Resistor Terms:

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

Fader. Another term used for a linear potentiometer which describes the application.

Ferrule-terminal Resistor. A Tubular resistor. Ferrule resistors use a tab at either end of the tub for mounting, and may also be referred to as Tab-terminal resistors [example MIL-PRF-26/3E]. Resistor Manufacturers

Tab-terminal Power Resistors
Ferrule-terminal Resistor

Film Resistor. The film type resistor is composed of a resistive film deposited on, or inside of, an insulating cylinder or filament. Film type resistors have the best high frequency performance. The effective dc resistance for most resistance values remains fairly constant up to 100 MHz and decreases at higher frequencies. Film resistor types include; Metal Film, Carbon Film, Cermet, Metal-Oxide and others. Film resistors are recommended where high stability and close tolerance resistance is required. Their resistance value can be accurately maintained over a broad range of temperatures and for long periods of time.

Fixed Film Resistor. Same as a Film Resistor but contains a network of resistors. Refer to Resistor Networks for an example schematic of different styles.

Fixed Resistor. A resistor having a definite resistance value that cannot be adjusted. A resistor whose ohmic value cannot be adjusted or varied. Also see Resistor Manufacturers. Types of fixed resistors include; fixed film, fixed composition, fixed wire wound.

Military Resistor Specifications, Color Bands
Resistor Color Bands

Flameproof Resistor. A resistor constructed of materials that will not ignite while under an electrical over-load. A flame-proof resistor may be constructed of a porcelain core with an element made of a Metal alloy. Also; Metal Oxide Flame Proof [MOFP]. A requirement, Non-Combustibility, Flame Retardant. These resistors eliminate fire hazard and circuit board damage due to overheated components.

Flameproof Fusible Resistor. A resistor that is both Flame-proof and Fusible.

Fusible Resistor. Acts as a normal resistor under normal conditions but opens under a fault condition. The resistors act as a wire-wound resistor and a fuse, and are used in applications where precise control of fusing point and time lags are necessary. Similar types include a Failsafe Fusible Resistor which combines a fuse and resistor in the same package.

Heat Dissipation. The manner in which a resistor gives off heat.

Hermetically Sealed Resistor. Sealed so that a resistor is gas-tight to a specific rate, normally less than 1 x 10-8 cc/sec of helium. A hermetically sealed resistor is one in which the resistance element is contained within a sealed enclosure of ceramic, glass, or metal, or combinations thereof.

Cut-away view of a Resistor
Hermetically Sealed Resistor Diagram

Inductive Resistor: A resistor having a higher than normal inductance. In many cases these will be wirewound types. Normally Inductive Resistors are not used in high frequency circuits because of their high inductance. In most cases a resistor is preferred to be Non-Inductive. Also refer to Non-Inductive Resistor.

Isolation Resistor. A resistor used to isolate one part of a circuit from another. A resistor used in a circuit to isolate a capacitive load from a driver. A resistor used to limit current as in isolate a component from a static discharge. A fusible resistor may also be used in place of a Isolation Resistor to provide both the current limit and would open on a high current discharge.

Insulation Resistance. The dc resistance measured between all terminals connected together and the case, exterior insulation, or external hardware. The resistance between a terminal and some point on the resistor body.

Jumper Resistor. see Zero-Ohm Resistor.

Kelvin Terminal. A four terminal fixed resistor having a very low resistance [milliohm range]. Although a Kelvin Terminal has four leads they are connector together internally to form two pairs [see schematic]. For each pair one lead is used as a voltage sense while the other lead is used as a current sense. Normally a Kelvin Terminal is used as a current sense resistor. [Manufacturers of Current Sense Resistor]. The diagram shows a 4-terminal Surface Mount Current Sense Resistor.

SMD Current Sense Resistor
Current Sense Resistor

Lead Free / RoHS Compliant: See the RoHS definition; leaves this section of the dictionary.

Lead-screw. A variable resistor that is actuated by a lead-screw. Resistors may be wire-wound or non-wirewound and may be single-turn or multi-turn. See the diagram to the right.

Lead-style. The lead type that a resistor uses; Ferrule, Lug Terminal, Solder Tab, Quick Connect. The manner in which the resistor connects to the circuit.

Light Dependent Resistor. [LDR] A component that changes resistance based on the amount of light the device detects.

Linear Potentiometer. A variable resistor using an adjustment that moves up and back in a straight line, as opposed to a rotational potentiometer in which the adjustment is is turned.

Linear Taper. An adjustable resistor that changes value in a linear manner. This term is used to describe a resistor that changes from a low to high value [or the reverse] increases or decreasing in a linear fashion and does not address error values or non-linearities in the value.

Load-Life Stability. The long term stability of a resistor over the life of the device, under load. The more stable the device, the less the change in resistance, the better the resistor. Resistor stability relates to a value change over time, which differers from resistor tolerance.

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