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Can you wire USB Ports in series? Answered

Hi, All.

New to the forums, but have used several instructables and love this site. I'm currently trying to make a notebook cooling fan using a 12 Volt fan pulled from an older computer. Obviously I can wire it to the USB ports, but the 5V I'm getting there aren't enough. Would it be possible to wire 2 usb connections in a series, giving me 10V at 500mA, or am I just asking to fry my ports? I've seen some external hard drives that use 2 USB ports for power, so I'm assuming it can be done, but I didn't know if you needed anything other than a series connection.

Thanks!

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The Skinnerz (author)2010-11-20

Low voltage fans are available relatively cheaply that will work on 5v from a usb. It is not too tricky to take a 12V ish tap off the battery if you feel confident enough.

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doublec5 (author)The Skinnerz2010-11-20

Someday I'll hit that level of confidence, but probably not now under warranty! Thanks for the all the info though, guys.

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ReCreate (author)2010-11-18

Think about it, if you did that, you'd be connecting 5+ to the computer's ground. As ground is shared between all the USB ports and so is 5+. So it would be pretty much the same as connecting the 5+ to ground.

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kelseymh (author)2010-11-17

I am fairly sure you'll fry your ports. I have one of those "two port" drives. It uses one port for power, and the other for signal (in my case, the drive enclosure has two USBs and a firewire connector -- you can connect for I/O through either USB or FW, but you have to use the other USB for power).

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doublec5 (author)kelseymh2010-11-17

Hmm. So much for an awesome 12V fan arrangement running. Thanks!

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