2007-10-20 16:22:27 · 6 answers · asked by helmerrox 1 in Consumer Electronics ➔ Other - Electronics
USB port provides only 500 mA and the max power a device can get is 2.25W
Here is a very good article on how to steal power from a USB port
http://www.edn.com/article/CA220400.html
2007-10-20 20:39:15 · answer #1 · answered by TV guy 7 · 0⤊ 0⤋
Again with the same question. Same answer: You don't.
In order to do what you want, you need to convert 5vdc to AC, using an oscillator. Then you go through a transformer to step it up to 12v, and then convert it BACK to DC.
By the time you get done with all that, you've spent a lot more money than what a 12v power supply would cost, which is just the second half of what you're trying to build.
On top of that, your USB is very limited in the amount of power it can supply, so you'd likely burn it out very quickly.
What you are trying to do is the same thing as alchemists tried back in the middle ages, trying to turn lead into gold. Today, it's possible to do it, but it would cost millions of dollars to convert lead into a dollar's worth of gold.
For any realistic, practical purpose, it can't be done, nor can your idea.
2007-10-20 16:36:44 · answer #2 · answered by Marc X 6 · 0⤊ 1⤋
you need a charge pump, or step up DC to DC converter. there is a number of types. depends on what you are wanting to power. it's important to consider firstly, how many watts at 12V output do you require, find a DC to DC converter to handle this. then, determine what current you will be drawing from your 5V USB, and is it acceptable.
as a starting point anyway ....
www.rsaustralia.com.au search for stock number 459-8135
this is not your solution, but look along these lines. If you have little or no electronics skills, i would look for another method, such the 12V wall adapter option.
2007-10-24 15:03:46 · answer #3 · answered by clobsi 1 · 0⤊ 0⤋
Well, a transformer won't do you much good as you are working with a DC signal. Use two 5V regulators. On one, use the +5V output and ground normally. On the other use the ground as your -5V output and your +5V output as ground (therefore the voltage difference between the two terminals is -5V). This will work as long as the regulator doesn't care that your are pulling current through the opposite direction that you normally would (depends on how the regulator is constructed I guess).
2016-03-13 09:59:56 · answer #4 · answered by Anonymous · 0⤊ 0⤋
5v To 12v
2016-11-13 19:47:48 · answer #5 · answered by ? 4 · 0⤊ 0⤋
Www.rsaustralia.com
2016-12-26 21:30:55 · answer #6 · answered by gunger 3 · 0⤊ 0⤋