GB762112A - Improvements in or relating to variable resistors - Google Patents

Abstract

762,112. Variable resistors. BRITISH INSULATED CALLENDER'S CABLES, Ltd. Dec. 1, 1954 [Dec. 2, 1953], No. 33485/53. Class 37. In a variable resistor comprising a discshaped rotor carrying a conducting ribbon on its periphery and two fixed contact members making contact with the conducting ribbon at angularly spaced points with respect to the rotor, each contact member comprises a metal ribbon of good conductivity which is so supported at its ends that it is maintained under tension while an intermediate portion thereof makes contact with the rotor, the contacts being so disposed with respect to the rotor that each makes contact therewith over a small arc. The rotor 2 is provided with three grooves 7, 7<SP>1</SP> into which clamping pieces 8, 8<SP>1</SP> are screwed. The conducting ribbon 10 on the periphery of the rotor 2 is in two portions. One portion, clamped between the member 8 and one of the members 8<SP>1</SP> is of high-resistance material, while the other portion which is clamped between the member 8 and the other of the members 8<SP>1</SP> consists of a ribbon of a good conductor, for example, silver. Each contact comprises a ribbon 13 of a good conducting material, for example, silver, supported between a fixed member 14 and a movable member 15 which movable member may be clamped in place by means of clamping screw 18. In order to maintain the contact ribbon 13 under tension, a bow-spring 22 is provided, the end portion of the spring fitting into slots in the support members 14 and 15. As can be seen in Fig. 1, the casing 11 of the variable resistor is cut away to provide room for the springs 22 and to permit access to the support members 14, 15 and clamping screw 18. On account of the constant spacing between the points where the contact member 13 touch the ribbon conductor 10, the variable resistor is of a constant inductance type.