Need help finding a transformer

Discussion in 'General Electronics Chat' started by Jotto, Dec 15, 2011.

  1. Jotto

    Thread Starter Member

    Apr 1, 2011
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    Have looked at digikey, allied, newark, but nothing is close to what I need.

    primary 120 vac input 1 amp

    secondary 6.3/3.15 center tap 300ma
     
  2. MrChips

    Moderator

    Oct 2, 2009
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    Jotto likes this.
  3. Jotto

    Thread Starter Member

    Apr 1, 2011
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  4. K7GUH

    Member

    Jan 28, 2011
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    Do you actually need the center tap? If not, see if you can find an inexpensive transformer with a 12 volt center tapped secondary. Connect two diodes across the 12 volt leads, back to back, so to speak. Your 6 volt
    fluctuating d.c. across the center tap and the joint of two diodes will give you a reasonable source for a 6 v.a.c. filament. I don't have a working scanner at the moment so can't post a diagram.
     
  5. Jotto

    Thread Starter Member

    Apr 1, 2011
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    I actually need 3.15vac secondary output. I was thinking of using a 6.3 filament transformer that was center tapped to get the 3.15.

     
  6. thatoneguy

    AAC Fanatic!

    Feb 19, 2009
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    Halfway down this page on the left is a 6.3vCT

    Filament Transformer
    6.3 vct @ 1 amp



    However, the price is worse than Radio Shack at $75 (Shipping included)

    This one looks much better (Down and to the right of the one above in the listing):
    Filament Transformer
    6.3 vct @ 4 amps


    Primary: 117 vac, 50/60 Hz
    Secondary: 6.3 vct @ 4 amps
    Dimensions: 3.675" x 2" x 2-1/4"H


    $18
     
    Last edited: Dec 15, 2011
  7. MrChips

    Moderator

    Oct 2, 2009
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    I think you misread the page. It says $10 for the F-13X 6.3V @600mA transformer.
     
  8. thatoneguy

    AAC Fanatic!

    Feb 19, 2009
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    I was looking at this one, diagonally up and right of the one you are referring to:
    (TP) P8648
    Stancor filament transformer. 1500 vrms test.
    Primary: 117 vac, 50/60 Hz
    Secondary: 6.3 vct @ 4 amps
    Dimensions: 3.675" x 2" x 2-1/4"H
    $18 each
     
  9. Bernard

    AAC Fanatic!

    Aug 7, 2008
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    Or how about an old ?-14-X Triad, 117V 60 C.P.S. Fil 6.3C.T.@1.2A, for $ 5.00, postage paid. Punch up Bernard to send a message.
     
  10. Jotto

    Thread Starter Member

    Apr 1, 2011
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    The problem here is that I need 3.15vac. That is why I want a 6.3vac center tap. The best one is with Hammond. 110vac dual primary, dual secondary of 3.15vac courtesy of Mr. Chips.

    Thank you for the offer though.
     
  11. Adjuster

    Well-Known Member

    Dec 26, 2010
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    If your requirement is for an accurate 3.15V at only 300mA, beware of the possibility that a filament transformer designed to deliver a very much higher current may give more voltage than its rated value. Not all transformers are rated this way, but because filament voltages are fairly critical, it is not uncommon for the turns ratio of a filament transformer to be corrected for the voltage drop on load.

    As a matter of interest, what is the 3.15V AC for?
     
  12. Jotto

    Thread Starter Member

    Apr 1, 2011
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    I am making a curve tracer
     
  13. Adjuster

    Well-Known Member

    Dec 26, 2010
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    But why would a curve tracer specifically require 3.15V AC? I am wondering if there may be any alternatives to this, but also would like to point out that the voltage you will get will not be precisely that value, even at nominal ratings. If you want to do something much more precise than say heating a lamp or tube filament, some other solution may be required.
     
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