Electronics Glossary – R
Distributors of Commercial, Industrial, Medical, Automotive, and Hi-Rel Electronic Components
| Term | Definition |
|---|---|
| R | Symbol used to denote resistance in ohms. |
| R1max | The maximum resistance of a PolySwitch device at room temperature one hour after being tripped or after reflow soldering. |
| RA Flux | Rosin-activated flux. |
| Ra max | Maximum functional resistance of device before and after defined stress tests. |
| Ra min | Minimum functional resistance of device before and after defined stress tests. |
| rack | A cabinet used to house components, which permits convenient removal of portions of the equipment for repair or examination. Original racks were standardized steel frames for 19-in. relay panels in telephone exchanges. Today, racks vary in size and shape to meet the specialized requirements of aircraft, computer, military electronics, and test equipment manufacturers. Racks accept equipment packages sometimes referred to as “bins,” “modules,” and “black boxes.” |
| rack and panel connector | Mating connectors of which one – usually the plug – is mounted inside a cabinet (rack). The receptacle is attached to the back of a sliding drawer, and mates with the plug when the drawer is fully inserted. |
| Radiated Frequency | The frequency of a signal that is transmitted by a radio, radar, navigational aid, or other radio frequency equipment. Radiated frequency is abbreviated as “RF.” |
| Radiation Crosslinking | The act of crosslinking a material with ionizing radiation. (Most Raychem products are radiation crosslinked, with an electron beam as the form of ionizing radiation.) See also Crosslinking by Irradiation. |
| Radio | A collection of circuits that converts electromagnetic energy gathered from free space to electrical or sound energy, vice versa or both. |
| Radio Frequency | Any electromagnetic frequency from a few hertz up to frequencies in the infrared portion of the spectrum, to approximately 300 THz (terahertz). |
| RADSL | Rate-Adaptive Digital Subscriber Line. A simple extension of ADSL to encompass a wide variety of data rates depending on the line’s transmission capability. RADSL can either CAP or DMT ADSL. |
| RAIM | Receiver Autonomous Integrity Monitoring |
| RAM | (random access memory). A storage arrangement from which information can be retrieved with a speed independent of its location in the storage. A core memory is a RAM, a magnetic tape memory is not. RAMs have read and write capabilities. |
| random-access memory | (RAM) A storage arrangement from which information can be retrieved with a speed independent of its location in the storage. A core memory is a RAM, a magnetic tape memory is not. RAMs have read and write capabilities. |
| Rated Current | The level of continuous DC current that can be passed through the inductor. This DC current level is based on a maximum temperature rise of the inductor at the maximum rated ambient temperature. The rated current is related to the inductor’s ability to minimize the power losses in the winding by having a low DC resistance. It is also related to the inductor’s ability to dissipate this power loss in the windings. Thus, the rated current can be increased by reducing the DC resistance or increasing the inductor size. For low frequency current waveforms the RMS current can be substituted for the DC rated current. The rated current is not related to the magnetic properties of the inductor (Also see Incremental Current and Saturation Current) |
| Rated Temperature | The maximum temperature at which a component can operate for extended periods with acceptable changes in its basic properties. |
| Rated Voltage | The maximum voltage at which an electric component can operate for extended periods without undue degradation. |
| Ratio | The division of one quantity by another, thereby indicating their relative magnitudes and phase. |
| raw data | Data which has not been processed; may or may not be in machine-compatible form. |
| Raychem Product Number | RPN – A 10-digit number (such as 123456-4-001) assigned to every standard product and every product manufactured on a special manufacturing order (SMO). The first 6 digits represent the PCN (Product Control Number), followed by a 1-digit MOD Code, and finally a 3-digit suffix. See also MOD Code and SMO. |
| Rayleigh scattering | The scattering of light that results from small inhomogenei-ties in material density or composition. |
| RC filter | A filter made of resistor and capacitor |
| RC, RC circuit | Designation for any resistor-capacitor circuit. |
| Reactance | Frequency-dependent impedance that is capable of storing but not dissipating energy. Reactance can be capacitive or inductive. |
