The use of voltage-variable diode-capacitors, such as varactor diodes, permits the electronic tuning of radio receivers and television receivers by the use of DC control voltages; so that the tuning elements no longer need to be intimately associated with the tuner. Thus, the tuned circuits of the tv receivers may be located remotely from the devices used to provide the necessary DC tuning voltages. In addition, the compact size of the voltage-variable diode-capacitor tuning circuits makes it desirable to use such tuning circuits in many tv applications which formerly used mechanically adjusted variable capacitors or the like as the tuning elements.
To employ voltage-variable diode capacitors in pushbutton tvs, however, especially in multiband pushbutton tv sets , a problem exists in providing a "memory," so that operation of a pushbutton will provide consistent tuning of the tv receiver to the station which is to be selected by that pushbutton. In addition it is necessary to provide some means for providing the initial tuning of the tv receiver for each pushbutton location in a manner which is reliable and inexpensive.
Power was obtained Both Mains and 12volt source.Recently, it has become more popular than ever to watch TV in a car as the number of cars increases. In general, a storage battery of 12 volts is used in small cars while one of 24 volts is used in large cars so that there is a disadvantage that a separate power supply device is required for driving a TV set in compliance with the respective battery used in the car. The present invention relates to a power supply circuit of a television receiver used in an automobile, and in particular to a power supply circuit of a television receiver which enables two different voltages from two kinds of supply respectively mains at 220v and dc 12v.
Black and white portable television set equipped with a semiconductor. Screen with a diagonal of 31 cm. A channel selector for I.-V. band, 8 presets mechanically actuated. Plastic cabinet, speaker and all the controls to the right of the screen. Possibility of mains or 12V car battery.
The set is a Czechoslovakia made type very solid with modular chassis entirely based on TESLA components.