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.
I usually am taking microwave oven transformers or metal halide lighting transformers and gutting them so I can rewrap them for some other propose. So far I have used them to make a spot welder and welding inductors. I break apart the welded core halves with a grinder. If I am not going to reuse the coil then I just chisel the unneeded coil apart.
Sounds weird, but back in the 60's I used to take apart small transformers for the fine copper wire and use it with a needle to sew up my gloves, mocs, etc. The old cotton thread used to sew them would rot in a couple of years and it was hard to find linen thread with bees wax, the standard rot resistant thread. It worked well and lasted for years. They had nylon thread back then, but it was slippery and would loosen up, the wire was flexible, but stiff. Used it to wrap knife and chisel handles, repair cracked hoe handles, etc.
It's great to re-purpose otherwise useless stuff. A little bit of thinking and physical effort can go a long way.
Beyond taking them apart for other projects , it is good to know what the transformer is good for the way it is. Knowing how and why things work is important . coils are practically a part of every aspect of electronics dropping and rising voltages and suppressing noise or creating it. Earliest electromagnets were transmitting Morse code across country also the beginnings of the telephone. If you know how these things operate, you can reproduce them your self, and if the grid goes down you can reestablish communications .
If they're older transformers they can contain some carcinogenic oils. Your buddy might have given them to you rather than hassling with proper disposal.
These don't appear to have been oil filled, but some of the larger old transmission transformers did contain PCB's.
Thats is the FIRST thing I thought of , NAW they are all dry mounts , in the posted pix .,,,or NON- PCB's . My trade & did the 60's with those & still to date . 750HL , PCA's , PCB's all the way down to PCN's is carcinogenic oils that you'll grow a second head .. PCA-PCN smell like fish -2- poop , the rest smell like new electronics or the smoke was set free ,As in burnt Sloth
