No no, I need two separate +15V supplies that are not only isolated from each other but isolated from the mains as well and they needed to be regulated. These supplies are super simple and I harvested the ICs, transformer cores, and the diodes from PC PSUs that I had laying around. I was just curious as to whether using the TL431 in the way I did would work in practice the same way it works in simulation. I assume it does, but sometimes Multisim does things that don't work in the real world. The datasheet for the TNY266 mentions using the TL431 instead of a zener but provides no example.