Electronic Engineering Dictionary

pi. A mathematical constant whose value is the ratio of any circle's circumference to its diameter [3.1415927].

PIC. A type of Microcontroller, which is ROM, EPROM, or EEPROM based, produced by Microchip. A 16F747 44-pin surface mount PIC microcontroller is shown to the right. Although many differen types and package styles are available, in addition the the example shown.

Pick-Up Noise. See Cross-Talk.

Pico. A prefix adopted by the National Bureau of Standards meaning 10^-12. Engineering Notation

Pierce Oscillator. A Colpitts oscillator that uses a piezoelectric crystal instead of a parallel-resonant circuit. A pierce oscillator uses the voltage from a tap between two capacitors in the tank circuit, as shown to the right. Read more on Pierce Oscillators.

Piezoelectric Crystal. A piece of quartz or other material that can demonstrate the piezoelectric effect.

Piezoelectric Effect. The effect of producing a voltage by placing a stress, either by compression, expansion, or twisting, on a crystal and, conversely, producing a stress in a crystal by applying a voltage to it.

Piezoelectric Speaker. A speaker that uses a piezo element as the transducer. Also refer to Piezo Speaker Manufacturers.

pi Filter. A filter circuit whose passive elements are arranged in the form of the mathematical symbol for pi.

Pigtail. Short wires which are connected to terminals on receptacles or switches. A short length of electrical conductor permanently affixed to a component, used to connect the component to another conductor.

Pig Tail Wire. A short length of wire pre-installed onto a component which uses wire leads. For example a connector, LED or connector with wire leads already installed [prewired]. The term 'short' is relative, but the government uses the word Pigtail for up to 36 inch wires

Pinch-Off Voltage. The gate voltage of an FET that blocks current between the source and drain under the junction breakdown voltage.

PIN Diode. Acronym for Positive-Intrinsic-Negative Diode. A photodiode with a large, neutrally doped intrinsic region sandwiched between p-doped and n-doped semiconducting regions. Note: A PIN diode exhibits an increase in its electrical conductivity as a function of the intensity, wavelength, and modulation rate of the incident radiation. Diode Manufacturers Listing.

Pin Header. An array of pins held together in a molded base. A Pin Strip. See Header.

Pink Noise. Noise that is inversely proportional to frequency, 1/f. In acoustics, noise in which there is equal power per octave.

Pin-Out. The identification of the terminal connections of a component and their names or functions. When only referring to the pin number and location of a connector pin, the term Insert Arrangements is used.

Pipeline. Relating to performing tasks in a serial operation, as it relates to dividing a task into operations, then performing those operations concurrently.

Pitch. The distance between terminals on an IC package. A term used to describe the frequency of a sound heard by the human ear.

Pixel. [Picture Element] In a raster-scanned imaging system, the smallest discrete scanning line sample that can contain gray scale information.

PLA. Programmable Logic Array. Refer to Programmable Logic Terms.

Planar Tube. An electron tube, constructed with parallel electrodes and a ceramic envelope, that is used at uhf frequencies. It is commonly referred to as a lighthouse tube.

Plane of Polarization. The plane (vertical or horizontal), with respect to the earth, in which the E field propagates.

Plane Wavefronts. Waves of energy that are flat, parallel planes and are perpendicular to the direction of propagation.

Plastic Film Capacitor. Any capacitor that uses plastic as the dielectric. For additional information refer to terms used with Capacitors, or Companies making Film Capacitors.

Plate. One of the electrodes in a storage battery. One of the electrodes in a capacitor. The principal electrode to which the electron stream is attracted in an electron tube.

Plate Dissipation. The amount of power lost as heat in the plate of a vacuum tube.

Plate Keying. A keying system in which the plate supply is interrupted. See Vacuum tubes.

Plate Modulator. An electron-tube modulator in which the modulating voltage is applied to the plate circuit of the tube.

Plate Resistance. The plate voltage change divided by the resultant plate current change in a vacuum tube, all other conditions being fixed.

Platter. The circular disk inside a Hard Disk Drive which holds the magnetic data.

PLD. Acronym for Programmable Logic Device. PLDs are devices that are programmed by the OEM customer or manufacturer. A PLD IC is normally considered to be one of the more basic Programmable Logic Devices having only a few logic elements to several dozen logic elements How ever, some consider FPGA devices to also be a PLD, even with several thousand logic elements. There are two main types of PLD devices; Simple PLD [SPLD], and Complex PLD [CPLD]. The most widely know PLD is the 22V10, having 10 Flip Flop I/O programmable blocks. [PLD Dictionary], [PLD Manufacturers].

Plenum. The air return path of a central air handling system, either ductwork or open space over a suspended ceiling. In a building, an enclosure, created by building components such as a suspended ceiling or false floor, and used for the movement of environmental air. A plenum may be used to contain communications and power cables, to reach equipment installed in open office or laboratory space. Cables installed in plenums must meet applicable environmental and fire protection regulations.

Plenum Cable. A fire resistant cable approved by a recognized agency such as UL for installation in plenums without the need for conduit. Also refer to Plenum Wire Manufacturers. Plenum cable is jacketed with a fire retardant plastic jacket of either a low-smoke polyvinyl chloride (PVC) or a fluorinated ethylene polymer (FEP).

Plug. The movable portion of a two connector system [when not connected to the mating connector]. The male end of a cable that mates to a female Jack or fixed connector. The example is a single pin plug suitable as a test plug or single channel audio plug. Also refer to the definition of a Jack.

Plug

Plug & Socket. A connector system that uses a Male plug and Female socket to engage and connect two systems together.

Plug Fuse. A fuse designed to plug into a receptacle.Plug fuses have glass tops to allow inspection of the fusible element. Also called Screw-In Fuse, Edison Base Fuse, or Threaded Edison Base Fuses. An out-dated fuse style used in residential electrical panels. See the Edison Base Fuse graphic to the right.

PMOS. A Metal Oxide Semiconductor [MOS] device made of an N-type substrate having P-type source and drain regions for conduction.

PN Junction. The boundary between the P-type and N-type material within a semiconductor.

PNPN Device. A four layer semiconductor. See Thyristor Terms.