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SAFE Regulated Power Supply

Discussion in 'Power Electronics' started by BlueJello, Jan 5, 2017.

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  1. BlueJello

    BlueJello

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    Dec 15, 2016
    I'm looking at an 800W power supply that outputs 12 DC. I've found that you can convert computer PSUs to fit this purpose. My question is what is the difference between these two products? They both look very different, and one seems to be a Chinese knockoff PSU.

    http://www.ebay.com/itm/HP-XW8400-C...991037?hash=item35faccc73d:g:8KkAAOSwDuJWukB8

    http://www.ebay.com/itm/Fujitsu-A3C...212015?hash=item2a7546f92f:g:kOcAAOSwt5hYZDbV

    My overall question is, which of these is safer to modify into a 12VDC 800W Power Supply. And if both of these are bad, are there better models than these, keeping within a $30-$40 range?
     
  2. Herschel Peeler

    Herschel Peeler

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    Feb 21, 2016
    I don't see any that look like 800 Watts. That is about 67 Amps at 12 V. Googling, they run about $200.
     
  3. BlueJello

    BlueJello

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    Dec 15, 2016
    The first one, when all the 12V positives and grounds are soldered together, it outputs the full 800W at 12V through those connections.
     
  4. Harald Kapp

    Harald Kapp Moderator Moderator

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    Nov 17, 2011
    800 W is the total power of the PSU. This doesn't necessarily mean that the full 800 W are available on one single rail (12 V). Typically this kind of PSU is designed to deliver the output power split among the several rails (12 V, 5 V). Drawing full power from only one rail may overload this rail, regardless of the number of wires you connect: within the PSU these all go to the same single output circuit.
    You'll have to look up the specs of the PSU and check the max. current on the 12 V rail. Unfortunately this information is missing on the ebay offers (at least I can't find it easily).
     
    davenn and hevans1944 like this.
  5. hevans1944

    hevans1944 Hop - AC8NS

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    Jun 21, 2012
    Read the label on the power supply. There are four outputs, each with different current ratings. And the current ratings depend on the power rating from 800 watts to 1000 watts.

    [​IMG]
     
  6. BlueJello

    BlueJello

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    Dec 15, 2016
    This looks like it should work, can anybody confirm that this will function as an 800W 12V DC Power Supply?
     
  7. hevans1944

    hevans1944 Hop - AC8NS

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    Jun 21, 2012
    Looks like it puts out 65.8 A at 12 V and 800 watts dissipation. That works out to 789,6 watts. Is that good enough for you?
     
  8. Colin Mitchell

    Colin Mitchell

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    Aug 31, 2014
    Buy a 12v car battery.
     
  9. Harald Kapp

    Harald Kapp Moderator Moderator

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    At 66 A the battery will be drained with ~ 1 hour, depending on capacity.
     
  10. BlueJello

    BlueJello

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    Dec 15, 2016
    This is being used to power sensitive equipment and circuitry, not for running off of decaying voltage and temporary power.
     
  11. BlueJello

    BlueJello

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    Dec 15, 2016
    Yes, I don't have much experience in regulated power supplies, I usually use much lower wattage or unregulated transformers. I just wanted to make sure before buying it.
     
  12. tedstruk

    tedstruk

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    Jan 7, 2012
    first year electronics lesson 1.
    There is no such thing as safe electricity.
     
  13. Harald Kapp

    Harald Kapp Moderator Moderator

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    Nov 17, 2011
    ... still most people die in their sleep...

    That's no excuse.
    Electricity has its risks, but you can minimize them by handling it as safe as possible. Or increase the risk by handling it in stupid ways.
     
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