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Glossary / Dictionary of Electronics Terms - P

paper capacitor - 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.

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.

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 dielectric.

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 1C 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

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