Technical Engineering Definitions
"A" "B" "C", "D", "E", "F", "G", "H", "I", "J", "K", "L", "M",
"N", "O", "P" "Q", "R", "S", "T", "U", "V", "W", "X", "Y", "Z"

"P" to Pd", "Pe" to "Pg", "Ph", "Pi" to "Pn",
"Po" to "Pot", "Pow" to "Pq", "Pr" to "Pt", "Pu" to "Pz"

Peak Amplitude. The maximum value above or below a reference line.

Peak Current. The maximum current that flows during a complete cycle.

Peak Detection. Detection that uses the amplitude of PAM or the duration of PDM to charge a holding capacitor and restore the original waveform. Read more on a Peak Detector Circuit.

Peak Envelope Power (of a radio transmitter). [PEP] The average power supplied to the antenna transmission line by a transmitter during one radio frequency cycle at the crest of the modulation envelope taken under normal operating conditions. Also refer to the Dictionary of Antenna Terms.

Peaking Coil. An inductor used in an amplifier to provide high-frequency compensation, which extends the high-frequency response of the amplifier, by compensating for capacitive reactance [capacitor coupling] already present in the circuit. A series peaking coil is shown to the right [L1] as part of an RF transistor circuit. A peaking coil may be either a series peaking coil or parallel coil [shunt peaking coil], or the circuit may use a combination of both configurations.

Peak Factor. Crest Factor. The ratio of the peak value to rms value of a periodically varying signal.

Peak Forward Voltage. The maximum instantaneous voltage applied to a device, in the direction the device is intended to pass current.

Peak Inverse Voltage. [PIV] The maximum voltage applied in reverse direction with-out damage to the semiconductor.

Peak Limiting. A process by which the absolute instantaneous value of a signal parameter is prevented from exceeding a specified value.

Peak Load. [Peak demand] The maximum load, or usage [average or instantaneous], of electrical power occurring in a given period of time.

Peak Output Power. The output power averaged over that cycle of an electromagnetic wave having the maximum peak value that can occur during transmission. Same as Peak Power Output.

Peak Power. The maximum value of the transmitted pulse. Power generated by a utility unit that operates at a very low capacity factor; generally used to meet short-lived and variable high demand periods. The mean power supplied to an antenna during one RF cycle.

Peak-Reverse Voltage. The peak ac voltage that a rectifier tube will withstand in the reverse direction.

Peak Signal Level. The maximum instantaneous signal power, voltage, or current at any point. At a given point in a transmission path, the maximum instantaneous signal power, voltage, or current that occurs during a specified period.

Peak Surge Current. The maximum amount of current a component can handle for some short duration of time, with out failure. Example chart of Peak Surge Current vs Surge Duration.

Peak-to-Peak. The measure of absolute magnitude of an ac waveform, measured from the greatest positive alternation to the greatest negative alternation. The absolute value of the difference between the maximum and the minimum magnitudes of a varying quantity. The peak-to-peak measurement can be made on any wave shape; including a square wave, triangle wave, sawtooth or sine wave [shown].

peak-to-peak value of a sine wave

Peak Value. The maximum instantaneous value of a varying current, voltage, or power. It is equal to 1.414 times the effective value of a sine wave.

Peak Voltage. The maximum value present in a varying or alternating voltage. This value may be positive or negative.

Pedestal. The flat-topped portion of a square wave. The constant amplitude portion of a waveform. The base or mechanical support of an antenna.

Pentode Tube. A five-electrode electron tube containing a plate, a cathode, a control grid, and two grids. A EL84 Pentode tube is shown to the right. Also refer to Vacuum Tube Classifications.

Schematic symbol of a Pentode Tube

Percent of Modulation. The degree of modulation defined in terms of the maximum permissible amount of modulation.

Perfboard. [Perforated Board] A Printed Wiring Board [PWB] having pre-drilled holes at distances of 0.1 inches square which will accept standard through-hole ICs and other components. The drilled holes normally have copper pads for soldering the components on one side of the board.

Circuit Assembly on a Perfboard

Perigee. The point in the orbit of a satellite closest to the earth [center].

Period Time. The time required to complete one cycle of a waveform.

Periodic Wave. A waveform that undergoes a pattern of changes, returns to its original pattern, and then repeats the same pattern of changes. Examples are square waves, rectangular waves, and sawtooth waves, as seen in the Periodic Waveforms Graph.

Peripheral Device. In a data processing system, any equipment, distinct from the central processing unit, that may provide the system with additional capabilities. External components attached to a computer systems CPU by controllers, connectors or cables.

Peripheral Driver. A component used to drive a higher current or voltage load than the class of components would normally be able to drive. An IC used to drive a relay or other high demand load. An Example IC schematic of a TTL input gate feeding a transistor output [graphic right] is used as a peripheral driver. The input is standard 5 volt TTL, but the output transistor is the high current driver operating off something other than 5 volts [if required]. The 55452 uses an AND gate input; however other possible devices are available including: 55451, NAND gate, a 55454, OR gate, and a 55452 using a NOR gate.

Peripheral Interface Adapter. [PIA] An IC used in conjunction with a microprocessor which provided external programmable data I/O and control lines. An IC that was used to interface a peripheral device to a uP. A 6820 PIA, used with a 6800 uP is shown to the right.

Permanent Magnet. A piece of magnetic material which retains its magnetism.

Permanent Magnet Speaker. A speaker with a permanent magnet mounted on soft iron pole pieces. Refer here for Speaker Manufacturers. A loudspeaker whose diaphragm movements are produced by a coil or iron armature moving in the field of a permanent magnet.

Permanent Magnet Motor. A PM motor uses a permanent magnet instead of armature windings. The permanent magnets are mounted [embedded] on the rotor. Permanent Magnet [PM] motors are normally small and produce little horsepower. Manufacturers of Motors

Permeability. The measure of the ability of a material to act as a path for magnetic lines of force.

Persistence. The length of time a phosphor dot glows on a CRT before disappearing. [CRT Definition]

PC motherboard

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