tutorials for autotransformer designing

Hello, Mighty. I built an autotransformer which caused the electricity in my room to go out when the fuse blew. The one-pound iron wire core had been driven into saturation, although I was able to get a common household light bulb to light dimly for a few seconds before the fuse blew. I will be needing a larger core. Actually, I have decided that to build a generator will be a better course of action. It is possible to arc weld with an automobile alternater. I am going to build from scratch, though.