| 摘要 |
PURPOSE:To realize no adjustment for the entire titled circuit by applying switching control to an amplifier so as to obtain an NTSC or a PAL burst signal thereby eliminating the need for the gain adjustment. CONSTITUTION:An oscillation circuit 10 forms an NTSC or a PAL chrominance subcarrier signal SS and the signal is fed to an adder circuit 23 via amplifiers 21, 22. A control signal SW is brought into an L level at the NTSC and switch circuits 31-33 are connected as shown in figure. Thus, the signal SS is extracted from the switch circuit 31 and the NTSC system burst signal is extracted from the adder circuit 23. Since the signal SW is switched at each 1H at the PAL, the switch circuits 31-33 are connected in the opposite way from the figure and the PAL system burst signal is extracted at an output of the circuit 23.
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