So, what the heck is a ghost box?

I mentioned in a class a while ago about the "ghost box" one of the guys used while we were investigating. I found a link that seems to explain it fairly well. Obviously, it's not a scholarly website, considering this a pseudoscience. However, it does mention the legend of Thomas Edison that the guy using the ghost box did mention to me.

Maybe I should try to make one?

http://www.angelsghosts.com/ghost_box