HV protection circuit for tv receiver tube - has comparators to reduce HV supply and disconnect it at higher level

摘要

The high voltage protection system for the tube of a T.V. receiver includes a voltage divider with two comparators in parallel with their outputs connected to a third comparator. The output of the third comparator is connected to a transistor stage with a connection to the rectified power supply section so that this is cut off when the high voltage supply exceeds a safe level. These comparators are also connected to a fourth comparator connected to the line between the power supply section and the high voltage transformer, with an output connected to a triac so that when the drive voltage reaches a given level, a proportion of the drive voltage is short circuited.