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Wireless Networking Hardware

Constructing A Low-Power 2U Wireless Rack-Box 127

Posted by timothy from the every-household-needs-one dept.
adelayde writes "Recently we decided to build ourselves a custom rack-mountable box that we could use as a web and DNS caching proxy and which would offer flexible wireless networking facilities and have an uniterruptible power supply. The result was a 2U rack-box with dual wireless networks built upon a low-power Via EPIA MiniITX motherboard. The box has two wireless networks built in with external antenna connectors, locking switches on the front to avoid tampering, a battery to give at least 20 mins of autonomous operation, a low wattage power supply and most importantly lots of blue LEDs :)"
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Constructing A Low-Power 2U Wireless Rack-Box More

Constructing A Low-Power 2U Wireless Rack-Box

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  • ooh, impressive =) (Score:2, Interesting)

    by orangesquid ( 79734 )
    1. Sell these
    2. Profit

    No ??? needed!

    Seriously...

  • Yay LEDs (Score:3, Funny)

    by Wtcher ( 312395 ) <exa+slashdot@minishapes.com> on Sunday June 06, 2004 @11:18PM (#9354278) Homepage
    Yay LEDs, they're the wave of the future because they're all blue and such. It reminds me of those old Flash Gordon episodes where everything was polished chrome and looked like it could kill you if someone flicked a switch somewhere.

    Oh yeah, and I already can't reach the site. *laugh*

  • Asking for a /. (Score:5, Funny)

    by KRYnosemg33 ( 709857 ) on Sunday June 06, 2004 @11:20PM (#9354284)
    With a domain name like flakey.info it almost makes me think they were expecting a slashdotting

    Let's see how long she lasts ...

  • Ummm... Priorities? (Score:5, Informative)

    by pla ( 258480 ) on Sunday June 06, 2004 @11:20PM (#9354285) Journal
    ...and most importantly lots of blue LEDs

    You may have meant that as a joke, but blue LEDs suck quite a lot more power than red or green ones.

    When you care about power consumption, rather than coolness, come back and ask again.

    • Re:Ummm... Priorities? (Score:5, Informative)

      by adelayde ( 185757 ) on Sunday June 06, 2004 @11:39PM (#9354347) Homepage
      Please correct me if I'm wrong but as all the LEDs used had the same voltage and current ratings, it would mean that they draw the same power. Isn't the difference in the intensity? For example for the LEDs used in this project, they are:

      Red: 3700cd/m2
      Green: 40900cd/m2
      Yellow: 15500cd/m2
      White: 29650cd/m2
      Blue: 4480cd/m2

      Blue being quite a lot less bright, though somehow strangely alluring and the power consumption I think the same.

      In the end even if they do draw a little more, surely it's not that much compared with the draw of the other components? The wireless cards for example seem to draw quite a lot. As what we were looking for was autonomy in the event of a brown-out (or someone tripping over the extension cable), the battery did the job and I don't think having a blue LED or two adversly affected things.

      The comment was a bit of humour on as usual a rather dry subject.

      • Re:Ummm... Priorities? (Score:1, Informative)

        by Anonymous Coward
        Of course the luminous output isn't the whole story here, as the blue will look far brighter than it should, only because the human eye is especially sensitive to blue light.
        • Not true, the human eye is least sensitive to blue. It's most sensitive to light in the middle of the spectrum, i.e. green light. This is why in advertising they say black type on a blue background is bad, because it doesn't show up, catch the eye, enough.
        • The human eye is especially sensitive at wavelength of 550nm, that is Green light and that's why for the same power output (watt), the green LED appears much brighter and has a much higher luminous intensity (unit in cd or mcd) than blue or red LED.

        • Re:Ummm... Priorities? (Score:5, Informative)

          by tap ( 18562 ) on Monday June 07, 2004 @03:18AM (#9354774) Homepage
          This is doubly wrong.

          First of all, the human eye isn't the most sentitive to blue light, it much more sentitive to green. You can see the human eye's response curve here [gsu.edu] and a breakdown of color vs wavelength [gsu.edu].

