AUTOMATIC CHANNEL SELECTION CIRCUIT FOR TELEVISION SET

摘要

PURPOSE:To simplify the circuit and to reduce the current consumption by using two voltage level comparators so as to decide high/low level and judging the tuning detection when an automatic frequency adjusting signal is at an intermediate level between the high and the low level. CONSTITUTION:The high level VHH of an automatic frequency adjusting signal representing the S-shaped characteristic near the tuning frequency is detected by a high level detection comparator 8 and the low level VL is detected by a low level detection comparator 9. Then an up-pulse inputted from a counter control circuit 3 to a tuning voltage generation counter 4 is stopped by a tuning detection signal from a tuning detection circuit 10 to stoop the automatic channel selection. Thus, the circuit is simplified and the current consumption is reduced.