| 摘要 |
1531009 CRT line output circuits COMMUNICATIONS PATENTS Ltd 17 Nov 1976 [26 Nov 1975] 48537/75 Heading H4T A TV receiver line output stage includes a line transformer 1, means 6 for drawing an EHT supply from the transformer, and means for controlling the flyback time to regulate the EHT. The regulation circuit includes a capacitor 9 which, during the rising positive part of the flyback, is coupled across a winding 10 of the transformer by the forwardly-biased diode 11. This slows down the flyback whereby the EHT is reduced. If, during a scan period, the capacitor 9 discharges through resistor 12 and transistor pair 13, then on subsequent cycles the flyback will be slower and the EHT reduced. The transistor pair is normally held conducting by the base current through resistors 14, 15. If the beam current increases, the EHT is reduced, causing a negative charge to build up on capacitor 8. The resulting current through resistor 7 reduces the base current in the transistor pair, thereby increasing the EHT. |
