an electronic power supply utilizes a full wave bridge rectifier circuit whose alternating current voltage source is derived from a multi - primary and multi - secondary winding transformer whose windings are selectively disposed in series or parallel circuits , thereby enabling the apparatus to be effectively employed on a wide variety of a . c . voltage sources . two adjacent legs of the bridge rectifier employ s . c . r .&# 39 ; s gated simultaneously symetrically by pulses obtained from a unijunction transistor driven by the output of an operational amplifier whose input terminals are coupled to voltage and current sensing networks located at the output terminals of a filter coupled to the d . c . side of the full wave bridge .