A buddy who works in the AC business gave me several old transformers that were removed from defunct rooftop AC units. These have the silicon steel plates welded together at the top and bottom for a total of 4 welds, and you have to cut these welds out with a hacksaw. Then you will need something to pound out the friction coil holder plugs, I used a bolt smaller than the diameter of the plugs. Once these are out the plate body will come apart and you will have to tap the coils off with a hammer using a block of wood against the coil to keep from damaging the wire, working them off carefully . I salvaged 3 lbs. of 18 gauge enamel coated copper wire, about 300 feet, and some smaller wire in the other coil too. I will be using the 18 gauge for a 100' long wire antenna, and to wind a coil for a crystal radio, which will be another how to do it.