Positive voltage converter.

[jorgen.bergfors at idg.se]

>OR Use a second bridge rectifier off the transformer, but connect it to the
>transformer through some bipolar capacitors. The rest of the circuit would
>be pretty much as per a standard regulator.

I don't think you need bipolar capacitors. I'm currently working on a project that uses this approach. And I use ordinary electrolytics.
I took this part of the circuit from Elektor Summer Circuits 1978, and there is no mention of bipolar capacitors in that mag.
Any other opinions?

/Jorgen