Can I fabricate my own USB power cable?

Hi all. Here's the situation:

I bought a Panasonic Toughbook CF-T2 laptop computer recently. It's
an awesome small light laptop. But it has no built-in optical drive.
The much more expensive W2 does, but I didn't buy one of those because
of the cost. What I did buy, however, was a NU-Tech external
"slimline" CD-RW/DVD-ROM USB 2.0 combo drive. See, I had this idea
that even though the NU-Tech drive is not advertised as being
powerable directly from the USB port, that I could make it work with a
little bit of work. I want to be able to use the NU-Tech optical
drive on the road with no A/C power available, and the drive comes
only with an A/C adapter power source. In fact, almost all "portable"
external USB 2.0 drives come with an A/C adapter. How is that
portable, I ask you? How can you be expected to use such a device in
all of the places that notebook computers are used where there is no
A/C power source available?

Well before buying the drive I did some research and determined that I
might be able to power it directly from the USB port, since it takes a
5V power input and USB ports provide 5V power out. It turns out USB
power cables are really hard to find. But I discovered that I could
buy a mini USB 2.0 hub on eBay that comes with a USB power cable. The
dimensions of the power connector are the same. And the hub was only
1 cent on eBay (with $12 shipping of course, which is where they make
their money).

So I get the laptop, get the drive, and get the hub. I plug the
drive's USB data cable into one of the T2's USB ports. I plug the
power cable into the other USB port, and into the power in port of the
drive. Bingo, the drive fires up and looks like it is working! Only
problem is, the bottom of the drive says "1.5 A" and I know that USB
ports are only supposed to be able to deliver 500 mA (i.e. .5 A) when
designed properly - and some aren't even well-made enought to deliever
the full 500 mA. But I'm going to give Panasonic credit, they make an
excellent laptop and I believe that I'm getting the full 500 mA out.

The problem is that the CD drive really does require more than 500 mA
in some situations. First, what works: playing a DVD works. This is
awesome, because now I can view DVDs on the road. I think this works
because playing a DVD only requires the drive to spin up to a certain
low speed, which takes less than 500 mA. Next, what partially works:
I can read data off of CD's most of the time but sometimes the drive
has problems, I think it's when it spins up too fast and then it kinda
spins all the way down for a second like it's lost sync or power or
something (probably had a problem driving the laser with all of the
power used up spinning the disc at a high speed?). After a few
minutes of spin up/spin down cycles, it seems like the drive finally
gives up and returns to a low spin speed. Then it continues to work
for that disc just fine. But this few minute interval is annoying and
can interrupt whatever process is using the CD drive. Finally, what
doesn't work at all: burning discs just does not work. Apparently 500
mA is just not enough juice for this.

OK, so I'm fine with not being able to burn discs when not near an A/C
power source. I don't really ever need to do this anyway.

But I really would like the reading of CDs and DVDs to be rock solid.
And for this, I think I need to deliver more power to the drive.

So my question is, will it help to somehow splice together the USB
power cable so that I can plug it into *both* USB ports? Will each
deliver the full 500 mA, and will I then be able to give a full 1 A to
the drive? Hopefully this will be enough to read any CD/DVD at any
speed.

I was thinking that I would just take another USB cable (I have
zillions), cut it open and untangle the wires. I believe there are 4
wires in there, 2 data and 2 power. I just have to splice the 2 power
wires into the 2 power wires of my USB power cable right? I remember
embarrasingly little from my college physics classes - will the
resulting cable still be 5 V or do the voltages add up (will the
resulting cable be 10 V instead?)? Finally, would I be able to take
the 2 data wires from the USB cable that I cut up and splice them into
a USB hub, so that I would have:

* Both USB ports delivering power to 1 power adapter
* One USB port connected to an unpowered USB hub into which I would
then plug all of my data devices?

Is this a crazy/useless idea?

Another way to solve my problem, that I actually think would be better
in many ways, would be to somehow limit the spin speed of the drive
itself. Is there some way under Windows to tell the drive to never
spin up to more than, say, 10x (I believe that it is a 24x drive)?
How about under Linux?