          Secondly, the lumen or candela rating already takes this into account. At the peak of photopic vision, 555 nm (green), there are 683 lumens per watt. If you had one watt of blue light, it would only be about 100 lumens, because the human eye is less sensitive to that wavelength.

          In other words, one watt of green light appears brighter than one watt of blue light, because humans are more sensitive to that color. One lumen of green light is just as bright as one lumen on blue light, because the lumen measurement takes this into account. That's the whole point of lumens, they are watts times luminous efficacy for human vision.

      • All LEDs don't have the same voltage rating. Blue LEDs have a much higher voltage drop across them than the other colors.
      • Blue/white/green LEDs tend to require a voltage around 3.5, while red/orange/yellow LEDs tend to require a voltage around 1.9. Finding a bunch of different colors that operate at the same voltage is generally quite difficult.

        The "cd" measurement is attuned to the spectral response of the human eye. If the output of the LEDs were radiometrically measured it would give a better inidication of how much overall emission is there. In general though, if you have three equally emissive light sources, one each of

    • Re:Ummm... Priorities? (Score:3, Funny)

      by Anonymous Coward
      Slashdot needs a "Grumpy Bitch" mod option for the above post.

    • Re:Ummm... Priorities? (Score:4, Funny)

      by RzUpAnmsCwrds ( 262647 ) on Sunday June 06, 2004 @11:43PM (#9354360)
      Right, because the extra 200mw those LEDs use is really going to destroy the environment.

      Come on. The CPU draws 30+ times as much power as those blue LEDs.

      • Re:Ummm... Priorities? (Score:2, Informative)

        by pappin ( 783362 )
        no fool... 200mw is quite a bit when runnig from batteries. As for 30+ time more power for the rest of the system sounds a little high... they are using a low power (and fanless) switching regulator. The HD is what... 200-500 mA, the network cards likely about the same so If I'm using up 30 mA on a single blue LED that a significant amount of current... Though how much current a LED draws is dependant on the dope and colour, it's the red that draw the least power... which is the point that the fellow above
      • Right, because the extra 200mw those LEDs use is really going to destroy the environment.

        Nope. But if one has the goal of the most energy-efficient system possible, using less than optimal parts for no reason other than "coolness" seems particularly unwise.

        For a comparison (and to demonstrate my point, since two responders called me just plain wrong), a typical red LED has a peak current draw of 30ma, with the minimum continuous activity draw of only 2-3ma. A typical blue LED peaks at 50ma (not that
        • But, with the fluorescents, I pay for the decreased electric bill with headaches from the 60hz flicker, and the piss poor lighting color that comes out of fluorescents.

          In other words, there are factors other than power consumption. The builder of the machine decided to use parts that suited his/her needs and desires. Why the hell do you care?
          • I pay for the decreased electric bill with headaches from the 60hz flicker

            Try getting the high frequency CFs... Regular fluorescents bother me as well, and the HF ones do not. But anyway...


            The builder of the machine decided to use parts that suited his needs and desires. Why the hell do you care?

            I coundn't care less if he wanted to use a live yak as the case to this machine (actually, that sounds like a neat idea, IMO). But the FP post has the title "Constructing A Low-Power 2U Wireless Rack-Box",

  • Damn Blue LEDs (Score:1, Redundant)

    by josh3736 ( 745265 )
    Bah, I hate those damned blue LEDs anyways.

    (I was going to post a link to an article/long thread where a bunch of people bitched about blue LEDs, but I can't find it at the moment... Damn.)

  • Mirror linked on page (Score:4, Informative)

    by Anonymous Coward on Sunday June 06, 2004 @11:22PM (#9354291)
    http://mirror.us.psand.net/plinth/

  • sexist computing (Score:4, Funny)

    by Anonymous Coward on Sunday June 06, 2004 @11:33PM (#9354320)
    good thing it's not a chick that made this thing, or I could get in a lot of trouble for say this....
    "Hey, Nice Rack!!"

