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saturation
Condition in which a further increase in one variable produces no further increase in the resultant effect. In a bipolar junction transistor, the condition when the emitter to collector voltage is less than the emitter to base voltage. This condition puts forward bias on the base to collector junction.

sawtooth wave
Repeating waveform that rises from zero to maximum value linearly drops back to zero and repeats. A ramp waveform.

scale
Set of markings used for measurement.

schematic diagram
Illustration of an electrical or electronic circuit with the components represented by their symbols.

Schmitt trigger
Circuit to convert a given waveform to a square wave output.

Schottky diode
High speed diode that has very little junction capacitance. Also known as a "hot-carrier diode" or a "surface-barrier diode."

scientific notation
Numbers entered as a number from one to ten multiplied by a power of ten. Example: 8765 = 8.765 × 103.

secondary
Output winding of a transformer. Winding that is connected to a load.

secondary cell
Electrolytic cell used to store electricity. Once discharged may be restored by recharging by putting current through the cell in the direction opposite to that of discharge current.

selectivity
Charistic of a circuit to discriminate between wanted and unwanted signals.

self biasing
Gate bias for a field effect transistor in which source current through a resistor produces the voltage for gate to source bias.

self inductance
Property that causes a counterelectromotive force to be produced in a conductor when the magnetic field expands or collapses with a change of current.

semiconductor
An element which is neither a good conductor or a good insulator, but rather lies somewhere between the two. Characterized by a valence shell containing four electrons. Silicon, germanium and carbon are the semiconductors most frequently used in electronics.

series circuit
Circuit in which the components are connected end to end so that current has only one path to follow through the circuit.

series parallel network
Network that contains components connected in both series and parallel.

series resonance
Condition that occurs in a series LC circuit at the frequency where inductive reactance equals capacitive reactance. Impedance is minmum, current is maximum limited only by resistance in the circuit.

seven segment display
Device made of several light emitting diodes arranged in a numeric or alphanumeric pattern. By lighting selected segments numeric or alphabet characters can be displayed.

shells or bands
Orbital path containing a group of electrons having a common energy level.

shield
Metal grounded cover used to protect a wire, component or piece of equipment from stray magnetic and/or electric fields.

short circuit
Also called a short. Low resistance conection between two points in a circuit typically causing excessive current.

shunt resistor
Resistor connected in parallel or in shunt with another component or circuit.

signal
Electrical quantity that conveys information.

signal to noise ratio
Ratio of the magnitude of the signal to the magnitude of noise usually expressed in decibels.

silicon
(Si) Non metalic element (atomic number 14) used in pure form as a semiconductor.

silicon-controlled rectifier
(SCR) Three terminal active device that acts as a gated diode. The gate terminal is used to turn the device on allowing current to pass from cathode to anode.

silicon controlled switch
An SCR with an added terminal called an anode gate. A positive pulse either at the anode gate or the cathode gate will turn the device on.

silicon dioxide
Glass like material used as the gate insulating material in a MOSFET.

silicon transistor
A bipolar junction transistor using silicon as the semiconducting material.

silver
(Ag) Precious metal that does not easily corrode and is more conductive than copper.

silver mica capacitor
Mica capacitor with silver deposited directly onto the mica sheets instead of using conductive metal foil.

silver solder
Solder composed of silver, copper and zinc. Has a melting point lower than pure silver, but higher than lead-tin solder.

simplex
Communication in only one direction at a time. Example: FAX.

simulcast
Broadcasting a program simultaneously in two different forms, for example a program broadcast in both AM and FM.

sine
Sine of an angle of a right angle triangle is equal to the opposite side divided by the hypotenuse.

sine wave
Wave whose amplitude is the sine of a linear function of time. It is plotted on a graph that plots amplitude against time or radial degrees relative to the angular rotation of an alternator.

single in-line package
Package containing several electronic components (generally resistors) with a single row of connecting pins.

single pole double throw
(SPDT) Three terminal switch in which one terminal can be connected to either one of the other terminals.

single pole single throw
(SPST) Two terminal switch or relay thet can open or close one circuit.

single sideband
(SSB) AM radio communication technique in which the transmitter suppresses one sideband and therefore transmits only a single sideband.

single throw switch
Switch containing only one set of contacts which can be either opened or closed.

sink
Device such as a load that consumes power or conducts away heat.

sintering
Process of bonding either a metal or powder by cold pressing it into a desired shape and then heating to form a strong cohesive body.
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