Electronic Engineering Dictionary

Series Peaking. A technique used to improve high-frequency response in which a peaking coil is placed in series with the output signal path.

Series-Positive Limiter. A diode connected in series with the output, in which the output is taken across a resistor. It eliminates the positive alternation of the input wave.

Series Resistance Formula. Rt = R1 + R2 + R3 = R total.

Series-Resonant Circuit. A resonant circuit in which the source voltage is connected in series with a capacitor and an inductor (also in series) to furnish a low impedance at the frequency at which the circuit is resonant. The circuit to the right shows a variable capacitor [C] in series with an inductor [L] connected in series with the supply voltage [Vcc].

Series Voltage Regulator. A regulator with a regulating device that is in series with the load resistance. Voltage Regulator Manufacturers

Series-Wound Motors and Generators. Machines in which the armature and field windings are connected in series with each other.

Server. A computer attached to a network that provides a location for the shared storage of computer files. A computer or device that manages network resources. There are a number of types of servers; for instance, a network server manages network traffic. A network device that provides service to the network users by managing shared resources.

Servo. A short notation for Servomotor.

Servoamplifer. Either ac or dc amplifiers used in servosystems to build up signal strength. These amplifiers usually have relatively flat gain versus frequency response, minimum phase shift, low output impedance, and low noise level.

Servomotor. An ac or dc motor used in servo-systems to move a load to a desired position or at a desired speed. The ac motor is usually used to drive light loads at a constant speed, while the dc motor is used to drive heavy loads at varying speeds. Another name for a Error Reducer. Motor Manufacturers

Servosystem. An automatic feedback control system that compares a required condition (desired value, position, and so forth) with an actual condition and uses the difference to drive a control device to achieve the required condition.

Settling Time. The time required for an output to stabilize following an input which caused a change in the output.

Setup Time. The time required for the input data signal at a flip flop to be valid before the incoming clock edge arrives. The time interval between the application of a signal that is maintained at a specified input terminal and a consecutive active transition at another specified input terminal.

Shaping Circuit. A circuit that alters the shapes of input waveforms.

Sharp-Cutoff Tube. The opposite of a remote-cutoff tube. An electron tube that has evenly spaced grid wires. The amplification of the sharp-cutoff tube is limited by the bias voltage and tube characteristics.

Set-Reset Flip Flop. [SR Flip Flop] A type of flip flop that will go high [Set] or low [Reset] depending on the condition of the SR inputs. The outputs change on the clock line. A 4043 CMOS latch. A TTL 7471 R-S master-slave flip flop.

SR FF

Sheath. Of a communications or power cable, the outer covering or coverings of tough material, often plastic, that is resistant to environmental hazards such as abrasion, liquid intrusion, solar radiation, etc., and is used to protect cable component(s) such as optical fibers or metallic conductors that transport the signal or power.

Shelf Life. The period of time that a cell or battery may be stored and still be useful. Shelf Life applies to ICs, capacitors and other electronic devices. Related topics; Capacitor Aging. In general, electron tubes have an indefinite shelf life.

Shell. The outer covering of covering of a connector plug or receptacle that provides mechanical support. An operating system command interpreter, a software utility that reads an input specifying an operation, and that may perform, direct, or control the specified operation.

Shell Type Core. A transformer construction method in which the windings are wound [around a paper core] and than the metal shell is added around the windings. Read more on Shell Core Transformers, including a graphic, on the transformer definition page.

Shield. A housing, screen, sheath, or cover that substantially reduces the coupling of electric, magnetic, or electromagnetic fields into or out of circuits or transmission lines. A protective cover that prevents the accidental contact of objects or persons with parts or components operating at hazardous voltage levels.

Shielded Cable. Cable surrounded by a metallic covering intended to minimize the effects of electrical crosstalk interference or signal radiation. Device surrounding that portion of a connector that is used for attaching wires or cables to shield against electromagnetic interference, and/or protect connector wires or cable from mechanical damage. See Metal Braid, as used with cable.

Shielded Pair. A line consisting of parallel conductors separated from each other and surrounded by a solid dielectric. A 2-wire transmission line surrounded by a sheath of conductive material that protects it from the effects of external fields and confines fields produced within the line.

Shielded Twisted Pair. [STP] A cable consisting of parallel conductors separated from each other and surrounded by a solid dielectric, and twisted together. The number of times the two conductors are twisted together per inch varies with different cables. Shielded Twisted Pair cables are much more common than simple Shielded Pair cables. The diagram above shows a Shielded Twisted Pair cable. Refer to the main listing on Twisted Pair cable. A transmission line composed of a twisted 2-wire metallic transmission line surrounded by a sheath of conductive material that protects it from the effects of external fields and confines fields produced within the line.

Shielding. A metallic covering used to prevent magnetic or electromagnetic fields from affecting an object. Technique designed to minimize internal and external interference. Shielding is required in electrical and electronic equipments to prevent the equipment from propagating interference and to protect the equipment from the effects of interference propagated by other electrical and electronic devices. [EMI Shielding Techniques].

Shielding Bead. See Ferrite Bead. A surface mount inductor.

Shift Register. A digital register that is loaded either in a serial or parallel manner that shifts data from one storage location to another. A 74HC595 DIP IC is shown to the right, also see Shift Register ICs. A logic network comprised of flip flops connected in series. A digital delay network.

Shock Hazard. The potential of receiving a shock with a current of 5mA or greater [5mA being the current when a slight shock is felt].

Shock Rating. Measurement (in Gs) indicating how much shock a device or component can sustain before damage could occur. Also refer to MIL-STD-901 for shock testing.

Short. A low-resistance path between a live wire and the ground, or between wires at different voltages (called a fault if the current is unintended).

Short Circuit. An unintentional current path between two components in a circuit or between a component and ground; usually caused by a circuit malfunction. A circuit shall be considered short-circuited if doubling the magnitude of the terminating impedance does not produce a change in the parameter being measured that is greater than the specified accuracy of the measurement.

Short Circuited Line. A transmission line that has a terminating impedance equal to 0. Also refer to Continuity Testers [vendor listing].

Shot Noise. Noise generated by a charge crossing a potential barrier, common in transistors and Op amps at higher frequencies. Also called Schottky noise.

Shrouded Header. A board mount connector or Header with sides around the header pins to form a connector. Normally a Shrouded Header will be keyed so the incoming connector will only be inserted in one particular way.