An AC electrical system has a source voltage and current interconnected through an energy storage device with a load. A unity power factor control circuit maintains unity power factor incorporating the steps of producing a sample and hold voltage related to the input voltage and an output voltage where the sample and hold voltage maintains constant values between pulses of a clock signal. A modulated signal at each clock pulse fall produces a current feedback voltage proportional to the source current, and as long as it is less then the sample and hold voltage, an inductor stores energy, and delivers it to the load each time the feedback voltage exceeds the sample and hold voltage and energy stored in the inductor is thereby delivered to the load, whereby controlling the amount of energy stored, the input voltage and current are drawn into phase thereby maintaining unity power factor.