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 c

Abstract: In a tuning apparatus for a broadcast receiver having a dial scale calibrated to represent broadcast frequencies over a predetermined frequency band, and along which an indicator is movable for indicating the broadcast frequency to which the tuning apparatus is actually tuned; a sensor is movable with the indicator, at least one presetting element is movable along the dial scale for indicating a respective preset broadcast frequency and each such element coacts with the sensor whenever the broadcast frequency to which the tuning apparatus is tuned corresponds to the respective preset broadcast frequency, a control signal generator produces a control signal in response to the coaction of the sensor with each of the presetting elements, and a control circuit is responsive to the control signal to control a function of the tuning apparatus, such as, a muting and/or automatic frequency control operation of the tuning Johnson 310 239

Abstract: A filter circuit includes an acoustic surface-wave filter device having an input transducer comprised of a set of interleaved electrodes disposed on a first portion of a body of piezo-electric material adapted to propagate acoustic surface waves for producing an acoustic surface-wave signal in response to an input signal applied to the input transducer, and an output transducer comprised of a set of similar interleaved electrodes disposed on a second portion of the piezo-electric body spaced a selected distance from the first portion for receiving the acoustic surface-wave signals so as to produce a corresponding output signal having a selected frequency response. The frequency response (e.g., bandwidth) of the acoustic surface-wave filter device is controlled by selectively changing the number of conductor elements constituting the interleaved electrodes of the input and output transducers.