Matsushita Electric Industrial Co., Ltd.

Tsuneo Takezaki

Sukeichi Miki

Osamu Yamazaki

Masashi Kanno

Syuichi Ninomiya

Masabumi Serizawa

A level indicator comprising a plurality of comparators for comparing an analog signal with a respective value of graduated reference voltages generates one or more output signals in response to the analog signal exceeding each reference voltage. A plurality of storage circuits is provided each associated with a respective comparator and with a respective one of successively arranged luminous elements. Each storage circuit is responsive to the output of the associated comparator and delivers a signal for the associated luminous element, which signal may also be used to inhibit the passage of the outputs of the other storage circuits of descending order.

Level indicator for indication of maximum values

In a voltage supply circuit for voltage-dependent capacitor diode tuning, a d.c. voltage is produced by a.c.-d.c. conversion of an a.c. voltage which is obtained by amplifying an a.c. signal from an oscillator with the aid of a transistor amplifier of the series-feedback type having an amplifying transistor having an amplification factor depending on a variable reactance coupled to an emitter of the amplifying transistor. The variable reactance controls the amount of negative feedback to obtain the corresponding gain of the amplifier. The degree of amplification decreases as the amount of the negative feedback increases, so that the output d.c. voltage will be stable especially in a low voltage region.

Voltage supply circuit for voltage-dependent capacitor diode tuning

A stereophonic signal generator for generating a composite signal for effectively attenuating undesired spurious signals in a modulated signal, e.g., in a four channel stereophonic signal. In the generator, the main spurious signal, which is a spurious signal most closely adjacent to a given or desired frequency band for a necessary signal, is cancelled by a cancellation signal which is in a compensation relationship with the main spurious signal. Thus, residual spurious signals are attenuated easily by simple filters without degrading the necessary signals.

Composite stereophonic signal generator

This invention provides an FM four channel stereo signal generator for generating from four stereophonically related audio signals an FM four channel stereo signal expressed by (S.sub.1 +S.sub.2 +S.sub.3 +S.sub.4) + (S.sub.1 +S.sub.2 -S.sub.3 -S.sub.4)sin.omega.t+(S.sub.1 -S.sub.2 -S.sub.3 +S.sub.4)cos.omega.t+pilot signals with or without (S.sub.1 -S.sub.2 +S.sub.3 -S.sub.4)sin2.omega.t. The generator includes a matrixing device for producing from the four audio signals four matrixed audio signals (aS.sub.1 +bS.sub.2 +bS.sub.3 +cS.sub.4), (bS.sub.1 +aS.sub.2 +CS.sub.3 +bS.sub.4), (bS.sub.1 +cS.sub.2 +aS.sub.3 +bS.sub.4) and (cS.sub.1 +bS.sub.2 bS.sub.3 +aS.sub.4), where 2b=a+c; a main gating circuit for producing from the audio or the matrixed audio signals a main gated signal including a four channel stereo signal and harmonics; and a subsidiary gating circuit for producing from the audio or the matrixed audio signals a subsidiary gated signal corresponding to a harmonic nearest the four channel stereo signal, whereby by combining the audio or the matrixed audio signals, the main and the subsidiary gated signals and the pilot signals, and by passing the thus combined signal through a low pass filter, the desired four channel stereo signal of high quality can be easily produced.

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Neyagawa, Japan

Tsuneo Takezaki