SURROUND_SOUND_INDICATOR

Published:2009/7/13 4:24:00 Author:May | From:SeekIC

The circuit indicates, with the aid of two LEDs, whether or not the input signal contains surround data. The criterion for this is the phase difference between the two channels: If this is zero, there is no surround data. In the circuit diagram, if there is a phase difference between the two channels, the output levels of comparators IC1b and IC1c will differ. These outputs are constantly compared by XOR gate IC2c; if there is a difference, the output of the gate will go high. Depending on the output state, the red or green half of D1will be actuated via gate IC2d, which is here connected as an inverter. If there is a pure surround signal, the red half will light brightly; if there is a mono signal, the green half will light. If the input is a standard stereo signal, the rapid changes in the output of IC2c will cause the diode to appear yellow-orange.



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