USB Power on Laptops

  dms05 12:30 31 Mar 2006
Locked

I saw elsewhere on the Forum a suggestion that Dell laptops have unpowered USB outlets. Another contributor felt they might share the normal USB power amongst the total number of USB sockets and were not individually powered as a USB powered hub would achieve.

This led me to think about an USB IR Dongle I have which I never have been able to operate on any of my laptops. The rated power for the dongle is 440ma which seems pretty close to the total that one would expect for a USB socket. However if each of my 3 USB sockets is sharing 500ma that may explain why the IR won't work - it hasn't enough power to drive the IR device.

It might also explain why a USB to RS232 cable doesn't work either (not to mention a Nokia DKU-5 USB to Mobile).

Any ideas?

  martjc 12:59 31 Mar 2006

...Ahh, Dell Laptops! I have experienced similar problems with Dell laptops. It would seem that the current applied to USB sockets is variable/unstable in some cases. In your case, 440 ma, I think, would be difficult to achieve, let alone sustain.

I think RS232 requires about 400ma. I'm sure you now understand the problem a bit better - it probably will be difficult to gat your device working! But, who knows, you may get more positive help from someone else.

Good luck.

  terryf 13:46 31 Mar 2006

You could try buying a powered dongle from click here . This is a clumsy solution but may be viable.

  terryf 13:47 31 Mar 2006

Sorry I meant powered Hub, Brain not in gear due to wine with lunch :-)

  dms05 16:36 31 Mar 2006

Thanks to you both. I'll try a Mains Powered USB Hub and see what happens. It may be clunky but it may be the only way!

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