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  • DIY self-powered USB hub... is it possible?

    So I've finished the CarPC, tucked it away somewhere nice and hidden, did some pretty little fabrication to the Xenarc 700TSV frame so it looks factory sitting in my Double-DIN hole, when I realized...

    I need more than the 6 USB ports my motherboard comes with -_-

    Problem is, host-powered hubs won't work as I've tried them, and has been a waste of money.
    7-port self-powered hubs cost about 20 bucks to buy, then the custom work to make em sit and look factory installed in my car is not worth the cost/work.

    So why not just buy USB extension cables, wire them up to have independent power (coming from the radio harness) and just wire the D+ and D- cables together... It should work... Right?

    The problem I'm running into is how will it differentiate the COM PORT data from say an iPhone and a WiFi adaptor if their D+ and D- wires are on the same line?

  • #2
    woah what?

    USB: clean, regulated 5volts.
    Car: Unregulated 10.5-15 volts.

    Any usb device taking in 12 volts will fry.

    Usb has 4 cables inside of it. Red, black, green, and white. Green and white are data. Black and red are power.

    USB ports are limited to 500mA.

    A usb hub uses 100mA to power itself. Then gives the remaining power available to the other ports.

    However you shouldn't push more than 500mA on a usb cable. This is why powered hubs exist.

    The data cables cannot be joined. A hub actually has a lot of electronic stuff going on.

    What you need is a powered hub powered by either a 5 volt regulator or by the computer power supply's 12 volt rail.

    From there you can plug in extensions to make it look OEM
    My Nearly Complete Car:
    http://www.mp3car.com/vbulletin/show...ed-car-pc.html

    Micro Control Center... Control Your Car Across the Internet
    http://www.mp3car.com/fusion-brain/1...-internet.html

    Website: (It's a work in progress, really. All my projects have taken me from ever really developing it.)
    http://paulfurtado.com/

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    • #3
      Originally posted by PaulF View Post
      woah what?

      USB: clean, regulated 5volts.
      Car: Unregulated 10.5-15 volts.

      Any usb device taking in 12 volts will fry.
      Exactly, which is why it would be wired to the 5v line, and would be fused >.>

      Originally posted by PaulF View Post
      The data cables cannot be joined. A hub actually has a lot of electronic stuff going on.
      Ok, that's what I was looking for. What is the "electronic stuff" that is going on? Would it be easy to manipulate with a PIC chip or ARV? If so, would the cost of that out-weigh just buying a self-powered hub?

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      • #4
        Originally posted by Chronus72488 View Post
        Ok, that's what I was looking for. What is the "electronic stuff" that is going on? Would it be easy to manipulate with a PIC chip or ARV? If so, would the cost of that out-weigh just buying a self-powered hub?
        That electronic stuff is USB itself, and they make chips specifically for that. They're the same chips inside a USB hub, and they're none too simple.
        "stop with the REINSTALLS, what do you think we got some lame-o installer!!!" - mitchjs
        RevFE
        My Shop

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        • #5
          Just get a hub with external power.
          Then connect a 5V supply of suitable output.

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          • #6
            Yea that's pretty much my plan, fuse it with a 7.5A and it should be good to go, just need to find a cheap one i can break apart and fabricate into the dash...

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            • #7
              USB Self powered hub

              http://store.mp3car.com/DC_Powered_4..._p/adt-015.htm

              And before anyone says it's too expensive, I have one and can highly recommend it as it has solved issues I had with three devices which would not be detected on a reboot and I had to keep plugging and unplugging them. With them plugged into this hub they work perfectly.

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              • #8
                If that's $85...

                http://www.amazon.com/D-Link-DUB-H7-...2520046&sr=1-1

                Shouldn't that be like... $150?

                Besides it being DC-powered and turning on with the ignition... I don't see the difference...

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                • #9
                  That's the difference...

                  If that D-Link one were made in such low production quantities and was a relatively new product to the market I'm sure it would cost significantly more.
                  "stop with the REINSTALLS, what do you think we got some lame-o installer!!!" - mitchjs
                  RevFE
                  My Shop

                  Comment


                  • #10
                    Cheap hubs.... yeah!
                    I had 2 that didn't work. Inspection showed misaligned SMD resistors.

