Video, synchronizing and A.G.C. circuits for dual-standard television receivers

The effects of different vision modulation polarities on the video amplifier and its associated a.g.c. system are discussed. It is shown that with mean-level a.g.c. some simple precautions are necessary to prevent blocking with negative modulation. Various circuit configurations are described and their limitations discussed. Flywheel oscillator circuit requirements are considered and a dual-standard line oscillator circuit is described.