  • mini-itx performance (Score:2, Interesting)

    by FrO ( 209915 )
    Do you actually get decent performance out of mini-itx computers?

    I've been toying with the idea of making a HTPC-ish box, but the performance questions stop me from buying anything.

    • Re:mini-itx performance (Score:5, Interesting)

      by Anonymous Coward on Sunday June 06, 2004 @11:42PM (#9354357)
      A lot of people have been use Mini-ITX for HTPCs. The one thing you're going to need to do though is get a hardware based capture card. Not a cheap ATI PCI-TV or anything like that.

      Also I believe the new VIA's have a special chip on them to help with the decoding, so you should be good there.

      If you can live with only 2 PCI cards, go for it (You can always use USB Tuners as well). They do make very quiet systems.

      A lot of people will use them as clients and have a server with the actual tuners in them though. Just another idea to toss out there.

  • 2u = 2 much (Score:5, Interesting)

    by moosesocks ( 264553 ) on Sunday June 06, 2004 @11:36PM (#9354336) Homepage
    Looking at the pics on the page, it looks like they could have easily built the thing inside a 1U chasis of they used the proper power supply and heatsink. All of the other parts should fit within 1U.

    That being said, they could have simply used an ultraportable laptop with the screen unplugged and unnecessary parts removed/disabled.

    You'd be amazed as to how little there really is inside a laptop. Think about it -- the drives and batteries take up about 75% of the chasis. Leave about another 10% for the power supply and heatsinking, and you've got a REALLY small PCB.

    If space, not power, was their main concern, they could have also used one of the Shuttle cube boxes. They pack an incredibly strong punch for their size, and are usually on par with their desktop equivilants. Hell... they've even got an opteron box. The performance on the EPIA boards is horrific. What were they thinking designing a processor without a FPU? That being said, they're pretty cool because they're small, low-power, and widely availible (which laptop MBs strangely aren't). Still, they're pretty expensive considering that you're getting a PC which would have been considered pretty slow 4 years ago.

    • Re:2u = 2 much (Score:5, Insightful)

      by jjshoe ( 410772 ) on Monday June 07, 2004 @12:25AM (#9354454) Homepage
      I agree. He should have purchased this single mini itx 1u [mini-itx.com] or this dual mini itx 1u [mini-itx.com]

    • Smaller is not necessarily better (Score:4, Insightful)

      by gorim ( 700913 ) on Monday June 07, 2004 @01:15AM (#9354551)

      He may have built this for remote locations
      or heat filled rooms/closets. In those cases
      you want decent space and decent airflow INSIDE
      the box.

      Laptops have neither, and tend to suffer heat
      related problems easily enough.

      Its good already that he went low power and
      low thermal, and put it in a good solid spacious
      chassis.

      If dollars were a concern, going down to 1U
      isn't bad, but no further for real applications.

    • What exactly does a "Web cache and DNS server" need with an FPU? Which of those functions is floating point unit intensive? As far as I can tell, FP is only used for graphics and scientific applications, neither of which are part of the design goals. Also, with the disclaimer that I have never done it, it seems that hardware modding a laptop is a tricky business at best. Not to mention more expensive (if they didn't just use an "extra" one)

    • Re:2u = cheaper than 1U (Score:4, Interesting)

      by anticypher ( 48312 ) <anticypher.gmail@com> on Monday June 07, 2004 @03:32AM (#9354798) Homepage
      Looking at this page, and a bunch of their other pages, I think cost was their main concern. They found a 2U box for only GBP29, while the 1U box mentioned in another post by jjshoe runs GBP149. The wireless access bridge "was just laying around".

      Most of their projects are of the "cheap and green" variety. They have built pedal powered repeaters, solar powered satellite receivers and the like.

