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USB voltage ?

diachi

diachi

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Hey everyone, does anyone out there know what the output voltage of a usb is ?? I think its 5VDC but im not sure.

Its not for anthything specific, but It may be good when my 35mW (5V) labby gets back from DX.

Im currently using it to power a fan, thats on a heatsink ;D

Diachi
 





Don't pull too much current out of them, I think they are rated to 200mA. I've heard that if you significantly overdo that rating you can fry stuff in your computer, but don't take my word for it.
 
I shorted it already.

As soon as the power drawn excedes the power suppliable it shuts of the USB port, as I found out when I shorted it, It came up with a message saying a device had malfunctioned causing too much power to be drawn, and as soon as it did it shut off then asked if I wanted to re-activate it  :)

So all seems fine  ;)

Diachi
 
Could you not technically attach two USB cables together and plug one intoeach port and get 10VDC ?

Diachi
 
Diachi said:
Could you not technically attach two USB cables together and plug one intoeach port and get 10VDC ?

Diachi
Click to expand...


Nope 5 + 5 doesn't make ten. There is only one 5 volt source, it makes no difference where you tap it and how many times it's still 5v.
 
Yeah but if you put 2 1.5V batteries in series they make 3V right ? so if I put it in series it would still make 10V because each one is able to supply 5V on its own ... :-?

Diachi
 
thejunkmonger said:
[quote author=Diachi link=1213368986/0#5 date=1213394494]Could you not technically attach two USB cables together and plug one intoeach port and get 10VDC ?

Diachi
Click to expand...


Nope 5 + 5 doesn't make ten. There is only one 5 volt source, it makes no difference where you tap it and how many times it's still 5v.[/quote]


lol we could break physics, divide by zero

divided_by_zero2.jpg


and get 20000000 volts out of our homes :D!!
 
With a common ground u can't put the 2 sources in series to have 5 volts. So use a voltage doubler & osc. circuit on one plug.
Osc. output goes to a diode- cap and then a diode- cap across the 1st diode = @10-1.4=8.6 of product voltage.
 
Yeah I was thinking 200mA is a bit low.

But windows does have software too prevent to much current being drawn, and the only way I have found out is by shorting it, ill test current when I get a working multi meter, both mines are broken, one wont turn on, and the other gives me strange readings ( Yes I have checked and changed the batteries )

Diachi
 
The motherboard has to support usb over current protection, but probably most boards will have one nowadays.

If you want to hook up a powerful device to your USB port, you could connect it to a USB hub with a separate power supply. A decent hub will give you 500mA per port or even a bit more before the surge protection kicks in.
 
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