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Wiring a block transformer

tasar731

May 30, 2021
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May 30, 2021
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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

Apr 24, 2015
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Apr 24, 2015
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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

May 30, 2021
4
Joined
May 30, 2021
Messages
4
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

Apr 24, 2015
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Then you will need to series up the secondaries, 0 12v --ov 12v
And make the 12v--0v the CT
 

tasar731

May 30, 2021
4
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May 30, 2021
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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

Apr 24, 2015
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Apr 24, 2015
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You don't join the two zero pins but 0 and the other 12v. IOW, 0-12-0-12
 

tasar731

May 30, 2021
4
Joined
May 30, 2021
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Thanks Minder, disaster averted. Wired up now and producing expected voltages, thanks again.
 
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