18WuD2x

472 neodymium • neper
neodymium Symbol, Nd. A metallic element of the
rare-earth group. Atomic number, 60. Atomic
weight, 144.24.
neodymium-YAG laser A laser that uses neodymium
and yttrium-aluminum-garnet (YAG)
crystal. It is used in medical applications, such as
surgery and various other jobs where high precision
is required. Generally, it is a low-to-mediumpower
laser.
neomatachograph An instrument used in psychology
to measure complex reaction time. Compare
NEOMATACHOMETER.
neomatachometer An instrument used in psychology
to measure simple reaction time. Compare
NEOMATACHOGRAPH.
neon Symbol, Ne. An inert-gas element. Atomic
number, 10. Atomic weight, 20.179. Neon, present
in trace amounts in the earth’s atmosphere,
is used in some glow tubes, readout devices, and
indicator lamps.
neon bulb A (usually small) neon-filled gas diode.
It has a characteristic pink glow and is ignited by
a firing voltage for the particular unit. Also called
neon glow lamp and neon tube.
neon-bulb flip-flop A flip-flop circuit (bistable multivibrator)
using two neon bulbs as the bistable
components.
neon-bulb gate A gate circuit containing a neon
bulb biased below the firing point. A trigger voltage
added to the bias voltage raises the applied voltage
and fires the bulb, producing an output pulse.
neon-bulb logic Logic circuits composed of neonbulb
gates.
neon-bulb memory See NEON-BULB STORAGE.
neon-bulb multivibrator A multivibrator using
two neon bulbs as the switching components.
neon-bulb oscillator A simple relaxation oscillator
consisting essentially of a neon bulb, capacitor,
resistor, and direct-current supply. The frequency
of the sawtooth-wave output depends principally
on the capacitance and resistance values. The
maximum operating frequency is limited to about
5 kHz by the deionization time of the gas.
neon-bulb overmodulation indicator The application
of a neon-bulb overvoltage indicator
as a monitor for amplitude-modulated radiofrequency
signals. The bulb flashes each time the
modulation percentage exceeds a predetermined
value. Also called neon-bulb modulation alarm.
neon-bulb overvoltage indicator A relatively simple
circuit in which a neon bulb flashes each time
a voltage monitored by the circuit exceeds a predetermined
value. The flash shows that the portion
of the voltage presented to the bulb has
exceeded the firing potential.
neon-bulb peak indicator See NEON-BULB
OVERVOLTAGE INDICATOR.
neon-bulb ring counter A ring counter composed
of neon-bulb flip-flops. The maximum counting
speed is limited by the deionization time of the neon
bulbs to approximately 300 events per second.
+150 V
Frequency
adjustment
Neon
bulb
neon-bulb oscillator
Output
neon-bulb sawtooth generator A relatively simple
relaxation oscillator using a neon bulb, capacitor,
and resistor. The output is a sawtooth wave,
whose frequency is determined principally by the
capacitance and resistance values.
neon-bulb scale-of-two circuit A scale-of-two circuit
(frequency halver) using neon bulbs as the
bistable elements.
neon-bulb storage A storage (memory) device composed
of neon bulbs. A fired bulb (representing a
bit of stored information) remains fired until
turned off by an erase signal.
neon-bulb stroboscope A stroboscope in which a
neon bulb supplies the light flashes. The circuit is
essentially that of the neon-bulb oscillator, the
flash rate being continuously variable by an adjustable
frequency control.
neon-bulb voltage regulator A simple circuit utilizing
the constant voltage drop across a fired
neon bulb as a regulated voltage. The usual circuit
configuration is a neon bulb and currentlimiting
resistor in series with a power supply.
neon-bulb volume indicator A neon-bulb overvoltage
indicator used in some tape recorders to
show when the volume exceeds a predetermined
level—especially when the volume is high enough
to cause an unacceptable amount of distortion.
neon glow lamp See NEON BULB.
neon lamp See NEON BULB.
neon pilot lamp A neon bulb used as a pilot lamp
operated from the power-line circuit of an electronic
equipment. Also called neon pilot light.
neon tube See NEON BULB.
NEP Abbreviation of NOISE EQUIVALENT POWER.
NEPD Abbreviation of noise equivalent power density.
neper Abbreviation, Np. A Napierian-logarithmic
unit expressing a ratio of power levels; Np = log e
(P 1 /P 2 ) 1/2 , where P 1 and P 2 are the power values
being compared and e is the Napierian logarithm
base, equal to approximately 2.71828. The neper
is related to the decibel (dB), a similar unit based