looking to make a rectifier to use on a 120VAC to 14VAC transformer

Discussion in 'The Projects Forum' started by 5thcorps, Mar 6, 2012.

  1. 5thcorps

    Thread Starter New Member

    Mar 5, 2012
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    0
    A wealth of information here and I'm excited to now be a part.
    I have a small transformer model: DB41X26.5 120V AC TO 14.5V aC
    Would like to add a rectifier circuit to it so I can use use it to power a dc project device. PLease, please, please forgive a guy like me who is somewhat new and trying to move forward into the more technical stuff other than just wires etc. Anyone have an idea for a rectifier circuit or is there anything they can be taken out of, like maybe a computer power supply?:)
     
  2. crutschow

    Expert

    Mar 14, 2008
    12,991
    3,226
    What DC voltage and current do you need?
     
  3. 5thcorps

    Thread Starter New Member

    Mar 5, 2012
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    12-14VDC at 4 amp maximum
     
  4. wayneh

    Expert

    Sep 9, 2010
    12,093
    3,031
    Yes absolutely, but I wouldn't disable a PSU to build another supply, since an old PSU can make a great benchtop power supply. And all but the oldest PSUs will be switch-mode anyway, and not as good a source of diodes or rectifiers.

    You can find rectifier diodes in many, many other old electronics such as radios, TVs or VCRs. Just look for the biggest diodes near where the AC power comes in, usually near a transformer. Occasionally you'll even find a single component rectifier, a square device with the 4 diodes already built in. And you can always build a rectifier out of 4 identical diodes.

    But you'll soon be back to crutschow's question: Just making a rectifier is easy, but assuming you want to actually power something, you need to know the current load or you risk frying your diodes. Your diodes will need to be rated to 20v or more, but that shouldn't be much of a problem. Don't forget to put a fuse on the primary (AC side) of the transformer.
     
  5. wayneh

    Expert

    Sep 9, 2010
    12,093
    3,031
    4A is more than you will easily find in most devices unless the device has a big motor, such as a paper shredder (typically 5A rectifier or more).
     
  6. 5thcorps

    Thread Starter New Member

    Mar 5, 2012
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    thanks a bunch, I'm on the hunt now
     
  7. 5thcorps

    Thread Starter New Member

    Mar 5, 2012
    4
    0
    I've noticed on power ac/dc adaptors that the secondary has 3 taps on it. is one tapped into the center of the secondary? if so what for?
     
  8. hwy101

    Active Member

    May 23, 2009
    91
    28
    some info on rectifier design, look here
    you will see center tap design
     
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