pulse induction

Hi all Newbie question. I've been playing around with my girlfriends Gold bug 2 at our property in Bealiba, central vic and discovering the joys of hot rocks. I've been reading that it's a good machine for small stuff etc but it's good to have a secondary rig to compliment it. The pi machines...

http://www.deeptech-bg.com/Understanding_The_PI_Detector.htm takes a bit of reading, if youre like me, maybe read it a few times, lol!