Dictionary of Electronics "paper" to "pythagorean"

paper capacitor 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." 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. pasive 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-oad 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 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. 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 representin the ratio between the circumference and diameter of a circle and equal to approximately 3.142. Symbolized by the Greek lower case letter p. 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 mwchanical pressure is applied and conversly 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 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 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-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.