i'd like a universal usb power cable plz.
February 1, 2011 3:04 AM Subscribe
i'd like to make or buy a custom usb cable that takes different power adapter tips.
so i have an increasing number of devices that draw 5V 500mA and they all seem to use different size sockets for their respective power adapters and i'd like to consolidate as many cables as possible.
seeing how i have enough usb ports around to charge all this stuff, is there such a thing as a custom usb cable that is type A on one end and that little itty two prong female on the other so it can take different kinds of adapter tips like what radio shack or frys sells? it seems like such a no brainer to make but radio shack doesn't have them and online places like pacific cable or monoprice doesn't have them or want to sell you their own pricey power supplies with their own proprietary tips.
so imagine this picture but on the left side a usb type A plug instead of a typical 2 prong AC
i know i can prolly hack something together but i dont want to make a different cable for every different size tip.
so i have an increasing number of devices that draw 5V 500mA and they all seem to use different size sockets for their respective power adapters and i'd like to consolidate as many cables as possible.
seeing how i have enough usb ports around to charge all this stuff, is there such a thing as a custom usb cable that is type A on one end and that little itty two prong female on the other so it can take different kinds of adapter tips like what radio shack or frys sells? it seems like such a no brainer to make but radio shack doesn't have them and online places like pacific cable or monoprice doesn't have them or want to sell you their own pricey power supplies with their own proprietary tips.
so imagine this picture but on the left side a usb type A plug instead of a typical 2 prong AC
i know i can prolly hack something together but i dont want to make a different cable for every different size tip.
I think the reason they don't make these things is that, although USB can supply power to, for instance, a phone or a media player, it's not really intended for use as a generic power supply for devices. People who don't understand the current limitations of USB shouldn't be randomly plugging things into a USB socket just because they've got a power adapter tip that fits.
So, although you can find vaguely similar things like this multi-tipped phone charger, for the exact thing you're talking about you'd probably have to take the home-made route as you say.
posted by le morte de bea arthur at 3:21 AM on February 1, 2011
So, although you can find vaguely similar things like this multi-tipped phone charger, for the exact thing you're talking about you'd probably have to take the home-made route as you say.
posted by le morte de bea arthur at 3:21 AM on February 1, 2011
I think it is more likely that manufacturers assume that most devices you will hook up via USB will also have data connections. But you can easily make this yourself. I spliced a USB plug onto a beard trimmer just last week, because the transformer died and I didn't have an extra one lying around.
http://pinouts.ru/Slots/USB_pinout.shtml
posted by Nothing at 4:25 AM on February 1, 2011
http://pinouts.ru/Slots/USB_pinout.shtml
posted by Nothing at 4:25 AM on February 1, 2011
Note this line: A simple USB charger should short the 2 data lines together. The device will then not attempt to transmit or receive data, but can draw up to 1.8A, if the supply can provide it.
posted by Nothing at 4:27 AM on February 1, 2011
posted by Nothing at 4:27 AM on February 1, 2011
I bought this in an airport for $25 for a phone emergency. It doesn't show in the picture, but it is exactly as you describe. It's an AC-to-USB wall plug, a standard USB-A male-to-female extension cord, and then five tips which are all USB-A male on one end and the other ends are micro, mini, micro mini, B, and A.
I think the wall charger itself puts out weird voltage because it makes my phone act funny, but you could just use the tips. In fact, at one point I didn't even use the extension cable, I just used the micro tip and attached my phone directly to my laptop, like it was a little shuttle docking to a space station. There might be a cheaper solution out there, though.
posted by Partial Law at 5:05 AM on February 1, 2011
I think the wall charger itself puts out weird voltage because it makes my phone act funny, but you could just use the tips. In fact, at one point I didn't even use the extension cable, I just used the micro tip and attached my phone directly to my laptop, like it was a little shuttle docking to a space station. There might be a cheaper solution out there, though.
posted by Partial Law at 5:05 AM on February 1, 2011
Do you mean the same kind of thing that comes up when you do a Google search for "USB phone charger"? I have bought several sets that consist of a retractable USB cable and a set of interchangeable tips. Zip-linq seems to be the market leader.
