Here is a direct quote from Paul McGwan: " we would look at the Harvester like this. A simple product designed to reduce power line noise above 10kHz. On its input there is a capacitor and a choke (inductor or magnetic device) placed across the power line, forming a simple bandpass filter. At the junction of these two elements energy is singled out at a specific frequency range. We then siphon off the noise energy and use it to fill up a capacitor. When the capacitor gets enough of the energy stored, it triggers an SCR which sends that energy to an LED and the light blinks; thus converting the noise energy to light. Bingo, the noise is removed from the line."
Tonight watching TV on the plasma. The Harvester ion the same duplex as the TV was going crazy. Steady blinking about 3/second.TV off. blinking stopped. (No other outlets affected, seems the Furman keeps the duplex separated electrically.)