Hi im trying to make a spot welder and i have a question about transformers. For the purpose of this conversation we are gonna say I have a transformer with 100turns primary coil and 1000 turns secondary coil. The primary is simple to hook up to because it has 2 tabs to connect my power to. The secondary on the the other hand only has one output. The other end of the secondary is attached to the core? HOW does the microwave connect to it? Where is the positive and neg.

 

If the other end of the secondary is connected to the frame it appears the frame is automatically the other end of the secondary, or common frame.
I assume you are not using the original secondary anyway, just the two turn secondary for welding?
BTW the output is AC so there is no + & -.
Max.

 

The original secondary produces voltage in a source-to-ground circuit. It feeds the magnetron, and all circuits go back to ground.

 

Go back to google or YouTube and keep searching. You are supposed to remove the secondary windings so the connection it makes to the transformer frame will not matter. You then add the 2 to 4 turns of large cable and use the two ends of the new secondary you have added. The transformer frame is then no longer connected to anything.