I'm not familiar with centre tapped transformers. I assume there is three terminals, 2x 12v and 1x 0v, and the two 12v can add up to 24v?
I have two transformers with varying ranges, but they don't sound like that. They have several output voltages.
Post what these voltages are.
If I had 15v coming out of the transformer, and in theory I had the the voltage regulator set to 1.5v, would a normal heatsink made for a voltage regulator be enough to dissipate the heat?
The 15Vac from the transformer would be rectified and smoothed to about 20Vdc.
So the 'off load' voltage would be 20Vdc, at 1amp into a load at 1.5V the
20Vdc would drop to about 15Vdc, so you would have 15V-1.5V across the regulator..
So thats 13.5V * 1amp = 13.5Watts!!!!!