low-Pass Filter.

Random Access Memory. [RAM] A read/write, non-sequential access memory used for the storage of instructions and data. Companies making Volatile Memory ICs. A memory chip that allows any data to be stored and retrieved randomly, directly and individually.

Random Error. A error that does not occur with any certainty. An error that does not always occur given the same conditions.

Random Noise. Background noise. Noise consisting of a large number of transient disturbances with a statistically random time distribution. Circuit noise generated by the random movement of electrons. Ground noise. A signal whose instantaneous amplitude is determined at random is unpredictable, and has a continuous frequency spectrum.

Random Number Generator. A circuit or device that produces a random number, or a number that appears to be random number under given conditions.

Randomize. The process of converting a regulator signal into a random signal.

Range. The length of a straight line between a radar transmitter and a target. [Radar Terms]

Range Marker. A movable vertical pulse on an A-scope [switches to the Radar Dictionary] or a ring on a PPI scope used to measure the range of an echo or to calibrate the range scale.

Ranges. The several upper limits a meter will measure as selectable by a switch or by jacks; for example, a voltmeter may have ranges of 1 volt, 2.5 volts, 10 volts, 25 volts, and 100 volts.

Rarefied Wave. A longitudinal wave that has been expanded or rarefied (made less dense) as it moves away from the source.

Rated Output Power. That power available at a specified output of a device under specified conditions of operation.

Rated Voltage. The maximum voltage at which an electric component can operate for extended periods without undue degradation or safety hazard.

Rate Gyro. A gyro used to detect and measure angular rates of change.

Rating. The nominal value of any electrical, thermal, mechanical, or environmental quantity assigned to define the operating conditions under which a component, machine, apparatus, or electronic device is expected to give satisfactory service.

Ratio. The value obtained when one number is divided by another. This value indicates the relative proportions of the two numbers.

Ratio Detector. A detector that uses a double-tuned transformer to convert the instantaneous frequency variations of the FM input signal to instantaneous amplitude variations.

Ratio of Transmitted Powers. The power ratio (FSK versus AM) that expresses the overall improvement of FSK transmission when compared to AM under rapid-fading and high-noise conditions.

Raw Data Rate. The actual or true signally rate of the data, not the message rate or throughput which would also include overhead and account for the complete time required to receive all the data [information and signaling].

RC Amplifier. A term that describes an amplifier that is coupled to another amplifier or circuit using a resistor and capacitor, as opposed to direct coupled or capacitor coupled.

RC Constant. Time constant of a resistor-capacitor circuit; equal in seconds to the resistance value in ohms multiplied by the capacitance value in farads. [RC Voltage Graph]

RC Coupled Amplifier. Two or more amplifier stages that are interconnected by resistors and capacitors. The capacitor is almost always used to block DC voltages between stages and is normally call AC coupling. The resistors are used to adjust the AC impedance between the stages or to bias the individual amplifiers. A two stage RC coupled transistor amplifier is shown to the right.

RC Differentiator. A series RC circuit in which the output is taken from the resistor. The Fall Time and output shape is determined by the values of R & C and the period of the square wave.

RC Differentiating Circuit
RC Differentiating Circuit

Read more on how the RC Differentiator Circuit functions.

RC Filter. A filter used in applications where load current is low and constant, and voltage regulation is not necessary. An RC filter is comprised of some number of Resistors and Capacitors. Also refer to the entry on Passive Filters.

RC Integrator. An RC circuit in which the output is taken from the capacitor and represents the integration [RC Time Constant] of the amplitude of the input voltage.

RC Integrating Circuit
RC Integrating Circuit

RC Network. A circuit containing resistance and capacitance arranged in a particular manner to perform a specific function.

RC Oscillator. An oscillator in which the frequency is determined by resistive and capacitive elements. [Oscillator Manufacturers]

Reactance. [X] The opposition offered to the flow of an alternating current by the inductance [XL], capacitance [XC], or both, in any circuit. That part of the total impedance that does not include pure resistance. The imaginary part of the total complex impedance formula; Z = R + jX. The reactance of a capacitor decreases with frequency, while the reactance of an inductor increases with frequency.

Reactance Amplifier. A low-noise amplifier that uses a nonlinear variable reactance as the active element instead of a variable resistance. Also called a parametric amplifier.

Reactance Tube. A tube connected in parallel with the tank circuit of an oscillator. Provides a signal that will either lag or lead the signal produced by the tank.

Reactance-Tube Modulator. An FM modulator that uses a reactance tube in parallel with the oscillator tank circuit.

Reactive Load. A load that causes the current and voltage to become out of phase.

Read Only Memory. [ROM]. A type of Non-Volatile Memory. A memory in which data, under normal conditions, can only be read.

Ready-for-Data Signal. A call-control signal that is transmitted by the data circuit-terminating equipment (DCE) to the data terminal equipment (DTE) to indicate that the connection is available for data transfer between both DTEs. One half of a Handshaking Protocol used to indicate that the sending side may place new data on the data bus.

Real-Time Clock. A clock that produces the actual time, instead of an elapsed time from some arbitrary starting point. Also refer to Timer IC Manufacturers.

 
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