Dan's Data letters #120
Publication date: 30 July 2004.Last modified 03-Dec-2011.
Drive saunas
If I'm going to purchase an external hard drive to dedicate to video capture and editing, and it's going to be about 160-200 GB with 8 MB buffer (I'm thinking Western Digital), how important is it that it come in a case with it's own cooling fan vs. a case that is aluminum with "superior cooling abilities" but no fan?
LTK
Answer:
In theory, 7200RPM (and slower) hard drives (as opposed to the hotter-running 10,000RPM and faster drives, which are
not yet available in the capacities you're interested in) need no special cooling. They're likely to run just fine
for a couple of years of quite hard use, or rather longer if they spend most of their time spun down, even if their
operating temperature is often too hot for you to be able to keep your finger on the casing. They have to be this
tough, because they're expected to be installed in poorly cooled cheapo mini-tower systems, in the not-much-airflow
part of the case behind the front panel.
Different external cases have different cooling features; not many of them are completely sealed. A completely sealed aluminium case that makes good thermal contact with the drive will probably keep it acceptably cool if there's a bit of airflow over it, but one with some quite unimpressive looking ventilation slots will probably cool a drive a lot better, thanks to convection through the case.
External boxes that're cooled by a dinky 40mm (or smaller) fan should work better than convection-cooled boxes, but I'm sure that the worse fan-cooled boxes aren't as good as the best convection-cooled ones. There are some really awful designs out there. 40mm fans don't tend to last very long, either; they've got tiny bearings and pretty high speed. Drive boxes with bigger, slower fans (like these ones) are more desirable.
You can also, of course, hack a low-power case fan onto most external boxes; if they've got a standard drive power plug in there (old-fashioned "Molex", preferably, not new-style SATA...), it's quite trivial to add a fan.
There are too many variables to say authoritatively how much cooling a box needs to deliver, though. For applications where the drive seldom or never spins down (including yours), pretty much any fan-cooled box ought to be fine, as should the better convection-only boxes, provided the ambient temperature is low enough and the air flow isn't occluded (box in drawer, box jammed between monitors...). But, as I said, steer clear of boxes with very small fans, if only because the fan's probably going to go bad well before the drive does.
Modem Of Death
My friend signed up for a dialup account yesterday. A day previous, some Bell technicians had been goofing around with the line outside and running lines to new development around his house. Mere seconds after plugging the phone cord into the modem, his computer flat out died - the RAM and hard drive are both verifiably dead. We noticed a few minutes later that you can now hear lights in his house being turned on and off while you're on the phone. Is it possible for a phone line to carry enough of a charge to zap hardware?
Questionable Origin [sic]
Answer:
Yes, it's possible, and there are many ways for the unwanted electricity to get there - incompetent rewiring work
by contractors, or wiring faults of other kinds, or lightning strikes.
Modems, however, are meant to be designed to isolate the hardware to which they're connected from unexpected voltages on the input cable. Just hooking up a phone cable to a mains plug and sticking it into a modem (the RJ-11 Killer!), should only toast the modem, not the computer. Modem protection will fail at extreme voltages (nearby lightning strikes), but should otherwise corral the damage quite effectively. It's possible that a faulty modem could let input voltages through too easily, though.
LCD resurrection
I have an LCD color monitor made by CTL, model 5TS. The external power supply (wall wart) is not available. The monitor's input requirements per the back label are "12V, 2.0A".
Now if I understand my electronics correctly (which is unlikely), might I be able to use any regulated 12 volt power supply which has over 2.0 amps flowing out of it, or am I about to blow up a fairly nice TFT LCD display? Would 12 volts from a spare PC power supply work?
Also, is there a way to remove a small scratch from the LCD screen corner?
Rob
Answer:
Yes, any 2A-capable PSU will do. You'd probably be able to squeak through with something with a somewhat lower rating,
but an ordinary 1A 12V plugpack would be very unlikely to cut it. Remember that a 2A-rated power supply doesn't actually
have two amps "flowing out of it" all the time; that's just the maximum current it can deliver into a device
that needs that much current.
The important part is getting the polarity right. Most barrel plug AC adapters have positive on the centre terminal and negative on the outside, but I wouldn't bet my monitor's life on that; your monitor may well not have reverse polarity protection. Most devices that run from DC have something on the label that tells you the polarity.
And yes, a PC PSU's 12V rail would probably work fine. Modern ATX PSUs should be perfectly happy supplying current only to the 12V rail, and any cruddy little PSU will be able to output 2A.
It's possible that you'll be able to fix the scratch, but you probably won't. The problem is not really getting a filler material that's close to matching the refractive index of the glass (many LCDs, and most desktops, have glass fronts; some have plastic); it's merging the crack-filler with the anti-reflective coating on the screen. Buffing the scratch out isn't an option, because you'll buff the coating off with it and get a much worse blemish, unless you buff the whole darn screen.
I don't think de-scratching LCDs is any easier than doing it with CRTs, and it's pretty much impossible then, I'm afraid.
I've talked about monitor scratch removal before - here, here, here and here.
Full and frank finger feedback
Three points about your UareU Personal Fingerprint scanner review that, to me, suggest you had prejudged the product and the technology; and that you may have been more interested to play with Silly Putty than to evaluate the product:
1. For more critical security applications, this product can indeed be used in conjunction with password authentication.
2. The social engineering and technical effort to produce a mold from a DUSTED fingerprint is hardly the cake walk that you imply.
3. To use a mold would require physical access to the machine, something an online hacker would not normally have. A fairer appraisal of the device ought at least mention this point, since it would be more difficult for someone to modify the password, especially over a network connect.
