TV receiver pulse separation and amplification circuit - has additional circuit for synchronisation pulse dependent clipping level control

摘要

The circuit consists of a high gain amplifier and an input network. The latter has a capacitor for D.C. component elimination. a series resistor between the capacitor and amplifier input delivers a nearly constant current sufficient for reliable limiting operation of the amplifier. An additional circuit consists of a resistor (8) connected to a keying stage (9). It generates a voltage during the rear blanking period of the line synchronisation pulse. This voltage is about equal to the blanking voltage of the frame blanking synchronisation signal at the required or correct synchronisation pulse amplitude between the junction point of capacitor (1) and resistor (2) and frame. This switching stage has a high source resistance during the remaining line deflection period.