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Thread: powering a usb hub

  1. #1
    Newbie elstev0's Avatar
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    powering a usb hub

    My problem is as follows:

    I have pulled apart my usb hub and connected a molex connector to the power input using +5v and -5v, everything works fine when connected to my pc at home running off 240v i can connect to all 4 ports and they all work fine.

    When connected to my car pc via my m2atx the power led comes on but i can only get my keyboard to work. I dont think ive run out of power as i can connect all the devices i want to run direct to the pc its just they wont run when i connect them to the hub.

    When i put the multimeter on im only getting 4.6 volts on the 5v rail, is this enough to power usb hub?

    My idea is to power the hub direct from the battery, do i need to install a 5v voltage regulator or is there a circuit i need to build?

    Any ideas more than welcome. Thankyou.

  2. #2
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    7805

    I say try using the LM7805C voltage regulator. Or you could get a hub that does not require any external power. It takes its power from the pc.

  3. #3
    Newbie elstev0's Avatar
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    My goal is to power the hub from the car battery and conserve the pc's power and i cant find a proven way to do this.

  4. #4
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    my point exactly mate. Use the lm7805c. its real simple to hook up and its way cheap. Its just input 12V, ground, and output 5V.Hook it up to your car battery and you're done!

  5. #5
    Newbie elstev0's Avatar
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    Awesome, thanks heaps.

  6. #6
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    just make sure you attach a heatsink to this regulator.

  7. #7
    Maximum Bitrate bratnetwork's Avatar
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    You could also use a Point of Load PSU like this one:

    [URL="http://store.mp3car.com/Automotive_Point_Of_Load_DC_DC_15W_Power_Supply_p/pwr-022.htm"]Opus 15w POL/URL]

    This is what I use to power my usb hub. I just cut the transformer off the power plug it came with and wire the 2 leads to the output of the unit and it runs just above 5 volts (like 5.06v or something like that)

  8. #8
    Low Bitrate chrislamb's Avatar
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    MINI COOPER S PRO

  9. #9
    Constant Bitrate
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    WTH? I have two powered USB hubs connected on the 5v rail of my power supply and they have both been working for years. What hubs are u using? Are they cheap? Have you checked the power supply's output to see if you're getting the proper power from there first? Where are you connecting the ground to?

    It will be much easier to have the hub connected to the computer then to regulators/battery, etc.

  10. #10
    Constant Bitrate Kalenth's Avatar
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    Quote Originally Posted by chrislamb View Post
    Your a genius! I had been looking into making something that did the same thing... a USB charger never came to mind.

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