ECN Forum Forums General Topics of the Trade General Discussion Area Charge your "Tesla"

The flaw in that theory is the 120 would not saturate the core of a 240v primary and your power would end up being very low. I have had that problem in the past trying to use 240v transformers on 120.
I was really thinking more along the lines of tricking up the voltage regulator in the alternator like those old JC Whitney boxes that gave you 120v from your car.
I know an alternator guy and I was going to ask him. I think you need an external VR to do it.

I don't think you want to saturate the core of the transformer. If you did, your inductive reactance will drop to almost nothing. Now have a very heavy iron core resistor.

If the automotive alternator uses the casing as the negative return path, you might be able to 'float' the alternator with a 30 volt zener to get the output up to 42 volts.

Twenty years ago when I used to fix welding equipment, there were some cheap motorized welders that were nothing more than a B&S engine driving an alternator with rheostat controlled field excitation.

Your alternator guy might be able to find a 36 volt regulator used for old boats.

Years ago I built one of those welders with an alternator from a Toyota.

Getting a regular alternator up to 42V shouldn't be a problem - mine gave 60V easily. Remove the internal regulator and provide field voltage from a different source. Vary your field voltage to "regulate" the output. If you have electronics background it's not a huge matter to rig up an op amp, power transistor, and a few resistors to regulate it to whatever voltage you want.

Thanks that was what I was thinking.
I may poke around on the internet a little, no use reinventing the wheel.