NSN 5905-01-554-5251

A resistor in which a sliding or rolling contact moves over an exposed area of the resistive element. Uniform contact pressure on the resistance element is maintained by positive pressure to permit smooth electrical and mechanical control of the resistor over the entire resistance range. The resistive element is constructed of a combination of two materials usually consisting of a wirewound element with a coating of conductive plastic applied over the resistance wire where the slider makes contact. May be constructed of a single or multiturns of wire supported on an insulating structure on which the wiper contacts the coated wire continuously in the direction of wiper travel. The opposition to the flow of current is an inherent property of the wire used and is manifested in the heat dissipated in the resistor itself. For items having manually positioned taps designed to be set and fixed prior to use, see resistor, adjustable. For items with step by step variation, see rheostat; and resistor, step by step. For tandem-mounted items designed to function together as an attenuator (and rated accordingly), see attenuator, variable. Excludes other resistor (1), variable, (as modified).