Abstract: In a television receiver having an SCR switching regulator power supply, excessive power supply loading or high line voltage may cause abnormal operation of the switching SCR resulting in a rapid variation of the regulated supply voltage above its regulated level. This voltage variation causes high peak current in the horizontal output transistor, causing it to fail. A detector circuit monitors both the average current and the peak current through the horizontal output transistor and causes the receiver to be disabled in the event either current level becomes excessive.

Abstract: A television receiver incorporates a common mechanism for disabling the receiver via the high voltage or fault protection circuit and via the remote control during normal operation. In one embodiment, the protection circuit is energized by the remote control in order to turn the receiver off. The remote control is used to reset the protection circuit in order to turn the receiver on.

Abstract: A horizontal deflection circuit for a television receiver includes a switching output transistor which may experience high collector current under certain receiver conditions. A resistor is placed in the transistor emitter path to provide negative feedback to the base drive circuit in order to control transistor conduction. The horizontal deflection yoke is returned to the emitter of the output transistor so that yoke current will not flow through the resistor, which would otherwise degrade deflection linearity.

Abstract: A high voltage generator of a television display is responsive to an alternating voltage, such as a retrace pulse voltage, for developing an ultor voltage at an ultor terminal. A protection circuit for the high voltage generator includes a comparator that develops a television display disabling signal when activated. A circuit that develops a sense voltage representative of the ultor voltage is coupled to an input terminal of the comparator so as to develop the disabling signal when the ultor voltage exceeds a predetermined level. To provide an overload disabling capability, an ultor beam current sensing circuit is coupled to the input terminal of an operational amplifier. The output terminal of the amplifier is coupled to a bias voltage source and to an input terminal of the comparator.

Abstract: A retrace pulse voltage is applied to a first flyback transformer winding of a horizontal deflection circuit to develop retrace pulse voltages across other flyback transformer windings. Second and third windings of the flyback transformer are coupled in a series arrangement with a controllable switch across a source of input voltage. A regulator control circuit turns on the SCR at a controllable instant within the trace interval of each deflection cycle to generate input current in the series arrangement. When the retrace pulse voltage is applied to the flyback transformer first winding, the input current begins to decrease in magnitude, commutating off the SCR within the retrace interval. The leakage inductance associated with the series arrangement of flyback transformer second and third windings and the total reflected retrace pulse voltage developed by the two windings determine the instant within retrace that the SCR is commutated off.

Abstract: A horizontal deflection circuit drives a deflection winding and an ultor voltage generator. The energizing voltage for the horizontal deflection generator is regulated by a switching regulator including an SCR, a filter inductor, a filter capacitor and an SCR turn-off winding. The turn-off winding couples a retrace pulse to the SCR during each horizontal retrace interval to turn the SCR off in preparation for the following regulation interval. A second winding is magnetically coupled to the deflection circuit and through a diode to the filter inductor for providing a path by which current can continue to flow in the filter inductor during SCR nonconduction and which effectively couples the filter inductance across the deflection winding. Variations in kinescope beam current cause corresponding variations in the current through the filter inductor at the end of the trace interval.

Abstract: A high efficiency switching regulator for maintaining a constant d.c. voltage is described. An efficiency improvement of better than 20 percent is realized by use of an alternate low impedance current source for supplying base current to the control transistor of a switching regulator.