My friend has a tire checking device that was homemade. It is simple looking, consisting of a small circuit board with a cable (6') going to a wand. Inside the wand is a coil similar to a small tesla type coil. When operating properly the device is turned on and the wand is moved inside a vehicle tire to find holes in the tire before the tire is repaired. Ther will be an arc from the wand (several inches)to the hole or nail or whatever is in the tire. It's a neat trick but unfortunatley it no longer works. Has anyone had any experience with such a device. Any help would be greatly appreciated. The guy that built this unit is no longer around.