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Thread: -12v & -5v

  1. #1
    Newbie
    Join Date
    Sep 1999
    Posts
    2

    -12v & -5v

    So I've just read on a page that you do not need to supply either of the negative power inputs. Is this correct?
    Also how do I work out the ampage I need for the positive inputs? I want to run two hard drives, an lcd, and possibly a cd-rom later on.
    I'm planning on using a dc-dc converter.
    Any help would be much appreciated.

  2. #2
    Newbie
    Join Date
    Sep 1999
    Posts
    4
    When you use serial devices you need the -12V. The -5V are only needed by old mainboards. for the -12v you can use a dc/dc converter. i use a lambda PM30-24d12 (i got this without saling something from the work of my dad) (poor english; i'm german)

  3. #3
    Newbie
    Join Date
    Sep 1999
    Location
    UK
    Posts
    20
    I measured my motherboard and found the negative rails were taking no current. I am not planning to use to serial poer so I can get away with it.

    Finding a -12 DC-DC convertor to handle any more than about 20mA is quite difficult to find in things like Maplins and Farnell, so you MAY have to build your own if necessary.

    Currents taken should be on the drive itself.
    Most IDE drives take 0.4 to 0.5 Amps at 5Volts and anything from 0.4 to 0.9 Amps at 12V as a guide.

    My P90 and Motheboard takes 3.0 Amps when fully running (including soundcard and gfx card).

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