I am currently building a DC power supply for a HHO Fuel cell. I am looking for HIGH current at a relatively low voltage (12-15 volts). I already have modified a MOT (Microwave oven Transformer) for high current. I replaced the high voltage secondary with 3 secondaries each consisting of 12 windings of 16 gauge wire. Each of the secondaries are in parallel and then rectified. The 16 gauge wire is rated at 24 amps according to MCMASTER-CARR where it was purchased(Here is the product number of the exact wire that I am using if you don't believe me - 7587K079). So do the math and my 3 coils can withstand 72 amps within the rating of the wire. Anyways my problem is that I get about 9.2 volts from the secondary and I am sure my bridge rectifier will drop that below 8 volts which is where it needs to be at to power my HHO cell. I have thought of a solution but was wondering if anyone could point out flaws or offer better solution. So here is my solution: I want to modify a 2nd MOT for high current and then put it in series with the other MOT I have. I think that this would double the voltage, however I have not had much experience with AC and especially power sources connected in a series-parallel fashion(Remember that each MOT has 3 secondaries that are in parallel). PS: FYI After much research I have found that a Router Speed Controller works wonders for controlling transformers.