help with power supply

Is there any way to build ~14VDC power supply from household current 115VAC that has alot of amperage.....I would like to put a car amp in my home and it pulls around 115 amps at 12VDC so my requirements would be a 13, 14, or 15VDC power supply that can produce ~120 amps. Can one be made from a microwave or something like that? or whats the highest ampreage one i can make around 14 volts?
 
Well, 115 Amps x 12VDC = 1380 Watts. So at least it's still somewhere in the basic range of being possible to have it run from a standard AC wall outlet in the USA.

You would need a hefty transformer VA rating, obviously, to make a linear supply of that size. But maybe you could use more than one (identical) transformer, running the secondaries in parallel. (Industrial/Control transformers might make it more economical.)

And the rectifiers would need to be quite beefy, rated to handle your current.

You would probably also need to parallel a lot of smoothing capacitors, to get each one's ripple current down to where readily-available caps with reasonable ripple current ratings could be used.

If you can find all of those parts (and I think that you could), then a linear supply should be possible. But that's not saying that you would want to do it that way.

Does it need to be regulated? If so, you'd need a little voltage headroom. But, conceptually at least, even a standard 12V three-terminal regulator should be able to work, for that, if you used enough pass transistors.

That seems like a terribly-'brute force' type of approach, though. You might have to be looking for arc-welder components. :)

Here's a nice little summary of many of the considerations needed for designing a simple linear power supply:

http://www.zen22142.zen.co.uk/Design/dcpsu.htm

I hope that someone else will come up with a more-sane-seeming way of approaching this.