Date: Sat, 20 Mar 2004 08:54:33 -0700 From: "Tory" <[EMAIL PROTECTED]> Subject: RE: [LIB] USB powered external HD
> But this is not a limitation of the Libretto. According to USB > specifications a USB-port should give 500mha (or less). Even my 6 build in > USB2.0 port in the desktop can only give 500mha. USB specs do say 500ma/Port. It is still a Libretto limitation though. Someone posted earlier that the libretto puts 500ma into the Cardbus ports, which seems to be the per slot limit of the cardbus specs. You should notice that I specified "Assuming the USB card itself draws no power" - Those cards get hot for a reason. How much power do you think the USB chipset uses, detracting from the power that the card passes through to the USB port? Power which, even at the fully specified power levels, is hardly enough to make a laptop drive work in the first place? > > So if it is true spinning up a 2.5" hd takes about 1000mha, not a single > USB-port in the world should be able to power it and they should ALWAYS > require a power-adapter of some sort. That means all external HD producers > are lying when they say it usually does not require external power (ok, > wouldn't be the first time but seems unlikely). Some USB ports can deliver more current, some lucky few drives can spin up with less current, and a lot of newer enclosures have *2* USB connectors so that they can draw up to 1 amp. I've seen people mod the 5volt line to come directly from the power supply, giving essentially unlimited power there. > > Or am I missing something? I've read some posts on the > http://www.everythingusb.com/ and there you also hear quite some stories > of > people requiring external power... > There is a good article on manufacturer's specs vs reality regarding bus powered laptop drives on www.dansdata.com, but I can't find it right now (little short on time this morning. I'll try and dig it up later) > Hmmm... so the only way to find out is to actually test it before > purchase! > > And how about those 1.8" HD's?? Like the Archos ARCdisk? Do they require > less power to spin? > Aren't 1.8" hard drives PCMCIA Type III drives in the first place, or is that 1.5"? If you've got a bare drive, just pop it in your cardbus slot and away you go. Tory > Thanks guys for all your thoughts! > > Regards, > Wouter > > ************************************************************** http://libretto.basiclink.com - Libretto mailing list http://www.silverace.com/libretto/ - Archives -------TO UNSUBSCRIBE------- Reply to any of the list messages. The reply mail should be addressed to: [EMAIL PROTECTED] - Then replace any text on the message's subject line: cmd:unsubscribe --------TO UNSUBSCRIBE DIGEST------ Do above but with this on subject line: cmd:unsubscribe digest **************************************************************
