| 摘要 |
PURPOSE:To make a circuit into a IC easy, by charging a capacitor in accordance with the level difference between a video signal and a DC potential to obtain DC potential and discharging its electric charge only for a prescribed time between adjacent synchronizing signals to separate signal from synchronization. CONSTITUTION:A composite video signal is inputted to one transistor TR of TRs for level comparison, and the other TR2 is adjusted and is turned on only in the time of of synchronizing pulse to flow the collector current, and positive pulses are applied to a TR15 through a TR14 to charge a capacitor 8. Meanwhile, a switching signal SW is supplied to a TR21 for timing control to discharge a constant electric charge from the capacitor 8 only for a prescribed time between adjacent synchronizing signals. As the result, the TR2 is turned on only in the time of synchronizing pulses, and a current is supplied to a TR12 through a TR11, and the synchronizing signal is taken out to an output terminal 13. Thus, the circuit is constituted with a small-capacity capacitor and is made into IC easily. |
