Portable Hubs? 103
Nahdude asks: "A friend of mine and I tend to have frequent mini-LAN parties in odd places like diners or parks with our laptops. We've been using a crossover cable with no problems, but recently we've attracted some attention from friends, and even some strangers, who want in on the action. So I've looked (without success) for a portable networking solution. Has anyone found and had luck with a battery powered network hub? Keeping in mind that wireless, although neat, will probably be a bit difficult because the expense of mobile wireless cards could be out of range of a lot of the people interested (we had 15 people last week in a bar, woot, but only 2 player games with crossovers because they wouldn't let us plug in a hub)." I haven't seen many of these now, but maybe if someone plants the idea in people's heads we'll see these several years from now...
The more I think on it... (Score:2)
How difficult would it be to coble together some form of power delivery device that one could carry in a backpack. Total wait of the entire contraption (hub + power device/battery) should not exceed 30lbs (I'm being generous).
Bonus points will be given for: integrated solutions, solutions under 15 pounds, solutions under 5 pounds, solutions with integrated firewall and/or 802.11b support and grand mal bonus points for something that's recharge-able.
First person to market wins my undying loyalty, gratitude and all the beer, soda and junk food I can provide on my meager salary.
Re:The more I think on it... (Score:5, Insightful)
For example, this [kan.org] is the device you're looking for.
How did I find it? Like this [google.com]. Note the search words; battery powered ethernet hub. Ok, so its a hub, not a switch, but still!
Ask
Re:The more I think on it... (Score:2, Informative)
Re:The more I think on it... (Score:1)
Re:The more I think on it... (Score:2)
The moral of this posting: Don't think someone DIDN'T check Google because you found something they didn't. This too is one of the primary reasons I do Ask Slashdot.
PS - Thanks for finding the right keyword set for this, I'll be digging around on my own, this weekend, to see if I can find something that suits me.
PPS - Re: lame submissions -- Yes, I do get my fair share of those. I've tried to let readers see the kind of stuff that I get that DOESN'T hit the pages every April 1st, but I have to give up that practice for something more original this next year because people hate it when I do that. (I wonder if I should start doing this on Halloween instead as a "trick" instead of the usual "treat".... nah.... I don't look good in digital tomato...)
Re:The more I think on it... (Score:1)
Of course, if you are truely desperate, you could always contact the Sacred Knights of Cyberspace [hamster.org]. Between Ask Jeeves and Google Answers, there's not much call for us anymore, but back in the day I'd get questions. Usually from kids needing help with finding information for their school assignments.
Ah, the old days... When the 'net, while not exactly innocent, was still at least collectively naive.
Re:The more I think on it... (Score:2)
The reject of the day section or something, where incredibly lame submissions that (if possible) have some comedic value get sloughed off into. [That way it wouldn't make it to FP, but would be around for people who are into gauging that sort of thing.
Google queries (Score:1)
How did I find it? Like this [google.com]. Note the search words; battery powered ethernet hub.
In the future, do you believe submissions to Ask Slashdot should include a list of Google queries that failed to produce anything relevant?
Re:The more I think on it... (Score:2)
Only problem is finding a way to stop that irritating alarm that UPS's have.
Regardless, this gives you a backpack-portable solution to multi-user networking.
To get your wireless solution, then use a wireless hub + cat5 switch combo device.
gus
Re:The more I think on it... (Score:1)
Dip switches on the back - RTM.
Re:hoopy doop (Score:1)
Re:hoopy doop (Score:2)
Re:Why not go wireless??? (Score:1)
Googled (Score:4, Informative)
Re:Googled (Score:2)
Lowest price I've seen is http://www.mypccity.com/proddetail.asp?linenumber
for 39.99
49.99 most other places, though its hard to find, couldn't find on pricewatch, but google for SW-005CM
gave me a few hits.
Ad-Hoc would work (Score:1)
Re:Ad-Hoc would work (Score:1)
Easiest way (Score:2)
Or, more simply, I just checked out my Netgear MR314 (wireless router, but has 4 wired ethernet ports). It has a DC 12 volt power supply on it (rated at 1.2 amps), so in principle you can run it off a (car?) battery directly. Car batteries come in different sizes, are rated at ~60-200 ampere hours, so you can size your battery on portability basis and on how long you want it to last.