| read | To copy, usually from one form of storage to another, particularly from external or secondary storage to internal storage; to sense the meaning of arrangements of hardware; to sense the presence of information on a storage medium. |
| read out | (1) A term used with pc boards and pc connectors, meaning the ability to make contact with certain circuits. Example: A dual read out pc connector will permit two wires to be connected to any one circuit on the pc board. (2) The display of data as an output of a computing, storing, or decoding device. |
| read-only memory | ROM – A storage arrangement primarily for information retrieval. |
| real-time operation | Solving problems as fast as they occur so that the results can be used to guide the operation. |
| Rear Release Contacts | Connector contacts designed to be released and removed from the rear (wire side) of the connector. The removal tool engages the contact from the rear and pulls the contact out of the connector contact retainer. |
| Receiver Protector | A circuit or device that prevents incident high power, potentially-damaging signals from propagating to sensitive receiver components. |
| Receiver Sensitivity | The minimum received signal power level for which a receiver can produce a discernible output signal. The following equation for the sensitivity of a receiver shows the parameters that affect a receiving system’s sensitivity |
| Receptacle | Usually the fixed or stationary half of a two-piece multiple contact connector. Also the connector half usually mounted on a panel and containing socket contacts. In coaxial rf connectors the receptacle is usually the fixed or stationary one that is mounted on a panel. In shell type multiple-contact connectors the receptacle usually contains the pin contacts and is mounted on the “cold” side of the circuit such as in a drawer or “black box.” Receptacles mate with plugs. |
| record | A line of information under a collection of fields. |
| Recover (Heat-shrinkable Components) | Activation of the elastic memory principle (usually with heat) to cause a tubing or molded part to return to its original size. |
| Recovered ID | RID – In heat-shrink tubing, the guaranteed maximum internal diameter of tubing after being freely recovered. |
| Recovery Temperature | The minimum temperature required to fully shrink a product, that is, for the product to recover completely. |
| Recovery Time | The time interval required, after a sudden decrease in input signal amplitude to a system or transducer, to attain a stated percentage (usually 63 percent) of the ultimate change in amplification or attenuation due to this decrease. |
| rectification | The process of converting alternating current into a unidirectional current, by removing or inverting that part of the wave laying on one side of the zero amplitude axis. There are two general types of retificitaion processes, half-wave and full-wave. |
| Rectifier | Device that allows current to flow in only one direction, such as a diode. |
| redundancy | Any deliberate duplication, or partial duplication, of circuitry or information to decrease the probability of a system or communication failure. |
| Reduntant Operation | Parallel configuration of converters used in distributed power system to increase system reliabiltiy. Converters may be used in a “N 1” architucture. |
| reflection | The backward transmission of electrical energy caused by a change in impedance. |
| Reflection Coefficient | At a specified plane in a uniform transmission line, the vector ratio of the reflected to the incident waves. The symbol for reflection coefficient is “G”. |
| reflection coefficient | The fraction of light power reflected backward at the fiber end face. This accounts for about a .2 to .3 dB loss, typically. |
| Reflection Loss | The part of transmission loss due to power reflected by a discontinuity (impedance mismatch) in a transmission line. |
| reflective codes | Codes which appear to be the mirror image of normal counting codes. |
| refractive index | (n) The ratio of the speed of light in a vacuum (c) to the speed of light in an alternate medium(v). n=c/v |
| Regenerative repeater | A repeater designed for digital transmission that bothamplifies and reshapes the signal. |
| Regional Bell Operating Companies | RBOC – Seven LEC telephone companies created after AT&T divestiture. |
| register | A memory device capable of containing one or more computer bits or words. |
| register mark | A mark used to establish the relative position of one or more printed wiring patterns, or portions thereof, with respect to their desired locations on one or both sides of a printed wiring base. |
