Double Fan Mod -> Push & Pull ?

Discussion in 'Modding Forum' started by BassKozz, May 1, 2006.

  1. BassKozz

    BassKozz Network Guru Member

    Has anyone ever tried a double fan mod...
    What I mean is one fan underneath the WRT (pushing air up) and one fan on top (pulling air out) ?

    The fan I purchased from newegg HERE (60x60x10) is small enough to fit underneath the WRT perfectly (on the outside)... although I will prolly add some silicone or rubber bumpy pads to the feet to give it an extra 1cm of clearance for maximum airflow...

    p.s. Can I hook both fan's up to 1 potentiometer ?
  2. SteelersFANinMA

    SteelersFANinMA Network Guru Member

    Sounds interesting. I haven't seen anyone do that yet. You should be able to connect two fans to one potentiometer, but one pot for two fans obviously won't allow for seperate control.

    My only concerns would be, how much strain will two decent sized fans put on the A/C adapter, and is it even necessary? The heatsinks and 60x60x10 fan I added, (forcing air out of the top) cooled my overclocked WRT more than enough. However, my adapter generated much more heat than it normally would. I've read of some people burning out their adapters because of the add-ons. Some have asked if you can get an adapter with a higher rating that will work, but I don't have the answer to that.
  3. Cenreyn79

    Cenreyn79 Network Guru Member

    The boards can take a lot more power than just 12v @ .5 amps. Based on the information published by Anachip and the post on openwrtdocs, it is possible to use another a/c adapter to power it. the posted maximums are 22v operating voltage @ 2.0 amps.

    Anachip AP1509 5v Regulator for wrt54g v3.
  4. BassKozz

    BassKozz Network Guru Member

    So is this as simple as using a different power brick adaptor ...
    Something like This one from RADIO SHACK?

    Can you point me in the direction of the post your referring to on openwrtdocs ?

  5. HiSpeed

    HiSpeed Network Guru Member

    I did this :


    I used the power supply from an old epilator and a transistor (in red) to limit the speed (noise)... :grin:
  6. Cenreyn79

    Cenreyn79 Network Guru Member

    yeah, that works well. all the way up to 24v, 2A.

    your idea, did you ever think of putting 2 small fans on the top of the router to draw air in, then across the board and out again? wouldnt this have a stronger pull than the normal force/suck single fan style?
    even if the fans were moderately small, 2 together would create an airflow that is ideal to remove large amounts of heat.

  7. Cenreyn79

    Cenreyn79 Network Guru Member

  8. HiSpeed

    HiSpeed Network Guru Member

    I chose a big fan to use all the holes on the top of the box...
  9. BassKozz

    BassKozz Network Guru Member

    How do I know how high I need to go for two of these fans?
    Or should I just connect a 24v adaptor and it will auto-regulate ?
    I assume 24v will be plenty for these fans?

    I was considering going that route, but I wanted to make this stelth as possible (top fan inside case / bottom fan outside... but it won't matter because you won't see it ;) )
  10. Cenreyn79

    Cenreyn79 Network Guru Member

    For that, you'll need another reg. you'll simply need to match the reg to the power markings of the fan. the standard power brick for the wrt54g(s) is 12v @ .5A so the fans already match the power supply. when you change the power supply and the power markings on the fan dont match, you run the risk of destroying the fan.

    the fan that im using has an on-board reg for the fan so that means i dont have to add another reg, however if not, then another one is needed.

    The power markings on your fan are the same as mine i believe. from what i assume to be correct, if there are power markings on the fan then it is probably internally regulated. however, like the AC1509, there could be a shutoff condition if too much power is supplied.

    Power +12v (X+??) ==> 12v Reg (X) ==> 12v Fan (X)
  11. Cenreyn79

    Cenreyn79 Network Guru Member

    Also, if you were looking to do a stealtch mod then the V5 is the best for that due to the board design. unlike the first models, the board was cut down for reasons that i dont know of. But, it created an area off to the side where one could cut out part of the botttom plate. so that way, you could get a stock looking stealth mod from the bottom.
  12. BassKozz

    BassKozz Network Guru Member


    I found a great resource on this issue:
    Computer Power User - Customized Cooling
    MY FAN (my model #: EC6010M12CA)
    Voltage = 12V
    Current AMP = 0.16
    Input Watts = 1.92

    So going forward I should beable to run 2 of these fan's on 1 pot of 5w 100ohm... But would I want to? Would it be more effiecient with two pot's ?

    Now, to try and figure out what cenreyn is talking about with the "reg's" ;)

    How would you configure this?

    Thanks for the help,

    Limited/POOR 3rd party support :(
    I use DD-WRT.
  13. Cenreyn79

    Cenreyn79 Network Guru Member

    Alright. ill see if i can compile all the crap spewing from my mouth.

    See below.

