GB559673A - Volume control for radio-phonographs and like sound reproducing apparatus - Google Patents

Abstract

559.673. Variable resistors. THORNTON, A. A. (Philco Radio and Television Corporation). Dec. 16, 1942, No. 17889. [Class 37] [Also in Groups XL, XXXVII and XXXIX] A potentiometer acting as a volume control over one part of its range for sound received by radio and over another for gramophone reproduction, actuates a switch when passing from one range to the other. The potentiometer resistance 12, Fig. 9, is traversed by a contact arm 16 mounted on the shaft 22 and connected to terminal 17. The terminal 14 for the radio input is preferably removed from the position 14a close to the terminals 13, 17 to a position near the earthed terminal 15, to avoid induction effects. The shaft 22 also carries a switch-actuating arm 45 formed as a plate with bent-up lugs 46, 47. In the central position these lugs lie in recesses 52, 53 in a member 49, Fig. 11, mounted on a spindle 51. When the arm 45 is moved in either direction, the lugs engage shoulders bounding the recesses 52, 53 and swing the member 49 clockwise on its pivot 51 to throw a snap switch (not shown) to the closed position. A lug 48 limits the outward movement of the arm 45 from its mid-position. In a modified switch-operating mechanism, Fig. 5, the member 49 is replaced by a pair of rocker arms 25, 26 pivoted at 28, 31 and inter-connected by pin and slot 32. Recesses 38, 39 in the outer ends of the arms 25, 26 cooperate with lugs on the actuating arm in a manner similar to that above described.