MANUALLY OPERABLE POTENTIOMETER VOLUME CONTROL

1282873 Knobs STANDARD TELEPHONES & CABLES Ltd 21 Aug 1969 [28 Aug 1968] 41147/68 Heading A4U [Also in Divisions G1 H1 H3 and H4] A manually operable potentiometer volume control has a knob 11 and a plastics cap 12 keyed together; the cap has control markings and the cap is flexible with respect to the knob so that the cap can be replaced by snapping it off the knob and snapping on another one. The volume control may have a switch. A worn cap 12 or the markings of a cap, such as numerals, letters, signs or language, may be changed by snapping on a new cap. The markings may be on the flat top of the cap on its rim between knurlings or ribs (120), Fig. 1 (not shown) and the cap may be domed as when used in a hearing aid, Figs. 5 and 6 (not shown). To ensure correct location of the cap relative to a pointer or zero indicator projecting keys K1, (K2), Fig.1 (not shown) of different widths are provided on the potentiometer knob 11 which locate in slots in the cap 12. In a modification the projecting keys could be on the cap 12 and the slots in the rim of the knob 11. The potentiometer has a cylindrical body 10 with a wiper terminal T 1 and track terminals T 2 , T 3 . The flexible plastics cap 12 enables a lip 121 to snap over a rim 111 on the knob 11. In a modification, Fig. 3 (not shown) the knob 11 is contained within the cap 12 which has a slot engaging a projecting key (K3) on the knob. In a further modification, Fig.4 (not shown), the cap 12 has press studs (P1, P2) which snap into holes in the knob 11.