A Transistorized Fifth Harmonically Tuned Horizontal-Deflection Circuit for Large-Screen Color TV

One of the problems associated with horizontal deflection and high voltage systems utilizing third harmonic tuning of the flyback transformer for large screen color TV (25"-90°tubes) has been the high voltage regulation. In tube sets, the shunt regulator has been widely used; and, more recently, a feedback scheme to the horizontal output tube has been used to achieve better regulation. However, the shunt regulator has proved undesirable because of reliability, and it is a potential source of X-rays. The feedback scheme does not lend itself to transistor circuitry because the horizontal transistor is operated as a switch. Therefore, in making a transition to transistor horizontal deflection and high voltage systems, regulation becomes a problem.