Personal computing discussed

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dashbarron
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Queer Power Adapater

Sat Jan 24, 2015 3:17 pm

Maybe I should post in mobile thread. Anywho.

I need a reverse USB to 12V outlet adapter/cord. I can't seem to find this in my internet travels and thought I'd post the question here in case anyone has seen something.

External battery -----> USB -----> 12V outlet ----> Device
 
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Re: Queer Power Adapater

Sat Jan 24, 2015 3:18 pm

Queer Power Adapater


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Arvald
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Re: Queer Power Adapater

Sat Jan 24, 2015 3:23 pm

Ignoring bad title...

USB 2.0 cannot provide 12V.

It is a 5V @ 1A

this would be too little power to do use.
 
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Re: Queer Power Adapater

Sat Jan 24, 2015 3:26 pm

If I am understanding you correctly, given the voltage mismatch, you are unlikely to find anything suitable. If you really do need something like this (why? I find it hard to imagine the use case) it is time to break out the soldering iron and hack together a DIY solution.

Maybe if you provide more details of what you're actually trying to do here we can be more helpful.
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Re: Queer Power Adapater

Sat Jan 24, 2015 3:30 pm

Arvald wrote:
Ignoring bad title...

I assume he's a Brit (or at least an import, if he lives in the US). Idioms can be a funny (queer?) thing when you move between cultures with the same nominal language but different slang.
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Arvald
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Re: Queer Power Adapater

Sat Jan 24, 2015 3:35 pm

just brew it! wrote:
If I am understanding you correctly, given the voltage mismatch, you are unlikely to find anything suitable. If you really do need something like this (why? I find it hard to imagine the use case) it is time to break out the soldering iron and hack together a DIY solution.

Maybe if you provide more details of what you're actually trying to do here we can be more helpful.

Not recommended...
power out of USB = 5V x 1A = 5Watts
take that to 12V = 5Watts / 12V = about 400 mA

Typical device running on a 12V circuit is 3A.

Most people think since you can go 12V to USB you can go the other way, but think of it in terms of a road.
12V = 12 lane road with a 15mph speed limit. USB is a 5 lane road with a 1mph speed limit. Think of these as the maximums before the road falls apart.
you can run multile USBs down that 12V road.
The other way around when you think of it cannot work...
 
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Re: Queer Power Adapater

Sat Jan 24, 2015 4:23 pm

Yeah, depending on the current draw, the wiring at 5V may not be able to handle the current without heating up. That's why we need more details!
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SecretSquirrel
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Re: Queer Power Adapater

Sat Jan 24, 2015 10:16 pm

Total power limits not withstanding....

https://www.pololu.com/product/2117
http://www.ebay.com/itm/Solar-Charger-B ... 0952649860
http://www.amazon.com/DROK-Adjustable-C ... B00J03PBW0

The first and last will require you to provide the appropriate cables and, in the case of the first, do some soldering. Both would need some sort of case. The middle one needs a case too, no soldering, but it would be shipping from china.

Remember this formular: P=VA. Power=Volts x Amps. Read the output capabilities on the device you plan on powering this from. It will say 5 volts at ? amp (up to like 2.5A possibly). Do the math then divide by 12V and you will get the theoretical max available amperage at 12V. Now take 80% of that and you have the practical maximum. At 5V@0.5A would give you something like 12V@170mA. 5V@1A would be 12V@333mA. 5V@2.5A would be 12V@0.83A.

--SS
 
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Re: Queer Power Adapater

Sat Jan 24, 2015 11:51 pm

More details for sure, I'm having hard time seeing why USB even needs to be in the loop.
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dashbarron
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Re: Queer Power Adapater

Sun Jan 25, 2015 1:06 am

Hmm.

Seems to answer my question then that it's not too practical (or safe). I wasn't sure if I had a low amp power draw on the 12V if it was possible to make it happen. I assume because most 12V devices would draw so much juice, that it's not entirely standard practice.

Thanks for the speedy responses on a Saturday night :)

Edit: I need to spend a few weekends learning more about electricity.
 
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Re: Queer Power Adapater

Sun Jan 25, 2015 7:05 am

You are over thinking this. Without knowing exactly what your trying to do, let me offer this. From your diagram you have a 12v device. I am betting that your not asking about how to power your device from within your home, so that leaves either a car or backpack solution. Cars run on 12 and you just need to find an adapter to the cars cigarette lighter. If you need something for a backpack then check out camping supplies.
 
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Re: Queer Power Adapater

Sun Jan 25, 2015 11:37 am

We still don't know what you're trying to do. There might be a dead simple solution, but we don't have enough info to know!

The big issue seems to be why you think USB needs to be in the loop at all; nothing you've told us sp far indicates that anything here is a USB device! We also need to know what the power draw of the device in question is.
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Re: Queer Power Adapater

Sun Jan 25, 2015 12:16 pm

just brew it! wrote:
Arvald wrote:
Ignoring bad title...

I assume he's a Brit (or at least an import, if he lives in the US).

Nah, unlikely - It means what you think it does here too (Weird title for a thread). I'll skip over the import bit... :roll:

To me, the title is interpreted as "Gay Power Adaptor" - Most of the UK would read it as such, and it's not the correct use of the word!

