Dan's Data letters #51
Publication date: July 2003.Last modified 23-Oct-2012.
Spicy USB
I have a question regarding current draw from a D-Link DSL-200 USB ADSL modem and I am hoping you can shed some light on the problem.
A friend has a "Chilli" computer. I went to the Web site, it scared me, I left.
(It also contains very little info of any help.)
The problem is this: The modem draws its power from the USB port. When the modem is plugged into the USB port, and is the only USB device on the system, it trundles along very happily and works well. However, if you attach a second USB device, say a webcam, the webcam will not work.
I am leaning towards the theory that the modem is drawing too much power to allow the other device to operate. I believe that a USB port supplies 5V at 500mA? I have Googled in vain to try and find how much current the DSL-200 draws, but have found the power consumption to be 2.5 watts.
Am I on the right track? Do you think that a powered hub may be the answer?
Geoff
Answer:
Oh, I don't know. I think it's very good of Chilli Computers to tell their
customers whether their PC's video adapter is "cool", "spicy", "awesome"
or "hot". It's much simpler than actually naming the video chip.
Oh well. At least their products are severely overpriced.
As regards your question - yes, you're on the right track, and yes, a powered hub would be a good idea.
The standard USB power supply for powered ports is 500mA at 5 volts, which is exactly 2.5 watts (watts equals volts times amps). Each port on a powered hub has its own 500mA power supply, and so should each root port on your motherboard or USB controller card. This means that if you're plugging the modem and the webcam into motherboard USB ports, there ought not to be a problem.
In the real world, there often is a problem when you're drawing something approaching the full rated power from one or more root ports, and that problem is usually solvable by getting a self-powered hub, connecting it to one of the root ports, and plugging the troublesome devices into the hub instead.
Owning your OKness. And your files.
Last week I got fed up with my computer's constant crashes and decided to wipe out and re-install Windows XP Professional. I had a few folders marked as "private" so that only I could access them, and didn't think to make them public again before reinstalling Windows. Now I can't access any of them!
My user account has the same name and password as the one I created the private folders with, and I can't seem to find anything in Windows' help.
Please tell me there is a solution! I have a huge collection of... uh... important documents and wouldn't like to lose them forever!
Erik
Answer:
Try
this.
More info here.
Breaking bits off
While giving the innards of my computer a couple of changes and a good dusting out I was replacing my Radeon 9700 Pro card and accidentally bumped it a little too hard on one of the RAM clips. To my horror the clip had hit it just in the right place with the right force to break the solder of a tiny component just next to a RAM-sink. After I stopped crying, I decided to think about getting the component back on. I'm pretty sure soldering it back on shouldn't be a big problem. The only problem is that all the other parts on the board that look the same seem to have a certain orientation marked on the board, but not on the component, and both ends look exactly the same.
I have no clue what the component does, but it looks like a tiny brownish cube with two tiny metallic plates stuck on each end and it is mounted on the back side in the left hand corner right next to a RAM-sink. The card is made by Creative, but doesn't seem to be much different from the ATI reference design (except for a few funky heat sinks).
Toby
Answer:
If it's got no markings, it's probably not a polarised component.
If it's just a little brown featureless thing, then it's probably a capacitor, non-polarised (most caps are non-polarised). Here are some pictures of surface mount components that may help:
If it's any kind of cap other than an electrolytic (if it's really tiny, it's not an electro), or if it's a resistor, or if it's an inductor, you're fine and can solder it back on either way around, presuming your hands are steady enough and you have some suitable tweezers or super-needle-nosed pliers, and a fine-pointed, fairly low power iron.
If it's a diode, it'll need to be replaced the right way around, but it probably isn't.
Note, by the way, that many cards (and motherboards) will actually still work fine if they're missing a capacitor or two. It depends very much on which components you knock off, but if all you've done is handicap a filter circuit, the card may still be perfectly happy.
Journeyman photographer
I intend to go overseas on a university study exchange in 3 months, for a total of six months. I will be visiting various sites in Europe, from museums to cathedrals, and as you can understand I wish to purchase a video/digital camera that would do them justice.
I do not wish to go exceedingly obscene on the spending, a trip costs enough, however after reading various reviews of the Aiptek Pocket DV II, I am decidedly against the baby-cams.
I was wondering if you could suggest a perfect cam, or a couple of good ones of a digital vid/still cam nature that would suit my needs, of decent quality and within a price range of about $AU500-2000.
