18WuD2x

voltage doubler • voltage peak 733
ac
Input
(E rms )
E dc = 2(1.41)E rms
voltage doubler A power-supply circuit that supplies
a direct-current output voltage of about
twice the peak value of the alternating-current input
voltage.
voltage drift See DRIFT VOLTAGE.
voltage drop Abbreviation, VD. The voltage (E) set
up across a resistance (R) carrying a current (I);
E = IR. For alternating current, reactance X and
impedance Z can be substituted for resistance,
where applicable.
voltage-equalizing resistors In a power-supply filter,
resistors connected across each capacitor in
a string of electrolytics connected in series to
withstand a high voltage. The resistors protect
the capacitors by equalizing the voltage across
them.
voltage-fed antenna An antenna in which the
feeder is attached to the radiator at a voltage loop
(current node). Compare CURRENT-FED AN-
TENNA.
voltage feed The delivery of voltage to a device or
circuit at a point where voltage, rather than current,
is dominant. Compare CURRENT FEED.
voltage feedback A feedback signal consisting of
voltage fed from the output to the input circuit of
an amplifier or other device. Compare CURRENT
FEEDBACK and CURRENT-VOLTAGE FEED-
BACK.
voltage-frequency transducer 1. A device whose
output voltage is a function of the frequency of a
signal at the input. 2. A device whose output
frequency is a function of the voltage at the
input.
voltage gain See VOLTAGE AMPLIFICATION.
voltage generator See VOLTAGE SUPPLY.
voltage gradient The voltage per unit length along
a defined path.
voltage increment A change in voltage represented
by E 2 – E 1 , where E 2 and E 1 are the voltages
at two defined points on a curve, and the
difference is finite (nonzero). Compare VOLTAGE
DIFFERENTIAL.
voltage input encoder An analog-to-digital encoder
for which the input is an analog voltage.
C1
C2
voltage doubler
+
_
dc
Output
(E dc )
See, for example, VOLTAGE-TO-SHAFT-POSI-
TION ENCODER.
voltage inverter A circuit or device whose voltage
output has the sign opposite that of the input
voltage. The device might or might not provide
amplification.
voltage jump 1. An upward transient in voltage.
2. In a glow-discharge tube, a sudden break or
increase in voltage drop across the tube.
voltage lag The condition in which voltage changes
occur after corresponding current changes. Compare
CURRENT LAG and VOLTAGE LEAD.
voltage lead The condition in which voltage
changes precede corresponding current changes.
Compare CURRENT LEAD and VOLTAGE LAG.
voltage level 1. A prescribed reference value of
voltage (e.g., the black level in a television picture
signal). 2. The discrete value of a steady voltage,
or the average value of a fluctuating voltage, as
observed or measured in a circuit.
voltage limit The maximum or minimum level in a
voltage range.
voltage loop In a standing-wave system, such as
an antenna or transmission line, a maximumvoltage
point. Compare VOLTAGE NODE.
voltage loss 1. Reduction of a voltage across a
load, occurring because of a series resistance.
2. The ratio, in decibels, between the input voltage
to a transmission line and the output voltage at
the load end of the line, assuming that the
impedance is the same at both points.
voltage maximum See VOLTAGE PEAK.
voltage minimum See VOLTAGE TROUGH.
voltage-mode switching circuit A resistor-transistor-logic
(RTL) NAND or NOR circuit in which
(in the off state) the transistor is cut off by the V BB
bias voltage. The output is then approximately
equal to the collector supply voltage, V CC . The
proper combination of input pulses overrides the
cutoff bias, and the transistor switches on. The
output then drops to a level equal to V CC minus
the voltage drop across the external collector resistor.
voltage multiplier A special type of rectifier circuit
that delivers a direct-current output voltage that
is a multiple of the peak value of the alternatingcurrent
input voltage, thus affording voltage stepup
without a transformer. See, for example,
VOLTAGE DOUBLER; VOLTAGE QUADRUPLER;
QUINTUPLER, 1; and VOLTAGE TRIPLER.
voltage node In a standing-wave system, such as
an antenna or transmission line, a minimumvoltage
point. Compare VOLTAGE LOOP.
voltage of self-induction The voltage drop across
an inductor, resulting from the flow of alternating
current through the inductor; it is caused by selfinduction.
voltage peak The highest value attained by a voltage
during an excursion. Also called voltage crest
or voltage maximum. Compare VOLTAGE
TROUGH.