| 摘要 |
PURPOSE:To decrease the number of pins of an IC, by connecting a diode and a de-emphasizing filter in parallel between an output terminal of a PAL or NTSC demodulating IC and an input terminal of a SECAM demodulating IC. CONSTITUTION:When changeover switches SW1 and SW2 are connected toward (c) and (e) respectively, diodes D1 conducts and D2 is cut off. A chroma signal of a PAL or NTSC system is delivered via the diode D1 an emitter follower 5, a level shifting circuit 8, a clamping circuit 6 and an amplifier 7 respectively. Then the switches SW1 and SW2 are changed to (d) and (f) respectively. Thus the diode D1 is cut off with the D2 conducting. Then chroma signal of SECAM system is delivered from a level shifting circuit 9 through the circuit 6 and the amplifier 7. |
