Dummy coils have been used in the past, but I've never seen it used in the manner that I used it in," he said. "It's wired into the circuit in a unique fashion to where it knows to get out of its own way when it's not needed."
"The user doesn't have to worry about turning it on or off; it automatically happens when he selects his pickups normal with the normal three-way pickup selector. When you are in the middle position, for example, the two normal pickups cancel each other out and the dummy coil is automatically inoperative. The pickups are 360 degrees out of phase with each other, which makes them actually in phase but opposite polarity. One pickup is picking up the top side of the sine wave and the other pickup is picking up the bottom half." - the blueshawk says - this is the same principle at work in humbucking pickups.