Abstract: An AC noise filter designed to filter the small amplitude AC noise of all frequencies by using inline reverse coupled parallel PN semiconductors which offer a high resistance to AC voltages of less than a diode voltage drop. Inline reverse coupled parallel PN semiconductors are used in the AC power line-side as well as in the neutral-line side. For additional AC noise filtering, capacitors are coupled across the AC or DC power source input and at the output to the AC or DC user. For the AC power, IEC connectors are used at the input and output for worldwide use.