I tried what Gunnar was doing in his video in all metal no motion, with a nail, a gold ring and foil. Not working very good, when pressing the retune button, it goes silent but when i move the coil it blares loud and stays on and won't go off, have to switch to all metal or discrimination to get back to normal. Also i'm getting static and when i ground balance in get static. Moved to different area and same static. I will check it out at the park and in different areas that i haven't had any problem with electrical interference