GB1357873A - Variable thermally sensitive resistance device - Google Patents

Abstract

1357873 Resistors with adjustable temperature coefficient; resistors BECKMAN INSTRUMENTS Inc 30 April 1973 [29 June 1972] 20362/73 Headings H1K and H1S Parts of two resistive tracks may be connected in series to provide a composite arrangement the temperature coefficient of resistance of which may be varied. The arrangement shown has two resistive tracks 42, 43, in this instance in end to end contact. These are disposed around the two conductive tracks 46, 47 which mount the terminals 48, 49 of the device. Greater amounts of one track and lesser amounts of the other are selected by rotation of the mechanically linked but electrically isolated wiper arms 44, 45. In the arrangements (not shown) of Fig. 2, Fig. 5, and of Figs. 6 to 8 there are two concentric resistive tracks bridged by a rotatable wiper. Each track bears one of the terminal connections of the device. In one case one terminal connection is itself a movable contact so that by use of this and the wiper both temperature coefficient and overall resistance may be varied as required. In another case the wiper is connected to a third terminal so that measurements may be made of the resistance of those parts of each track in circuit at any setting. The arrangements (not shown) of Figs. 1 and 3 use linear tracks, either parallel or end-to-end. In all the devices at least one track must have a non-zero temperature coefficient of resistance. Subject to this limitation either track may have a positive or negative coefficient of low or high value. If one track has a positive coefficient and the other a negative, one setting of the device provides an overall zero temperature coefficient of resistance.