Connect with us

Pwr Supply Problem

Discussion in 'Electronic Basics' started by scott93727g, Nov 20, 2008.

Scroll to continue with content
  1. scott93727g

    scott93727g Guest

    I made a power supply with 3 paralelled LM338 Regulators in paralell
    (24V 12A trans), with 2 paralelled 20A rectifirs, worked great for 1
    week, then all of a sudden, output dropped to 2 amps max (from 15A), ,
    all componed seem to check out ok, getting full current out of filter
    caaps past rectifiers, any ideas, tried substituting a good regulater,
    and same thing, any ideas.
  2. ehsjr

    ehsjr Guest

    I have mostly questions, but first a couple of points:
    First, your transformer current rating needs to be about
    1.5 - 1.8 times greater than the maximum current you will
    draw. You didn't say what that is.
    Why did you put rectifiers in parallel? That doesn't
    give you the equivalent of a 40A rectifier - I assume
    you thought it might.

    Ok, now to the problem. How do you balance the current
    drawn from each LM338? Schematic please.
    How did you test that you are getting full current
    out of the filter caps past rectifiers, and what is
    "full current" - how many amps?
    Are your LM338's installed on heat sinks?
    How much current do you want to be able to draw?

  3. neon


    Oct 21, 2006
    I don't know what rectifiers has to do with your problem. But seriously putting 3 regulators in parallel is fine the only problem you have is which is it going to regulate ini mini moe. unless you take steps to make sure the load is shared by each equaly. I don't gety it if they are regulating i asume voltage then is every thing is fine your words how can it be 2A did the load change or you have no idea what?
Ask a Question
Want to reply to this thread or ask your own question?
You'll need to choose a username for the site, which only take a couple of moments (here). After that, you can post your question and our members will help you out.
Electronics Point Logo
Continue to site
Quote of the day