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  • Relay switchable USB hub?

    I have two peripherals that I want to connect to my Kenwood DNX7100.

    One is an iPod, the other is a USB Thumb-drive.

    Trouble is, I can't have them both hooked up to a "Y" connector and still be able to use them.

    So what I would LIKE to do is have a switch box.

    BUT, it must be relay-switchable. The Kenwood has a relay output control module which will allow me to switch the hub from peripheral to peripheral using the touch-screen.

    Does ANYONE know of a product that will work, or can at least be modified to work like this?

    I don't want to have a visible connector or anything protruding from the dash, so this is really something out of necessity for a clean install.

    Anyone have any ideas?

  • #2
    I can't just use a standard hub and plug both in at once. If a USB is plugged in at the same time my iPod is, they will conflict. I'm not using a carputer, just a DVD/NAV headunit.

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    • #3
      I realized that after my post went up. I think you will have to build something. I would think that a three-pole double throw relay would work. USB devices have four leads. Leave the ground always connected and switch the other three lines.
      ~Jimmy

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      • #4
        I did not know there were only 4 leads. Do any retail stores stock three-pole double throw relays? Obviously Radio Shack doesn't (not the ones here anyway). All of the TPDT's I've seen are 110VAC. Probably won't work well with 12VDC.

        I do have a spare Radioshack Project Box lying around. I'd also need a way to flush-mount the female ends of the USB to the box though.

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        • #5
          Heck, I could use a 4-pole, double throw relay and just leave one pole empty, right?

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          • #6
            Originally posted by BAC5point2 View Post
            Heck, I could use a 4-pole, double throw relay and just leave one pole empty, right?
            Yes.

            Here are several choices starting at about $4. You might want to get a socket that mates as well, depending on your selection:
            http://www.newark.com/jsp/search/bro...001_PRICE1%7c0
            ~Jimmy

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            • #7
              Cool, I may just build my own then. It looks fairly simple. I'll have the normal pole be for the iPod since I'll use it far more frequently.

              Hmm, those all look comparable. One no better than any other. Is there any preferred one? This will be a pretty fun little project!

              Just gotta find flush-mount USB bits then. Any ideas for that?

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              • #8
                I can forsee one potential problem: A relay may switch so quickly that the host (your Kenwood) may not notice the swap. It might need a certain lag time where the first device is removed from the circuit --- wait, wait, twiddle thumbs -- then the second device connects. This would be easy to accomplish with 2 relays and a simple RC timing delay.

                I have no idea if this will work, but it seems like it would be easy to try, low cost, and low risk of damaging anything.
                ~Jimmy

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                • #9
                  I think I'd wire it something like this:



                  That's a good point about the latency for shifting. The unit CAN differentiate between input sources (it can tell the difference between an iPod and a USB drive), so I bet it would work...

                  Another consideration: The USB input for the headunit also provides power to accessories (the USB port is the method for charging the iPod, for example), that function should be retained with the switching system, right?

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                  • #10
                    As long as you have the iPod as the active usb device it will charge. Once you switch over it won't any more. Now if you just switch the io pins and not the power pins, when you switch over it will go from a usb data port to a usb charging port. Though I don't know if you head unit can supply enough power for both devices.
                    Failure is not an option....



                    It's installed by default on every version of Windows.

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                    • #11
                      Originally posted by BarryWoods View Post
                      As long as you have the iPod as the active usb device it will charge. Once you switch over it won't any more. Now if you just switch the io pins and not the power pins, when you switch over it will go from a usb data port to a usb charging port. Though I don't know if you head unit can supply enough power for both devices.



                      Your circuit looks like you have the right idea. You could try Not switching the power lead like Barry says if you want both to charge at the same time. But that may be more likely to make the Kenwood host not see the swap of devices. Trial and error will get you an answer to that.
                      ~Jimmy

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                      • #12
                        One of the ports will only be for USB thumb-drive, so I won't have any reason to charge both ports at once. I'll likely just switch all 3 wires and ground the 4th. I suppose I could actually even use the 4th pole to switch ground too, right? That's only a little more soldering...

                        Still, I need a flush-mount USB connector. I can't find any commercial 2 port hubs that are large enough to house a 4PDT relay. So I'll make my own, but I don't want it to look ghetto. Plus, I need to mount a USB port in my center console, and don't want that to look bootleg either.

                        Ideas on that?

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                        • #13
                          Originally posted by BAC5point2 View Post
                          One of the ports will only be for USB thumb-drive, so I won't have any reason to charge both ports at once. I'll likely just switch all 3 wires and ground the 4th. I suppose I could actually even use the 4th pole to switch ground too, right? That's only a little more soldering...

                          Still, I need a flush-mount USB connector. I can't find any commercial 2 port hubs that are large enough to house a 4PDT relay. So I'll make my own, but I don't want it to look ghetto. Plus, I need to mount a USB port in my center console, and don't want that to look bootleg either.

                          Ideas on that?
                          http://store.mp3car.com/Automotive_M..._p/com-040.htm

                          I wouldn't switch the ground wire.
                          ~Jimmy

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                          • #14
                            I saw that, but I want something small so I can fit it on a small project box that'll be behind the dashboard. I need 3 of them (so I don't have to hardwire the iPod connector and the other connector to the switch unit).

                            You wouldn't switch ground? Fair enough, it's easy to run a ground wire.

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                            • #15
                              So would you use this:

                              http://www.newark.com/64K3142/electr...EW-HC4-H-DC12V

                              and this:

                              http://www.newark.com/64K3145/electr...C-EW-HC4-SFD-K

                              I'd like to build this fairly soon. I still don't know exactly how I will build the module though.

                              Does anyone have a USB pinout chart?

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