I just tried my Cardbus USB adapter with an external HDD (no external
power) and the HDD does not work, can't even hear it spin up. I know the
HDD and cable (three connectors, pigtail) are good because the setup
works perfect when using the two built-in USB ports on the notebook.

It seems the adapter is fine because the mouse, webcam etc work fine in
its USB ports (just the HDD won't start).

Question is, is there a particular brand of PCMCIA USB adapter which can
provide the 500ma per port which is needed for powering the HDD? Would
prefer to NOT need external power. Can my ThinkPad T41 provide the 500ma
needed from the internal PCMCIA/Cardbus connector?

Thanks

none wrote:

Yes, and this was discussed extensively in a previous thread. Can you
actually believe the manufacturer's specs is the real question!

"http://www.trendnet.com/products/TU2-H2PC.htm"

"ftp://ftp10.dlink.com/pdfs/products/DUB-C2/DUB-C2_ds.pdf" Amazon and
NewEgg both have it.

Also understand that the computers USB ports are usually capable
providing well over 500mA, so just because the HDD works on a USB port
on the laptop, doesn't mean that it will work on a USB port from a
Cardbus slot that provides 500mA, though most external notebook drives
do draw less than 500mA.

Can my ThinkPad T41 provide the 500ma needed from the internal
PCMCIA/Cardbus connector?

That's the real question. Actually it's much more than 500mA. The card
is rated to supply two ports at 500mA/5V, while the Thinkpad is
supplying 3.3 volts in CardBus mode. So the CardBus card has a DC-DC
converter to up-convert the 3.3V to 5V. So the slot must provide 5/3.3
*1000mA, plus whatever extra for the losses in the DC-DC converter
(typically 80-90% efficiency). However if you're only using one of the
two ports on the CardBus card, it'll probably work just fine.

none wrote:
Can one end of the double USB connector reach an USB port?

Q

yes, the cable can reach both USB ports in the Cardbus adapter
___
"Quaoar" <quaoar@marcabfleet.net> wrote in message
newses_i.4886$LZ7.859@newsfe15.lga...

SMS, interesting comments, especially about the Dc-Dc upconverter. I
wonder if ALL adapters can furnish this 500ma power we've talked about
or just those that advertise. Any idea?
___
"SMS ???. ?" <scharf.steven@geemail.com> wrote in message
news:4739d371$0$79897$742ec2ed@news.sonic.net...

none wrote:
Definitely they all cannot. Some are specced at 300 mA, and some don't
say and are probably even less, maybe 100 mA. I've never known of a
CardBus USB card that doesn't provide any power at all, at the very
minimum they are able to power a mouse or keyboard.

none wrote:
No. One end (the "thick cable") is in the Cardbus adapter, the other
(the "thin cable") is in a nearby USB port. The thin cable supplies
additional amperage to the drive.