This is a fairly simple booster with a resonance switch in front. The switch will drop the resonant frequency by 2-3 kHz in one position and 3-5 kHz in another. It's the resonance adjustment that I'm really interested in.
Thanks Vince for the Link. I Built this boost and was very impressed by the full, rich tones it gives single coil pickups and I also tried it on Humbucker pickups. Great Stuff.