| Regulation | Ability of a converter to maintain an output voltge to within specified limits under varying conditions of input line and output load. Also see Linear Regulation. |
| relay | An electrical device that is designed to interpret input conditions in a prescribed manner, and – when specified conditions are met – to respond by causing contacts to operate, or similar abrupt changes in associated electric control circuits. Inputs are normally electric, but may be thermal, mechanical, or other qualities. Limit switches and other such simple devices are not to be considered as relays. A relay is an electrically operated switch. |
| relay contact bounce | Undesired intermittent closure of open contacts or opening of closed contacts. This may occur either when the relay is operated or released, or when the relay is subjected to external shock or vibration. The term “bounce” is normally associated with internal causes. |
| Reliability | The probability that a device, component or system will perform adequately for the expected time under given conditions. |
| Remote LAN Access | A data communications such as a corporate or campus environment in which the computer networks can be accessed remotely via public telecommunications networks. |
| Remote Sensing | Using sense leads connected at the output load provides feedback to voltage regulation circuits of a converter. This arrangement is used to compenate for voltage losses from long leads to a load. Also see Local Sensing. |
| Remote Shutdown | See Logic Inhibit/Enable. |
| Removable Contact | A contact that can be mechanically joined to or removed from an insert. Usually special tools are required to lock the contact in place or remove it for repair or replacement. |
| Repeater | A device that receives, amplifies (and perhaps reshapes), and retransmits a signal. It is used to boost signal levels when the distance between repeaters is so great that the received signal would otherwise be too attenuated to be properly received. |
| Repetition Rate | The number of occurrences of an event per unit time. |
| reset | The operation of returning an electronic, or electrical, device to its original or “start” point. Most AMP data terminals offer manual reset, automatic reset, or both. |
| Residual Flux | The flux that remains in a core when the applied MMF is returned to zero. |
| Residual FM | Undesirable, apparent frequency modulation of a signal source caused by noise or spurious signals. |
| residual forces | The elastic forces which remain after each contact member has been deformed or deflected to its final state. |
| resiliency | That property of a strained body which enables it to recover its size and shape as it is unloaded after some initial deformation. |
| resist | A material such as ink, paint, metallic plating, etc used to protect the desired portions of the conductive pattern from the action of the etchant, solder, or plating. |
| Resistance | (1) The frequency-invariant opposition to current flow, abbreviated as “R.” The unit of resistance is the ohm (Ω). (2) The resistance of a PolySwitch device under specified conditions (e.g., 20¡C), before connection into a circuit. Devices of a particular type will be delivered with a range of resistances; therefore, a minimum value, Rmin, and/or a maximum value, Rmax, are often given. |
| Resistance bias | A situation where the positive and negative leads of a DC power supply (or hot and neutral leads for an AC power supply) are erroneously reversed and would cause current to flow in the wrong direction. |
| Resistance Binned Devices | Resistance binned devices are supplied such that all parts in one package are within 0.5 ? of each other. Individual binned packages are supplied from the full resistance limits of the specified product. |
| Resistance Sorted Devices | Resistance sorted devices (part number suffix ‘Rx’) are supplied with resistance values that are within specified limits of the product’s full range of resistance. |
| resistor | A circuit component which offers resistance to the flow of electric current. Its electrical size is specified in ohms or megohms (1 megohm = 1,000,000 ohms). A resistor also has a powerhandling rating measured in watts, which indicates the amount of power which can safely be dissipated as heat by the resistor. |
| resonance | The frequency at which capacitive reactance and inductive reactance are equal and therefore cancel one another’s effects. |
| Resonant Converter | Switching converter technology in which a resonant tank circuit operating at very high frequencies is used to transfer energy to the output. |
