Re: External Hard Drive - USB Connectivity?

Alex Fraser wrote:
Chris Whelan wrote:
IMHO, external drives with a separate PSU are far better; the specification
of available power to a USB port is so loosely interpreted that I would not
trust it in situations where the power demand is high.

Yup - I'm like-minded there ...

I'm not sure "loosely interpreted" is accurate - it's more like "completely ignored". In theory, even with one power/data and one power connection, the maximum permissable current is 600mA (500mA negotiated plus 100mA unnegotiated) while a 2.5" HDD is likely to take around 1A at startup. In other words, the only reason these drives work at all is because the specifications are not enforced.

I've found some "flakiness" here too. Some will, some won't. Not good. Don't like that.

No such problem with a separate PSU of course, but there is something to be said for the convenience of not having one - especially for use with a laptop.

Agreed yes. I have a little idea wrt to this (with desktops) - well really just a possible way to eliminate _another_ feckin wall-wart/need for yet _another_ mains socket.

I think the miniature DC barrel connector (3.5mm or so) is the same as found on some Nokia mobile phone chargers. So get a scab one from a boot fair for a quid, chop the cable off near the charger end and connect up to a male molex connector yellow 5V line - with an inline fuse holder + 3A or so fuse ...

This could then supply :-

Any 2.5" external HD's that pass through
or a "powered" USB hub that comes with a weedy little 1A wall-wart supply.

Good idea ?
.

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