Again, UareU is not a silver bullet. You review however was so casual as to ignore its potential in a number of settings.
Glenn
Answer:
The UareU scanner I reviewed can't be used along with a password, as I mentioned. This seems to
still be the case. Also, print scanners
still seem to be about as easy to fool as they were when
I wrote that review.
I pointed out that the more expensive "Pro Workstation" version supports passwords as well, and is therefore far better.
I also mentioned that fingerprint scanners only suck "if used as the only source of identification". Regrettably, at least some fingerprint scanner manufacturers continue to fail to mention this fact to their customers.
I linked to the famous Matsumoto study on the making of "gummi fingers"; anybody can see how much, or how little, of a "cake walk" it is, in their opinion.
Even if compromising biometrics is quite difficult, though, it's a big deal, because your biometrics cannot be changed. If all a biometric authentication system is being used for is local PC login, you're already pretty much screwed if an attacker has physical access to the machine regardless of the login method used. So, in that particular case, using biometrics is less of a problem - though an attacker who can log in exactly as you do, with a copied thumbprint or a stolen password, is obviously more likely to get away with it than one who has to boot a Linux CD, or crack the case and cart away your hard drive.
But once your right index finger "key" has been copied, you can never change it. Identity theft is already a big business, and a big problem, and biometrics companies - or, at least, their marketing departments - continue to have a similar attitude to the weaknesses of their various systems as tobacco companies had to lung cancer.
The identity theft industry will be very happy to go to the trouble of snarfing that glass you held at the bar in order to rip off all of your right hand fingerprints, if by so doing they can get their fangs into you forever, and make it very difficult indeed for you to ever get out from under a situation where bad debts, crimes, and numerous other terrible things get ascribed to you instead of to them. Identity theft victims today can, generally, eventually, clear their names, even if the people pretending to be them are really good at it. If biometrics companies manage to get away with the same kind of fast one that the computer-based voting machine industry is currently trying to pull in the USA, though, this could change.
Labour-increasing device
After reading your piece about "less slobby living through technology", I raced out and ordered a Roomba off of eBay. I too am lazy enough that a vacuum that does it own work seemed like a great idea.
I understand that eBay is not particularly reliable in terms of getting equipment that actually works, however my Roomba has arrived but I am totally stuffed at actually getting it to work. When I turn it on and press the room size button it makes reassuring noises along the lines of a pretty tone and then rotates about 1 inch before deciding that it has had enough and sitting there occasionally beeping. The battery light on the Roomba is flashing green (though on the Roomba site it apparently can only flash red). Do you have any idea if I have bought a dud (always a possibility) or am I doing something totally wrong (and/or stupid)?
I have tried removing and reinstalling all the parts of the Roomba and given it a total clean, and I have been assured (not that it actually means anything) that the unit was working when it was shipped. I have also checked the Roomba site out but have failed to locate any useful (read successful at fixing my problem) information.
David
Answer:
Regarding buying gear on the eBay flea market - it all depends on who you buy from. I've bought two A-OK Roombas on
eBay (you can not spend your wedding present dollar better than on a Roomba...). Caveat emptor applies, of
course, and some eBay dealers are shameless about selling total
garbage, but well-established dealers with lots of positive
feedback are, in my experience, a very good bet.
Regarding your Roomba's failure to proceed - use the super secret diagnostic mode to find out if any sensors or motors aren't working. Roombas with fluff-clogged sensors, for instance, can behave very oddly.
If everything seems to be functional, try asking around on the Roomba Community forums.
Meanwhile, back in Scamtown...
I was amused to read about your altercations with various "Harmonic" vendors, and as a lawyer and casual tinkerer I received a press release from the Australian Competition and Consumer Commission quite some time ago.
I'm not completely sure if this is the same crowd that you had a dust-up with, but no matter what, it's definitely a happy ending.
Andrew
Answer:
No, I don't think this was the same people - the surname of the proprietors of Harmonic Energy Products was Orchard.
The Australian "Purple Plates" outfit was separate from them, though the two companies sold similar anodised aluminium
talismans, which may or may not have been made and mystically energised in the same way.
And as for happy endings... well, not so much.
That's a different outfit in the USA, but it's the same scam.
People are still selling EMPower Modulators, too.
But a Google search currently turns up three of my pages before any of theirs!
And now: Magic rocks.
I realise you've probably seen 'em all when it comes to scams, and that that many keep popping up that you are probably well and truly over the whole "wonder product" scam anyway. I just had to link you to the Sixth Element A1 Power Chip, though - it's a whole new level of ridicularity.
This thing is amazing. You've seen fuel conditioners and whatnot, but this is the performance enhancing doodad to end all doodads! You can attach it to a battery terminal of the car, to the fuel pipeline, to ignition cables, air filter, shock absorbers, brakes, speaker cables, video cables, air conditioning(!) and more, and it will improve everything you can name. All for just $785! Wait until the Formula 1 guys hear about this!
It uses quantum physics, don't you know!
I know they always talk shit with these products, but the item description for this product is the most 100% completely and instantly implausible bunk I've ever had the pleasure to laugh at.
Ryan
Answer:
I found a few Web pages about this product, too (which'll be good news for those readers who've come to this page
late enough that the above-linked eBay item is no longer accessible). The pages (here,
here and
here) are almost all in Chinese,
regrettably.
Babelfish massages that last URL into something that makes about as much sense as this product deserves.
"The useless people all very much have suspected its effect", indeed.
(A reader has pointed out to me that a correct translation of that part would be "Those people who have not used it before might be skeptical of its effects", but where's the fun in that?)
