Video output stage for cathode of in=line colour tv crt - has series resistor circuit applying AC and DC signal to feedback circuit

摘要

The stage consists of a differential amplifier, an output stage and a negative feed-back circuit between the stage output and differential amplifier for adjustment of the d.c. voltage working point determining the black level, and of the output signal level. A series circuit comprising at least one potentiometer (B4) and a variable resistor (R2) is inserted between the video output stage output (A) and a supply voltage source terminal. The potentiometer (R4) wiper and the resistor (R2) are connected through a switch and a capacitor (C1) with each other and with the feed-back circuit. The negative feed-back a.c. signal at the potentiometer wiper determining the amplitude, and the feed-back d.c. signal at the variable resistor determining the differential amplifier working point, are fed into the negative feed-back circuit.