Hi,
i wannto generate current via usb port .Can anyone send me the circuit for it....or details? plz

thanks in advance

 

For a start you have to be more explicit in what you want - a USB port can supply 5V at a fairly reasonable current level.

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I'll point you in the right direction... Look here, under cables and power: http://en.wikipedia.org/wiki/Usb. Connect to pin1 (VCC) and 4 (GND) for 5V of up to 100mA.

 

You can get up to 500 mA, but if you want more than 100 you're technically supposed to ask the usb host for it. Ie, you would need a USB endpoint and get a micro to ask for more power.

 

I need to know the circuit for generating voltage from USB port for running two smps fan??

 

Do you mean to say that you need to know the voltage/current that is available at a USB port? Typically it is this: http://www.connections-usa.com/usb_pinout.html

Pin 1 ... VCC ... Red wire ... +5 VDC
Pin 2 ... D- ..... White wire ...Data
Pin 3 ... D+ ..... Green wire ...Data
Pin 4 ... GND ... Black wire.....Ground

Operating two fans to cool a SMPS may exceed the 500ma. supply current. Of course that depends on what the fans ratings are.

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There are many examples that show up in a google search.

 

Depends on the hub entirley. The USB specs say the host is supposed to shut down any port that draws more than 100ma without requesting it. Try it and find out, just don't depend on it to work on varried systems.

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Thanks dear!!!
for the details

 

Try here www.google.com

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