posted by nowonmai at 5:07 AM on February 1, 2011
posted by nowonmai at 5:07 AM on February 1, 2011
It was annoying me that none of the pictures of that Brookstone charger demonstrate that it has the tips you seek, so here are some hasty pictures of the box and the tips from mine. Those are all the tips except the micro one, and the extension cable (because those are the only parts of the kit I actually use). Like I said, a little pricey for your purposes since you don't want the charger block itself, but it's proof that the tips exist in a non-proprietary form.
posted by Partial Law at 5:16 AM on February 1, 2011
posted by Partial Law at 5:16 AM on February 1, 2011
I may be incorrect, but I believe the poster is asking about charging non-usb devices (which generally have a round plug like this), not just the various USB formats.
posted by Nothing at 5:44 AM on February 1, 2011
posted by Nothing at 5:44 AM on February 1, 2011
My mistake Nothing, you're absolutely right. I've finally gotten so used to everything being micro- or mini-USB at this point, that I didn't parse the question right. In that case I agree that it's going to have to be homemade.
posted by Partial Law at 5:50 AM on February 1, 2011
posted by Partial Law at 5:50 AM on February 1, 2011
If you go to Monoprice you can buy AC-to-USB charger warts for about $2/ea, IIRC. I actually use an old USB 1.0 powered hub as a "charging station" for cellphones, Bluetooth headsets, etc., all of which charge via either mini or micro USB.
I'd say your best bet would be to buy a bunch of cheap USB cables from Monoprice or some other store — Monoprice is very cheap, though — and then hack the ends on.
If you wanted to do it sort of non-destructively, you could buy USB extension cables (which have a male-A connector on one end an a female-A connector on the other), and insert the male and female connectors into the middle of your existing charging cords, so that the male-A end is connected to the end of the cord that goes into the device.
E.g.:
[wall wart]------[usb A female]=[usb A male]----[proprietary connector]=[device]
I would short the data lines together inside the USB A male connector and just leave them floating on the USB A female side (where they won't have anything to connect to).
If you did it this way, you'd be able to use the existing chargers normally, but would also have the option of undoing the USB connector in the middle, and taking the end (without the wall wart on it) and plugging it into a USB hub/charger while on the road.
You may run into issues connecting too many of these devices to a computer, because (I believe, and this is based on hearsay, I haven't actually read the USB spec) if the device doesn't handshake with the computer and specify its current draw requirements, the computer will assume it's 1.5A, and most computers (laptops esp.) can't actually source 1.5A on all their ports simultaneously.
posted by Kadin2048 at 8:04 AM on February 1, 2011
I'd say your best bet would be to buy a bunch of cheap USB cables from Monoprice or some other store — Monoprice is very cheap, though — and then hack the ends on.
If you wanted to do it sort of non-destructively, you could buy USB extension cables (which have a male-A connector on one end an a female-A connector on the other), and insert the male and female connectors into the middle of your existing charging cords, so that the male-A end is connected to the end of the cord that goes into the device.
E.g.:
[wall wart]------[usb A female]=[usb A male]----[proprietary connector]=[device]
I would short the data lines together inside the USB A male connector and just leave them floating on the USB A female side (where they won't have anything to connect to).
If you did it this way, you'd be able to use the existing chargers normally, but would also have the option of undoing the USB connector in the middle, and taking the end (without the wall wart on it) and plugging it into a USB hub/charger while on the road.
You may run into issues connecting too many of these devices to a computer, because (I believe, and this is based on hearsay, I haven't actually read the USB spec) if the device doesn't handshake with the computer and specify its current draw requirements, the computer will assume it's 1.5A, and most computers (laptops esp.) can't actually source 1.5A on all their ports simultaneously.
posted by Kadin2048 at 8:04 AM on February 1, 2011
You may run into issues connecting too many of these devices to a computer, because (I believe, and this is based on hearsay, I haven't actually read the USB spec) if the device doesn't handshake with the computer and specify its current draw requirements, the computer will assume it's 1.5A, and most computers (laptops esp.) can't actually source 1.5A on all their ports simultaneously.
I agree with this- I wouldn't want to trust my computer's life on tiny devices knowing not to try and draw too much power through my USB port.
