| 摘要 |
<p>1358801 Automatic voltage control BURROUGHS CORP 28 Jan 1972 [10 Feb 1971] 4064/72 Heading G3R In a regulated power supply, a series impedance is varied in response to a control current produced by a comparator receiving a reference voltage from a battery, and a second voltage indicative of the voltage supplied to a load. In the circuit shown in Fig. 2, a load 12 is supplied from an A.C. source 18 over a transformer 20 and rectifier 28, 30, and is connected in series with a transistor 62. Also connected across the rectified supply is a battery 52 with an associated charge control unit 54. In operation, when a switch 76 is closed, a coil 46 receives sufficient current from an auxiliary transformer winding 26 to close a reed switch 72 through which current may flow to the base of control transistor 62. The magnitude of the base current is determined by the output of a differential amplifier 94 which receives a signal proportional to the load voltage from a divider 88, 90 for comparison with a reference voltage across a Zener diode 82 connected across the battery 52. The transistor 62 regulates the output voltage between predetermined limits. If the A. C. supply fails, the load continues to be energized by the battery 52, until its voltage drops to a value at which the current in the coil 46 is insufficient to hold the switch 72 closed, whereupon the transistor 62 is turned off. The Zener diode 82 and resistor 78 provide a high resistance discharge path for the battery 52 which permits deep discharge during periods of non-use to overcome losses caused by cycling in nickel-cadmium cells.</p> |
