GB523881A - Improvements in or relating to radio-receiving apparatus - Google Patents

Abstract

523,881. Electric control systems. NAAMLOOZE VENNOOTSCHAP PHILIPS' GLOEILAMPENFABRIEKEN. March 15, 1939, No. 8352. Convention date, March 18, 1938. [Class 40 (i)] In a radio receiver wherein tuning is effected by a motor under the control of a keyboard and a positioning disc is provided for each station for controlling the motor, each disc is provided with two guide tracks which differ in operative height and co-operate with a control member for the motor. The guide tracks extend over an angle larger than 180 degrees and the discs are driven at a higher speed than the shaft of the tuning device. Figs. 2 and 4 show the positioning disc of one station and its operative association with a push button 35. The disc 8 is provided on its outer cylindrical surface with two helical guide tracks 29, 30 having different operative heights h<SP>1</SP>, h<SP>2</SP> and merging into each other at the depression 31. Upon operation of. the button 35, the pivoted lever 38 depresses a feeler 34 on a lever 33 into contact with either the track 29 or 30 depending on the position of the disc. The levers 33, 38 carry extensions 36, 41 which co-operate with contacts 43, 44, 45 connected in the motor circuit., If the feeler 34 engages the track 30 the extension 42 moves the contact 44 into engagement with contact 45 to close the motor circuit and cause the motor to drive the disc until the feeler 34 enters the depression 31 and the downward movement of the extension 36 operates the contact 45 to open the circuit. Operation of the feeler into engagement with the track 29 allows contact between contacts 43, 44 and causes reverse operation of the motor. In a modification, the two tracks may be arranged to merge gradually into each other; alternatively a step which makes an angle of 90 degrees or less to the track of greater height may beprovided and arranged to co-operate with a bell-crank lever which operates the motorcontrol contacts in such a manner that for one direction of rotation, the lever opens the motor circuit to stop the disc directly in the predetermined position and for the other direction the disc runs past the correct position and then is reversed into that position. In a further modification, a spiral track is provided on the flat face of the disc, the inner and outer turns of the spiral being used for operating the motor in opposite directions.