Electronic Engineering Dictionary

Steady-State. A system condition reached after the response to a system upset. The normal operating condition of a circuit.

Steerable Antenna. An antenna having a main lobe that may be shifted in direction. For more information on antennas refer to the Dictionary of Antenna Terms.

Steering Diode. The application of a diode used to steer currents away from a protected line or component.

Normally a Steering Diode is used as a pair of diodes with one connected to Vcc and one connected to ground, so currents are steered to either Vcc or ground and away from a data line.

Step Attenuator. A variable attenuator which may be adjusted in steps [1dB, 5dB, 10dB, 20dB], and may be programmable or manual. Devices using toggle switches are the most common, but rotary step attenuators are available. A related page covers RF Attenuators.

Step-Down Transformer. A transformer that has a secondary voltage lower than the primary voltage. Also refer to a separate Dictionary of Transformer Terms

Stepper Motor. A motor that operates in discrete angular motions of uniform magnitude. [Stepper Motor Manufacturers]

Stepping Switch. A relay or switch that operates by rotating through 360 degrees in two or more discrete steps.

Step Recovery Diode. A charge-controlled switch which ceases current conduction so rapidly that it can be used to produce an impulse. Synonym; snap-off diode or charge-storage diode.

Step-Transmission System. A data transmission system that operates on direct current. It consists of a step transmitter (rotary switch) and a step motor interconnected to transmit data (information) between remote locations.

Step-Up Transformer. A transformer that Steps up the secondary voltage compared to the primary voltage. A transformer with a higher secondary voltage. Also refer to Transformers Definitions, or Manufacturers producing Step Up Transformers.

Stereo. Short for Stereophonic, basically sound that is reproduce in two or more channels. Example Op Amp Stereo amplifier circuit.

Stereo Jack. [Phono Jack] A male connector designed to handle two channels. There are many different sizes and styles of stereo jacks, one example. Audio Connectors.

Stick Magazine. A plastic tube used to ship and store integrated circuits and other small components. A shipping tube. The physical size and shape of the tube is changed depending on the component being shipped.

Stickoff Voltage. A low voltage used in multi-speed synchro-systems to prevent false synchronizations. Refer to synchro.

Stop-Band. The frequency band that is attenuated by a filter.

Storage Area Network. [SAN] A dedicated storage system accessible to a network.

Storage Life. The minimum length of time a component or device can remain in a non-operating condition before the performance characteristic of the device changes. Also see shelf life which is a the related term.

Storage Oscilloscope. A term applied to analog scopes that describes the ability for the screen display to persist for a certain length of time after the screen was written. An obsolete term, as all digital Oscilloscopes are by definition storage scopes.

Storage Temperature. The minimum or maximum temperature a device may be safely stored while not in use. Storage temperature is normally higher or lower than a devices operating temperature range. Storage temperature is a temperature at which the device may be stored without any power being applied.

Storage Time. An increase in time required to turn off a transistor after the device was driven into saturation.

Strain Gage. A resistive transducer that produces an output that is proportional to the amount the device is deformed.

Strain Relief. A connector device that prevents the disturbance of the contact and cable terminations. Strain Relief vendors.

Stranded Conductor. A conductor composed of a group of wires. The wires in a stranded conductor are usually twisted together and not insulated from each other.

Stranded Wire. See Stranded Conductor

Strands. Fine metallic filaments twisted together to form a single wire.

Stratosphere. Located between the troposphere and the ionosphere; it has little effect on radio waves.

Stratum Clock. A clock in a telecommunications system or network that is assigned a number that indicates its quality and position in the timing hierarchy. The highest quality clocks, called stratum 1 clocks, have a frequency offset of 1 x 10-11 or less, which means that they can keep time to within about one microsecond per day. stratum clocks specifications; ANSI standards T1.101-1999 and T1.105.09-1997.

Stray Capacitance. Any capacitance that is caused [normally unintended] by the proximity to two circuits or elements. Also Capacitive Coupling and Parasitic Capacitance.

Stripline. Traces routed in inner layers and have two reference planes. In a Printed Circuit Board [PCB] stack-up, striplines are on internal layers. Related definition Microstrip.

Strobe Pulse. A gating pulse used to enable a circuit for some length of time.

Stub. A short section of a transmission line used to match the impedance of a transmission line to an antenna. Can also be used to produce desired phase relationships between connected elements of an antenna. Related pages Terminating Traces, and Dictionary of PCB Terms. A short branch off a transmission line.

Stub Cable. A short section of cable used to branch off a main cable. A short cable assembly used as a branch from a main cable.

Subassembly. Consists of two or more parts that form a portion of an assembly or a unit.

Subcarrier. A carrier that was used to generate a modulated wave, and that wave is then used in the generation of another modulated wave.

Subharmonic. An exact submultiple of the fundamental frequency. Even sub-harmonics are one-half, one-quarter, and so on. Odd subharmonics are one-third, one-fifth, and so on of the fundamental frequency.

Subroutine. A section of code that is entered from a main routine, is executed, and than passes control back to the main routine or section of code.

Substrate. The supporting material upon or within which the elements of a microcircuit or integrated circuit are fabricated or attached. Mounting surface for integrated circuits. May be semiconductor or insulator material depending on type of IC. The material underneath the magnetic coating of a hard disk.

Sudden Ionospheric Disturbance. An irregular ionospheric disturbance that can totally blank out High-Frequency [HF] radio communications.

Summing Amplifier. A circuit that performs both a summing function and amplification. A Summing Op-Amp circuit. The summing circuit to the right may also be a Summing Amplifier depending on the value of Rf and Rn [the input resistors].

Summing Circuit. See Summing Network.

Summing Network. A combination of two or more parallel resistors used in servo-systems as an error detector. The output of the network is the algebraic sum of the inputs. The circuit example shows an Op Amp summing circuit [R1 to Rn].

Sum-of-Products. A product term of several product terms logically added together.

Sum Term. A single term or the sum of several variables.

Sunlight Readable. A display with an output which is visible under direct sunlight conditions when illuminated and hidden when not illuminated.

Superheterodyne: The process of translating a high frequency to a lower frequency.

Superheterodyne Receiver. A type of receiver that uses a mixer to convert an incoming RF signal into an IF signal for amplification. Read more about the Superheterodyne Receiver.

Superhigh Frequency. The band of frequencies from 3 gigahertz to 30 gigahertz.

Super-Multiplexing. A method of increasing channel capacity by multiplexing multi-levels.

Suppressed Carrier Transmission. Radio transmission in which the carrier is not transmitted, only one or both or both of the sidebands are transmitted.

Suppression. The process of eliminating an undesired portion of a signal.

Surface leakage. Undesired current flow along the surface of a material rather than through the bulk of the material.

Surface Wave. Radio waves that travel along the contours of the earth, thereby being highly attenuated.

Surge. The sudden change in voltage or current in a circuit. Surge current is a sudden change in line current to a user equipment that occurs during start-up or as a result of a change to the operating mode.

Surge Resistor. A small value resistor placed in series with a diode to limit the forward current through the diode, so the peak current rating of the diode is not exceeded.

Surge Suppressor. A 2-terminal device that will conduct in either direction once a specific voltage level is reached. A Transient Voltage Suppressor [TVS]. Two back-to-back diodes. A device used to protect equipment from a voltage spikes. Also refer to AC Surge Suppressor Devices, and UPS gear.

Surge Voltage. A large increase in voltage. See surge.

Susceptance. [B] The imaginary part of admittance and measured in siemens.

Suspension Insulator. A glass insulator used on power line suspension cables which supports the power cable. A graphic of different size glass suspension insulators is shown to the right.