Transformer Connections

Discussion in 'The Projects Forum' started by williamthomas, Aug 20, 2013.

  1. williamthomas

    Thread Starter New Member

    Jul 26, 2013
    17
    0
    Hi...
    I'm building a power amplieir. I want to connect my power transformer with two bridge rectifiers so that the output will be 2 x +- 24 volt. how should the transformers wires and bridge rectifiers be connected?

    Thanks
     
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  2. Ramussons

    Active Member

    May 3, 2013
    557
    92
    As Shown. You need 2 of these.

    Transformer White & Blue is One set of AC input
    . . . . . . . . . Yellow & Green is the Second set of AC input

    Ramesh
     
  3. williamthomas

    Thread Starter New Member

    Jul 26, 2013
    17
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    what about if i want a common ground for them?
     
  4. MaxHeadRoom

    Expert

    Jul 18, 2013
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    If separate AC secondaries, the DC commons can be connected.
    Max.
     
  5. williamthomas

    Thread Starter New Member

    Jul 26, 2013
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    you can see the attached diagram in thread nr 1.
     
  6. MaxHeadRoom

    Expert

    Jul 18, 2013
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    I just mentioned in case someone tried it with windings in common.
    Max.
     
  7. Johann

    Senior Member

    Nov 27, 2006
    190
    30
    Yes, like Ramussons suggested, make two circuits like that and connect the dc sides of the rectifiers in series, i.e. negative of top rectifier connects to positive of bottom rectifier. This becomes the common or 0V rail. The top rectifier's positive becomes your positive rail and the bottom rectifier's negative becomes your negative rail.
     
  8. MaxHeadRoom

    Expert

    Jul 18, 2013
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    I took it to be Commons connected/referenced together not in series?
    Max.
     
  9. williamthomas

    Thread Starter New Member

    Jul 26, 2013
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    0
    then i still have two of each wires left..
     
  10. ErnieM

    AAC Fanatic!

    Apr 24, 2011
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    Try this:

    [​IMG]

    (FYI: It's not a guess)
     
  11. Ramussons

    Active Member

    May 3, 2013
    557
    92
    The 2 wires are Orange and Orange, which, as per your post, are 230 V AC.

    Ramesh
     
  12. JoeJester

    AAC Fanatic!

    Apr 26, 2005
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    I took that to mean two +/- 24V supplies.
     
  13. MaxHeadRoom

    Expert

    Jul 18, 2013
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    That was my take also?
    With the intention of making both -ve's common?
    Max.
     
  14. Johann

    Senior Member

    Nov 27, 2006
    190
    30
    Check out your bridge: 2 cathodes = Pos. out and 2 anodes = Neg. out.
     
    ErnieM likes this.
  15. JoeJester

    AAC Fanatic!

    Apr 26, 2005
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    As far as being two +/- 24V supplies, that's not going to happen with two 18 volt secunder coils in the illustrated transformer. You can get one. You can however, get two +/- 9 volt supplies.
     
  16. shortbus

    AAC Fanatic!

    Sep 30, 2009
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    Doesn't the secondary voltage times 1.41 minus two diode drops still apply to this circuit? 18 X 1.41 - 1.4 = 23.98 Isn't that close enough for government work?:D
     
  17. JoeJester

    AAC Fanatic!

    Apr 26, 2005
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    It is under most circumstances. But I took it as the OP wanted two + and - supplies. If they wanted one + supply and one - supply, that might be "close enough" depending on the load and the current rating of the transformer.
     
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  18. ErnieM

    AAC Fanatic!

    Apr 24, 2011
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    Thanks Johann, serves me right for not double checking an image I got off teh interwebs.


    [​IMG]

    This is what I meant. Really. Note the dots on the secondaries, that's important. Colors same as the original (I just couldn't fit them at 5 o'clock in the morning).

    I'll be quiet now.
     
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