If you do use a car battery, check the voltage before you connect it, 12.5 volts or so should be OK, but car batteries are only around 12 volts, I've seen them go as high as 13.5 volts (particularly while charging), that could fry your router. So you could connect it up to your car, but it might not be a good idea to leave the engine running in that case.
Re:Easiest way (Score:2, Funny)
Seriously, somebody else posted a link to a genuine battery-powered hub. You should check that out. You should also get your head checked out
Re:Easiest way (Score:1)
Re:Easiest way (Score:2)
You're off by a factor of 15 with your weight.
A car battery on the other hand is good for a week-long party.
Re:Easiest way (Score:1, Flamebait)
Yeah, I did. You're a total spanner. They took a standard hub and connected a battery to it, just like I was suggesting. It's a smaller one, and so it doesn't last as long. But if you'd actually read my posting, you'd note that I only gave a car battery as an example. You're a total div, you know that?
Replacing the wallwart by a battery should be easy (Score:2)
The wall wart of my 5 ports Linksys 10/100 switch gives 7.5VDC at a maximum of 700mA, which is about 5W of power. I'd have to check with a multimeter or use one of the DC power supplies at school, but under normal usage I'm sure it's way lower than that maximum. Even with a 12Ah 12V battery, plus a voltage regulator, you'd still have enough juice to outrun the laptops.
That's something just thought about: your laptops will drain faster than the hub. So even a smaller battery than the 12Ah I mentionned would do the trick. Pick a rechargeable battery if you don't wan't to throw away too much metal in the trash.
The only thing you'll need to do is a small package to transform the 12V to 7.5 (7808 or even a small transformer), and wire it to the right DC plug for the hub, and there you go!
Re:Replacing the wallwart by a battery should be e (Score:2)
See, this is one of my pet peeves: people talking authoritatively about stuff they have no concept of.
Well, I'll give you a half point, you did say 7808 which is an 8-volt regulator. But...a small transformer? That's right off the scale. Transformers don't work on DC.
The regulator is definitely the best way to go, and you'll need a battery voltage that's decently higher than required supply. The reason is that your battery voltage will drop as the hub runs, and I'm not sure how low it will go before the hub quits working. So, don't pick up five 1.5V nickel-metal-hydride AA's to get 7.5 volts.
A small 12V gel cell battery would be ideal. Put everything into a project box and add a charger, and you've got a solution.
Re:Replacing the wallwart by a battery should be e (Score:2)
That's right off the scale. Transformers don't work on DC.
My knowledge about transformers is, I confess, rather limited. That's why I put the 7808 before in my list of possible solutions.
Of course, thinking more about it, since it's DC there's not change in the voltage in the input coil, so no current is inducted in the core of the transformer. No core current, no voltage at the output coil. So yes, the transformer was a very bad idea, unless you want to drain the battery rather quickly :)
Thank you for pointing out the obvious.
Another point against 5 1.5V AA batteries is that the energy they have is somewhat limited. So not only their output voltage will drop, but even if they keep their output voltage somehow they won't be able to power the hub (or anything else) for as long as your gel cell battery.
Bonus question: why do they need 7.5V? I've handled a couple hubs/switches (5 to 8 ports, 10 or 10/100Mbps), and they all need 7.5V. Normal chips need 5V or lower. Is it to drive the Ethernet signals?
Re:Replacing the wallwart by a battery should be e (Score:2)
Re:Replacing the wallwart by a battery should be e (Score:2)
Check the Power Pac (Score:1)
How about a small UPS? (Score:1)
I've used one for a digital readout system before and it lasted for about 8 hours. I'm sure that APC [apcc.com] would have something small that you could plug in and charge, then plug your hub in wherever you wanted to use it.
Re:How about a small UPS? (Score:2)
I have seen some that work otherwise, but my suggestion would be to get something a little "easier" on the weight requirement. I believe Radio Shack has "D" size Nickel-Metal Hydride (sp?) batteries that are 4-6 AH. Select the right amount of batteries, grab a battery holder while you're at it (as well as a plug if you don't want to castrate the original power supply), hook it all together, and you've got a cheap, rechargeable portable solution.
Oh -- you will have one more cost -- you'll need a charger for the batteries as well. Maybe it's not the cheapest solution, but it will definitely be lighter than a UPS.