Beau
Answer:
Frankly, if you don't really want to make The Great Australian Travel Movie,
don't bother with a video camera. It is my considered opinion that amateur
video footage sucks, very seldom gets viewed, and looks like crap if you
try to print out frames and stick them on your wall. And you have to spend
altogether too much time seeing the sights through a bloody viewfinder.
Other people's opinions clearly differ; I care not for them.
[Beau replied and said that despite this, he actually rather does want to shoot some video. But I'm not very hip to the current DV camera scene, man, so I can't make any good recommendations in that area anyway.]
In the still camera department, what you want is a point and shoot (P&S) camera (not that you were considering a separate-lenses SLR behemoth, of course, but lots of people spoil their holiday by taking a big bag full of film photography gear; bugger that for a joke, I say) with a decent zoom range. You could make do with the 3X zoom that many mainstream P&S digitals have, but one of the less usual models with 5X or more will let you take much more interesting pictures in many travel situations.
From my own experience, I'd say that if you can find an Olympus C-2100 Ultra Zoom cheap, buy it. It's only 1600 by 1200 and hardly a new model, but it's got monster zoom and an image stabiliser, and its lens quality is pretty good considering its ludicrous zoom range. 2100UZ's are a bit thin on the ground these days, though; when they show up on eBay they tend to sell for little more than $US500, but finding them's the trick.
To cast the net further, the Digital Photography Review camera database lets you search by specification, which is very handy for this sort of thing.
Select a zoom range from "< 38mm" to "200mm +", and select "Don't mind" in the "Only current?" option at the bottom so you can search old models as well, and you'll get more than the 10 maximum displayable results, so you can get pickier about other features to narrow things down. There are still seven results even if you specify a price below $US600!
It's generally a good idea to go light on the accessories, as well. Extra batteries and memory cards and such, of course (I leave the problem of where you're going to put your images when the memory cards are full as an exercise for the reader; a laptop with a CD burner lets you carry them with you and mail copies to yourself at home, but you might want a more compact option; if you're staying with geeky friends, this problem will evaporate), and a lens cloth or two, and at least a tiny "tabletop" tripod to make low-light shots feasible. But that's where I'd stop, if I were you.
Driver patrol
I have to reinstall Windows 98 on my (very) old Toshiba 740CDT laptop. Some professional (charging more than £200!) had the "great idea" of installing Windows XP, against my wishes, and of course it is so slow it needs hours even to start up. Furthermore, he has now disappeared, having accepted a new job in South Africa.
I can foresee a quite significant problem with the reinstallation, because the last time I did this myself on the same computer I was missing a driver - I forgot which one. But the effect was that the screen image was quite small, and in the middle.
I have tried Toshiba for help, and this is of course like squeezing a stone to extract orange juice.
Gina
Answer:
WinXP on a 740CDT? Yeesh.
The 740CDT is a 166MHz Pentium machine, which is well below the minimum XP CPU requirement, guaranteeing that your XP experience is pretty much going to suck no matter how much RAM you have. And the 740CDT can only accept 144Mb of RAM anyway, which is definitely on the low side for XP, no matter how fast a CPU you have. I've got a 366MHz P-II laptop here with 192Mb of RAM, and XP Pro runs tolerably well on that, but I wouldn't want it to be much slower.
You probably already know this (now...), but I couldn't resist the chance to marvel at this decision on your professional's part. Indeed, Win98 is a much better OS choice for your computer.
Fortunately, you don't need a lot of drivers for the 740CDT, and they're all downloadable from the Toshiba support site. Pick your laptop model on that page, then use the filter function on the resulting monster list of files to show only Win98 files (not Win98SE files; that'll get you one downloadable Media Player skin, or some such nonsense), and then download everything that turns up. That little lot, copied to floppies or a CD, should get you going again.
The little-display-in-the-middle symptom you mention suggests that you were missing the right graphics driver.
Battery bludgeoning
I bought a portable CD/MP3 player for my wife yesterday as an anniversary present. It claims to run for 20 hours or something similar on a pair of alkaline AAs, but I wanted to get her some high-capacity NiMH AAs and a charger. There were three similar kits available - all came with a 4-cell charger and 4 AA NiMH cells of approximately the same capacity (two claim 1800mAH, the other 1950mAH). They're all the same price ($CDN70 or so). But one (Duracell brand) is a five-hour charger, one (Panasonic brand) is a two-hour charger, and one (Energizer brand) is a one-hour charger. I bought the one-hour.
