This circuit, suggested by National Semiconductor, decodes audio signals from stereo TV broadcasts. Note that the frequency of the pilot signal is 15 734 kHz, different from the 19 kHz used in stereo FM broadcasts. The adjustment of the "capture" by the VCO frequency is done in the 5k potentiometer or trimpot (4k7). The supply is made with voltages in the range of 16 to 18 V. The capacitors must be of good quality, with special attention to the connection between pins 2 and 12, which must be 10 ° / o of tolerance. The resistor in series with the adjustment pot or trimpot must be made of metal film with a zero-temperature coefficient. The L + R and L-R outputs can be played directly on the input of an audio amplifier.
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