| 摘要 |
A series regulated power supply arrangement for an image intensifier tube, comprises an oscillator circuit, a high voltage multiplier and an automatic brightness control (ABC) circuit. The ABC circuit includes a series regulator for producing a variable voltage to be supplied to the microchannel plate of the image intensifier tube. The series regulator comprises a junction power transistor having a load resistor connected to its collector. The junction of the collector and the load resistor is connected to one output terminal and the other end of the resistor is connected to a fixed, high voltage line derived from the oscillator circuit which is the second output terminal. A feedback amplifier is connected to the base of the transistor and one input of the amplifier is coupled to a tap of a potential divider coupled between one output terminal (CPI) and ground. The transistor is an off-the-shelf power transistor which is operated in class A with a current gain less than unity and at such a low maximum collector current that the risk of thermal runaway which would lead to secondary breakdown is avoided.
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