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Portable Hubs?
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...
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.
If it's just for games, you can use 5-port mini hubs with keyboard power supply. Mine came with an adapter for the PS/2 port. Should work fine with a laptop. You can daisychain them to get more ports.
Has anyone found and had luck with a battery powered network hub?
Unless you're playing on laptops, this request seems completely pointless to me. It would have been better for you to simply ask "Does anyone know of a wireless hub?" rather than qualifying it with such a silly example. If you're playing games on desktop PCs then for 2 people there must be at least 4 wall jacks available. Get a surge protector and plug in an 8-port linksys switch that sells for $50.
However, if you ARE playing on laptops, then that's another story entirely. Though I still think it's a rather ridiculous request, but I guess that's just me.
Why don't you connect the computers up wirelessly?
Then you wouldn't need any hubs. You could even put wireless cards or USB adapters onto your desktop machines.
Any you'll love it for other things when you're home and just surfing the web in front of the TV.
http://www.w-linx.com.tw/products/network/mini-hub s.htm
You could just set everything up as an Ad-Hoc wireless network, you don't need a hub.
http://www.google.com/search?hl=en&ie=UTF-8&oe=UTF -8&q=%22battery+powered+hub%22&btnG=Google+Sea rch
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.
-WolfWithoutAClause
"Gravity is only a theory, not a fact!"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!
If it says (eg) 9VDC, then get 6 D-size and tape and a connector (cut it off the power pac if you have to). Schweet. If it needs AC ge a DC to AC module from Tandy or somewhere and your christmas (for a few hours at least)
--
"we live in a post-ideological world..." - Billy Bragg.
I've used one for a digital readout system before and it lasted for about 8 hours. I'm sure that APC would have something small that you could plug in and charge, then plug your hub in wherever you wanted to use it.
Overrated / Underrated : Moderation
So these people dropped $1000 or more on a laptop but can't afford a $50 WiFi card?
Is this a joke?
Sorry, I don't have a link.
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.
Vacuum cleaners suck. Kings rule.
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
Denken hilft.
Try this hub. It is powered from a standard keyboard socket and they can be cascaded together.
-----------------------
Political Correctness is doubleplusungood.
You can pick up a basic 802.11b card for $30, so price is a flimsy excuse. If they can't afford $30, maybe your friends should play battleships on paper instead? Or maybe they can't afford that fancy paper either?
Don't know too much about it, but, check out Power Over Ethernet (POE). Runs things like hubs by delivering electricity over cat5.
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
I might get laughed out for this, but what about usb networking? Aren't usb hubs powered off the same 5V that feeds devices?
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.
Shouldn't there be bassive hubs that require no electricity?
The subject says it all! string loads of coax around and enjoy. carry a tool and extra connectors with you, and as you gain more players, go grab some cabling from the nearest TV antenna...
(yes... I -am- kidding)
a grrl & her server
When I was in college, we used to do the same basic thing but none of us had a hub. The solution we found was to get combo ethernet cards that had rj-45 connectors as well as coax connectors (I think that's what they're called). But a few lengths of coax along with t-connectors and terminators and there's no need for a hub. Works great and is (relatively) portable, just throw all the cables and connectors in a bag.
--trb
"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" OK, I agree multiplayer games are **way cool** and I play them every chance I get...but in a bar ??? WTF??? Tell me I'm not the only one who finds this odd...offensive even.
Use a battery to power the hub. Essentially, you could probably get a mini switch or hub powerted by 9V, 12V, 24V etc.
;)
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
It might be worth looking into BNC networking, the cables are heavier and less flexable but it is entirely passive. For a small ad-hoc network the low bandwidth and maintenance issues can be overcome. Older PCMCIA cards should be realtively easy to find, I have one in a box somewhere myself and there is one on ebay or there are converters .
I will not be pushed, filed, stamped, indexed, briefed, debriefed or numbered.....my life is my own.
Check out http://www.dlink.com/products/hubs/de805/. Small 5 port hub, but it can be powered off of your PS/2 port with a little bit of work(see http://www.aitech.com/support/aig2install.htm) for an example.
Maybe the bar across the street would.
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.
