External drives NO power brick?

[severtki]

I've spent a good amount of time researching external drives, but there's no easy way to search for drives that are powered through the USB port -- no power brick. It doesn't seem to be a feature that is touted all that much, for some reason.

Does anyone have a favorite external drive (or enclosure) that fits this description? Looks like it has to be a 2.5" HDD -- though not all 2.5" are "brick-less". Haven't seen a 3.5" that fits the bill yet...

Thanks in advance!

 

[Peter]

Simple: Even the lowest power 2.5" hard disk drives exceed the USB power allowance of 500 mA - and that's not counting the USB-IDE adapter board inside the case.

Thus, (reliable) USB powered HDD enclosures are technically impossible even with 2.5" drives. (That doesn't keep them from being offered though.) With 3.5" drives, you're nowhere near this "pushing my luck" territory.

 

[Ayah]

Somehow (?) I have a 60GB 2.5" 5400rpm IDE drive that runs on USB only.

 

[severtki]

Hmmm.. Any better power supplied through FireWire?

I remember seeing a unit that connected to TWO USB ports for the power. Can't find it now, though.

 

[Zepper]

3.5" drives require 12V and 5V power - can't run at all on USB. 2.5" drives need only 5V power thus it is possible for them to run on USB power though generally they come with two USB taps in parallel (one carries just power, the other signal and power) or one USB and one PS/2 to hopefully get adequate current (Amps). I would not buy any external drive that is not self-powered, or I'd get a self-powered hub to use with it. S-P hubs can almost always supply more current than integrated USB ports.

I don't think FW can source enough power for a 3.5" drive either. FW should drive a 2.5" drive OK as the 12V on the FW port can be regulated down to the 5V the drive needs along with yielding adequate current..

Some external housings have the power supply built inside the housing so all you need to carry around is a power cord.

.bh.

 

[Peter]

Originally posted by: Ayah
Somehow (?) I have a 60GB 2.5" 5400rpm IDE drive that runs on USB only.

Like I said - pushing-your-luck territory. The power allowance on USB is 500mA. There are NO 2.5" drives with an operating power draw of less than 500 mA; spinup power draw typically is twice that. Add in 100 mA for the USB-IDE logic, and you'll see why these assemblies are beyond spec.

If you're lucky enough that the power limiters on your particular USB ports leave you the required headroom, then fine. Don't rely on it working everywhere.

 

[corkyg]

And, generally the same thing applies to Firewire. The 2.5 external will require separate power (5 vdc) with a laptop - and one will run OK on a desktop with a good Firewire source. 3.5-in externals will always require their own power source. So do printers and scanners and digital cameras.

As Peter says, you may be OK right now with one partocular device - but anything can be the straw that breaks the camel's back.

The operating word is reliability. To have it, you will have external power for externals with motors.

 

[AnMig]

Quick and easy solution is get a video ipod


I use my 30gb video Ipod as quick no frills mass storage device.

XP recognizes it as a mass storage device with no drivers needed.


You just nee to enable hard disc use during setup

good luck

 

[corkyg]

Originally posted by: AnMig
Quick and easy solution is get a video ipod

True! The iPod is self powered. I have the Zen Vision, - 30 GB drive, - can do it also. It will also accept a CF card!

 

[Ayah]

Originally posted by: Peter

Originally posted by: Ayah
Somehow (?) I have a 60GB 2.5" 5400rpm IDE drive that runs on USB only.

Like I said - pushing-your-luck territory. The power allowance on USB is 500mA. There are NO 2.5" drives with an operating power draw of less than 500 mA; spinup power draw typically is twice that. Add in 100 mA for the USB-IDE logic, and you'll see why these assemblies are beyond spec.

If you're lucky enough that the power limiters on your particular USB ports leave you the required headroom, then fine. Don't rely on it working everywhere.

Probably, but so far it works fine for all the machines in my house.