Transformer conversions

Discussion in 'The Projects Forum' started by kw0me, Jul 31, 2012.

  1. kw0me

    Thread Starter New Member

    Jul 4, 2012
    12
    0
    Ok this may seem simple but I can't quite work it out.
    I have a 230vac to 2x12vac 1.5va (vb 1.5/2/12 pcb mount) transformer.

    What is the formula to work out the amps I can pull out of it?
    I know it has something to do with the va rating. I need a really simple example for me to learn how to do it.

    When I plug it in I get 17vac on the secondary is this right?

    Using diodes and a capacitor to convert to dc I get 24v does that sound about right?

    Any feedback is much appreciated :D
     
  2. kw0me

    Thread Starter New Member

    Jul 4, 2012
    12
    0
  3. wayneh

    Expert

    Sep 9, 2010
    12,126
    3,048
    A volt-amp is similar to a watt (same units). So 1.5VA at 12V is about 1.2A combined current on the two secondary circuits.

    The 17V you measured was on a single secondary, with no load? The unloaded voltage will be higher than the rated voltage. Also, be aware that when you rectify and filter, the unloaded DC voltage will also be well above 12V. Use a regulator if you need a more consistent output.
     
  4. #12

    Expert

    Nov 30, 2010
    16,298
    6,810
    The amps you can get from a transformer depend on the rectifier circuit you use. Look at the chart.
     
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