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7345AW: [nslu2-general] NSLU2 using 7805s and a 12V battery

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  • Klaus Ruebsam
    May 3 6:11 AM
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      Efil,

      12V-5V=7V

      7V*1A=7W (heat!!)
      7V*1.5A=10.5W (even more heat!!)

      >So far, I've tried a few different regulators (rated 1 or 1.5 amps), and
      when I turn the NSLU2 on, after about 30 seconds, the regulators are too hot
      to touch and soon shut themselves down.

      They are rated 1 or 1.5A as long as you take care on proper cooling
      (heatsink).

      >I'm not sure what the problem is.

      You quite likely forgot the hitsink for the regulator

      > I connected the regulators in parallel with each other to provide up to 3
      amps (more than the NSLU2 power supply), so I figured that I wouldn't need
      heatsinks for them. Am I wrong, or is my NSLU2 just behaving strangely?

      Conneting them in parallel makes a shortage on their output. Never ever do
      that!!! It is OK to do so with transistors, but not with power regulators
      that have protection circuits in them.


      I would search for a DC/DC-converter that converts your 12V down to 5V but
      without converting the voltage difference into heat. Those DC/DC-comvertrs
      actuaklly comnvert the input DC into an AC, route it through a transformer
      and rectify it again. The loss within the transformer is little compared to
      the loss you would have in a normal regulator (with ist proper heatsink
      attached!!!).

      Best regards,

      Klaus
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