    You and i have the same fans. they are both 12v @ .16A, coming to a total of 1.92 Watts. With both of the fans, you're looking at a maximum of 3.84 watts which means a 5W pot should do you just fine. The page you posted (Customized cooling) was for the pots. One pot be used for to fans. connect the power source to the red outlet of the rheostat (pot) then connect the red wire of both fans to the black outlet of the pot. also with the pot, there is a middle outlet, that is the ground. that is not completely neccesary b.c there are not other circuits that are being blocked.

    now on the the regs. each fan has an internal regulator which keeps the fan board from becoming fried if too much power is applied. the power markings on the fans indicate how much the reg can hold (12v .16A 1.92W). however, this is not the maximum operating voltage of the fan and more can be applied other than the stated conditions. if too much power is applied, then the regulator will cut off all power to the fan and instead route it through to the negative outlet.

  14. BassKozz

    BassKozz Network Guru Member

    WOW... Thanks for the awesome reply :thumbup:
    Now this is making sence.
    I'am going to go pickup a 5w100ohm POT tomorrow.
    I'll let you know how it goes.

    Thanks again, you rock :rockon:
    Where did you learn all this stuff ?
  15. Cenreyn79

    Cenreyn79 Network Guru Member

    im not really sure where i pick up most of the stuff that i learn? who really knows where all their knowledge comes from?
  16. BassKozz

    BassKozz Network Guru Member

    Ok, So I finally got around to testing these pot's...
    I only used the 100ohm and 500ohm pot's because using a 50ohm pot is not going to limit the RPM's enough (according to Cenreyn79's formula the min RPM with full resistance = 3420RPM's).

    So I used a digital Multimeter to get a reading on the voltage coming from the adaptor going to the FAN's w/ the POT's attached (NOTE: This is w/o being attached to the WRT, I connected the adaptor directly to the POT's and 1 FAN)...
    I used the adaptor I purchased (12v 1500milliamps [1.5amps])...

    Digital MultiMeter Readings
    Nothing attached = 17.55v
    100ohm POT
    Min Setting (No resistance) = 8.4 ~ 8.54 Volts
    Max Setting (Full resistance) = 15.81 ~ 15.84 Volts
    500ohm POT
    Min Setting (No resistance) = 4.49 ~ 4.62 Volts
    Max Setting (Full resistance) = 15.76 ~ 15.83 Volts

    Why is it reading above 12Volts if the Adaptor is rated for 12Volts?

    I also noticed when the 500ohm pot was first hooked-up to the fan and was set to Max Setting (full resistance), the fan didn't even spin... once I got it to spin up (turn'ed down the resistance - Min Setting) I could turn it all the way back up to Max Setting and it would continue to spin, but VERY slowly, and it would make noise like it wanted to stop running, it sounded like the bearings were scraping slightly (or something).

    So after running these tests, I think I am going to go with the 100ohm pot, and see if I can find a 3w version (just to be safe).
    [EDIT: I Found a site that sells these POT's (both 5w and 3w):
    I do have a question about this... should I get a Inductive POT or Non-Inductive POT ?

    Unforunatly I wasn't able to record the exact RPM's of the fan's because the fan doesn't have a RPM monitoring feature. :(
    But even if it did I don't have a fan controller to read these readings, is there another way to do this?

    p.s. I never heard back on weather I should use the OEM linksys adaptor (12v 1amp) or this new adaptor I purchased (12v 1.5amp) to compensate for the fan's?

  17. RonWessels

    RonWessels Network Guru Member

    I have no idea why your readings were above 12V. Are you sure you had your multimeter set on the correct setting (DCV rather than ACV)?

    As for inductive vs non-inductive POTs, it won't matter in your case.

    An inductive POT is one that is made using loops of resistive wire, which means that the POT will introduce an inductance as well as a pure resistance. If you're building a highly tuned amplifier circuit, you'd care about that.

    I'm not sure why you really care about the exact RPM's of your fan. Simply eyeball the air circulation generated until you get what you want. RPM monitoring is good for diagnostics of fan failures: knowing the fan is still turning without having to open up the case.

    As for which adapter to use, again it doesn't matter. There is no way that a WRT is drawing even close to the 1A capacity of the stock adapter, so there should be plenty of power left to drive the fan.
  18. BassKozz

    BassKozz Network Guru Member

    Ron Thanks for the reply... I thought I had lost everyone :thumb:
    I do have my multimeter set to DCV, and I've tried 2 different multimeters, as well as 2 different adaptors (the OEM linksys adaptor & the one I purchased - 12v 1.5amp) and they both are reading ~17v w/ nothing attached. This doesn't make sense :???:
    Thanks for clearing this up for me, I just purchased a bunch ($40 worth) of pot's from the site I mentioned in the previous post... I plan on running lotsa tests to find the best one.
    Yah, now that I think about it your right, I can make a judgement based upon what I see feel and hear comming from the fan... I was more just curious if there was such a device to measure a fans RPM's or it's CFM... but if there is such a device I am sure it costs and arm and a leg :D
    Remember I'll be using two fan's (Double Fan Mod)... that will take up roughly 300-400milliamps combined... are you sure the OEM adaptor (1amp) is ok, or should I use the one I purchased (1.5amps) just incase?

    Thanks again for all the help,
    You Rock :rockon:
  19. RonWessels

    RonWessels Network Guru Member

    You certainly shouldn't hurt anything going with the higher capacity adapter. One thing you could do is put your multimeter in series with the power supply to measure the drawn current without any mods. That'll tell you how much capacity is still available.

    If you're at all worried about it and already have the higher capacity adapter, by all means use it.
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