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Compensated Bidirected NAL Deflection Yoke Driver

IP.com Disclosure Number: IPCOM000076667D
Original Publication Date: 1972-Apr-01
Included in the Prior Art Database: 2005-Feb-24
Document File: 2 page(s) / 35K

Publishing Venue

IBM

Related People

Williams, ER: AUTHOR

Abstract

Illustrated is a circuit for providing a linear current ramp through a single-ended yoke winding, which does not require heat sinks and which can be readily altered to compensate for a wide range of yoke resistances.

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Compensated Bidirected NAL Deflection Yoke Driver

Illustrated is a circuit for providing a linear current ramp through a single- ended yoke winding, which does not require heat sinks and which can be readily altered to compensate for a wide range of yoke resistances.

At the input I the potential is positive during retrace and at a zero level during sweep time. When the input voltage is at zero, transistors T2, T4, and T5 are off. During this time T1 and T3 which along with resistors R2 and R4 and capacitor C1, which form a Miller integrator, are active and impose a voltage ramp across the deflection yoke. During the first half of the sweep, current flows from C5 through diode D3 and the deflection yoke to the power supply since at the end of the previous retrace, the current through the yoke was negative and thus flowing into the supply. This negative flow resulted from T5 and T2 being on due to the positive potential on the input. This caused T3 to be off, thus causing the current which had been flowing from the power supply through T3 to ground to flow through the tuned circuit formed by the deflection yoke and C3. During the second half of the sweep, the current flow reverses and flows from the power supply through T3 to ground when the voltage across the deflection yoke overcomes the negative current flow.

The ramp to overcome the resistance in the yoke, which resistance causes nonlinearity is provided by R2, C1 and R4 as is conventional in a Miller integrato...