18WuD2x

Dietzhold network • differential input 185
Dietzhold network A four-terminal, shunt m-derived
circuit used in some wideband amplifiers.
Dietzhold peaking In some wideband amplifiers,
frequency compensation obtained with a shunt
m-derived network (see DIETZHOLD NETWORK).
difference amplifier See DIFFERENTIAL AMPLI-
FIER.
difference channel In a stereophonic amplifier, an
audio channel that handles the difference between
signals in the right channel and those in
the left channel.
difference detector A detector whose output is the
difference between two simultaneous input signals.
difference frequency A signal frequency produced
by mixing or heterodyning of signals at two other
frequencies. If the lower input signal frequency is
f 1 and the higher input signal frequency is f 2 ,
then the difference frequency f d is equal to f 2 – f 1 .
difference of potential The absolute value of the
algebraic difference of voltages at two points of
different electrical potential. Thus, the difference
of potential between a +5-V point and a –5-V
point is +5 – (–5) V = 10 V. Also see POTENTIAL
DIFFERENCE.
difference quantity See INCREMENT.
difference signal 1. The resultant signal obtained
by subtracting, at every instant for at least one
full cycle, the amplitudes of two signals. 2. The
difference of the left- and right-channel outputs
in a stereo system.
differential 1. A device, consisting of a gear system,
that adds or subtracts angular motions and
delivers the result. 2. A gear system in which the
motion of a shaft is transferred to two other
shafts aligned with each other and perpendicular
to the first shaft. 3. One of two coils arranged to
produce opposite polarities at a point in a circuit.
4. Pertaining to a difference between two signals
or quantities.
differential amplifier A circuit, usually an operational
amplifier, that amplifies the voltage difference
between two input signals. The
instantaneous output voltage is equal to some
constant multiple of the difference between the
instantaneous input voltages.
differential analyzer An analog computer that
solves differential equations using integrators.
differential angle For a mercury switch, the angle
between operation and release positions.
differential capacitor A dual variable capacitor
with two identical stator sections, and a single rotor
section that turns into one stator section and
out of the other. The capacitance of one section
decreases while that of the other increases.
differential coil See DIFFERENTIAL, 3.
differential comparator A linear integrated circuit
(IC) that delivers an output proportional to the
difference between two input signals.
differential compound dc generator A compound-wound
dc generator in which the magne-
End view
Rotor
differential capacitor
Stator A
Stator B
tomotive force of the series field opposes that of
the shunt (main) field.
differential compound dc motor A compoundwound
dc motor in which the magnetomotive
force of the series field coil opposes that of the
shunt (main) field coil.
differential cooling Reducing temperature at different
points on a surface at different rates.
differential delay The difference d max – d min across
a frequency band, where d max is the maximum
frequency delay and d min is the minimum frequency
delay.
differential discriminator A device that passes
pulses, whose amplitudes are between two predetermined
values above or below zero.
differential distortion In an automatic-gaincontrol
circuit, distortion from effects that cause
shunting of the diode load resistor.
differential flutter Fluctuations in the speed of a
magnetic tape that are nonuniform in different
parts of the tape.
differential gain In a differential amplifier, the average
gain of the two sections of the amplifier.
Compare DIFFERENTIAL UNBALANCE.
differential gain control A circuit or device for
setting the gain of a radio receiver in terms of an
anticipated change in signal strength, to reduce
the receiver output signal differential.
differential galvanometer A galvanometer in
which currents in two similar coils neutralize
each other; thus, there is zero deflection when the
currents are equal.
differential gap The smallest range of values that
a controlled variable must take to change a threeposition
controller’s output from on to off, or vice
versa.
differential heating Increase of temperature at
different points on a surface at different rates.
differential impedance See DIFFERENTIAL-
INPUT IMPEDANCE.
differential induction coil An induction coil having
two differentially wound primary coils.
differential input In a differential amplifier, the
circuit between input terminals 1 and 2, as opposed
to the circuit between input 1 or input 2
and ground.