Fixed capacitor using oiled or waxed paper as a
dialectric.
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."
pasive filter
A filter that contains only passive or non amplifying
components.
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 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 indefinately.
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 oscilator 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.<OLORS.< p>
photoconduction
A process by which the conductance of a material is
change by incident electromagnetic radiation in the
visible light spectrum.
photoconductive cell
Material whose resistance decreases or conductance
increases when exposed to light.
photo detector
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.
photo resistor
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.
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.
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.
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
Travelling 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 attatching 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.