Re:How about a small UPS? (Score:2)
Too expensive? (Score:2)
So these people dropped $1000 or more on a laptop but can't afford a $50 WiFi card?
Is this a joke?
Re:Too expensive? (Score:1)
PS/2 powered 5-port 100Mbps hub (Score:2)
I saw it in a shop (in Rome, Italy) last year: a small 5-port (with 6th connector also, which is 5th port but crossed over) which would run off a 5v DC power supply or a little pass-thru PS/2 adaptor which would suck the power off the port.
I know PS/2 only gives very little power, but evidently it was enough.
I don't know by how much it would shorten a laptop's battery life, but heck, that was a nice, and Tiny! thing to carry along.
USB- or PS/2-Powered Hubs (Score:1)
Have you tried to search for an USB- or PS/2-powered hub ? They may cost a few bucks more than a standard wall-plugged hub, but they do not need a separate battery, they just slowly suck out your Laptop battery.
(Please note: I do not think of USB Hubs, but USB powered Ethernet hubs.)
Tux2000
Good old Hubby. (Score:4, Informative)
-----------------------
Re:Good old Hubby. (Score:2)
Re:Good old Hubby. (Score:1)
That is true, but I have a Hubby. Checking the web site again I find the de906 kit [dlink.com]. On that page it says:
"Includes [...] two keyboard power cables for hub [...]"
and
"For hub features, see DE-805TP/C", which is the product for the original link i provided. They could have made that information a little more straight forward to find!
Wireless expensive? Give me a break! (Score:4, Insightful)
Re:Wireless expensive? Give me a break! (Score:3, Insightful)
> doing things for them instead of wasting money on luxuries.
Oh, but they do have laptops?! Hey, just because I own a Porsche doesn't mean I can afford to gas it up, right? I'm sorry, but that's screwy logic no matter how you look at it, especially considering the $30 price point.
POE (Score:2)
You need a special "injector", to get power into the cable, though.. might be able to find a battery operated injector.
Worth a check, at least.
S
What about USB (Score:1)
Also, what kind of bar are you in that you start an impromptu lan game, and *15* people have laptops and want to join. I want to move to whatever utopia you inhabit.
Re:What about USB (Score:2)
Passive hubs (Score:1)
Re:Passive hubs (Score:1)
passive hub 10baset [google.com]
Regeneration? (Score:1)
Re:Regeneration? (Score:1)
How about coax? (Score:3, Informative)
--trb
Re:How about coax? (Score:2)
An additional piece of related off-topic info is that connector sex is determined by the innermost conductor. So a thinnet cable has a male plug and the card has a female jack, though it might appear to be the opposite if you don't look closely.
That "other" connector on combo cards is not a joystick port, it is an AUI connector which can be used in conjunction with vampire clips (which are exactly what they sound like, they clip through the insulation on a cable to provide a drop) to connect to thicknet.
Interestingly enough, this same topology is still the basis for Ethernet networking, but the thicknet bus became a thinnet bus became the interior wiring of the hub. Everything related to computers shrinks!
-Peter
Re:How about coax? (Score:1)
Regular AUI Transcivers were a pain in the rear because they were bulky (they used to stick out of the back of a machine 3-4 inches!), and unless you physically screwed them to the network card they would always fall off when someone moved the table. AAUI connectors had this cool built-in clipping mechanism that held them tight, and the transceivers had a short "tail" so that they could dangle down under the table.
The other nice thing about the AAUI 10b2 transceivers was that they were self-terminating, meaning you didn't need a terminator (a little resister thingy, not a killer robot) if you were at the end of the chain. Then the Web got big, more consumer machines started coming with Ethernet standard, and RJ45 won the battle. Simple wiring is better for home users at the expense of needing an extra device (a hub) to conenct multiple (more than 2) devices.
Re:How about coax? (Score:1)
Re:How about coax? (Score:1)
C'mon! (Score:1)
Re:C'mon! (Score:1)
Use batteries with a normal hub! (Score:1)
Then link batteries of any value, + to - to + to - and so on.
Link batteries of any type until you've got the correct voltage.
Then strip open a power cable that you can slott into the DC input and connect one wire to + and one to -.
