PEDESTAL PERIOD WIDTH ENLARGING CIRCUIT FOR VIDEO SIGNAL

PURPOSE:To obtain very stable pictures by enlarging the width of pedestal clamping period substantially and making pedestal clamping operation in a wide pedestal period in the display side. CONSTITUTION:Composite video signals (a) impressed to an input terminal 1 are applied to the base of a transistor Q2 through an emitter follower connection transistor Q1. A pedestal clamper 20 is connected to the base of the transistor Q2. Clamping pulse 13 is inputted to the clamper 20, and when the clamping pulse 13 is positive pulse, voltage E of a battery 15 charges a capacitor C1 rapidly, and when the clamping pulse 13 is gone, charge in the C1 is discharged through a leak resistance of the transistor Q2 in long time constant. The clamped composite video signals are set to the same voltage with pedestal clamping level by a multiplexer in a synchronizing signal period.