Automatic sound system selector for television - has FM detector and inverter selecting signals and setting resonance frequency

摘要

The ceramic filter (CF1-CF4) wave-shapes the audio or sound frequencies according to the B/G, I, D/K and M systems. A frequency converter (2) gives out the sound signals with a determined frequency upon reception according to the B/G, I and D/K system. A frequency-modulation detector (4) and a level amplification inverter (5) convert the sound frequency signals into a logic magnitude. A circuit (6) selects the sound signals according to the B/G, I or D/K systems, or the signals according to the M system by use of the logic magnitude. It applies the signals to an audio or sound detector (3). A resonant circuit (8) has its resonant frequency controlled for use of the M system, or for use of the B/G, I or D/K system, by the output signal of the inverter (5).