Transformer and bridge rectifiers

Discussion in 'General Electronics Chat' started by john.snow, Dec 20, 2015.

  1. john.snow

    Thread Starter New Member

    Dec 17, 2015
    3
    1
    Why do we use bridge rectifiers with laminated core transformers? If the transformer steps down the voltage to 24v volts (in my case) why should i use a bridge rectifier if i am building a linear voltage regulated power supply.

    Currently working on an LM338K linear power supply.
     
  2. #12

    Expert

    Nov 30, 2010
    16,284
    6,797
    Because a full wave bridge has all of the transformer doing work on each half cycle. This means you can buy a smaller transformer.
     
  3. #12

    Expert

    Nov 30, 2010
    16,284
    6,797
    Here's an example I did a day or two ago:
     
  4. ErnieM

    AAC Fanatic!

    Apr 24, 2011
    7,388
    1,605
    Because your LM338 is designed for a DC input and a transformer puts out AC.
     
    RRITESH KAKKAR likes this.
  5. MaxHeadRoom

    Expert

    Jul 18, 2013
    10,542
    2,369
    Laminated cores eliminates eddy currents which tend to produce heat.
    Max.
     
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  6. crutschow

    Expert

    Mar 14, 2008
    13,009
    3,233
    The lamination of a transformer core has nothing to do with using a rectifier to convert the transformer AC to the DC required by the regulator.
    Why did you think there was some relation between those?
     
  7. Picbuster

    Member

    Dec 2, 2013
    374
    50
    I am missing the cap's over the diodes these are needed to conform with the emc directive.
    Reason: The diode goes on when the voltage goes above the .6V approx this could produce a spike.
    Caps at the Dc site will not eliminate this (it is a short cut for that spike) and the spike goes into the mains.
     
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