      I'm a bit appalled by their lack of engineering knowlege on some of their projects. But I do admire their "slap it together cheap" attitude. They are not building reliable, production level kit, they are tweaking items they found in the spare parts bin and making useful one-off projects.

      the AC
    • If space, not power, was their main concern, they could have also used one of the Shuttle cube boxes. They pack an incredibly strong punch for their size, and are usually on par with their desktop equivilants. Hell... they've even got an opteron box. The performance on the EPIA boards is horrific. What were they thinking designing a processor without a FPU? That being said, they're pretty cool because they're small, low-power, and widely availible (which laptop MBs strangely aren't). Still, they're pretty e

  • Mirror (Score:3, Informative)

    by Novanix ( 656269 ) * on Sunday June 06, 2004 @11:44PM (#9354361) Homepage
    Incase it is needed: http://fluky.org/slashdot/flakey.info/plinth/index .html Their site seems to be slowing quite fast:)

  • Nice but ... (Score:5, Interesting)

    by mike_lynn ( 463952 ) on Sunday June 06, 2004 @11:49PM (#9354370)
    Personally, I found their antenna [flakey.info] designs [flakey.info] much more interesting.

    • Re:Nice but ... (Score:3, Interesting)

      by Technician ( 215283 )
      With the 70 degree pattern of the bow-tie antenna, it would make an excelent feed for an old Dish Network antenna. It would beat a quarter wave feed many use. I have an old dish. When I get some time I think I'll make the bow-tie and use it with the dish and see how many open networks I can find. ;-)
  • Actually, I've been planning on getting one of these little things for a a while now (the pcmcia model). I want it to replace my current PII 233 bulky router. The only drawback is the price of it I think. Size is really small, it's fast, and really quiet. The space where my servers are is very limited, and I'd rather not have it all used up by a router...
    • You can get something like a Netscreen 5xp for a lot less then a Mini-ITX system. I just dont see the point in using these as routers/firewalls. That haveing been said, I do use one as a mail/web server.

  • Hrmmm (Score:4, Interesting)

    by Judg3 ( 88435 ) <<moc.kcelvap> <ta> <ymerej>> on Sunday June 06, 2004 @11:57PM (#9354392) Homepage Journal
    There has to be something special or unusual about this setup, but damn it all I can't see it.

    Sure, they integrated a wireless bridge into it, but with all that room, it doesn't look like anything special... So where's the nifty part that makes this thing "News For Nerds"?

    • Re:Hrmmm (Score:2, Funny)

      by Anonymous Coward
      It Runs Linux?

    • Re:Hrmmm (Score:1, Insightful)

      by Anonymous Coward
      There has to be something special or unusual about this post, but damn it all I can't see it.

      Sure, he integrated a comment about "News For Nerds" into it, but for such a short post, it doesn't look like anything special... So where's the nifty part that makes this thing "(Score:4, Interesting)"?

    • Ummmmm ... well, I guess they did build a neat breadboard for the power here.

      I actually found that to be the single most technical thing in here. The importance or uniqueness here is lost on me, too, I must admit. :-|

      I get the impression, too, that by the time all is said and done, they may well have actually saved some money in going with a BTO or COTS system instead of rolling their own. I know, that'd have not been nerdish enough for us, but still - to spend good money and come out with something tha

  • My 8 steps to building the same in less space. (Score:5, Funny)

    by Kenja ( 541830 ) on Monday June 07, 2004 @12:01AM (#9354401)
    1. Go to ebay.
    2. Find and buy cheap notebook.
    3. Get into argument with seller over shipping.
    4. Wait for notebook to arive.
    5. Pick up hammer.
    6. Open notebook.
    7. Hit notebook screen with hammer until it comes off.
    8. Stick some WiFi cards in notebook and put it on shelf.
  • Mirror here [pbp.net] - and this is kind of a neat looking project. Do they have any plans to make any more? From the looks of it, they want to be able to take these things out in public to create a WiFi network.

    Maybe they can hook up with the Huge Ass WiFi Backpack Guy from the other day?

  • Soekris (Score:2, Insightful)

    by N4DMX ( 614024 )
    Soekris has an interesting board that is said to be optimized for use as a wireless router(Model net4526)

    I imagine it would fit in to a project such as this quite easily, and it has pretty low power consumption.
    But, at 133 Mhz and 128 Mbytes of RAM, it's not as powerful.