Thanks for any suggestions, and very best wishes,
Bryan

(Bryan Ischo) wrote in message . com...
So my question is, will it help to somehow splice together the USB
power cable so that I can plug it into *both* USB ports? Will each
deliver the full 500 mA, and will I then be able to give a full 1 A to
the drive? Hopefully this will be enough to read any CD/DVD at any
speed.

I was thinking that I would just take another USB cable (I have
zillions), cut it open and untangle the wires. I believe there are 4
wires in there, 2 data and 2 power. I just have to splice the 2 power
wires into the 2 power wires of my USB power cable right? I remember
embarrasingly little from my college physics classes - will the
resulting cable still be 5 V or do the voltages add up (will the
resulting cable be 10 V instead?)? Finally, would I be able to take
the 2 data wires from the USB cable that I cut up and splice them into
a USB hub, so that I would have:

* Both USB ports delivering power to 1 power adapter
* One USB port connected to an unpowered USB hub into which I would
then plug all of my data devices?

Is this a crazy/useless idea?

Yes. Probably all USB ports are sharing 500ma.

Another way to solve my problem, that I actually think would be better
in many ways, would be to somehow limit the spin speed of the drive
itself. Is there some way under Windows to tell the drive to never
spin up to more than, say, 10x (I believe that it is a 24x drive)?
How about under Linux?

Yes, under Windows there is such a program. Search for CD Drive Speed
Limiter or something like that, and you should find what you need.

http://www.cdspeed2000.com/

Aaron

Maybe a capacitor spliced inline would be the best choice. It will
store the excess power that is not being used by the drive in the low
power situations and make it available when the drive demands more.

(Aaron) wrote in message . com...
(Bryan Ischo) wrote in message . com...
So my question is, will it help to somehow splice together the USB
power cable so that I can plug it into *both* USB ports? Will each
deliver the full 500 mA, and will I then be able to give a full 1 A to
the drive? Hopefully this will be enough to read any CD/DVD at any
speed.

I was thinking that I would just take another USB cable (I have
zillions), cut it open and untangle the wires. I believe there are 4
wires in there, 2 data and 2 power. I just have to splice the 2 power
wires into the 2 power wires of my USB power cable right? I remember
embarrasingly little from my college physics classes - will the
resulting cable still be 5 V or do the voltages add up (will the
resulting cable be 10 V instead?)? Finally, would I be able to take
the 2 data wires from the USB cable that I cut up and splice them into
a USB hub, so that I would have:

* Both USB ports delivering power to 1 power adapter
* One USB port connected to an unpowered USB hub into which I would
then plug all of my data devices?

Is this a crazy/useless idea?

Yes. Probably all USB ports are sharing 500ma.

Another way to solve my problem, that I actually think would be better
in many ways, would be to somehow limit the spin speed of the drive
itself. Is there some way under Windows to tell the drive to never
spin up to more than, say, 10x (I believe that it is a 24x drive)?
How about under Linux?

Yes, under Windows there is such a program. Search for CD Drive Speed
Limiter or something like that, and you should find what you need.

http://www.cdspeed2000.com/

Aaron

Thank you very much for your response. I guess the program you
mention sounds like a better option than messing with the hardware.

Thanks again, and best wishes,
Bryan

(JAJ) wrote in message . com...
Maybe a capacitor spliced inline would be the best choice. It will
store the excess power that is not being used by the drive in the low
power situations and make it available when the drive demands more.

How big would be capacitor need to be to satisfy up to 500 mA extra
load for minutes at a time?

Thanks!
Bryan

Hi,

Yes you can limmit the speed.

As already said, on a notebook, the 500mA will be shared, so more usb
ports = same power.

Anyway, back to limiting the speed. Nero Drive Speed

Download a trial version of Nero, its included in the package. You set
the capable speeds and the max speed you would like the drive to spin
at.

I think you can also download just Drive Speed as a freeware program
as part of their utility pack.

Good luck.

Tarl