| 摘要 |
The circuit generates control signal for switching the inner circuit of TV having multi scan function according to the horizontal synchronous frequency of picture signal. The circuit includes a modulater (1) modulating the horizontal synchronous signal, a switch (2) driven by the output signal of the modulator (1), a detector (3) charging or discharging the power according to the switch, a comparator (4) comparing the reference voltage and output voltage of the detector (3), and a multivibrator (5) transmitting voltage with high or low level according to the output signal of the comparator (4).
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