Fixed capacitor using oiled or
waxed paper as a dielectric.
parallel
Circuit having two or more paths
for current flow. Also called
shunt.
parallel resonant circuit
Circuit having an inductor and a
capacitor in parallel with one
another. Circuit offers a high
impedance at resonant frequency.
Sometimes called a "tank
circuit."
pass band
The range of frequencies that
will be passed and amplified by
a tuned amplifier. Also the
range of frequencies passed by a
band pass filter.
passive component
Component that does not amplify
a signal. Resistors and
capacitors are examples.
passive filter
A filter that contains only
passive or non amplifying
components.
passive system
System that emits no energy. It
only receives. It does not
transmit or reveal its position.
peak
Maximum or highest amplitude
level.
peak inverse voltage
(PIV) The maximum rated value of
a AC voltage acting in the
direction opposite to that in
which a device is designed to
pass current.
peak to peak
Difference between the maximum
positive and maximum negative
values of an AC waveform.
pentavalent element
Element whose atoms have five
valence electrons. Used in
doping intrinsic silicon or
germanium to produce n-type
semiconductor material. Most
commonly used pentavalent
materials are arsenic and
phosphorus.
percent of regulation
The change in output voltage
that occurs between no-load and
full-load in a DC voltage
source. Dividing this change by
the full-load value and
multiplying the result by 100
gives percent regulation.
percent of ripple
The ratio of the effective rms
value of ripple voltage to the
average value of the total
voltage. Expressed as a
percentage.
period
Time to complete one full cycle
of a periodic or repeating
waveform.
permanence
Magnetic equivalent of magnetic
inductance and consequently
equal to the reciprocal of
reluctance, just as conductance
is equal to the reciprocal of
resistance.
permanent magnet
Magnet normally made of hardened
steel that retains its magnetism
indefinitely.
permeability
Measure of how m how much better
a material is as a path for
magnetic lines of force with
respect to air which has a
permeability of one. Symbolized
by the Greek lower case letter
mu (m).
phase
Angular relationship between two
waves.
phase angle
Phase difference between two or
more waves, normally expressed
in degrees.
phase shift
Change in phase of a wave form
between two points, expressed as
degrees of lead or lag.
phase shift oscillator
An oscillator that uses three RC
networks in its feedback path to
produce the 180° phase shift
required for oscillation.
phase splitter
Circuit that takes a single
input signal and produces two
output signals that are 180°
apart in phase.
phonograph
Piece of equipment used to
reproduce sound stored on a disk
called a phonograph record.
phosphor
Luminescent material applied to
the inner face of a cathode ray
tube that when bombarded with
electrons will emit light of
various colors.
photoconductive cell
Material whose resistance
decreases or conductance
increases when exposed to light.
photoconduction
A process by which the
conductance of a material is
change by incident
electromagnetic radiation in the
visible light spectrum.
photodetector
Component used to detect or
sense light.
photodiode
A semiconductor diode that
changes its electrical
characteristics in response to
illumination.
photometer
Meter used to measure light
intensity.
photon
Discrete portion of
electromagnetic energy. A small
packet of light.
photoresistor
Also known as a photoconductive
cell or light dependent
resistor. (LDR) A device whose
resistance decreases with
exposure to light.
photovoltaic cell
Component commonly called a
solar cell used to convert light
energy into electrical energy.
pi
Value representing the ratio
between the circumference and
diameter of a circle and equal
to approximately 3.142.
pierce oscillator
A variation of the colpitts
oscillator. This oscillator uses
a quartz crystal in place of the
inductor found in the colpitts
oscillator feedback network. The
crystal maintains a highly
stable output frequency.
piezoelectric crystal
Crystal material that will
generate a voltage when
mechanical pressure is applied
and conversely will undergo
mechanical stress when subjected
to a voltage.
piezoelectric effect
The production of a voltage
between opposite sides of a
piezoelectric crystal as a
result of pressure or twisting.
