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usb fan question

Discussion in 'General Electronics Discussion' started by tooncinator, Jun 19, 2011.

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  1. tooncinator

    tooncinator

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    Jun 19, 2011
    Hello all,

    I'm definitely a beginner when it comes to electronics but I've been slowly learning when I can.

    Here's the issue I have and the idea I have to try and solve it, and was hoping I could get some comments and/or pointed in the right direction.
    We have a dsl modem, and it seems to be getting pretty hot. At times our internet has been cutting off and on a lot and we were thinking it might be due to the modem getting really hot. So I was thinking about taking an old 5 volt computer case fan I have laying around, building a little rig to have the modem sitting on the fan (the rig would be simple and keep the fan elevated and the modem on top , elevated above the fan. But thats the easy part.)

    I was trying to figure a good power source for the fan, since it would be running fairly constantly, I dont think battery power would work well, and I dont think im at a point where I can safely rig it up to run on a house power outlet. But since it sits close to a computer, and I believe a computer usb slot gives out 5 volts, I was thinking it would be perfect to just rig it up to run off the computer usb (that computer is almost always on so it would constantly have a power source.)

    SInce its a 5 volt fan, and a 5 volt source, would it be as simple as stripping the connector off the fan and taking a a usb end and soldering the wires together and plug and play? or would there be more to it than that?
     
  2. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,448
    2,809
    Jan 21, 2010
    Yes, it is pretty much that easy.

    Make sure you don't get a fan that draws more than 500mA and you should be right.

    Providing clearance and good airflow around the ADSL modem may be an easier thing to try first though. Raise it a few cm placing something under the legs, or stand it on its side. Don't have it in a closed cupboard or under/over something else that gets warm.
     
  3. tooncinator

    tooncinator

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    Jun 19, 2011
    Thank you for your reply, I'm going to give it a try and see how it goes.

    And true, it may be easier to just elevate it, but not nearly as fun! Lets just hope I dont ruin anything in my attempt at fun.
     
  4. MagicMatt

    MagicMatt

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    Jun 15, 2011
    Just a word of caution about what you're intending to do - the modem should not be getting that hot. It's normal for it to get quite warm to the touch, but if it's getting hot enough for it to be failing, then there's a fault somewhere that is causing it to overheat. You should either be replacing the modem, or if it's suppled by your ISP, contacting them and get them to send you a replacement which will be free of charge.
     
  5. tooncinator

    tooncinator

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    Jun 19, 2011
    THanks for your reply, and you're probably right.

    Got it all together and it was as easy as it sounded. Will it solve the problem and prevent me from having to replace it? Probably not. But, the important thing is, I was able to take two things apart, put them together, and actually have them work as intended. That, in my book, is a win.... Yes i really do have that low of standards.
    Now on to bigger, better, more useful projects! :)
     
  6. MattyMatt

    MattyMatt

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    Mar 24, 2011
    Just out of random curiosity, who's your ISP? I used to work with AT&T a lot, and their semens speedstream boxes and some of their westell boxes would get BLAZING hot according to the customers.... I generally told them to call the tier 1 DSL people and tell them that their modem was getting EXTREMELY hot, and they would generally replace them for free.

    Oh and a note on the USB fan... I have a 12V one I hooked to a USB cable... this worked wonderfully for me and it brings in the extra air between my laptop and the stereo receiver. It spins a little slower but puts out enough to keep both nicely cool :) I can post a picture if necessary, but it sounds like you have it under control.

    Matty-
     
  7. MagicMatt

    MagicMatt

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    Jun 15, 2011
    Quite a few 12V fans will run off 5V, but need a boost of about 7V to get moving. I'd never run a 12V fan off 5V if it had to be reliable unless there was a circuit to kick-start it will a little boost.
     
  8. tooncinator

    tooncinator

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    Jun 19, 2011
    Actually it is att dsl. I'm at work so not sure which brand it is ( i think motorola but ill have to check when i get home)
     
  9. tooncinator

    tooncinator

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    Jun 19, 2011
    I do have a cople 12 volt fans laying around, maybe i'll give them a try. It only needs to be reliable enough to move the air. ALthough I'm not really sure how to go about making a circuit that would kickstart it at 7 volts, but I'd be interested to try it if you have any more info on how it can be done or any links that might give an explaination.

    Again I'm new at this but wanting to learn,
     
    Last edited: Jun 24, 2011
  10. MagicMatt

    MagicMatt

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    Jun 15, 2011
    The reliability issue comes from when power is lost, and then restored. Supplying 5V to a 12V fan is often just not quite enough to get it going from stationary (though give it a nudge with a finger and it'll run ok again).

    I don't have a circuit - I'd imagine the unit I've used is just a capacitor and resistor, as it's only a little unit that goes inline (bought at a PC fair and called a "fan kicker").
     
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