I see, one issue is the current drawn from the variac when its o/p is 12v will be over 3 times what the 36v o/p is, would this overload the variac?, I suspect so.
Yes there are devices that will do that, one of the lm25xx monolithic simple switchers might do it though I think they top out at 30v, so you might have to use a switcher chip such as the staple diet TL494, or maybe sg3525.
Yes there are devices that will do that, one of the lm25xx monolithic simple switchers might do it though I think they top out at 30v, so you might have to use a switcher chip such as the staple diet TL494, or maybe sg3525.