Wiring a block transformer

[tasar731]

Hi All,
I'm new to this game and looking for a bit of advice.
I'm building a blue tooth loudspeaker for my shed and had ordered a typical frame type three wire output transformer to power the pre-amp section of the speaker. However I was sent a block transformer which I was told would do the job but it has a four wire output marked 12v ; 0v and 12v ; 0v.
The pre-amp has input for 12v ; 0v ; 12v. I'm unsure what to do.
Can anyone point me in the right direction?

 

[Minder]

Appears to have dual secondary windings, they would be paralleled if just needing one 12v source.
They should be indicated as to the connecting polarity, normally by a Dot on the DWG or marked as 0 & 12 on the transformer.
Ensure the 0's go together and the 12's go together.
If not sure, there is a guaranteed method using a meter. I can post it if you need it.

 

[tasar731]

Appears to have dual secondary windings, they would be paralleled if just needing one 12v source.
They should be indicated as to the connecting polarity, normally by a Dot on the DWG or marked as 0 & 12 on the transformer.
Ensure the 0's go together and the 12's go together.
If not sure, there is a guaranteed method using a meter. I can post it if you need it.

Thanks for the reply Minder, the pins are clearly marked on the transformer so no issue there. If I wire the transformer in parallel as you suggest this would give me a two wire output 12v 0v, but the preamp is looking for 12v 0v 12v. I must be missing something basic?

 

[Minder]

Then you will need to series up the secondaries, 0 12v --ov 12v
And make the 12v--0v the CT

 

[tasar731]

Then you will need to series up the secondaries, 0 12v --ov 12v
And make the 12v--0v the CT

Thanks Minder, I think I've got it now, I didn't realise i can join the two 0v pins to form the CT, cheers.

 

[Minder]

You don't join the two zero pins but 0 and the other 12v. IOW, 0-12-0-12

 

[tasar731]

Thanks Minder, disaster averted. Wired up now and producing expected voltages, thanks again.