| 摘要 |
PURPOSE:To obtain an AGC circuit to which no blocking occurs by connecting between a synchronous separation output terminal and a halfway point of a charging path to the capacitor of an AGC output circuit by a horizontal pulse together through a diode. CONSTITUTION:A transistor (TR)Q8 constitutes the output part of a synchronous separating circuit which is not snown in a figure, and the anode of a diode D5 is connected to the collector of the TRQ8. Therefore, when the TRQ8 turns on, the diode D5 also turns on, and consequently the hatched part of a horizontal output pulse shown in a figure C is not discharged to the ground side through the diode D5 and TRQ8 and the capacitor C2 is not charged either. Thus, the capacitor C2 is charged by a diode D4 and a resistance R6 less normally and a synchronizing signal is out of phase with the horizontal pulse [see figure (a)], so the diode D5 is off during channel switching, so that no blocking occurs. |