The opposite can also be true, although I have no proof. It would make sense that a USB controller would shut down the power if it doesn't handshake with a device.
Maybe the controllers know that if they see their data lines shorted that it SHOULD give power, because the short IS a handshake of sorts, simply telling the host that "yes, I'm a real thing, but I've got nothing to say and please just feed me power"?
Also, beware of devices that were designed to depend on its particular charger to regulate charging current. If a "thing" knows its charger only can give it 100mA, why would it incorporate a regulator too? If it suddenly gets 500mA or 1500mA, it will lose its mind.
All of that said, I would say that if you are careful, damage isn't all that likely. But certainly possible. Just make sure you get the polarity right.
posted by gjc at 8:38 AM on February 1, 2011
I agree with this- I wouldn't want to trust my computer's life on tiny devices knowing not to try and draw too much power through my USB port.
The opposite can also be true, although I have no proof. It would make sense that a USB controller would shut down the power if it doesn't handshake with a device.
Maybe the controllers know that if they see their data lines shorted that it SHOULD give power, because the short IS a handshake of sorts, simply telling the host that "yes, I'm a real thing, but I've got nothing to say and please just feed me power"?
Also, beware of devices that were designed to depend on its particular charger to regulate charging current. If a "thing" knows its charger only can give it 100mA, why would it incorporate a regulator too? If it suddenly gets 500mA or 1500mA, it will lose its mind.
All of that said, I would say that if you are careful, damage isn't all that likely. But certainly possible. Just make sure you get the polarity right.
posted by gjc at 8:38 AM on February 1, 2011
Response by poster: yeah i guess it looks like i'll have to hack a cable together.
kadin: i dont think i have any wouldn't be connecting it to a computer i'd be connecting to a hub just like you do with your setup. but i assumed the ports on a hub would give 500mA to its ports regardless if it's attached to a computer or not right? as long as it's plugged in to an external power outlet?
gjc: yeah i was gonna say another advantage to the radio shack style adapter tips is that i can easily change the polarity by reversing the way the tips plug in.
posted by sammich at 1:59 PM on February 1, 2011
kadin: i dont think i have any wouldn't be connecting it to a computer i'd be connecting to a hub just like you do with your setup. but i assumed the ports on a hub would give 500mA to its ports regardless if it's attached to a computer or not right? as long as it's plugged in to an external power outlet?
gjc: yeah i was gonna say another advantage to the radio shack style adapter tips is that i can easily change the polarity by reversing the way the tips plug in.
posted by sammich at 1:59 PM on February 1, 2011
"You may run into issues connecting too many of these devices to a computer, because (I believe, and this is based on hearsay, I haven't actually read the USB spec) if the device doesn't handshake with the computer and specify its current draw requirements, the computer will assume it's 1.5A, and most computers (laptops esp.) can't actually source 1.5A on all their ports simultaneously."
According to the USB specs, if a device doesn't negotiate for more current then the host is only supposed to supply 100mA (0.1A) (maybe 150mA for USB3; I can't recall the spec) on a standard port. The later USB Battery Charging Specification adds a couple of 'dumb' modes that basically top out at ~1.5A, but good luck finding anything other than a USB power adaptor / charger - or maybe some USB3 chipsets; again, I haven't looked - that supports that.
"Also, beware of devices that were designed to depend on its particular charger to regulate charging current. If a "thing" knows its charger only can give it 100mA, why would it incorporate a regulator too? If it suddenly gets 500mA or 1500mA, it will lose its mind."
Current doesn't work that way - just because a charger can supply 1500mA or whatever doesn't mean that devices connected to it are forced to suck on 1.5A or die. Current is an 'up to, and including' thing; if the device requires 5v @ 150mA, then it will only ever draw 150mA even from a 1500mA supply.
(Oh, and don't go shorting the data pins; it'll gain you nothing unless the charging device adheres to the Battery Charging Specification for a Dedicated Charging Port, or is something dedicated & non-standard (i.e. an Apple iPhone charger). If you must do it, I think the USB Consortium recommend a 100 ohm resistor, not a short.)
