A system for extracting energy from an energy storage device configured to supply direct current (DC) energy at a nominal voltage rating comprises a first node dimensioned and arranged to receive direct current energy from the energy storage device. Embodiments include a self-oscillating circuit having primary and secondary windings wound around a ferrite core, wherein a positive terminal of the primary winding is tied to the negative terminal of the secondary winding at the first node, and wherein a positive terminal of the secondary winding is coupled to a second node, the second node being coupled to a load requiring power to be supplied at one of a voltage less than, equal to, or higher than the nominal voltage. Some embodiments further include a transistor having a base resistively coupled to a negative terminal of the primary winding and a collector coupled to the second node.