A power supply apparatus and method of regulating is provided. A converter circuit includes a primary switching element and an auxiliary switching element. The auxiliary switching element is for transferring a reflected voltage signal. A transformer includes a primary and a secondary, the primary is coupled with the converter circuit. The primary and secondary each include a single winding. An output rectifier circuit is coupled with the secondary of the transformer. A resonant circuit is included in the converter circuit and is coupled with the primary. The resonant circuit includes one or more resonance capacitors that are configured for providing a transformer resonance. The transformer resonance comprises the reflected voltage signal, the capacitance of the one or more resonance capacitors and a parasitic capacitance of the transformer. The reflected voltage signal is reflected from the secondary to the primary. The resonant circuit converts a pulse train to produce a voltage potential, the voltage potential varying in proportion to an output voltage, the pulse train comprising a duty cycle proportional to a load current. A virtual output voltage feedback loop is provided. The converter circuit is responsive to a virtual output voltage reference signal in regulating an output voltage.