Voila
Re:Use batteries with a normal hub! (Score:1)
Re:Use batteries with a normal hub! (Score:1)
Look at BNC (Score:1)
Dlink (Score:1)
They wouldnt let you plug in a hub?!? (Score:2, Insightful)
I never ask if im plugging in somenting small and non dangerous, like my cellphone charger or laptop, and noone has ever had a problem with it. It also helps that i generally go to places im at regulary, and i always tip well. Wen i usually drop 30 buks an evening, and a pretty good tip on top of that, i dont think thryre going to worry about the 25 cents of electricty im getting.
Re:They wouldnt let you plug in a hub?!? (Score:1)
Re:They wouldnt let you plug in a hub?!? (Score:1)
Solutions, wireless, etc etc. (Score:4, Informative)
Price is a useless excuse for not going wireless. If you search, you can get WLAN cards for $30 on sale these days. And as many pointed out, if you plunked down $1000-2000 for a laptop, you can afford a WLAN card even if it's $100.
That said, for another year or two, strangers are less likely to have WLAN cards. (But this is changing VERY quickly... It's getting to the point that having a laptop without getting a WLAN card is just plain silly.)
So your two solutions are:
PS/2-powered hub. Good if you have a decent mobo, but some laptops don't quite meet the PS/2 power supply spec... And there's no way to tell w/o risking damage to the mobo. Also, it'll drain your battery.
Homebrew battery-powered hub. IMO this is the way to go. There were a few links to a 9V powered one. Note that trying to find the smallest hub might not give you the one with the lowest power consumption. Also, 9V batteries have VERY low capacity compared to AA/AAA batteries. 4 AA rechargeables will cost you about as much (or less than) a 9V rechargeable and last much longer. I think most 9V rechargeables are 15 mAh rated, "cheap" Walmart AAs will be 1200-1300 mAh. Sears has the best deal on NiMhs I've seen - 1500 mAh units, $10 for 4. I have tons of DieHards now.
4.2V will be a bit iffy with a 5V hub, but it'll be easier to charge than having more than 4 batteries. Plus the more rechargeables you have in series, the more likely you are to have problems with cell imbalances. With a step-up regulator (not expensive if you're comfortable with homebrewing some elctronics - Maxim sells some great switching regulator ICs at http://www.maxim-ic.com/), you can power 9V hubs from 4 AAs.
Don't discharge the battery pack below an average of 1 volt/cell (4.0 volts total) - Any lower and you risk a cell reversal, which will kill the cell for sure and possibly damage other cells in the pack. (Not as much of an issue if each battery is individually removable - it matters more for packs of cells.)
Re:Solutions, wireless, etc etc. (Score:1)
Guess things have changed. (Score:2)
Maybe Wal-Mart has improved prices then.
Buy a 12v-powered hub (like a Netgear)... (Score:2)
There are places that'll sell you this whole thing for cheap. I power my Tascam portable DAT deck with something similar; the battery set with charger cost me about $200, but you can make one yourself (as long as you have the charger) for probably $50.
- A.P.
Just get any old 12v hub and... (Score:1)
Looking at the crappy hub on my desk... (Score:2)
So, what you do is you get yourself a hub with a wall wart. Ditch the wart. Wire up a bunch of batteries (five in series, then more in parallel if you need more run time) and plug it into the hub.
If you are truly '733+, then get a plastic box from someone, and hack things together so that the batteries and hub fit in one box.
No Battery Needed: Passive Hub (Score:2, Interesting)
A Passive hub, which uses no power, as opposed to an Active hub, which you asked about.
You aren't reaching your 150meter limit on 10bT cables, so there should be no problem.
~DW
WIFI (Score:1)
you and your friend with WIFI cards (maybe a few extras too) and game on... perhaps hack a batterie powered AP. Many small hubs only take 5-9 volts DC.
Bar (Score:2)
You guy obviously don't drink enough. A group of 15 regulars who are going to show up en mass and stay for hours, and on a weekday. Heck I'd figure they'd let you plug in your own rack of routers.
skip the hub (Score:2)
Linksys 5 port / 7.9v / run from battery (Score:1)
12 V ( 13-14 ) car system with Radio Shack's
12 volt to ?? voltage selector system.
A small 12 volt ( think alarm system battery )
would work as well- Duration for a small ( D cell )
pack might be a problem but the 8x3x6 inch motorcycle/alarm batteries will last -
Party On
rcb
This is not rocket science.... (Score:3, Informative)
Even expensive hubs, like the (older) 10/100 Kingston rackmount that I have here runs at 5VDC internally, despite its direct connection to 120VAC. Even the fan is 5VDC. (and, yes, that did take some time to find a replacement for, but the bearings in the new Sunon are doing justfine, thanks.)