All Troll + "offtopic" mods are meta moderated as "Unfair", because you abused the system.
Your post: 12:20 AM September 13th, 2002
The story: 08:19 AM September 13th, 2002
See the problem? Your made a post to a story *8* Hours before the world even saw it!!!!
Why does the waveform need to be regenerated?
For one:
:) Getting back the 9V vs. AA, a 9v 150 mAh battery is approxibately equivalent to a 4.5v 300 mAh battery. 4 AAs gives you 4.2v at 1200-1500 mAh or more, which is 4x or more the capacity at the same price.
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.)
retrorocket.o not found, launch anyway?
...and then buy a sealed lead-acid 12 volt battery and charger, and pick up the proper plug at Rat Shack.
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.
"Remember when the U.S. had a drug problem, and then we declared a War On Drugs, and now you can't buy drugs anymore?"
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!
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.
...
Run it off a small lead acid battery... There are many small ones that would outlast your laptop batteries (which I'm assuming your not plugging in your laptops since you want a battery powered hub).
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?
Looking at the cheapy $40 hub (they go for much less these days) I see that it has a wall wart attached to it. DC, 7.5v.
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.
Jesus was all right but his disciples were thick and ordinary. -John Lennon
Get a hub, and take the thing to Radio Shack. They have this AC Adapter product that you can get different end connectors for. Find one that fits your hub and get an extension cord (not like a normal AC extension cord, but one for the product to make it's cord longer). Put the little connector onto the extension cord and cut off the other end (so you have the connector and alot of wire, common sense, I know). Then take the connector and attatch the cut end to a 6V lantern battery (that's what I used and what I use to power everything else I own that's portible, and they always work great), making sure to get the right positive (some things have center positive, some have it the other way around), and then secure the wires to the battery with tape or something. Duct tape the battery to the hub, and plug it in when you want it on (Or if it has an on off switch that would work too). I've done this on a bus trip with 4 laptops and quake, worked great.
It's harder to find theses days, but you could also make one if you wanted.
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
~Donald / Just RTFM
setup an AP in your car guess you could use AD-HOC.
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.
Most transciever circuits do operate from 5 VDC. I'd bet the wall wart is a very inexpensive unregulated one, and the real regulator is inside the hub. So, technically, you could look inside and find the 7805 on the hub, and maybe just bypass it with your own regulated battery source. That would be more efficent than 12V > regulator > 8V > regulator > 5V.
...
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
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.
use a crossover-y cable and route
-I like my women like I like my tea: green-
I have run a linksys workgroup switch from a
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
We create our society every time we interact with each other. What kind of society did you create today?
http://www.usbgear.com/usa/item_165.html
Better still, if it's already got a regulator, why bother with another one outside? Or... Why not just get 6 D-size nicads, for a nominal voltage of 7.2v, or 7, for a nominal voltage of 8.4v, and run them off that?
Nearly any cheap hub you can find today will be running on 5VDC internally.
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 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.
Kid-proof tablet..
I have a project battery sealed lead acid battery i bought from radio shack. You can use a 12 volt charger for it from the same shop. The thing about lead acid batteries, you can charge them any time you want unlike nicads alkies and such. Your only worry is overcharging to the point of overheating causes leakage and leaving uncharged for too long will cause crystals to build up on the terminal rods.
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-
Consider yourself blessed if you are sneezed on by a dragon and only get wet, it could have been a fireball.
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.
I've done what you've said with a variety of hardware - notebooks, all sorts of test equipment, etc. You -must- use a in-line fuse if you are powering something off a battery source that isn't going to have one internally. If there is a short, the battery can easily source enough current to cause a fire hazard. An in-line fuse will run you a few bucks.
.5A or 1A fuse.
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.
..don't panic
When I last priced NiMHs, Wal-Mart had 1200s or 1300s for $11-12 per 4-pack whereas Sears had 1500s for $10.
:)
Maybe Wal-Mart has improved prices then.
retrorocket.o not found, launch anyway?
Most small (5-8 port) hubs/switches that I've seen are powered by like 9V, maybe 12V. At any rate, you can just hook up batteries to those! I don't know what the battery life would be like though.
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?
Will I retire or break 10K?