18WuD2x

pickoff • Pierce oscillator 533
turbing the operation of the circuit. 2. A device for
electronically monitoring linear or angular displacement.
pickup 1. A device that serves as a sensor of a signal
or quantity. This covers a wide variety of
items, including temperature sensors, vibration
detectors, microphones, phonograph pickups, etc.
2. Collectively, energy or information that is received
(e.g., sound pickup).
pickup arm The pivoted arm that holds the cartridge
and stylus of a phonograph.
pickup cartridge See PHONO CARTRIDGE.
pickup current 1. The current required to close a
relay. 2. Current flowing through, or generated
by, a pickup.
pickup pattern The directional pattern of a microphone
or other transducer that converts acoustic
energy into electrical signals.
pickup voltage 1. The voltage required to close a
relay or circuit breaker. 2. The voltage delivered
by a pickup.
pico- 1. Abbreviation, p. A prefix meaning 10 –12 .
2. A prefix meaning extremely small.
picoammeter A usually direct-reading instrument
used to measure current in the picoampere
range. Also see CURRENT METER.
picoampere Abbreviation, pA. A small unit of current
equal to 10 –12 ampere.
picocoulomb Abbreviation, pC. A small unit of
electrical quantity equal to 10 –12 coulomb.
picocurie Abbreviation, pCi. A small unit of radioactivity
equal to 10 –12 curie.
picofarad Abbreviation, pF. A small unit of capacitance
equal to 10 –12 farad.
picohenry Abbreviation, pH. A small unit of inductance
equal to 10 –12 henry.
picosecond Abbreviation, ps or psec. A small unit
of time equal to 10 –12 second.
pi coupler See COLLINS COUPLER.
picovolt Abbreviation, pV. A small unit of voltage
equal to 10 –12 volt.
picovoltmeter A usually direct-reading electronic
instrument used to measure electromotive force
in the picovolt range.
picowatt Abbreviation, pW. A small unit of power
equal to 10 –12 watt.
pictorial See PICTORIAL WIRING DIAGRAM.
pictorial diagram See PICTORIAL WIRING DIA-
GRAM.
pictorial wiring diagram A wiring diagram in the
form of a drawing or photograph of the components,
as opposed to one of circuit symbols. The
components are shown in their positions in the
finished equipment, and the wiring as lines running
between them.
picture black In facsimile or television, the signal
condition resulting from the scanning of a black
portion of the image.
picture detector See VIDEO DETECTOR.
picture diagram See PICTORIAL WIRING DIA-
GRAM.
picture element See PIXEL.
picture information In a television signal, the
variable-amplitude component (i.e., the one carrying
energy corresponding to the picture elements)
that fills the space between blanking
pulses.
picture-in-picture Abbreviation, PIP. In some television
receivers, a feature that allows simultaneous
viewing of two programs. One program
occupies the full screen, and another program
appears in a small portion of the screen.
picture reception 1. See PHOTOGRAPH RECEP-
TION. 2. The reception of television signals.
picture transmission 1. See PHOTOGRAPH
TRANSMISSION. 2. The transmission or broadcasting
of television signals.
picture tube The cathode-ray tube used in a television
receiver to display the image. Also called
KINESCOPE.
−
+
Electron
gun
Grids
Signal
input
Housing
Deflecting
plates
or
coils
picture tube
Phosphor
screen
pie chart See CIRCLE GRAPH.
Pierce oscillator A simple crystal oscillator in
which the crystal is connected directly between
the input and output terminals of the active device
(usually a bipolar or field-effect transistor). A
tuned inductance-capacitance (LC) circuit might
be included, but is not required.
Y1
RFC
B+
B−
Pierce oscillator
RF
output