Short version: on a standard USB1 or 2 port, you'll only ever get 100mA without negotiation. With negotiation, you can get 500mA. Non-standard implementations may supply more, but you can't rely on it. USB3 ups those numbers a bit (to 150mA and 900mA respectively). There is a USB Battery Charging Specification that can go up to 1500mA, but so far it's largely limited to battery chargers.
posted by Pinback at 2:52 PM on February 1, 2011
According to the USB specs, if a device doesn't negotiate for more current then the host is only supposed to supply 100mA (0.1A) (maybe 150mA for USB3; I can't recall the spec) on a standard port. The later USB Battery Charging Specification adds a couple of 'dumb' modes that basically top out at ~1.5A, but good luck finding anything other than a USB power adaptor / charger - or maybe some USB3 chipsets; again, I haven't looked - that supports that.
"Also, beware of devices that were designed to depend on its particular charger to regulate charging current. If a "thing" knows its charger only can give it 100mA, why would it incorporate a regulator too? If it suddenly gets 500mA or 1500mA, it will lose its mind."
Current doesn't work that way - just because a charger can supply 1500mA or whatever doesn't mean that devices connected to it are forced to suck on 1.5A or die. Current is an 'up to, and including' thing; if the device requires 5v @ 150mA, then it will only ever draw 150mA even from a 1500mA supply.
(Oh, and don't go shorting the data pins; it'll gain you nothing unless the charging device adheres to the Battery Charging Specification for a Dedicated Charging Port, or is something dedicated & non-standard (i.e. an Apple iPhone charger). If you must do it, I think the USB Consortium recommend a 100 ohm resistor, not a short.)
Short version: on a standard USB1 or 2 port, you'll only ever get 100mA without negotiation. With negotiation, you can get 500mA. Non-standard implementations may supply more, but you can't rely on it. USB3 ups those numbers a bit (to 150mA and 900mA respectively). There is a USB Battery Charging Specification that can go up to 1500mA, but so far it's largely limited to battery chargers.
posted by Pinback at 2:52 PM on February 1, 2011
Nothing: "Note this line: A simple USB charger should short the 2 data lines together. The device will then not attempt to transmit or receive data, but can draw up to 1.8A, if the supply can provide it."
Hang on a minute.
Unless I am mistaken, this is meant to signal to the device (phone, ipod, etc.) that it can safely draw more current from the power source, because that power source is a dedicated charger; i.e. not a computer, but a wallwart with a usb port. This assumes that the device you are charging is usb aware, and probably came with some sort of usb cable anyway.
I have no idea what shorting data lines, or having the device attempt to draw more than 500mA of current will do to an actual on-board usb port, but I can't imagine it's recommended.
The best thing to do (and I have actually done this to good effect with 5V <500mA devices), is to leave the data lines disconnected.
posted by HFSH at 3:21 PM on February 1, 2011
Hang on a minute.
Unless I am mistaken, this is meant to signal to the device (phone, ipod, etc.) that it can safely draw more current from the power source, because that power source is a dedicated charger; i.e. not a computer, but a wallwart with a usb port. This assumes that the device you are charging is usb aware, and probably came with some sort of usb cable anyway.
I have no idea what shorting data lines, or having the device attempt to draw more than 500mA of current will do to an actual on-board usb port, but I can't imagine it's recommended.
The best thing to do (and I have actually done this to good effect with 5V <500mA devices), is to leave the data lines disconnected.
posted by HFSH at 3:21 PM on February 1, 2011
I don't have the spec in front of me at the moment but IIRC looping the data pins is done in the device to signal to the charger that - despite being 'dumb' and unable to ask for more current - it's USB-charging compatible. Basically a cheap, minimal parts (1 resistor), way around USB's base 100mA limit.
Again, IIRC, it's all tied up with both the USB Battery Charging Specification extension and the EU's push towards a standard charging interface/connector for portable devices.
posted by Pinback at 4:08 PM on February 1, 2011
Again, IIRC, it's all tied up with both the USB Battery Charging Specification extension and the EU's push towards a standard charging interface/connector for portable devices.
posted by Pinback at 4:08 PM on February 1, 2011
From what I can make out from the specs, A dedicated charging port should identify itself to the device by shorting the D+ to the D- line (with an impedance of 200Ω?), This makes sense, as the cheaper of the two will often be the 10$ charger.
