P
P TYPE - A semi-conductor material that has holes or a lack of electrons.PARALLEL CIRCUIT:
PARALLEL - Electrical design in which two or more circuits, batteries or components share common negative and positive connections.
PASSIVE CIRCUIT - A circuit consisting of all passive elements, resistors, capacitors or inductors.
PASSIVE SENSOR - A sensor which modifies the output of a voltage-divider network that the sensor is part of.
PERMEABLE - A characteristic of how good a material is as a magnetic path.
PHOTOELECTRIC CELL (PE) - A light sensitive material that changes variations of light into varying voltage signals.
PHOTOTRANSISTOR - A light sensitive transistor that generates an output signal in proportion to the light picked up.
PICKUP COIL:
PICKUP COIL - An electromagnetic device in the distributor of the electronic ignition system. It creates an electromagnetic field due to the permanent magnet that is part of the pickup assembly. Then the magnetic field produces an a.c. signal to the control module, informing the module of the turning position of the distributor shaft.
PIEZOELECTRIC - Refers to an electronic device which is capable of generating a voltage when subjected to mechanical pressure.
PLATE - (1) Component of a storage battery, one of a series of flat lead sheets with which acid reacts to produce electricity. (2) A pivoting flap in the choke or throttle valve of a carburetor. (3) To apply a coating or layer of one material over another.
PNP - A transistor with an N type base sandwiched between a P type emitter and collector.
POINT GAP - The space between the point contacts which is adjusted to provide the correct dwell.
POLARITY - The difference in properties or powers between two bodies or the ends of one body, as in a magnet. According to the Current Theory, polarities in an electric circuit are established by an excess of electrons on one side (negative) and a deficiency on the other (positive).
POSITIVE TEMPERATURE COEFFICIENT (PTC) HEATER - A heater system used on chokes and on diesel fuel heaters. PTC heaters are self regulating because as their temperature rises so too does the resistance limiting the amount of electrical flow and overall heating.
POSITIVE TERMINAL - That terminal in a circuit to which current flows.
POTENTIAL - Electrical force measured in volts. Sometimes used interchangeably with voltage.
POTENTIAL DIFFERENCE - A difference of electrical pressure that sets up a flow of electric current.
POTENTIAL DROP - A loss of electrical pressure due to resistance.
POTENTIOMETER:
POTENTIOMETER (POT) - A variable resistor with three connections. The third connection (wiper) moves physically up and down the resistive element which has each end attached to one of the other two connections.
PRIMARY - (1) A low-voltage circuit or part of a circuit. (2) The input coil of a transformer.
PRIMARY WINDING - Low voltage winding of the coil which is electronically connected to its secondary only by the magnetic field they share. When the primary winding is connected across, a potential current flows through it, building a magnetic field around itself and inducing a voltage in the secondary. When disconnected, the cease in current through the primary again induces a voltage in the secondary which is used to ignite the air/fuel mixture.
PRINTED CIRCUIT - Electrically conductive metal paths that are produced by printing a pattern on a board, then etching away all areas that are not printed.
PROCESSOR - A metal housing which contains a microcomputer and other components used in providing electronic system control. The Electronic Control Assembly (ECA) is often referred to as the processor.
PROGRAM - A set of detailed instructions which a microcomputer follows when controlling a system.
PULSE - An abrupt change in voltage whether positive or negative.
PULSE WIDTH - The length of time an actuator, such as a fuel injector, remains energized.