| Resonant Frequency | The frequency at which the inductive and capacitive reactances of a circuit are equal in magnitude, thereby canceling each other’s effects. The symbol for resonant frequency is “fR.” |
| Responsivity | The ratio of a photodetector I s electrical output to its optical input in amperes/watt. |
| restricted entry | A design feature incorporated in a female contact to prevent the entry of an oversize pin or test probe. |
| retaining ring | A small circular steel ring, often resembling the letter “C,” that is usually inserted into a slot in a pivot pin to hold the pin in a specified position. |
| retaining spring | Used to balance contact pressure and increase board retention when a single-sided pc board is used in a connector designed for two-sided boards. A limited number of springs are used to replace the contacts in the unused side of the connector. |
| RETMA | Abbreviation for Radio-Electronics-Television Manufacturers’ Association. Now changed to Electronics Industries Association (EIA). |
| Return | Common terminal on the output of a DC-DC converter. It is the return current path for the output. Also see Common. |
| Return loss | A measure of the signal reflected back toward the transmitter as a result of impedance variations in the cabling system. |
| Return reflection | Reflected optical energy that propagates backward to the source in an optical fiber. |
| Return reflection loss | The attenuation of reflected light; high return loss is desirable, especially in single-mode fibers. |
| Reverse Current | Current flowing from input to output or input to case of an isolated converter at a specified voltage level. |
| Reverse Voltage Protection | Converter feature that prevents damage to internal components if a reverse voltage is inadvertently applied to the input or ouput terminals. |
| Reversible Temperature Coefficient | Changes in flux which occurs with temperature change. They are spontaneously regained when the temperature is returned to its original point. There are two values reported: reversible temperature coefficients of inductance (Br) and Coercivity (Hci). The temperature range over which they have been measured and specified should be stated. Most materials exhibit a non-linear response with temperature. |
| Rex Univariable Whisker Press | A machine invented at Microwave Associates (predecessor of M/A-COM) to form and manufacture the precise, sharply pointed whiskers that were required for point contact diodes. |
| RF | Radiated Frequency. Also used as an abbreviation for Radio Frequency, used as a noun or adjective. |
| RF Frequency | The frequency in the portion of the electromagnetic spectrum that is loosely considered to be between above the audio-frequency portion and the infrared portion. It is normally 20 kHz to hundreds of GHz. |
| RF Impedance | The impedance of a circuit or component at high frequencies. |
| RFI | RFI is an acronym for Radio-Frequency Interference. It is an older and more restrictive term that is used interchangeably with EMI (Also see EMI.) |
| RFP | request for proposal |
| RG/U | RG/U is used to designate coaxial cables that are made to a Government specification. In the case of RG58/U, the “R” means RADIO FREQUENCY, the “G” means GOVERNMENT, the 58 is the number assigned to Government approval, and the “U” means it’s a UNIVERSAL specification. |
| rib | Configuration designed into a plastic part to provide lateral, horizontal, or other structural support. |
| Ribbon Cable | Flat cable with conductors that have been individually insulated together. Its structure is usually characterized by individual colors of insulation for each conductor, although a single color may be used for all conductors. |
| ribbon cable | Round conductor flat cable. A form of flexible flat cable (ffc) consisting of parallel round conductors in a flexible insulating material and designed for mass termination. |
| RID | Recovered Inside Diameter |
| right-angle edge connector | The plug is mounted to a chassis or back panel, and the receptacle is mounted along an edge of – and soldered to – the circuits of a printed circuit board. Pins of the receptacle are generally simple rod stock bent at right angles and molded into the receptacle insert. The board and receptacle assembly is mated with the plug to complete circuit wiring. |
| ring counter | A loop or ring of “counter” stages, so interconnected that only one stage is “on” at any given time. An input trigger pulse causes the “on” state to move to the adjacent stage. Thus, the “on” state moves around the loop. |
| Ring network | A network topology in which terminals are connected in a point-to-point serial fashion in an unbroken circular configuration. |
