Here`s the "alternative", regulated versions, pretty common. See "ordinary", not CT transformer and Graetz bridge of your choice (probably the best - Schottky). Regulator(s) need some heat sinks. Also, two version of grounding, one simple - negative pole to common star ground, and other "symetric", center tap is grounded (2*100 Ohms resistors) - preferable, but not really critical...