Inductorless pincushion correction circuit

摘要

An internally generated raster scanning circuit includes self correction for pincushion distortion by multiplying the horizontal parabolic wave form by the vertical saw-tooth wave form. The multiplier is biased to provide the required 180 DEG phase shift at the midpoint of the waveform. The multiplied signals are coupled back to an input of the existing power amplifier and a corrected current is then supplied to the vertical yoke coil, requiring no added reactor transformer. The balance or ratio of the top and bottom correction currents can be adjusted as required by a simple control in the multiplier circuit.