My question is: is the one-hour charger going to cook the batteries it came with? Is trying to charge an 1800mAH NiMH cell in one hour an excessively fast charge?
Charles
Answer:
Generally speaking, the faster the charge, the meaner it is to the batteries.
Anything under 90 minutes is likely to reduce battery life; one hour is
really extreme. That's not to say that there aren't chargers that can do
it (I've had
a Maha one on my to-review pile for a shamefully long time now; it's
good, and everyone reading this should go and buy one to make up for my
slowness at writing the review), though. The major problem is picking the
end of the charge cycle reliably, because you're only really in trouble
if you go into overcharge with a super-fast charger; overcharge is where
cells leak and pop and smoke. That said, though - if you want to buy new
NiMHs as seldom as possible, then you should do nothing but 14 hour trickle
charges.
NiMH cells normally get hot when charging. Just because the things are too hot to hold when the charge cycle finishes doesn't mean they're being especially badly treated. And, no matter what you do, they will wear out; on average, every single charge will be slightly less good than the last one.
So don't sweat it. Your one hour charger is convenient, and it probably won't wear the batteries out a great deal faster than a two or three hour charger would.
Lights in the
skyenvelopeOn Friday night at around 9pm, my girlfriend and I were going out to pick up some Chinese food for dinner. As I walked past the mailbox to the car I remembered I hadn't checked the mail that day. I opened the mailbox and found a letter from one of my clients. "Ah, a cheque", I thought as I took the letter with me to the car.
I hopped into the car and the internal light faded away. I started the engine, but didn't turn on the lights. It was essentially pitch black.
It was then that I started to open the envelope. I didn't tear it open, I peeled the seal open, and as I did, I noticed something very odd. As I pulled the flap away from the back of the envelope the tearing and separating glue quite visibly glowed. It was a bluey-purple glow that was emitted just as the glue tore.
I looked at my girlfriend and asked her if she saw what was going on - yes, she did, I wasn't crazy. I continued to peel, a bit at a time, marveling at this strange light.
Now I understand that most people wouldn't open envelopes in pitch darkness, and that's probably why I've never heard of this phenomenon.
My question for you Dan is a simple acronym - WTF?
Clancy
Answer:
What you saw was, and is, triboluminescence - mechanical generation of light,
arising from the breaking of chemical bonds. Adhesive tape commonly exhibits
this phenomenon, but people don't usually rip tape off the roll in the dark,
so this isn't commonly known. It's not much of a stretch to imagine that
envelope adhesive would too.
[Update: After replying to Clancy, I tried it myself with a randomly chosen envelope. Yup; a faint blue glow just where the adhesive was tearing. Detailed experiments are clearly called for, to determine which envelope might most profitably be employed for development into a product for illuminating stadiums and runways.]
The usual physics-demonstration example of triboluminescence is the wintergreen-flavour Life Saver, which will fill your mouth with sparkles if you crunch one between your teeth, with your lips open, in the dark.
This Straight Dope piece talks about the Life Savers phenomenon, and also about a glow from tearing tape off the end of a roll of film (which I haven't personally witnessed, but that's because Digital Dan has only loaded film into a camera about twice in his life).
Here's some more info.
Tiny tanks redux
I understand that those guys at Konami still haven't motorised the Combat Digi-Q turrets. Am I wrong? Do you know if the motorised turret versions are on the market already?
Edwin
Answer:
No, they're not.
There's a standalone sound system (makes noises in response to transmitter signals; see it here with some amusingly machine-translated text), but that's the most interesting recent Combat Digi-Q release.
Works on contingency? No, money down!
I came upon this "free" iPaq when I was surfing eBay.
[Note: That particular auction will drop off eBay's servers soon enough, but you can easily find lots more of the same type.]
What the hell is this Dan? Do you know anyone who's actually bought it?
Igor
Answer:
You'll be astounded to learn that it's a scam. More than one scam, actually.
You can read all about these "free electronics" scams here.
The particular eBay dealer whose auction you saw insists, of course, that his method is all new and completely different from those employed in any other free electronics scheme.
There is no way in the world that he could be lying, of course.
(When you've had your fill of free electronics, by the way, why not get yourself a free car?)
