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  • Powered USB Hub

    I have a Belkin USB hub that can work in external powermode or bus power mode. Until now i have been fine using it in bus powered mode. I would like to use my extrnal usb 2.5" HD with it which can be powered by USB. There's not enough power to run it in bus powered mode on the hub . I would like to tap the 5v rail of my M1-atx to power this device but the problem is the PS that came with hub is 7v there is no marking on the hub that says anything about power requirements. Do you think I would be safe using the 5v rail of the my PSU?

    Thanks

  • #2
    use your computers 12 and 5v power supplies. I just wired this up last night. I was tired of using electrical tape and screw on wire connectors. it wasn't pretty and wasn't safe so I took a hard drive power splitter and cut off the one Molex connector. I ran wires from the 12v, 5v and two grounds to a connector peice. I'm not sure what it's called but it has 8 connections on one side and 8 on the other side and lets you screw wires into place connecting from one side ot the other. Anyway, i connected the 4 connections to this wire connector (bridging the wires so that each peice, 12, 5, gnd, gnd) occupied two spaces. Then on the other side i connected some devices. my fans and lcd screen run on 12 volts so they got that, and the USB hub gets 5v so i connected a wire and ran it outside of the box to the USB hub. i purchased a connector from radio shack to connect into the hub. take your hub in and see which fits.

    sorry if the description isn't great. i hope to have pictures soon.
    Progress - VIA EPIA SP8000 | 120 Opus Power Supply & Case | 1GB Ram | 120GB 2.5" Hard Drive | Bluetooth 2.0 | GPRS/3G | Wifi | Road Runner/LSX 2.0 (waiting for a day skin for 3.0) | iGuidance 4.0 | Lilliput 7"

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    • #3
      I remeber reading somewhere that if you use the 12 volt line(yellow) and the 5v ground(the adjacent black wire to the red wire) You will either get 7.5 volts or 7 volts. I will try this out when I go home with my multimeter.
      Computer:
      COMPLETE SYSTEM OVERHAUL!!!!!!
      STAY TUNED IN THE UPCOMING WEEKS!

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      • #4
        Originally posted by DJKhan85
        I remeber reading somewhere that if you use the 12 volt line(yellow) and the 5v ground(the adjacent black wire to the red wire) You will either get 7.5 volts or 7 volts. I will try this out when I go home with my multimeter.
        I found that both grounds were the same. maybe you were connecting +5 to +12? that would give u difference of 7 volts.
        Progress - VIA EPIA SP8000 | 120 Opus Power Supply & Case | 1GB Ram | 120GB 2.5" Hard Drive | Bluetooth 2.0 | GPRS/3G | Wifi | Road Runner/LSX 2.0 (waiting for a day skin for 3.0) | iGuidance 4.0 | Lilliput 7"

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        • #5
          It's true that all black ground wires are the same. You have to use 12v and 5v, but I can't honestly recommend doing this for anything other than a tiny fan or two. Power supplies just weren't made to use the +5v rail as a negative rail.

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          • #6
            Originally posted by numbers
            It's true that all black ground wires are the same. You have to use 12v and 5v, but I can't honestly recommend doing this for anything other than a tiny fan or two. Power supplies just weren't made to use the +5v rail as a negative rail.
            voltage is all relative. if you aren't comparing voltages to ground, the device and PS will never know the difference. I haven't had a reason to use 7 volts versus 5 or 12, so i'm not doing it.
            Progress - VIA EPIA SP8000 | 120 Opus Power Supply & Case | 1GB Ram | 120GB 2.5" Hard Drive | Bluetooth 2.0 | GPRS/3G | Wifi | Road Runner/LSX 2.0 (waiting for a day skin for 3.0) | iGuidance 4.0 | Lilliput 7"

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            • #7
              To run a USB hub you'll be needing 12 Volts, well mine did atleast.

              As for getting 7 Volts, from what I remember it was getting the 12 and 5v lines and regulating them :/ I can't really remember since its been that damn long since I looked at it and never having needed to do it

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              • #8
                Originally posted by ninjageek
                To run a USB hub you'll be needing 12 Volts, well mine did atleast.
                Mine takes 5v
                Is this where the witty comment goes?
                97 Black pearl Mazda Miata MX-5 Carpc V2? maybee..

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                • #9
                  mine is 5v too.
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                  Nissan Aux-in MOD


                  Originally posted by bgoodman
                  We're an international forum, post in whatever langauge you like.

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                  • #10
                    Dangerous to produce 7 volt from 12 - 5 volt.
                    0 V = Ground = signal common = connected to case sometime.

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                    • #11
                      Originally posted by warnockm
                      voltage is all relative. if you aren't comparing voltages to ground, the device and PS will never know the difference. I haven't had a reason to use 7 volts versus 5 or 12, so i'm not doing it.
                      I don't know how best to say this... That just isn't true. The power supply knows the difference very much.

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                      • #12
                        MOST usb hubs should take 5V not 12V. If it takes 12V, it internally converts back to 5V...

                        As for 12-5=7 stuff.. you might want to check this thread:
                        http://www.mp3car.com/vbulletin/show...270#post539270
                        Especially read the two posts I have in there..

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                        • #13
                          There shouldn't be a problem with the reference being 5v rather than 0v. In fact, many devices use a reference that is actually above 0v rather than going to the trouble of creating a negative voltage for swinging below reference. Only if the device that you plug in to the sound card is poopy and insists on using it's own reference would you have problems. And if that's the case then that device is going to cause lots of noise issues even with something using 0v for reference.

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                          • #14
                            I think the problem with having 5V as reference is that when this thing wants to send data from the HDD, it will send it with a 0 bit = 5V, and a 1 bit = 12V. That may confuse the crap out of the usb controller on the motherboard.

                            Who knows, maybe they have some sort of protection against that.. Either way, it *should* be set up to set 0V to 5V (or whatever high voltage) over the hub.

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                            • #15
                              Originally posted by wizawuza
                              I think the problem with having 5V as reference is that when this thing wants to send data from the HDD, it will send it with a 0 bit = 5V, and a 1 bit = 12V. That may confuse the crap out of the usb controller on the motherboard.

                              Who knows, maybe they have some sort of protection against that.. Either way, it *should* be set up to set 0V to 5V (or whatever high voltage) over the hub.
                              as i said earlier, you shouldn't be using this method to run anything that compares voltages to ground on the rest of the system. That means anything connected to any other device outside of your 5-12 system. The 5v would be a floating ground and as soon as you ground that to the rest of your system you will have a 5v to ground short and hopefully your PS would turn off, or worse, burn out. use the 5-12 v system for a fan, LED, whatever, but not a HUB.
                              Progress - VIA EPIA SP8000 | 120 Opus Power Supply & Case | 1GB Ram | 120GB 2.5" Hard Drive | Bluetooth 2.0 | GPRS/3G | Wifi | Road Runner/LSX 2.0 (waiting for a day skin for 3.0) | iGuidance 4.0 | Lilliput 7"

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