GB684067A - Improvements in potentiometers - Google Patents

Abstract

684,067. Variable-contact resistors. SOC. FRANCAISE DE L'ELECTRO-RESISTANCE. May 3, 1951 [Feb. 7, 1951], No. 10406/51. Class 37. A liquid-tight radio-type rotary potentiometer, Fig. 1, has a metal casing 1 closed by a plastic moulding cover 2 and is provided with an insulating rotor head 16 which is recessed as indicated in Fig. 5 to accommodate lengthwise a U-shaped springy metal contact member, Figs. 8 and 9, having a central tongue 26 and contact fingers 23 sloping in opposite directions and maintained respectively in contact with a central output terminal stud 7 and the arcuate resistance track 8 as a triangular spring plate 18 disposed in the casing 1 co-operates to bias inwardly a cone-shaped or tapered operating spindle 13 in a complementary cone-shaped bearing 14. In the contact member/rotor head assembly a notch 24, Fig. 9, butts against a boss 21, Fig. 5. The plastics moulding cover 2 is formed with the three terminal studs 5, 6, 7 as inserts projecting through a triangular raised portion 4, Fig. 2, and is faced with metal 3 whose edge is sealed to the periphery of the casing 1. The terminal studs 5, 6 contact the terminal coatings on the resistance track 8, Fig. 3 (not shown), which may be a semiconductive varnish on a resin-impregnated glass fibre or cardboard backing. In a modification, Figs. 10 and 11, the contact fingers terminate in wipers 27, 28 spaced radially.