Anything that wants to charge a battery from a standard downstream port has to ask nicely to be compliant. Of course, it seems that many USB host devices will happily provide more current to non-compliant devices.
So as long as long as the devices don't suck up too much current, and the USB host doesn't do any tricky enforcement, he should be able to power his devices.
The last section of this paper has some interesting observations on the subject.
posted by HFSH at 6:03 PM on February 1, 2011
Anything that wants to charge a battery from a standard downstream port has to ask nicely to be compliant. Of course, it seems that many USB host devices will happily provide more current to non-compliant devices.
So as long as long as the devices don't suck up too much current, and the USB host doesn't do any tricky enforcement, he should be able to power his devices.
The last section of this paper has some interesting observations on the subject.
posted by HFSH at 6:03 PM on February 1, 2011
Ah, yes, now that I look at the spec again you're right - the charger announces that it's a charging spec compatible device by looping the D+ & D- lines with a max of 200Ω (I'm sure I've seen 100Ω recommended somewhere as a nominal value, though it may seem my memory is otherwise suspect! ;-)
That "What Your Mom Didn't Tell You About USB" section is interesting. Guess it depends if the particular host device is using hub power controllers or not. TI's TPS2070, for example, includes facility for per-port current monitoring, limiting, and disconnection - though I wonder now how often such devices are used in the real world.
(I think, just to be on the safe side, I'll keep using them ;-)
posted by Pinback at 7:33 PM on February 1, 2011
That "What Your Mom Didn't Tell You About USB" section is interesting. Guess it depends if the particular host device is using hub power controllers or not. TI's TPS2070, for example, includes facility for per-port current monitoring, limiting, and disconnection - though I wonder now how often such devices are used in the real world.
(I think, just to be on the safe side, I'll keep using them ;-)
posted by Pinback at 7:33 PM on February 1, 2011
Current doesn't work that way - just because a charger can supply 1500mA or whatever doesn't mean that devices connected to it are forced to suck on 1.5A or die. Current is an 'up to, and including' thing; if the device requires 5v @ 150mA, then it will only ever draw 150mA even from a 1500mA supply.
I almost posted this exact comment :)
Theoretically though, it isn't necessarily exactly right. Some devices might require input current limit for protection. If they are designed as cheaply as possible they might rely on the limitations of the charger to provide that current limit. This kind of thing is pretty much ancient history..
posted by Chuckles at 12:16 PM on February 3, 2011
I almost posted this exact comment :)
Theoretically though, it isn't necessarily exactly right. Some devices might require input current limit for protection. If they are designed as cheaply as possible they might rely on the limitations of the charger to provide that current limit. This kind of thing is pretty much ancient history..
posted by Chuckles at 12:16 PM on February 3, 2011
Chuckles: "Theoretically though, it isn't necessarily exactly right."
True, but if I explain it properly I pretty quickly end up climbing on one of my particular hobby-horses involving the kind of people who can figure out curve-fitting algorithms or better-than-n2 sorts from basic principles, but get all confused solving V=IR and W=VI for constants. Throwing non-linear load behaviours and the design shortcuts made around them into the equation would only end in tears and recriminations ;-)
posted by Pinback at 12:28 AM on February 4, 2011
True, but if I explain it properly I pretty quickly end up climbing on one of my particular hobby-horses involving the kind of people who can figure out curve-fitting algorithms or better-than-n2 sorts from basic principles, but get all confused solving V=IR and W=VI for constants. Throwing non-linear load behaviours and the design shortcuts made around them into the equation would only end in tears and recriminations ;-)
posted by Pinback at 12:28 AM on February 4, 2011
I think the reason they don't make these things is that, although USB can supply power to, for instance, a phone or a media player, it's not really intended for use as a generic power supply for devices.
Intention != use, though.
posted by flabdablet at 4:36 PM on February 15, 2011
Intention != use, though.
posted by flabdablet at 4:36 PM on February 15, 2011
This thread is closed to new comments.
posted by sammich at 3:10 AM on February 1, 2011