USB 3.0 voltage transformer

[somawhees]

Hi
doe anyone know of a way to convert usb 3.0 voltage up and amp down?
It for powering a a 12v 0.2 A appliance of my laptop.

 

[makkem]

Hi
you can't use a transformer as it is DC .
It would be possible to use a DC to DC converter like this one
http://

 

[somawhees]

why these stepup converters output as much heat as they describe?
i don't really want a dangerous hot hing next to my arm

 

[makkem]

They only generate excessive heat if they are overloaded,the one on that site they warn about is if it is delivering 2A that is 10 times more than you will be using so it will run cool in those circumstances.

 

[somawhees]

i will be using a modem router of usb. rating is 0.6 amps at 9v, i know that's more than 5 watts, but it is a 4 port router and i will only ever be using 2, i also have very low broadband speeds (1.5 mb/0.35 mb broadband) so it should never use more than 5 watts.

 

[makkem]

I take it you want to power a modem/router off your laptop usb.
You do know that this will reduce how long your battery lasts .
You would need a dc to dc converter 5V to 9V with a power rating of at least 6W.
The higher the power rating the cooler it will run.

 

[somawhees]

I cant find a 5v - 9v dc converter anywhere, i did order a 5 watt max 5v to 12 dc converter, and i know for a fact the modem router works and doesn't blow using 12v input.
hopefully it'l be fine as it will never be tranfering data at more than 260 kb/s all in all (am i right in thinking that downloading at high speeds will significantly increase the modem routers power usage? and low speeds will use very little?)

 

[makkem]

I think you will find that download speed will have very little effect on the power consumption of the router.

 

[somawhees]

I think you will find that download speed will have very little effect on the power consumption of the router.

how do you know this? when we are talking 5.4 Watts (thats pretty damn low!).
Surely the modem router would consume far more than 0.4 watts extra if 4 computers are downloading as well as lan sharing through the router (i wont be using LAN sharing)

 

[makkem]

Right,the power rating of the modem is the maximum power it will use,so no matter what you do it will not exceed the 5.4 Watts.
The modem effectively runs at maximum speed all the time, the download speed is determined by other factors such as the line speed and the server speed from where you are downloading.
If 4 computers are downloading they are sharing the download speed ,if you have 40MB/s broadband each of the 4 computers does not get 40MB/s they will each get somewhat less but due to diversity it will be more than 10MB/s.
You may find that when 1 computer is using the modem by itself the power draw will be slightly less due to reduced switching but it will be by a very small amount .

 

[somawhees]

I'm running this 5.4w modemrouter from the dc usb to 12v converter right-now and its fine, no heat coming from it that i can feel.
Does lan sharing use very little power aswell? that could be why Im not getting problems from to much power draw?( the voltage converter says 5w is the max)

 

[makkem]

Yeah,LAN will only add a very small amount to the power draw.
The chances are that you are using less than 5W,the 5.4W is an absolute maximum figure that you will rarely achieve in practice.