TL;DR entire thread, but:
dashbarron wrote:
External battery -----> USB -----> 12V outlet ----> Device

Are you trying to step up the 5V/1A power from a USB, to carry 12V and an exponential increase in Amperage, and pass it back over USB? This doesn't sound particularly safe, unless I am missing something???
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Re: Queer Power Adapater

Sun Jan 25, 2015 12:39 pm

geekl33tgamer wrote:
Nah, unlikely - It means what you think it does here too (Weird title for a thread). I'll skip over the import bit... :roll:

OK, I stand corrected. For some reason I thought it was more of a US idiom. :oops:

geekl33tgamer wrote:
Are you trying to step up the 5V/1A power from a USB, to carry 12V and an exponential increase in Amperage, and pass it back over USB? This doesn't sound particularly safe, unless I am missing something???

The whole issue with this thread is that the OP's intent is still unclear, so we have no idea whether what he needs is reasonable/practical/safe. It *might* be, or it might not. :roll:
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Re: Queer Power Adapater

Sun Jan 25, 2015 1:19 pm

It's not used as much these days but it doesn't have to mean what you think it means. Queer - adjective - Strange; odd:
 
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Re: Queer Power Adapater

Sun Jan 25, 2015 2:35 pm

Agreed that the OP needs to explain the USB in the middle. My assumption was that it was because he had something like this and was trying to run something that plugs into a 12V outlet off of it.

--SS
 
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Re: Queer Power Adapater

Sun Jan 25, 2015 3:37 pm

SecretSquirrel wrote:
Agreed that the OP needs to explain the USB in the middle. My assumption was that it was because he had something like this and was trying to run something that plugs into a 12V outlet off of it.

If so, that's a lot more than just a simple cable hack job. And the 12V device better be drawing less than ~1.5A.
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Khali
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Re: Queer Power Adapater

Sun Jan 25, 2015 3:39 pm

Just to clear up the confusion.

queer
[ kwi(ə)r ]
ADJECTIVE

strange; odd:
"she had a queer feeling that they were being watched"
synonyms: odd · strange · unusual · funny · peculiar · curious · bizarre ·
More

NOUN

a homosexual man.

VERB

spoil or ruin (an agreement, event, or situation):
"Reg didn't want someone meddling and queering the deal at the last minute"

Powered by OxfordDictionaries · © Oxford University Press

So the OP used the word correctly, you all are just used to the noun/slang usage of recent years.
 
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Re: Queer Power Adapater

Sun Jan 25, 2015 4:23 pm

Yes, I'm well aware of the multiple meanings. However, the slang usage isn't all that new; as a result it tends not to be used much as a synonym for "strange/odd" these days, because of the slang meaning. At least, that's been my experience. So when I see/hear it used that way it seems anachronistic and old-fashioned. Or perhaps I should say it seems queer? :lol:
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dashbarron
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Re: Queer Power Adapater

Sun Jan 25, 2015 9:27 pm

Quite the slew of responses here, half of them pretty comical, all thirsty for more information!

Someone gave me a decent sized external battery brick as a gift (15000mAm) as I'm frequently out for long periods of time. I have a Surface Pro 2 and in trying to make use of the brick, was hoping I could leach extra power when needed. Unfortunately, the propriety magnetic connection makes that a bit more of a challenge, further so by the brick's output options. There are some external bricks that have a DC outlet, which would work dandy with one of these http://www.amazon.com/EZMAX-Mobile-Charging-Microsoft-Surface/dp/B00LRH99Y8/ref=sr_1_2?ie=UTF8&qid=1421980074&sr=8-2&keywords=dc+to+surface+pro+2 Seeing as power specs sheets are a little harder to scrounge up, at least according to the link the tablet would draw 3.6A and the device only provides USB power for 2.4a. If I understand it correctly though, at 2A it would only supply 5V and it wouldn't do me much good anywho. For some reason, I was thinking there was some USB extension that powered more (I've seen some flatbed scanners that had them, and seem to have a slightly more robust cord?).

Eitherway, I was looking to probably spend more money than it was worth just to use a gift from a friend :)

And I meant it as [strange | odd]. I have a tendency to use non-colloquial language; there was that time I told a woman they had a frumpy looking shirt and they took it the wrong way....
 
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Re: Queer Power Adapater

Sun Jan 25, 2015 9:42 pm

Yeah, this is a total non-starter if you've only got 2.4A available at 5V. That's 12 watts total. 3.6A at 12V is 43 watts, or more than 3x the wattage available from your battery. And that's not even counting power losses in the voltage converter you would need to rig in order to step 5V up to 12V; at the end of the day, you'd probably be getting something closer to 10W out of it.

Oh, and is there a *right* way to take "your shirt is frumpy looking"? I can't imagine that conversation ending well any way you slice it! :lol:
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dashbarron
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Re: Queer Power Adapater

Tue Jan 27, 2015 9:51 am

Thanks for the explanation JBI.

Well, to be fair she had one of those naturally wavy-textile shirt and I was commenting on its texture. Noone knew that frumpy was archaic for wrinkly.

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