| 摘要 |
A projection cathode ray tube burn protection circuit includes a buffer transistor supplied with a 60 Hz square wave signal from an optical coupler. A PNP and NPN combination of transistors full wave rectifiers the buffer output. The rectified signal is divided down to reduce the magnitude of the alternating current components therein and applied to the base of a switch transistor that is normally maintained in saturation for swamping out the alternating current components. The switch transistor drives a high voltage shut down transistor and a blank transistor for shutting down the high voltage generating system and for blanking the cathode ray tube, respectively, in the event the power input to the optical coupler is disrupted.
|
