In an example embodiment, an apparatus includes an LC circuit having a capacitive circuit and an inductive circuit connected in a circuit loop. The inductive circuit includes one or more inductive elements and a switching circuit. In a first mode, the switching circuit provides a direct-current charge voltage across the LC circuit and prevents oscillation of energy between the capacitive circuit and the inductive circuit by opening a switch in the circuit loop of the LC circuit. In a second mode, the switching circuit enables oscillation of energy between the capacitive circuit and the inductive circuit by closing the switch in the circuit loop.