GB1413585A - Motordriven tuning apparatus - Google Patents

Abstract

1413585 Automatic control of tuning R C A CORPORATION 11 May 1973 [15 May 1972] 22562/73 Heading G3N [Also in Division H3] A motor driven tuning apparatus which can be programmed to pass by selected channels comprises a first rotary switch 103 having stator terminals each connected to a respective one of a plurality of adjustable potentials 115, 117 and having a rotor terminal R to provide a selected one of the adjustable potential to an electrically tuned tuner, 119, 123, a motor 101 to drive the first rotary switch 103 so that the stators are contacted in sequence, a motor control circuit 109 to activate or inactivate the motor, the motor control circuit 109 being arranged to activate the motor when provided with an over-ride signal and being otherwise responsive to operator control, and a voltage sensing arrangement 155 responsive to each selected adjustable potential when it is within a certain portion of its adjustment range to provide the over-ride signal. In the television tuner shown by pressing time button 113 a transistor 181 conducts and operates a bi-stable circuit 111 to make 171 off and 177 on. This starts the motor 101 which drives the gauged rotary switches 102-105 until the button 113 is released. The motor 101 continues to be driven after the button has been released until the rotor R of switch 102 contacts a channel contact 3-13, A-H which connects a +6V supply via diode 189 to turn on the transistor 171 and turn off the transistor 177 of the bi-stable circuit 111. A channel position can be set to be over-ridden by setting the potentiometer, such as 117, to provide a tuning voltage, via transistors 131, 133 and 149 below a certain value so that a transistor 155 is made non conductive. This makes a transistor 163 on and a transistor 157 off so that channel indicator lamp 119 is not lit and a diode 169 conducts to maintain the bi-stable circuit transistors 171 and 177 off and on so that the tuning motor 101 continues to drive the channel reflector switches 102-105 until the rotor R of the switch 102 contacts a stator contact corresponding to a non over-ridden channel position. When a tuning position is selected the tuning voltage from the selected potentiometer 115, 117 is fed to the VHF tuner 123 or UHF tuner 119 which is supplied with power via rotary contact R of switch 105. Also the selected tuning potential is fed via 131 and 133 to a channel indicator meter 135 and via 149 to turn transistors 155 and 157 on and 163 off so that the selected channel lamp 119 is lit. When the UHF tuner 119 is selected the VHF tuner 123 operates as an IF amplifier. In order to enable the higher VHF channels 7-13 to be over-ridden a +B potential from the rotar R of switch 105 turns on a transistor 147 so as to enable the potential at the input of the transistor 155 to be adjusted low enough by the potentiometers 115 corresponding to the higher VHF channels to provide the override operation.