Back to back transformers - connecting the secondaries

[Yazoo]

I am going to use two back to back transformers to power a tube project. When I connect the secondaries together, in this case 0 - 12 and 0 - 12, which pins should be connected together? In one example I saw, it was 0 on one to 12 on the other and 12 on one to 0 on the other.

[mth5044]

I am going to use two back to back transformers to power a tube project. When I connect the secondaries together, in this case 0 - 12 and 0 - 12, which pins should be connected together? In one example I saw, it was 0 on one to 12 on the other and 12 on one to 0 on the other.

There isn't any 0 or 12 on transformers since you are using AC. The way you are phrasing it makes me thing you are using a DC? This will not work. You need to use an AC wall wart feeding a transformer, then rectifying afterwards. When you use AC, I don't believe it matters what you connect to what as you'll have a tough time distinguishing differences anyway.

[amptramp]

The only difference from connecting 0-0/12-12 and 0-12/12-0 is the phase of the output, which will not matter and not even be detectable if you are using a bridge rectifier.  If you are using a half-wave rectifier (not recommended), you may be able to see a difference on a scope, but it won't make any difference.

[Yazoo]

Great, that's put my mind at rest. Many thanks.

[GibsonGM]

Great, that's put my mind at rest. Many thanks.

It's been 20 minutes - are you still ok? 

[Yazoo]

Mellowed out nicely thanks. Could devote myself properly to watching Umbrella Academy with the full attention it deserves.