Yoke Analog Vertical Deflection Systems

The yoke analog consists of a series RC network connected across the yoke. If the time constant of this network is exactly equal to the L/R time constant of the yoke, the voltage across the resistor of the RC network will, at all times, be the same as the voltage across the inductive component of the yoke. Since a linear current ramp through the yoke requires a constant voltage across its inductive component, linear scan can be achieved by sensing the analog voltage, comparing it to a D.C. reference voltage and amplifying any error voltage so as to change the yoke current in the required manner. The discussion compares the yoke analog system with conventional systems and cites the relative merits of the analog approach. The generalized design procedures for yoke analog systems are discussed and one particular circuit is covered in detail.