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Do I need -5V for an AT

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  • Do I need -5V for an AT

    I have a DC-DC power supply model: MDP-8051S , it doesn't have -5V.

    do I really need it?
    if I need it, how can I get that voltage?

    Im using Irman, and serial character LCD from Crystafontz.

    anybody using this PS?
    www.mp3commander.tk

  • #2
    That really depends a lot on the motherboard you are using. I'm running an embedded mobo which only requires +5v and +12v for example.


    Rob
    Old Systems retired due to new car
    New system at design/prototype stage on BeagleBoard.

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    • #3
      not essential, BUT serial ports and some onboard sound cards need -5V to function..... since you have an Irman, your gonna need it!....

      unless you can use a USB ---> serial converter.... since the USB port only has 5V+ in its plug......
      Project - GAME OVER :(

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      • #4
        Can I do this?

        www.mp3commander.tk

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        • #5
          No, you can't do that, the input to the -5volt regulator should go to the -12volt rail..
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          • #6
            Sorry that was a mistake. now should be ok.
            www.mp3commander.tk

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            • #7
              Yes, that will be fine. Though I would also put a 10uF capacitor at the input of the regultor, and add a 0.1uF unit at the output. The result will be a much more stable -5V.
              Player: Pentium 166MMX, Amptron 598LMR MB w/onboard Sound, Video, LAN, 10.2 Gig Fujitsu Laptop HD, Arise 865 DC-DC Converter, Lexan Case, Custom Software w/Voice Interface, MS Access Based Playlists
              Car: 1986 Mazda RX-7 Turbo (highly modded), 1978 RX-7 Beater (Dead, parting out), 2001 Honda Insight
              "If one more body-kitted, cut-spring-lowered, farty-exhausted Civic revs on me at an intersection, I swear I'm going to get out of my car and cram their ridiculous double-decker aluminium wing firmly up their rump."

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              • #8
                Originally posted by Aaron Cake
                Yes, that will be fine. Though I would also put a 10uF capacitor at the input of the regultor, and add a 0.1uF unit at the output. The result will be a much more stable -5V.
                do you mean like this?



                sorry for my ignorance, I don't know much about electronics.
                www.mp3commander.tk

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                • #9
                  Ahh, I don't think you need the 220uF on the output..
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                  • #10
                    Aaron Cake I need your confirmation...
                    www.mp3commander.tk

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                    • #11
                      Originally posted by mp3commander


                      do you mean like this?



                      sorry for my ignorance, I don't know much about electronics.
                      That should do. Though I would switch the position of the 220uF and 10uF capacitor. And change the 10uF to 100uF.
                      Player: Pentium 166MMX, Amptron 598LMR MB w/onboard Sound, Video, LAN, 10.2 Gig Fujitsu Laptop HD, Arise 865 DC-DC Converter, Lexan Case, Custom Software w/Voice Interface, MS Access Based Playlists
                      Car: 1986 Mazda RX-7 Turbo (highly modded), 1978 RX-7 Beater (Dead, parting out), 2001 Honda Insight
                      "If one more body-kitted, cut-spring-lowered, farty-exhausted Civic revs on me at an intersection, I swear I'm going to get out of my car and cram their ridiculous double-decker aluminium wing firmly up their rump."

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                      • #12
                        This is what I did.


                        the Output is droping like -2V
                        And the 7905 gets extremly hot. WHY??

                        Is something wrong?

                        Somebody help me!!
                        www.mp3commander.tk

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                        • #13
                          Well, if you have wired it like that, it should work... If you are having problems, then you probably haven't wired it like that..
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                          register another account and you're gone for good.

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                          • #14
                            Try the regular 7905 instead of the L. Also, you will need a heatsink on the regulator regardless. How much current are you trying to draw through it? Is one of your capacitors bad?
                            Player: Pentium 166MMX, Amptron 598LMR MB w/onboard Sound, Video, LAN, 10.2 Gig Fujitsu Laptop HD, Arise 865 DC-DC Converter, Lexan Case, Custom Software w/Voice Interface, MS Access Based Playlists
                            Car: 1986 Mazda RX-7 Turbo (highly modded), 1978 RX-7 Beater (Dead, parting out), 2001 Honda Insight
                            "If one more body-kitted, cut-spring-lowered, farty-exhausted Civic revs on me at an intersection, I swear I'm going to get out of my car and cram their ridiculous double-decker aluminium wing firmly up their rump."

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                            • #15
                              problem solved. I thought that the 7905 pinout is like the 7805.
                              That was my mistake.

                              7805:
                              1. input
                              2. ground
                              3. output

                              7905:
                              1. Grund
                              2. input
                              3. output

                              Thank you for your help.
                              www.mp3commander.tk

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