Excal 1000, Excal II, Sovereign GT, CZ-20, Tiger Shark, Tejon, GTI 1500, Surfmaster Pulse, CZ6a, DFX, AT PRO, Fisher 1235, Surf PI Pro, 1280-X, many more because I enjoy learning them. New Garrett Ca
Yes, it is not worth the trouble unless you have all the testing equipement, and materials. You could fry the guts of the detector with the wrong setup. It is far cheaper to buy a new coil.