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USB hard drives.

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G0AOZ

Technical User
Nov 6, 2002
2,342
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Not an area I've any knowledge in...

Got a couple of desktop PCs in different locations which could benefit from using an external USB hard drive as a backup. Something easily detachable and could be locked in the safe etc.

Machines have USB2 but not firewire, and run W2K. Already have some suitable 3.5" IDE drives, just need external boxes, cables etc.

Now the questions:-

1. Is there likely to be sufficient power available from the USB port to run a 3.5" drive, or would an external PSU be needed?

2. If 2.5" drives were to hand, would the USB port cope with these?


ROGER - G0AOZ.
 
G0AOZ
1) External hard drive enclosures have their own power supply, usually in the form of a power adaptor but sometimes built in to the enclosure itself.
I would recommend a 3.5inch alluminium housing type, with an on/off switch.
Example:


2) There are smaller 2.5inch HDD based enclosures abvailable as well, not as quick and although the enclosure itself is cheaper 2.5inch HDD's are considerably more money.
The upside is that they are smaller and more portable.
They work in exactly the same way as the larger 3.5inch versions.
Examples:


As you are probably aware, all of the top manufactures off "ready built" external hard drives that work out more expensive but do have some useful additional features, for example one button "BackUp" facility.

See reviews:


Martin



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Thanks for the info Martin. So I can say with certainty then that a USB port has insufficient power to drive either a 2.5" or 1 3.5" HDD irrespective of capacity...

ROGER - G0AOZ.
 
I have never seen an external hard drive that didn't have a seperate power supply?? I would assume that they draw too many amps for the power out on a standard USB/USB2 port.

I did a quick google and found one reference to 2.5watt output, don't know if thats correct but whatever the technical specs I am pretty sure external hard drives exceed USB rated supply.

Martin

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If they didnt need that extra power they wouldnt have it built-in or somehow supplied, and they all do, so that should settle that issue.
I can say that with some experience as between usb1, usb2, and firewire i have or have had about 15 of them, all had their own power in some manner. I use 6 of them fairly regularly, backup, mp3's, programs, etc. I have a few more i use sparingly, mp3 and wav mainly.
They also have circuitry built into them as well.
they also, for the most part, work great, just make sure you disable them when turning your computer off, there is a little green arrow in your system tray to do that job.



Good advice + great people = tek-tips
 
Well you've confirmed my thoughts re the power issue. And yes, little green arrow, same as other USB devices I guess... Thanks.

ROGER - G0AOZ.
 
The enclosures for 3.5 HD will need external power. But the ones for 2.5" HD(laptop HDs) do not, though there is a socket on some of them just in case you USB port is not providing enough power.
I'm using a Lacie 40G USB 2 (actually it is a Toshiba MK 4024 laptop drive), pretty fast, back up 60mb data in less than a minute. Also tried 2 other generic enclosures with 2 other laptop drives, all don't need external power.

 
pcs007
Interesting!
I have to admit I have mainly seen 3.5inch devices but the couple of 2.5's that I've seen had seperate power.

Martin

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I've been using the 2.5" HD enclosures for a while now and none require external power. The ones I have came with a '2-1' USB cable - you would plug in both the USB cables in to the PC/laptop to provide additional power to HD if needed (there are different power requirements (well two that I know of) for different laptop HDs).

Sunil
 
I think i would want to stick with a powered unit no matter what, just in case. Or at least the capability to make it powered.



Good advice + great people = tek-tips
 
There are actually many HDD enclosures that allow power though the USB for both 2.5" and 3.5" drives.

An exmple of one for 3.5" would be


By the looks of it you've all seen the 2.5" models. The only thing to keep in mind is that if you don't have an external power supply that means your computer's power supply has to take on the extra work. As long as your computer can handle it there really is no reason to get an enclosure that requires extrnal power. One other thing you may want to keep in mind is that some enclosures will not support large harddrives(usually over 120GB). However if you are just using old drives that probably isn't an issue.
 
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