Abstract: Electrostatic air cleaner apparatus is disclosed for use in conjunction with existing space conditioning apparatus which includes a transformer providing a low voltage (typically 24VAC) power signal. The apparatus includes a power supply which is adapted to be coupled to the output of the transformer for providing a low voltage DC power signal. A high voltage generator and regulator is included which is powered by the low voltage DC power signal. The generator and regulator includes a flyback transformer arrangement which generates a high voltage DC signal suitable for energizing the collector and ionizer stages of an air cleaner assembly. The generator and regulator also includes closed loop feedback for regulating the amplitude of the high voltage DC signal so that it remains at or near the optimum amplitude regardless of variations in the amplitude of the low voltage power signal supplied by the existing low voltage transformer.