| Ripple | Variation in magnitude |
| Ripple and Noise | Periodic and Random Deviation – Noise and ripple voltage superimposed on a converter’s DC output. Typically specified at full load, it is expressed in peak-to-peak or RMS volts over a given bandwidth. |
| Ripple Voltage | The periodic alternating voltage imposed on the voltage output of a switching voltage converter. The ripple voltage is normally specified as a peak-to-peak value. |
| rise time | The time required for a component, or logic circuit, to change from the quiescent to the transient state, when an input is applied (ie elapsed time between application of input and attainment of full output level). |
| Riser | Backbone cabling connecting telecom closets situated vertically on separate floors. |
| RJ11 | A wiring pattern for 6-position modular jacks.Used to refer to the jacks themselves. |
| RJ21 | A wiring pattern for a 25-pair (AMP CHAMP) connector.Also used to refer to the connectors themselves. |
| RJ45 | A wiring pattern for8-position modular jacks.Used to refer to the jacks themselves. |
| RMA Flux | Rosin-mildly-activated flux. |
| Rmax | The resistance of a PolySwitch device under specified conditions (e.g., 20¡C), before connection into a circuit. Devices of a particular type will be delivered with a range of resistances; therefore, a minimum value, Rmin, and/or a maximum value, Rmax, are often given. |
| RMC | An NMEA message |
| Rmin | The resistance of a PolySwitch device under specified conditions (e.g., 20¡C), before connection into a circuit. Devices of a particular type will be delivered with a range of resistances; therefore, a minimum value, Rmin, and/or a maximum value, Rmax, are often given. |
| rms | Root Mean Square – The effective value of an alternating current, corresponding to the direct current value that will produce the same heating effect. |
| robotics | The theory and application of robots, a completely self-contained electronic, electric, or mechanical device, to such activities as manufacturing. |
| roentgen | The amount of radiation that will produce one electrostatic unit of ions per cubic centimeter volume. |
| ROM | Read-only memory. A memory, usually a semiconductor chip, in which the information is permanently stored. ROMs offer random-access read capabilities. May be programmed during manufacture or by the user. Some are reprogrammable. See PROM and EPROM. |
| root mean square | RMS – The effective value of an alternating current, corresponding to the direct current value that will produce the same heating effect. |
| Rope Lay | A type of conductor lay that uses stranded conductors as components to build a larger conductor. |
| rotary switch | A multiposition switch operated by rotating a control knob (attached to its shaft) either clockwise, counterclockwise, or both. |
| rotor | The rotating member of a motor that includes a shaft. Commonly called the armature. |
| routine | A series of computer instructions for performing a specific, limited task. |
| Royer Converter | Self-oscillating, push-pull switching circuit configuration commonly used in low cost, low power DC-DC converters. Also called the classical converter. |
| RPN | Raychem Product Number – A 10-digit number (such as 123456-4-001) assigned to every standard product and every product manufactured on a special manufacturing order (SMO). The first 6 digits represent the PCN (Product Control Number), followed by a 1-digit MOD Code, and finally a 3-digit suffix. See also MOD Code and SMO. |
| RS 232, 422, 449 A2043 | A series of standards defining the physical link between units of data communication equipment. |
| RT and RW specifications | Specification that describes standard product properties. Qualification and acceptance inspection criteria are incorporated into RT and RW specifications. RT and RW specifications are issued and controlled by the Specifications Group. |
| RTCA | Radio Technical Commission for Aeronautics (For WAAS & EGNOS services) |
| RTCM | Radio Technical Commission For Maritime Services (Special Committee 104 – A committee created for the purposes of establishing standards and guidance for interfacing between radio beacon-based data links and GPS receivers, and to provide standards for ground-based differential GPS stations. ) |
| RTK | Realtime Kinematic |
| rubber | An elastomer capable of rapid elastic recovery. Specifically, natural rubber, the standard of comparison for elastomers. |
| RZ data rates | Return to zero. A data transmission format in which the circuit must switch from 0 to 1 and back to 0 in a single clock pulse each time a logical 1 is presented. RZ rates are generally half those of NRZ rates. See also NRZ data rates. |