Apparatus and methods disclosed herein are associated with a primary side voltage and/or current regulator (PSR) in a flyback power converter. Apparatus and methods sense characteristics of a waveform generated in an auxiliary primary winding of a flyback transformer at a single terminal of the PSR. The waveform is analyzed, and error signals derived therefrom are used to maintain constant voltage and/or constant current regulation and to generate a peak current stabilization signal that is independent of line input voltage.