[sdiy] Easy transformer question

[Stephen Begin]

I finally got around to ordering the parts for a passive ring modulator, and
I remember somebody told me that the transformer they'd seen used was mouser
# 42tl028.  http://www.mouser.com//catalog/specsheets/164249.pdf

The circuit (http://www.synthfool.com/ringmod.html) shows two connections on
one side of the transformer and three on the other, but this transformer has
three connections on one side and four on the other, and I've been
unsuccessful in my search for some sort of transformer 101 type pages.
Basically what it boils down to is...do i only use two pins on the four pin
side, or do I pair some of the pins together, or what?

Thanks,
Steve