Elimination of the ballast resistor in D-C power supplies

BALLAST RESISTORS, when required with conventional d-c power supplies, can be eliminated by designing appropriate terminal load characteristics directly into ¿virtual-ballast¿ power supplies. There are several ways in which this might be done. One method, the inductive-ballast power supply, is presented in this paper. It permits operation at close to 100-per-cent efficiency and, moreover, places minimal stress on circuit components. This type of supply may therefore be considerably smaller, less expensive, and more efficient than its conventional equivalent.