18WuD2x

step-down ratio • stop amplifier 657
step-down ratio In a circuit or device, such as a
step-down transformer or cathode follower, the
ratio of the low output voltage to the high input
voltage. Compare STEP-UP RATIO.
step-down transformer A transformer delivering
an output voltage that is lower than the input
voltage. In such a transformer, the secondary
(output) winding contains fewer turns than the
primary (input) winding. Compare STEP-UP
TRANSFORMER.
step function See UNIT FUNCTION.
step generator 1. A signal generator that delivers
a step function (see UNIT FUNCTION). 2. A circuit
or device that generates a STAIR-STEP WAVE.
stepped leader The probing flow of electrons
through the atmosphere preceding a lightning
stroke. Once the path has been established, the
discharge takes occurs along the ionized path
determined by the stepped leader. It is so called
because the electrons move in hesitations,
jumping several meters with each advance or
step.
stepper motor A motor in which the shaft advances
in uniform angular steps, instead of rotating
continuously. These motors are extensively
used in robotic devices. When such a motor is
stopped and its coils are carrying current, the
shaft resists turning.
stepping relay See STEPPING SWITCH.
stepping switch A multiposition rotary switch in
which an electromechanical ratchet mechanism
advances to the next contact position each time
that a pulse of current is received.
step-through operation A way of operating a computer,
usually during a debugging operation, in
which program instructions are executed one at a
time by direction of the user. Also called singlestep
operation and step-by-step operation.
step-up ratio In a circuit or device, such as a stepup
transformer or voltage amplifier, the ratio of
the high output voltage to the low input voltage.
Compare STEP-DOWN RATIO.
step-up transformer A transformer delivering an
output voltage that is higher than the input voltage.
In such a transformer, the secondary (output)
winding contains more turns than the
primary (input) winding. Compare STEP-DOWN
TRANSFORMER.
steradian
A unit of solid-angle measure. A coneshaped
solid angle that has a vertex at the center
of a sphere (of radius r), that cuts off a portion of
the sphere’s surface whose outer perimeter is a
circle, and that has an area (as measured on the
sphere’s surface) of r 2 . Also see SOLID ANGLE.
Sterba array See BARRAGE ARRAY.
Sterba curtain See BARRAGE ARRAY.
stereo 1. Contraction of STEREOPHONIC. 2. General
term for a two-channel high-fidelity audio reproduction
system.
stereo-adaptable Pertaining to a television receiver
or videocassette recorder (VCR) that requires a
special circuit to obtain stereo sound from Multichannel
Television Sound signals. Compare
STEREO-READY.
stereo amplifier A two-channel amplifier for binaural
reproduction (see BINAURAL).
stereophonic Pertaining to equipment or techniques
for producing a (somewhat) three-dimensional
perspective of sound reproduction.
stereophonic sound system See STEREO SYSTEM.
stereo-irrelevant Pertaining to sound components
in a stereo system that are of equal magnitude
in both (or all) channels. Thus, these
components sound the same whether the system
is reproducing stereophonic sound or monaural
sound.
stereo phono cartridge A phono cartridge capable
of reproducing sound from stereo discs.
stereo-ready Pertaining to a television receiver or
videocassette recorder (VCR) that can deliver
stereo sound from Multichannel Television Sound
signals without the need for a decoding circuit.
Compare STEREO-ADAPTABLE.
stereo recording A method of recording in which
two independent sound channels are transferred
to some medium simultaneously, with the intention
that the two channels be reproduced at the
same time.
stereoscopic television Television in which the
reproduced image appears three-dimensional.
stereo system A multichannel, high-fidelity sound
reproduction system including an amplifier and
various other components, such as a radio receiver,
compact-disc (CD) player, tape player,
turntable, and speakers.
stereotape Magnetic tape bearing more than one
channel (usually two channels) for the recording
and reproduction of stereophonic sound.
sterilizer Any electronic device, such as an ultraviolet
generator, used to kill germs.
stethoscope An electronic or nonelectronic instrument
used by physicians to listen to the heartbeat
and other body sounds, and by technicians
to listen to mechanical sounds.
still 1. A stationary picture on television. 2. A picture
transmitted or received by means of facsimile.
3. A print on photographic paper of a negative.
still television See FACSIMILE.
stinger A brief, loud sound burst, such as a musical
chord, sometimes used for effect in recorded
audio or audio-visual presentations.
stn Abbreviation of STATION. (Also, sta.)
STO Abbreviation of STORAGE FUNCTION.
stochastic The condition in which, at any instant,
a given variable can assume a state dependent on
previous states, as well as chance elements (e.g.,
words uttered extemporaneously by a speaker are
random in that they cannot be predicted), while
also being dependent, by the application of grammar,
on previously spoken words (i.e., previous
states).
stop amplifier
See REJECT AMPLIFIER.