GB1262173A - Tuning device for radio frequency apparatus - Google Patents

Abstract

1,262,173. Push button tuners. INTERNATIONAL STANDARD ELECTRIC CORP. 13 Aug., 1969, No. 40559/69. Heading H3Q. [Also in Division H1] In a tuning device for radio apparatus such as a TV receiver, in which a resonant circuit is tuned by at least one voltagevariable capacitance semi-conductor element, a plurality of knobs 2 each carry a push button 5, whose operation connects output terminals to a voltage control arrangement associated with the knob and pushbutton, rotation of any of the knobs over a predetermined range operates via a respective wheel 3 a slider 12<SP>1</SP> of a potentiometer which has a gapped annular resistive track 8 and rotation of the knob beyond the range operates a switch 4 so as to enable the voltage applied to the potentiometer to be changed. Rotation of knob 2 is coupled by gearing 21, 20 to rotate the slider 12. At each 180 degree turn of the potentiometer shaft 17 projections 32 co-operate with slots 31 in a Geneva mechanism 22 to rotate a movable contact 23 of a waveband switch. Each waveband switch 4 has three fixed contacts 24 connected via tags 26 to different voltages so that on rotating the potentiometer shaft 17 through the 180 or 360 degrees positions the movable contact 23 moves from one fixed contact 24 to the next. The fixed contacts 24 and circuit connections are formed as a printed circuit. Each potentiometer 3 has the resistive track 8 deposited on an insulating plate 11. Each waveband switch 4 and potentiometer 3 is connected to a common switch output conductor 30 and common potentiometer output conductor 16 by switch contacts springs 28, 15 actuated when a push button 5 is pressed, by ramps on either side of a slot 36 in the push button. The push button 5, knob 2, cam wheel 17 and Geneva mechanism 22 may be of plastics, metal or both these materials.