Abstract: A power supply apparatus in which a full-wave rectifier is connected to an A.C. power source, a load circuit as a parallel circuit of a smoothing capacitor connected in parallel to a load is connected to outputs of the full-wave rectifier through a switching element and a capacitor, and a control means for adjusting a voltage across the capacitor is provided in parallel to the capacitor to cause a sum of voltages across the capacitor and smoothing capacitor to be proportional to an input voltage and to cause a voltage corresponding to a difference between the input and output voltages to appear across the capacitor to apply a desired constant voltage to the load, whereby an envelope line of an input current becomes proportional to the input voltage under control of switching elements.

Abstract: A power source device minimized in size with required number of switching and energy-storing elements for a power conversion reduced is provided by connecting a first energy-storing element through a first switching element in parallel to a power source, connecting a load circuit having a parallel connection of a voltage stabilizer and a load through a second switching element in parallel to the first energy-storing element, connecting an ON/OFF controller to the first and second switching elements for their controlling, and providing a voltage controller including a second energy-storing element and further switching elements for controlling an output voltage to the load circuit through switching operation of the further switching elements.