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I have portable Harddrive without a power supply.

It works with a short USB cable but not with cable length more than 1m.

Any solutions?

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Your title contradicts your question. I'm assuming the small length cable works, correct? – John T Mar 7 '10 at 7:51
sorry for that , i corrected the question – Mirage Mar 7 '10 at 8:54
up vote 2 down vote accepted

Your HDD is self powered by usb, so the cable length affect the power consumed !

Longer the cable is, bigger the resistance will be. (P = I^2 * R).

You can to the following to solve your problem :

  • Use short USB cable all the time
  • Use a USB cable built with a low resistance material (Gold would be perfect)
  • Use a USB Splitter: the power will be taken from a other USB port in addition to the one you're using
  • Try to find a way to power you HDD with an external power supply
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I will try the USB splitter cable – Mirage Mar 7 '10 at 11:23

My guess is that your drive needs more power than can be transmitted out of that port down that length of cable.

Get one of those USB leads that lets you use two ports. This should then provide enough power, even if you use a longer lead (with an adapter to connect that to your double one).

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