In one embodiment, a power supply circuit has a power source, an inductor in series with a switching transistor connected to the power source, a pair of isolation capacitors connected across the switching transistor, a load connected to the isolation capacitors such that they isolate the load from low frequency energy from the power source, and a resonance circuit configured to amplify resonant ringing connected at least one of in parallel to the inductor or in parallel to the switching transistor.