The wall-wart they come with will deliver a stiff 5 volts, or 7.5 volts, or 12 volts, or whatever. First thing that happens inside of the hub is that it goes through a regulator to bring things down to 5VDC, and this regulator cares not about what the voltage is (within reasonable limits), as long as it is >=5VDC.
[note: some hubs may have low-voltage AC power supplies. avoid these unless you feel like modding them to bypass the internal AC -> DC conversion.]
So. What you need is a way to get 5 volts in a portable fashion. Something like this keyboard power tap [compgeeks.com] would make a smooth way to do it.
All you'd need, given the above, is a durable-looking portable hub and a length of wire with appropriate connectors. You've already got the former, and RadioShack will provide the latter. Or, just cut and splice your existing wire into the adapter. There's a thousand ways to go about it, and they're all sensical and easy.
If you suspect that your laptop won't supply sufficient power from its keyboard port to power a hub, as some posters have suggested might be a problem, look to Ebay for an all-in-one kit labeled as a "USB Cell Phone Charger."
USB supplies - you guessed it - 5VDC. Current is spec'd to be something like 500 milliamps, or 2.5 Watts, so you might get pinched if your hub is inefficient about its power draw. (If in doubt, have one of your technologically-inclined LAN-buddy friends measure it.)
If you feel like it, grab one of those USB cables you've got in a drawer, and hack it into a power supply for a hub.
I've got a tiny 4-port 10baseT Netgear hub here with what I'd like to say is the same connector as my Nokia cell phone, FWIW. They've probably also got 6- or 8-port versions that are the same. (it's also small, lightweight, and made of steel - great for throwing into a backpack.)
Else, run it from its own battery supply. Feed it with 6 D cells in series, and it'll outlive any laptop which happens to be connected.
Other people have suggested sources for seriously low-power ethernet hubs, so I'll skip that research.
Just don't make the project any harder than it needs to be. You've probably, between you and a few friends, already got everything you need to make it work.
Minor omission - get a in-line fuse (Score:2)
I definately think the way to go is just get the smallest hub you can find (d-link has a great one) and then put batteries on it. Just don't forget that fuse. One thing companies do to protect their equipment is use a reverse-connected diode on the power supply pins. If for some reason you ever hooked something up backwards, for example, that diode can draw enough current to vaporize of a battery. With a in-line fuse, you'd just blow that. Most electronics are fine with a
The optimal solution is to go wireless, but this requires a little more long term planning on the part of all your friends.
Re:Minor omission - get a in-line fuse (Score:2)
The diode is another good idea, as long as there's a fuse between it and the battery.
I have a pretty nice 2.4GHz Uniden cordless phone here, which I somehow managed to reverse the battery polarity on. The smell of burnt components was instantaneous.
Upon further investigation, it had a diode across the battery, but no fuse. The first thing that happened was that it blackened the diode, and then vaporized the PCB which connected it. As the latter occured, any potential that the diode had for saving the device was quickly eliminated, as the other traces from the battery remained intact.
Talk about bad engineering...
Power supply (Score:1)
The battery I own is simply a 5Ah battery I use it to test 12 volt dc lighting before I incorprate them into my car as well as for emergency lighting . One bright neon will light a room or porch just fine and if you choose the right colors, it wont attract bugs.
Anyways to get along, i would suggest getting 2 of these batteries or look at lawn mower batteries although some larger batteries dont nessecarily have larger run time but have higher amperage for cranking power. Watch your Ah ratings. If i remember things correctly a 4 Ah battery will last 4 hours with a continuous 1 amp draw (typical alarm circut backup battery) and will last longer with less than amp draw.
Btw, I would advise using a fuse to protect your gear. One lose wire can cause a lot of heat really quick! If you create a wire harness be sure the side for the power source (the battery side) is a female acceptor type plug to protect the terminals within the plug from connecting with any old piece of metal thereby causing a short during travel and a subsequent boom or fire.
DRACO-
IR or Bluetooth (Score:2)
Bluetooth is another choice: tiny USB dongles and standardized. Up to 1Mbps. The software isn't quite as mature yet, but it's getting there.