    Link: Soekris [soekris.com]

  • "Low power"??? (Score:4, Informative)

    by darrylo ( 97569 ) on Monday June 07, 2004 @12:32AM (#9354463)

    I'm curious as to what their definition of "low power" is. Low, compared to a power-sucking P4 or Athlon, maybe, but probably not very low by low power standards.

    I've just set up a similar system as an home file server (no wireless, though, and I've added a cheap DVDROM drive), and my box is sucking up around 55-60W, idle. That's measured via an actual wattmeter connected to the power cord, and not by multiplying V*A.

    On second thought, maybe a soekris board and a 2.5" disk drive might have been a better solution (less RAM and CPU, which would probably be fine for an home fileserver, but the power usage would probably be in the 10-20W range).

    • What kind of server performance can you get with that?
      My ISP (http://www.aa.nu - amazing company...don't all run at once...) offers a racked EPIA 10000 with 250Gb storage and 512MB Ram on a 1Gb switch for ukp50 per month with service terms of a monthly 95th percentile of 1Mb/s per 1U. (I said DON'T all run at once...)
      You have to buy the hardware from them for ukp500 + VAT but that is pretty much the going rate anyway...

      I'm tempted as hell but i need to know if it will be able to cope with my Postfix/Amavi
  • So, he writes up some stuff about his new box, and then posts it on Slashdot to stress-test the thing? Clever, clever...

  • UPS battery naked ? (Score:3, Informative)

    by freaker_TuC ( 7632 ) on Monday June 07, 2004 @01:36AM (#9354593) Homepage Journal
    I find that UPS battery being too naked next to the powersupply... It rather be protected by itself in a cage because battery's can do strange things sometimes (I can tell :S)

    if that thing explodes in your rack you can throw away the hard drive, maybe the mainboard and wireless bridge ..

    so far for a rendundant/autonome system ...
    although a beowolf cluster of blue leds? hmmmmz...

  • For those of you interested in applying this sort of thing in the real world, we'll be taking this box out into the field along with the rest of our kit in a couple of weeks in an event taking place simultaneously in Tarifa, Spain and Tangiers, Morocco, as well as elsewhere in the world.

    Transacciones / Fadaiat [radiovague.com]

  • I'm still looking for a mini-itx rack case that isn't so deep. Maybe 20cm or so. (For a musician's rack setup.)
  • here [slashdot.org]
  • * You can run linux on them
    * You can reduce the power consumption in the same way (hard drives etc)
    * They are quite powerful

    One thing I didn't understand ... although I understand status lights and the fact that the LED lights use VERY little power, why include them? Any power saved in a low power consumption setup is good

    For the $1250 that this thing cost to build you could have a much better tested and reliable system. The thing with "homebrews" is ... can you REALLY trust your own setup vs a commercial
    • It was a prototype, so the cost is justified I think. The advantages of building your own are that you get exactly what you want and you also learn more along the way. But yes, it does work out quite pricey really compared with something off the shelf, but we haven't found anything off the shelf that does what we want - save perhaps a laptop, which we were actually replacing.

      It's a shame that Bugs Bunny sold out to AOL.
  • This is all fine and dandy but wouldn't anyone who actually needs this complicated of a system to run wireless off of probably need more access points than the 2 this thing's going to hide back in the server room?

    • For a good idea of the sort of thing we do with this sort of thing, check out http://psand.net/itrike/ [psand.net].

      In short two wireless networks are normally adequate, we use other APs in different locations as repeaters etc. Also this is to mount in a flight case or mobile vehicle, not a server room.

  • The hand nibbler tool from Radio Shack is great for cutting square holes, provided the sheet metal you are cutting is thin enough. (Surely must exist in the UK too) Or, an air-powered nibbler. That's the next toy I want to get.

    Also why use a switch for a hard drive? Just use hdparm to turn it on and off; I doubt the electronics on the drive take a lot of power in "sleep" mode. Besides, powering it on with a switch might be able to cause transient pulses that could be harmful to the IDE controller, may
  • Would using flash instead of a hard drive save power?

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