| 摘要 |
PURPOSE:To limit both of an inverse phenomenon and the waveform strains by providing a white clip level modulating circuit which varies the degree of modulation in response to the change of the level of a record signal at the output stage of a pre-emphasis circuit. CONSTITUTION:Diodes D1 and D2 are connected between the base of a TRQ4 and a point P1. Therefore the diodes D1 and D2 are turned on and clipped when a video signal is input which is higher than the potential of the point P1 by a degree equivalent to the forward voltage drops of the D1 and D2. Thus the voltage higher than a fixed level (white clip level) is never supplied to the base of the TRQ4, and therefore no video signal higher than a fixed level is not delivered to a white clip output line 24 which is led from the emitter of the TRQ4. Here an output line 25 of a white clip level modulating circuit 11 is connected to a white clip level setting input line 22. As a result, the AC component obtained from a BPF14 is added to a DC white level. |
