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Thread: How to power 5V usb hub from 12v

  1. #21
    phc
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    Quote Originally Posted by spaceman
    Today i received samples of the LM338T regulator.
    The data sheet can be found here http://www.national.com/ds/LM/LM138.pdf

    Im not all that great at elctronics, so i was just wondering if anyone can help to set this up. Ive worked out that i need 2 resistors and maybe a capacitor.

    But i really dont know what value resistors to get and exactly how to set it up. Also, do i need a heatsink?

    Any help would be hugely appreciated

    Thanks
    You didn't need an adjustable regulator since you need a standard voltage, the LM1084IT-5.0 would be a better choice. Less components.

    Just follow the data sheet application examples, 2 resistors sized to the given equation and add a few caps on the input and output. You will need a breadboard to wire that many components.

  2. #22
    What can I say? I like serial. Curiosity's Avatar
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    Yes. You'll need a HUGE heatsink for that. Linear, yuck!

  3. #23
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    After alot of searching, i finallyfound a converter, the TEN25-1211:

    http://rswww.com/cgi-bin/bv/rswww/su...5&cacheID=ukie


    What really ****es me off is that RS is the first place i phhoned to find something like this, even before starting this thread. They told me they didnt have anything that matched the output requirements.

    The only thing is that it costs a bit more than i really want to spend on this. I didnt think it was going to be such a hassle to power the usb hub.

    Can anyone point me to where i could get something that does the same job for a bit cheaper fi possible. Otherwise i might just bite the bullet and buy this.

    EDIT: fixed link

  4. #24
    MySQL Error scott_fx's Avatar
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    didn't you say that your psu would be able to handle the hubs? why not go that route?
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  5. #25
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    There is also the Carnetix P5V coming in the next few days....
    Old setup
    Epia M10k, Cubid 2699R case, 512MB, 40GB 3.5" drive
    New setup
    Optiplex 260SX (2.8GHz P4, 512MB, 30GB, DVD)
    Xenarc 700IDT, USB hub, 802.11g, bluetooth, P2140, P5V

  6. #26
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    The psu should beable to handle it according to figures given by the epia power calculator. But im not sure if these are accurate, other calculators give higher usage figures. I guess i just wanted to be safe and give a seperate supply incase i ever add anything else in future. Ill prob just go and buy a multimeter and check what is actually being used.

    How would i check the highest draw on the 5v line? play a disc for the dvd drive, but how would i get the highest draw on the HD?

  7. #27
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    The P5V would be great if it was 5A rather than 3

  8. #28
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    Quote Originally Posted by spaceman
    The psu should beable to handle it according to figures given by the epia power calculator. But im not sure if these are accurate, other calculators give higher usage figures. I guess i just wanted to be safe and give a seperate supply incase i ever add anything else in future. Ill prob just go and buy a multimeter and check what is actually being used.

    How would i check the highest draw on the 5v line? play a disc for the dvd drive, but how would i get the highest draw on the HD?

    Play a video file off the hard drive.

    However, tou can usually check the manufacturers specs for the HD and DVD/CD Rom you are using. They generally list the startup current, and continuous use current, for thier products.

    Michael
    ...I love the French language...especially to curse with...Nom de Dieu de putain de bordel de merde de saloperies de connards d'enculés de ta mère. You see, it's like wiping your *** with silk, I love it.

  9. #29
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    I am very new to this but...

    Hello all,

    My truck doesn't have a cigarette lighter and while I am considering wiring one in to power my mp3 player and cell phone, I thought it would be cool to do a direct 12v dc to 5v USB port. Obviously from reading this post, it is much more complicated than I had anticipated.

    My question is this, is there any reason I couldn't cut the cigarette lighter plug off of one of these http://www.amazon.com/Multi-Use-Vehi.../dp/B000PB8CQI

    and wire it in directly?

    If that is true, why can't any cigarette lighter to USB charger converter be hacked and spliced into a dashboard for 5v usb power?

    Thanks and please forgive my ignorance,

    Mike

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