Abstract: To provide a power rectifier for connection to an a-c power network which has low ripple at the d-c output, and low harmonic content at the a-c side, particularly for feeding a d-c - a-c inverter frequency generator providing output in the audio or low supersonic range for supply of gas discharge or fluorescent lamps, a wave-shaping network is connected to the a-c side of a standard bridge rectifier unit such that the a-c power applied to the rectifier is of approximately trapezoidal or rectangular or square-wave shape; a suitable network is the combination of an inductance (D) and a storage capacitor(C1) in a T-network or in a series resonant circuit, in which the quadrature VA of the choke (D), at network frequency, is about 60% of the power to be supplied by the rectifier, with a capacitor (C1) in a T-network configuration of such value that the resonant frequency of the L/C circuit is about 2.2 to 2.6 times network frequency or equal to network frequency, when in a series resonant circuit.