| 摘要 |
A television tuning system for generating a tuning voltage for a varactor controlled local oscillator includes a continuous resistive element having first, second, third and fourth points along its resistive path which define first, second and third resistive sections corresponding, respectively, to the low VHF, high VHF and UHF tuning bands and a movable contact. A position detecting arrangement determines the position of the movable contact along the path of the resistive element to determine which band is being tuned and in response selectively couples voltages corresponding to the magnitudes of the tuning voltage corresponding to the beginning and end points of the various bands to respective points along the resistive element. As a result, with continuous motion of the movable contact a tuning voltage for each channel in the television range is developed at the movable contact. |
