Colour tube convergence correction coil - has superimposed AC and DC currents adjusted by resistance network and differential amplifier

摘要

A static and dynamic convergence correction system is for colour television tubes. A correction coil for each beam on a magnetic core on the tube neck carries correcting currents at line and frame frequencies; each coil is connected between the output terminals of a differential amplifier with two amplifier units to the inputs of which the dynamic correction signals are applied through a resistance network; the bias voltages for the amplifiers are derived from a potentiometer with earthed tap forming part of a second resistance network connected between the third electrodes of the amplifiers. The superimposed AC and DC currents through the correction coil are varied by adjustments to the resistance networks.