At one time I had a better pic of the K-II innards and the IC appeared to be a LM324 quad op amp (of course I can't find that pic now). They're probably wired up as comparators to light the LEDs at different signal levels.
You think those 4 traces are the "coil"? I think they're just circuit traces to other components on the board.
The K-II wasn't designed to be a ghost detector, even though some ghost hunters (both real and fraudulent) do use them. The K-II was intended as a device to detect EM fields, such as those coming from electrical wires. Here's a link to the manufacturer's web page (no ghost hunting content here):
Safe Range K-II EMF Meter
What I find interesting about the K-II is it detects the ELF range down to 50Hz.
As for ghosts, AFAIK they can manipulate electrical fields to do their ghostly things. These manipulations can be picked up by an EMF meter. My hunch is their manipulations would be in the ELF range down to near-DC frequencies.
But, back to my project. No more ghost talk to rile up the skeptics. I attached pics so you guys can see the end result. Yes, messy I know, I'm not that good with a dremel, yet.
I'm also starting work on "Revision 2". I wound the "Coil from Hell" last night. Almost 400 feet of 30-gauge magnet wire on a ferrite core. The thing is almost an inch around. Some informal tests with an op-amp and a pair of headphones doesn't show much of a gain increase over the original circuit, but I am still working on the op-amp circuit. Sort of doing the "Op-amps for Complete Morons" google course at this point.
My goal is get it to have good gain down to a few hertz.
UPDATE: Here's another pic of the K-II innards. In this pic you can read the markings on the IC, and it definitely appears to be a LM324.
**broken link removed**