GB531141A - Improvements in or relating to setting mechanisms, more particularly for tuning wireless receivers - Google Patents

Abstract

531,141. Push button tuning mechanism; conjoint operation. COSSOR, Ltd., A. C., JOLLYMAN, F. A., JONES, K. I., and PARKER, E. L. July 13, 1939, No. 20390. [Class 40 (v)] [Also in Groups XXIV, XXXVI and XXXVII] In tuning the rotary condensers of a wireless receiver 'to predetermined wavelengths by means of a motor operated under the control of selector keys e.g. push buttons, the presetting mechanism comprises a pair of particular cams for each required wavelength, mounted on the condenser rotor shaft and co-operating with a pair of stop members, which lock the cams in the predetermined tuning position, but when not in the tuning position operate switch mechanism controlling the rotation of the motor in the required direction. The rotor shaft is driven from the motor through a clutch so that further rotation of the motor may be used to effect wave band switching. In Fig; 2 a pair of cams 12, 13 is shown mounted on the 'shaft 19 of the tuning condensers the perimeter of the cams being 'cut away in part to provide upper and lower riding edges for the stop members 8, 9 which slidefreely in holes in the head of an arm 7 and are constrained towards the cam edges by springs 10, 11. When the key or push button 1 is depressed it moves an actuating bar 2 to engage by means of a projection 4 the end 6 of the arm 7 thus bringing the spring 10 into contact with a finger 14 on a comb 15 while the spring 11 is held out of contact with a finger 16 on a corresponding comb 17 by the upper edge of the cam 13 engaging and holding back the stop 9. The comb 15 is thus rotated about its extension 20 carrying an arm 31, Fig. 6, which on rotation operates switch contacts 38-42 to energize the motor to move the rotor shaft 19 in the required direction. Rotation of the shaft continues until the end 101 of the cam 12 engages the stop 8 when the stop 9 falls over the edge 102 of the cam 13 and the shaft 19 is then locked against rotation in either direction. Wave change mechanism. Further rotation of the motor after the cams have been .locked effects automatic wave band switching through the medium of a slide bar 27 and a switch 70 rotated by the motor and coupled directly to the wave change switch. The slide bar 27 is mounted at right angles to the actuating bars 2 and is provided with bevelled notches 28, 29, 30 shaped so that the bar 27 is moved to the right or the left by depression of a bar 2 and closes or opens . pairs of switches 51, 52; 47, 48 or 50, 51; 48, 49, from which contact is made or broken to the rotating contacts 54, 59, 64 of the switch 70. These contacts co-operate with fixed three point contacts 53, 55, 56; 58, 60, 61 ; and 63, 65, 66 corresponding to each position of the wave change switch, the contacts 55, 58, 66 being insulated while the remaining contacts are connected to the switch contacts 37, 42. The further rotation of the motor thus continues until one of the rotating contacts reaches one of. the insulated fixed contacts whereupon the motor. is de-energized and brought to rest while the wave change switch is moved to the required position during the rotation. An additional slide bar may be provided for on-and-off switching of the receiver.