| 摘要 |
<p>1496294 Automatic control of voltage and current NCR CORP 4 March 1976 [10 March 1975] 08683/76 Heading G3R A D.C. supply circuit includes a first differential amplifier which controls a voltage regulating device by comparing the value of the circuit output voltage with a reference voltage. The magnitude of the reference voltage is automatically reduced by a second differential amplifier if the output current exceeds a predetermined level. As shown, a load 2, which may be a data processor, is energized by a number of identically constructed supply circuits 1, 1', 1" connected in parallel. Each circuit includes a series regulating transistor 4 controlled by an amplifier 5 responsive to a potentiometer 10 sensing the load voltage and a reference voltage at the junction 6 of a divider 7,8. The load current is sensed by a series resistor 15 providing one input to a second amplifier 12 which is also connected to a reference source 13, 14. When the current exceeds a given level, the amplifier 12 turns on a transistor 11 which effectively reduces the reference voltage for the first amplifier 5, thus limiting the current by reducing the regulated voltage. When several supply circuits 1, 1' &c. are used, that regulated to the highest voltage will initially supply the load until the limiting current value is reached, whereupon constant current operation will take over and further current demand will be supplied by one or more of the other circuits.</p> |
