TELEVISION RECEIVER HIGH VOLTAGE PROTECTION CIRCUIT

摘要

RCA 74,681 A television receiver high voltage generator includes a high voltage transformer for developing an ultor accelerating potential at an ultor output terminal. A high voltage protection circuit comprises a comparator and a disabling circuit coupled to an output terminal of the comparator. An ultor accelerating potential representative signal is applied to an input terminal of the comparator to disable normal television receiver operation when the ultor accelerating potential exceeds predetermined values. To avoid nuisance tripping or energization of the disabling circuit at lower beam current levels, beam current information is applied to an input terminal of the comparator such that at low beam current operating levels, a greater ultor accelerating potential must be exceeded before the disabling circuit is energized, than at high beam current operating levels. The beam current information is applied to the comparator through an amplifier having an output terminal coupled to an input terminal of the comparator and having a beam current representative signal applied to the input terminal of the amplifier. Biasing of the amplifier is such that over a substantial range of ultor beam current values, the amplifier exhibits a certain gain characteristic but exhibits a substantially different gain characteristic outside this range in order to provide the disabling circuit with an overcurrent shutdown capability.