Resistor Terms:

'A', 'B', 'C', 'D/E', 'F-L', 'M', 'N', 'O', 'P', 'R', 'S', 'T', 'V-Z'

Panel Mount Resistor: A style of resistor that mounts to a panel, normally an adjustable resistor or potentiometer. Types of Panel Mount Resistors; graphics

Phenolic Molded Resistor: A synthetic thermosetting resins such as Bakelite, obtained by the reaction of phenols with simple aldehydes and used to make molded products, as in a resistor shell.

Photocell: A light-controlled variable resistor which has a light-to-dark resistance ratio of 1:1000.

Photoresistor: Another name for a light dependent resistor (LDR). A resistor whose resistance changes based on the light intensity.

Pi Network: A resistor network in the form of a Pi or Delta configuration. Also refer to a more detailed definition of Resistor Attenuator Networks.

Resistor Pi schematic
Resistor Pi Network

Potentiometer: A variable resistor. Designed for frequent changes, a volume control. The output of a Potentiometer is a voltage that is variable depending upon the position of the wiper contact. The potentiometer is commonly referred to as a variable voltage divider. It, in effect, converts mechanical information into an electrical signal.Companies that Manufacturer Potentiometers.

Potentiometer Resistor case drawing

Power Rating: The maximum power the device can dissipate with out damage at some defined ambient temperature [Still-Air]. Power Ratings are provided with a continuous full-load condition. Resistor Derating must occur to allow the device to operate at higher temperatures. Maximum power dissipation normally increases as the resistor package increases in size.

Derating MIL-PRF-83401 Resistor Networks graph
Power Rating Curve

Power Rating Curve: A curve that indicates the percentage of nominal wattage to be applied at a temperature other than that specified as Maximum power dissipation. A Power Rating Curve may also be called a Derating Curve. Note the curve shown above relates to MIL-PRF-83401 [Resistor Networks]. The Power Rating for this series is given at an ambient temperature of 700C, so for temperatures below that value the device may be operated above the maximum power rating [above 100 percent].

Power Resistor: A resistor with a power dissipation higher than a quarter watt [0.25w], or half watt [0.5w]. However the military classifies power resistors as resistors having power a dissipation above 3 watts. The classification of a power resistor is subjective; a resistor having a higher power dissipation than normally used.

PTC: (Positive Temperature Coefficient) A device with a the resistance that will increase as temperature does A type of Thermistor as shown by the picture to the right. A related topic; Manufacturers of Thermistors.

Pull-up Resistor: A resistor used to pull-up or tie an unused IC input-pin to a voltage or an open-collector IC output-pin to a voltage. How to Calculate a Pull-up Resistor Value. Tri-State Outputs may also need to be pulled-up.
How to Calculate a Tri-State Pull-up Resistor Value

Pulse Duration: In some cases the power dissipation of a resistor is provided as power dissipation vs pulse duration. Normally the pulse duration curve is provided to show the peak dissipation of a resistor over 100 percent dissipation as the pulse duration is decreased.

Resistor peak dissipation vs pulse rate
Resistor Peak Dissipation vs Pulse Rate
PC motherboard

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