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Transformers and rectifiers

Discussion in 'The Projects Forum' started by kw0me, Jul 25, 2012.

  1. kw0me

    Thread Starter New Member

    Jul 4, 2012
    Just a quick question!
    I'm new to using mains transformers. I'm making a car battery charger just to practice and test myself out seems quite simple to do. The circuit I'm using requires 18vdc so I've picked a transformer that goes from 240vac to 18vac 1.5va now to change that to dc I'm using a bridge rectifier. Will this drop the voltage below 18vdc or will it stay at 18vdc?

    Thanks in advance :)
  2. #12


    Nov 30, 2010
    A rectifier will allow peak pulses of almost 24 volts.
    A bridge rectifier can get you almost 48 volts, depending on how you wire it.
    You need to study first and buy later.
    Last edited: Jul 25, 2012
  3. crutschow


    Mar 14, 2008
    As #12 noted, rectifying 18VAC (RMS) gives more than 18VDC . The rectifier DC output is nearly equal to the peak AC voltage, which is 1.4 times the RMS. Obviously it's not as simple as you thought. :rolleyes:
  4. gerty

    AAC Fanatic!

    Aug 30, 2007