Help About Center Tap Transformer

Discussion in 'General Electronics Chat' started by johnb01, May 31, 2017.

  1. johnb01

    Thread Starter New Member

    May 31, 2017
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    If I use one end of secondary wire and a center tap to create power supply,
    can I ground the another end of the secondary wire (unused) or use a wire cap to be floated?
    If I should ground, better to tie with the center tap??
     
  2. Dodgydave

    AAC Fanatic!

    Jun 22, 2012
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    1-7 are the Primary windings, the thicker wires on the other side are the output, if you want more voltage out, use 1-6 as primary, or use 2-7, .

    It's probably designed for 0-250v in steps.....

    35_1323968058.png
     
    Last edited: Jun 1, 2017
  3. R!f@@

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    Apr 2, 2009
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    It depends on your rectifier configuration.
    4 diodes without the center tap or 2 diodes with the center tap ?
     
  4. johnb01

    Thread Starter New Member

    May 31, 2017
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    For instance, if I want to make a single end 12v power supply out of this transformer, I`m wondering for the another end, which is supposed to use for -12v line. If I short it with the center tap, that would destroy the transformer by drawing too much current?

    How would it be difference btw 4-diode configuration and 2-diode one?
     
  5. R!f@@

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    A center tap Tx can be used to make ±12V supply.
    You need to show us your transformer.
     
  6. bertus

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  7. AlbertHall

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    You can leave one of terminals floating but never short them together.
     
  8. R!f@@

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  9. ian field

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    If you ground anything other than the CT - you're confined to half-wave rectifiers.
     
  10. AlbertHall

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    I am not sure whether this counts as half or full wave but as far as the transformer winding is concerned it is full wave. It has one end of the winding grounded.
    [​IMG]
     
  11. ian field

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    Its a half-wave split rail supply.

    With a CT secondary & 2 more diodes; you can have FW split rail.
     
  12. Tonyr1084

    Distinguished Member

    Sep 24, 2015
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    This drawing shows two ways to hook up a transformer. The first is a transformer without center tap. Assume for the sake of argument it's a 12 volt output. The second is a transformer WITH center tap. Assume for the sake of argument it's a 24 volt output with center tap. From top and bottom leads (in the picture) you get 24 volts. BUT the center tap to either leg is going to be 12 volts. This is the situation where you can use just two diodes. Both drawings will produce the same sine wave.

    Transformer & Rectifer.png
     
  13. ian field

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    3 ways - add 2 more diodes to the CT secondary and you have a negative O/P as well.
     
    Tonyr1084 likes this.
  14. bertus

    Administrator

    Apr 5, 2008
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    Hello,

    As Ian told you two extra diodes and a buffer capacitor and you will have a dual voltage powersupply.
    Here is a random schematic with an example:

    Dual_supply.png

    Bertus
     
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