Switching power supply of Beijing brand black and white TV

Published:2011/11/13 21:28:00 Author:May | Keyword: Switching power supply, Beijing brand, black and white TV | From:SeekIC

The diagram shows switching regulated power supply of Beijing brand white and black TV. It is a typical example of low voltage switching regulated power supply. This power supply has three ways of DC output that is 18V, 28V and 12V. Among them, 28V is directly outputted by bridge type rectifier; 12V is output after 28V voltage beingregulated by switching voltage regulator; 18V is output by half wave rectifying and filter circuit. VZ601 is switch power adjustable tube. Self-excited harmonic oscillator consists of VT601~VT603, R601, C601, etc. This power supply belongs to pulse width modulation type switching regulated power supply. When 12V voltage isincreased because of some reasons, the base potential of error amplifier tube VT601 is increased. Its collector potential is decreased, base potential of VT603 is also decreased, the output pulse width of switching adjustable tube VT601 is narrow, it makes increased voltage decreased again.



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