GB1058728A - Improvements in or relating to potentiometers - Google Patents

Abstract

1,058,728. Variable resistors. IRC Inc. May 12, 1964 [May 21, 1963], No. 19720/64. Heading H1S. A miniature trimmer potentiometer comprises an insulating rectangular base 12 having a surface 18 on which is seated an annular wire wound resistance element 44, the spaced ends of the winding 48 being bonded to terminal strips 50a, 50b in turn bonded to the bent-over upper ends 52a of terminal wires 52, 54 extending through holes 42a, 42b in the base. A contact terminal wire 56 extends through a hob 40 in the base 12 and is bent to provide a portion 56a extending through a groove 36 in a rib 32 of the base, the wire being further bent to provide a portion 56b extending through a groove 38 in a hub 30 of the base. The portion 56b is at the centre of the element 44 and serves as a pivot for a resilient contact member 58 seated on the end of the hub. The contact member 58 has a finger 66 engaging the element 44 and a pair of holes 62, 70 receiving the wire 56, a wiper 71 on the member making electrical contact with the wire. An actuator knob 72 has a recess 76 receiving the hub 30, a slot 78 receiving the contact member 58 for driving the latter and a hole 80 receiving the wire 56. The knob is adjusted by a screw-driver slot 86 and has an arrow 88 co-operating with index marks 104 on a cover 90. A sealing washer 100 is provided between a projection 98 on the cover and a groove 82 in a flange 74 of the knob, the cover being cemented to the base 12. A stop lug 84 on the flange 74 co-operates with a stop lug on the cover to limit the rotation of the knob. In a modification (Fig. 6, not shown) the wires 52, 54, 56 are bent to extend along the outer surface of the base 12 so that the wire ends project from a side of the potentiometer instead of from the base and a grooved insulating plate for covering the wires is cemented to the base.