                    I ended up getting the formerly bling "Shining Light" brand.
                    I have since bought many Shining Light and rebadged similar hubs, card readers, and combined card-readers & hubs. The only failure - one memory stick slot (in well over a dozen units purchased).

                    The Shining Lights are white with a large round light-blue lit area, but they are not bling because they work well.
                    Typically priced here from $15-$25 at Computer Swap Meets (new unused products).

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                    • #11
                      ... can't you just cut the coaxial plug and wire in your own "DC-connection" and fuse it? And as for the ignition switch, if it's hooked up to the right line, shouldn't it automatically turn off when the key is out?

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                      • #12
                        Originally posted by Chronus72488 View Post
                        ... can't you just cut the coaxial plug and wire in your own "DC-connection" and fuse it? And as for the ignition switch, if it's hooked up to the right line, shouldn't it automatically turn off when the key is out?
                        Sure, you could run power out of your computer's PSU to the hub, (Not ignition, since that's unregulated voltage and a good way to kill it). Let us know how that works for you? It won't turn the devices off before your PC shuts off, which could cause issues if you run hibernation but I don't see any other problems with that setup besides having to hack it together.
                        "stop with the REINSTALLS, what do you think we got some lame-o installer!!!" - mitchjs
                        RevFE
                        My Shop

                        Comment


                        • #13
                          Originally posted by Chronus72488 View Post
                          If that's $85...

                          http://www.amazon.com/D-Link-DUB-H7-...2520046&sr=1-1

                          Shouldn't that be like... $150?

                          Besides it being DC-powered and turning on with the ignition... I don't see the difference...

                          Why are DC-DC ATX PSU's much more expensive than standard ATX supplies?

                          Because they are specially designed to work in the car. And work is the operative word here.


                          Like I said, don't argue the price.

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                          • #14
                            Originally posted by Chronus72488 View Post
                            ... can't you just cut the coaxial plug and wire in your own "DC-connection" and fuse it? And as for the ignition switch, if it's hooked up to the right line, shouldn't it automatically turn off when the key is out?
                            Yes, you can do that. I presume you mean you will be running the proper voltage into the DC connection. Most USB stuff is 5 volts, so don't run 12v into it unless that's what it says on the power supply.

                            The additional features of the mp3car hub include a timer that keeps the hub on for a certain amount of time to allow you to stop at, say, a gas station without the USB devices going offline. The hub also solves many of the problems people have with USB devices that go missing when the system hibernates or sleeps.

                            And yes, you can wire up a timer relay to a powered hub and it will work. You can hack it all together if you want. The mp3car hub just does it in a nice package that works properly.
                            Originally posted by ghettocruzer
                            I was gung ho on building a PC [until] just recently. However, between my new phone having internet and GPS and all...and this kit...Im starting to have trouble justfiying it haha.
                            Want to:
                            -Find out about the new iBug iPad install?
                            -Find out about carPC's in just 5 minutes? View the Car PC 101 video

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                            • #15
                              The voltage is the number one issue here.
                              Pumping 12 volts from the car into a USB device will fry it.
                              You need to give a hub 5 volts.

                              I agree that the $85 hub price is a bit ridiculous, but it saves a lot of the trouble found with other solutions and is much more rugged/reliable.


                              If you do want to go the cheaper route, get a hub with an external power supply. Cut the wire and feed 5 volts over the wire with the proper polarity. If ever confused about whats positive or negative, check it with a multimeter.

                              Ways to get 5 volts:
                              -12 volt to 5 volt "point of load" power supply.
                              ---Converts 12 volts from the car into 5 volts for the usb hub
                              ---This costs about $30.

                              -Using the 5 volt power supply that the computer already has.
                              --This costs whatever the length of wire from the computer to the USB hub will cost you
                              --Look at a hard drive connector from the computer's power supply. The red wire is positive 5 volts, the black wire closest to it is the negative wire for the 5 volt rail.
                              My Nearly Complete Car:
                              http://www.mp3car.com/vbulletin/show...ed-car-pc.html

                              Micro Control Center... Control Your Car Across the Internet
                              http://www.mp3car.com/fusion-brain/1...-internet.html

                              Website: (It's a work in progress, really. All my projects have taken me from ever really developing it.)
                              http://paulfurtado.com/

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