| 摘要 |
PURPOSE:To enable the sweep stop circuit of an automatic sweep receiver to make extriction easily when a sweep is restarted especically after the end of a temporary stop period. CONSTITUTION:During a sweep, the output of holding circuit 12 maintains a tuning voltage equivalent to the previous receiving station and is applied to the negative- side input terminal of comparator circuit 11. The output of 1st amplifier 8, on the other hand, increases gradually during the sweep and is applied to the positive-side input terminal of comparator circuit 11. During the sweep, therefore, the output of circuit 11 is at a low level while the output of inverter circuit 13 is at a high level; when tuning signal S3 is generated as a result of receiving a broadcast in this state, a stop signal is led out from AND gate 14. After the sweep stops, a tuning voltage at that time is held by circuit 12 and the output of circuit 11 is inverted into a high level. Once the sweep is restarted afterwards, the tuning voltage inputted to the negative-side terminal of circuit 11 starts a sweep from C'' and when the voltage inputted to the negative-side terminal becomes fixed-value higher than C'', circuit 11 is inverted into a low level. |
