RE: USB power?

Very interesting article!

And explains why I've got one USB device (infrared reader for a Polar S625x
watch) that will NOT work when plugged into a usb hub.  It is port powered
and uses to much power.  Would have been great if Polar tech support could
have told me that.

Bob

> -----Original Message-----
> From: pctech-bounces@xxxxxxxxxxxx [mailto:pctech-bounces@xxxxxxxxxxxx] On
> Behalf Of Booth Martin
> Sent: Thursday, December 29, 2005 12:17 AM
> To: PC Technical Discussion for iSeries Users
> Subject: Re: [PCTECH] USB power?
> 
> Here is a link that discusses the choices of power:
> 
> http://tinyurl.com/9arab
> 
> David Gibbs wrote:
> > Folks:
> >
> > Anyone know why some external USB hard drive chassis need external power
> > and some don't?
> >
> > A few months ago I bought a USB 2 drive chassis for a 2.5" laptop drive.
> >  I was quite disappointed when I found out it required either two USB
> > connections or a power brick (larger than the drive itself).  I returned
> it.
> >
> > The other day I found a similar drive chassis that didn't have a power
> > plug.  It took it's power directly from the USB bus.  I picked it up
> > ($25 at compusa) and it works fine.
> >
> > So my question is ... why did the first one require extra power and the
> > second one doesn't?  They were both driving the same hard drive.
> >
> > Thanks!
> >
> > david
> >
> >
> >
> 
> --
> -----------------------------------
> Booth Martin
> http://martinvt.com
> -----------------------------------
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