Multi-band voltage variable capacitance tuner having automatic and

Abstract

A tuning apparatus includes a dial plate marked with broadcast frequencies thereon, a guide shaft provided in parallel with the dial plate, a substrate having a resistive layer thereon, the resistive layer having varying resistance values distributed therealong which correspond to the broadcast frequencies on the dial plate, the resistive layer being supplied with a DC voltage at opposite ends thereof, a plurality of markers, each slidably disposed with respect to the dial plate to indicate a predetermined broadcast frequency, and each having a first engaging portion and a first electrically conductive slide element for slidably contacting the resistive layer to detect a predetermined DC voltage in response to the location of the markers, a mounting member slidably disposed on the guide shaft in parallel with the dial plate, and including a display member extending therefrom toward the dial plate to indicate a manually selected broadcast frequency, a second electrically conductive slide element for slidably contacting the resistive layer to detect a predetermined DC voltage in response to the location of the mounting member, and a sleeve member slidably mounted on the guide shaft and including a projecting portion adapted to engage the engaging portions of the markers, and a switching circuit supplied with the DC voltages from the first and second slide elements and selectively supplying one of the DC voltages to a tuning circuit as a tuning control voltage.