Also the reverse effect which
the application of a voltage to
opposite sides causes a
deformation to occur at the
frequency of the applied
voltage. (Converts mechanical
energy into electrical energy
and electrical energy into
mechanical energy.)
pinch-off region
A region on the characteristic
curve of a FET in which the gate
bias causes the depletion region
to extend completely across the
channel.
plastic film capacitor
Capacitor in which alternate
layers of aluminum foil are
separated by thin films of
plastic dialectric.
plate
Conductive electrode in either a
capacitor or battery. In vacuum
tube technology, it is the name
given to the anode.
plug
Movable connector that is
normally connected into a socket
or jack.
pnp transistor
A bipolar junction transistor
with an n-type base and p-type
emitter and collector.
pole
In an active filter, a single RC
circuit. A one pole filter has
one capacitor and one resistor.
A two pole filter has two RC
circuits and so on.
polar coordinates
Either of two numbers that
locate a point in a plane by its
distance from a fixed point and
the angle this line makes with a
fixed line.
polarity
Term used to describe positive
and negative charges.
polarized
A component which must be
connected in correct polarity to
function and/or d/or prevent
destruction. Example:
Electrolytic capacitor.
positive
Polarity of point that attracts
electrons as opposed to negative
which supplies electrons.
positive charge
A charge that exists in a body
that has fewer electrons than
protons.
positive feedback
A feedback signal that is in
phase with an amplifier input
signal. Positive feedback is
necessary for oscillation to
occur.
positive ground
A system whereby the positive
terminal of the source is
connected to the system's
conducting chassis.
positive ion
Atom that has lost one or more
valence electrons resulting in a
net positive charge.
potential difference
Voltage difference between two
points which will cause current
to flow in a closed circuit.
potential energy
Energy that has potential to do
work because of its position
relative to others.
potentiometer
A variable resistor with three
terhree terminals. Mechanical
turning of a shaft can be used
to produce variable resistance
and potential. Example: A volume
control is usually a
potentiometer.
power
Amount of energy converted by a
circuit or component in a unit
of time, normally seconds.
Measured in units of watts.
(joules/second).
power amplifier
An amplifier designed to deliver
maximum power output to a load.
Example: In an audio system, it
is the power amplifier that
drives the loudspeaker.
power derating factor
A transistor rating that tells
how much the maximum allowable
value of PD
decreased for each 1°C rise in
ambient temperature.
power dissipation
Amount of heat energy generated
by a device in one second when
current flows through it.
power factor
Ratio of actual power to
apparent power.
power loss
Ratio of power absorbed to power
delivered.
power supply
Electrical equipment used to
deliver either AC or DC voltage.
power supply rejection
ratio
A measure of an op-amps ability
to maintain a constant output
when the supply voltage varies.
primary
First winding of a transformer.
Winding that is connected to the
source as opposed to secondary
which is a winding connected to
a load.
primary cell
Cell that produces electrical
energy through an internal
electrochemical action. Once
discharged a primary cell cannot
be reused.
printed circuit board
Insulating board containing
conductive tracks for circuit
connections.
programmable UJT
Unijunction transistor with a
variable intrinsic stand-off
ratio.
propagation
Traveling of electromagnetic,
electrical or sound waves
through a medium.
propagation delay
Time required for a signal to
pass through a device or
circuit.
propagation time
Time required for a wave to
travel between two points.
protoboard
Board with provision for
attaching components without
solder. Also called a
breadboard. Primarily used for
constructing experimental
circuits.
proton
Sub atomic particle within the
nucleus of an atom. Has a
positive charge.
pulse
Rise and fall of some quantity
(usually voltage) for a period
of time.
pulse fall time
Time for a pulse to decrease
from 90% of its peak value to
10% of its peak value.
pulse repetition
frequency
The number of times per second
that a pulse is transmitted.
Pulse rate.
pulse repetition time
Time interval between the start
of two consecutive pulses.
pulse rise time
Time required for a pulse to
increase from 10% of its peak
value to 90% of its peak value.
pulse width
Time interval between the
leading edge and trailing edge
of a pulse at a point where the
amplitude is 50% of the peak
value.
push>push-pull amplifier
Amplifier using two active
devices operating 180° apart.
Pythagorean theorem
A theorem in geometry: The
square of the hypotenuse of a
right triangle equals the sum of
the squares of the other two
sides. In electronics used for
vector analysis of AC circuits
