I'm working on building a power supply (120VAC to ~12VDC). The Transformer puts out 13.6VAC without any modifications. But once I put on a diode on each side (make into DC) then put on a 1000 microfarad capacitor to eliminate the cosine curve it bumps up to 18VDC. Without said capacitor it registers 6VDC (probably due to the cos curve still existing). I'm at a loss here, I tried to use a larger (4700) capacitor and the voltage was the same, so I don't believe it was that at fault. It's a typical 3 output transformer with one black and two yellow wires with the yellow ones being used. Thnx ahead of time!