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simple 12v,5v,-5v,-12v power supply

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  • simple 12v,5v,-5v,-12v power supply

    if i have an input of + and - 12v and ground, whats the simplest way to get +12v, +5v, -5v and -12v? with a regulator.

    edit: this is for a PC supply, so i needs to be 2A?

  • #2
    Have a look at the Power Supplies section.
    Or search for DC-DC.

    Your looking for 12v DC-DC power supply.

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    • #3
      I'd say that a sproggy psu would be the easiest way. Get a semi-kit from mastero and the rest of the parts from renco and maxim, more resellers too.
      -
      My cars
      -

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      • #4
        ok, ill do a search.

        i want to build one so i want a circuit diagrma, not a kit

        for an old PC, a 486 for example, how much current for the +12v and +5v supplies do i need?

        if i have a 1A regulator, can it regulate higher currents if i keep the chip cool? with a huge heat sink and fan(s).

        how do i get 3.3v? and do i need it?

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        • #5
          The amount of current all depends on the components. Old hdd's can draw an amp on the 12v line but a laptop hdd may draw max of 1/2 amp on only the 5v line. An old 486 won't need 3.3v but may take 5a on the 5v line. You can't run a regulator over its spec, most have overload and thermal shutdowns inside them.

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          • #6
            but you can use a power transistor as a current bypass and use the voltage regulator as a reference to it. ie using a 2n3055 and a 7812 you can get a 3 a 12v psu......... circuits should be on any site with basic electronics....
            Volvo V40 Phase 2 2002. T4 turbo upgrade.... currently no mp3 or carputer..... researching options

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            • #7
              Originally posted by spud42
              but you can use a power transistor as a current bypass and use the voltage regulator as a reference to it. ie using a 2n3055 and a 7812 you can get a 3 a 12v psu......... circuits should be on any site with basic electronics....
              any links? i have some 2n3055's.

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              • #8
                can i use this website? voltage regulator

                and is the MJE340 the same as the MJE34?

                if not, which of the following can i use instead of a MJE34?

                BD132
                BD140
                BD712
                MJ2955
                TIP32A
                TIP32C
                TIP36C
                TIP42A
                TIP127
                TIP147
                TIP2955

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                • #9
                  This took me about 2 minutes to find with Altavista:

                  http://www.repairfaq.org/sam/samschem.htm#schslp2
                  Old Systems retired due to new car
                  New system at design/prototype stage on BeagleBoard.

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                  • #10
                    Here are more:

                    http://www.mitedu.freeserve.co.uk/Ci...wer/boosti.htm
                    http://www.chantronics.com.au/Data/V...regulators.htm

                    This one is for a regulator with feedback (and adds headroom requirement due to the additional Vbe drop).

                    http://dbserv.maxim-ic.com/appnotes....ote_number/295
                    Old Systems retired due to new car
                    New system at design/prototype stage on BeagleBoard.

                    Comment


                    • #11
                      thanks a lot ill try those.

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