Abstract: Disclosed is a tuning indicator circuit including a receiver in which an output signal voltage of a detector circuit of the receiver is compared with a reference voltage from a voltage divider by means of a voltage comparator, whereby a tuned or untuned state of the receiver will be detected. The tuned or untuned signal is applied to a light emitting diode driver circuit via an AND circuit, together with a light emitting diode driving signal from an oscillator. The driving circuit allows a light emitting element for power supply and tuning indication to be continuously on in a tuned state, and turns the element on and off in a untuned state with power on.

Abstract: A tuning indicating device in a radio tuner displays S-meter and T-meter tuning information in a single, two-dimensional display. The display unit forms a two-dimensional pattern in response to drive signals corresponding to the S-meter and T-meter tuning information and preferably comprises two groups of electrodes disposed to sandwich a plate-shaped member made of a material whose optical characteristic is changed in response to an electrical field strength applied thereto. One of the groups of electrodes is a plurality of film electrodes which are aligned in one and the same direction, while the other is a plurality of film electrodes which are arranged in such a manner that the configurations thereof are different from one another gradually in a predetermined direction and which are aligned in a direction different from the direction of the one group of film electrodes.

Abstract: An indicating system for a radio receiver is formed of an indicator and associated control circuitry. The indicator is comprised of two emitting diodes wired in parallel and in reverse polarity, and encapsulated in a translucent package. Each diode in an indicator emits light of a visibly distinct wavelength when energized. The control circuitry causes a change in polarity of bias voltage applied to the indicator, and, in so doing a change in color of the indicator. With appropriate control circuitry, the color of the indicator indicates whether the receiver is tuned to an AM or FM station, or whether the station is broadcasting in mono or stereo. The indicator can be mounted to the dial pointer causing a change in pointer color with a change in receiver function. Additionally, the amount of current through the light emitting diodes and thus the intensity of emitted light may be varied in accordance with a parameter variation as, for example, accuracy of receiver tuning.