[sdiy] basic transformer question (delurk)

[ftg]

Hi,

Building my first PSU and have a really basic question.

My circuit requires 18/0/18 from the transformer (it's a for +/- 15 PSU).

The 2nd windings on my transformer are labelled as 0 18 0 18.

ie there is no center tap as such??

So do i wire it in series or parallel?

1) join the two 0v outputs and use each of the 18s

or

2) join the central 18 & 0 and us the outside 0 & 18 to the PSU PCB.

This is really dumb, i know. And dump questions and mains voltage are
not a good combination!

Any help appreciated.

ac