Dan's Data letters #85Publication date: 17 Jan 2004.
Last modified 03-Dec-2011.
I'm going to be the pround owner of a new, bleeding-edge Althon 64 CPU (the poor-man's 3000+ variant though). I have an older 300W PSU that I've been using and it's been great. Quiet, too. Oh, and it's LED-free as well (harder to find these days). I'd hate to get rid of it. But reading through various forums on the web, there are many Chicken Littles that say "you're doomed if you don't have a 1,200W PSU!!!"
Well, from reading all your emails religiously I know that you're more of a realist and have said that for most people 300W is just fine, provided the brand isn't the "yum cha" variety.
I don't plan on doing anything exotic like powering my television or margarita mixer from my PSU - I'm just an average guy that has one HDD, two optical drives, and a floppy. But the AMD64 gives me pause since it is new and might have some kind of exotic power requirement.
Athlon 64s are pretty juice-hungry CPUs, but not amazingly so. AMD quote (PDF datasheet here) the Thermal Design Power (TDP) of the Athlon 64 3000+, 3200+ and 3400+ as being 89 watts. Which is a bit dodgy - all things being equal, faster chips draw more power - but which tells us that these chips are in the same ballpark as the current high-end P4s. TDP is a decent rough estimate of the actual worst-case power draw; you're unlikely to come terribly close to it in normal operation of a PC, though.
I'm not certain that your 300W PSU will be happy running a system with an 80-watt-plus CPU and a hot graphics card in it, but I also wouldn't stampede out to buy a new PSU, except for my oft-repeated reason that it's always good to have a spare.
Build the box, and try to install your OS. If the computer isn't flaky during an OS install, that's a good sign; if it holds up through a night of looping Sandra or 3DMark testing (it's not a bad idea to burn in any new computer, rather than start doing important stuff on it right away), then you're probably going to be fine.
I have a question about digital photography which isn't about the digital image - it's about the information stored in the header. My camera (HP Photosmart 850) adds some useful information to its files, such as the date and time the picture was taken, f-stop setting, shutter speed, etc. I can read the data using a program called "Thumber" or one called EXIFRead, but I haven't figured out how to edit the information. I took some nice photos last summer, but in changing the batteries the date got reset, and it is wrong. A minor problem, I know, but an annoying one. I experimented by opening a copy of a photo in Wordpad, but saving the corrected file makes the image unviewable.
Do you know of any way to edit the data in those headers so I can correct the date?
I recently broke the AC adapter for a Fujitsu LifeBook (an E Series 6644). The output is 19 volts, 2.5 amps, and I can't find another one that matches it. Now, I know nothing of electrical matters. I can find adapters that output 19V at 3.5A, but I'm concerned about doing damage to the thing. Would it be OK to use a different spec adapter, or do I need to keep hunting for the exact right one?
Yes, a generic adapter should work, and an over-high current rating is not dangerous; that's how much current the adapter can deliver, not how much it delivers all the time.
Not long ago it was quite difficult to find AC adapters to suit laptops, because laptops generally want an odd voltage (between 15 and 20 volts DC) at a couple of amps or more. You could run a laptop from a beefy bench power supply, but you couldn't just buy a plugpack to suit; old-fashioned linear plugpacks (the heavy ones) don't generally come in those voltages, and can seldom deliver more than about an amp.
Now, generic mains and cigarette lighter adapters for laptops are quite commonly available. Some even have switchable output voltage to suit various computers. Any good electronics store should stock them, or know where you can find one, and $US100 is a high price for one (you're likely to find an official adapter costs a lot more; spare parts for superseded laptops are well into price-gouge country).
If you buy something that's actually meant to be a laptop adapter (which means it'll be regulated, and won't deliver higher voltage when it's less than fully loaded) and has the right voltage and 2.5 amp or higher current specs, it should work - but you might need to make sure you've got the polarity right. It's probably tip-positive, barrel-negative, if you're using the usual tubular kind of connector, but I wouldn't bet my laptop's life on that.
Do you think it's possible to make your own LED headlamp for exploring caves, etc? What would you house it in?
Sure, it's possible - though unless you value your time fairly lowly, you may find a commercial product to be a better option. Generic Chinese-made LED headlamps are pretty commonly available these days - here in Australia, Jaycar has a few, for instance.
The housing is is more of an issue for headlamps than for flashlights; you don't want to just strap a project box to your forehead. If I were intent on building my own stylish LED headlamp, I think I'd buy a broken brass calcium carbide miner's lamp, core out the acetylene-generating hardware, and install my electronics in that.
(People still use carbide lamps, by the way, thanks to their excellent brightness and decent run time, and they're not the bombs-strapped-to-your-head you might think they'd be, as long as you keep them in good order.)
After I told him what you said about installing a full height 2.5 inch drive in a case made for a thinner one, my local Mac guy said this:
- "Most all 2.5" FW drives use the FireWire bus for power, and there is not enough current (milliamps) available to spin up the older "fat" hard drives (they all take in excess of one amp DC to spin up - not available on the FireWire bus). If you can find a powered (HAS to have sufficient power - more than 1.5 amps DC) drive enclosure, it should work.
- "Also, you are taking a big chance on overloading and blowing your FireWire bus (on the motherboard) by placing a peripheral load far in excess of the spec (not to exceed 500mA maximum). This can cause permanent damage to your computer."
Do you have any thoughts or recommendations how to work around this?
Your local Mac guy seems to be trying hard to reinforce prejudices about "Mac guys".
My recommendation: Plug the drive in and see if it works. It probably will. A decent selection of 3.5 inch drives will work fine from FireWire power, after all, through a suitable adapter.
Fat 2.5 inch drives really don't draw much more juice than thin ones. They're still laptop drives, with dinky little motors and lightweight platter stacks.
The FireWire spec allows for current up to 1.5 amps (see page 4 of the the PDF FireWire 800 Tech Brief here). It also allows for up to 30 volts, though (according to that Tech Brief; I've also seen the ceiling quoted as 40V). I don't know how close to the spec numbers any real FireWire controllers can manage. I think the limitations are more likely to be on maximum voltage rather than maximum current, though; I think most FireWire controllers top out at 12V, because that's all they get from the computer's PSU.
Your correspondent may be thinking about USB, which does have a 500mA current limit per root port or self-powered hub.
In any case, I've never heard of anybody damaging any FireWire (or USB) controllers by trying to connect too demanding a drive. FireWire and USB both handle overcurrent elegantly, as far as I can see; they just don't deliver the juice, and the drive doesn't spin up. I'm not an authority on the subject, but I think I've got more experience than your non-spec-reading buddy there.
If you dead-short the FireWire power rail to ground then you might perhaps damage something.
So don't do that.
I recently purchased a Kensington Pocket Mouse Pro Wireless for the bargain price of $AU20, which seems to work OK (apart from very agressive battery saving) but the included alkaline AAA batteries were practically unusable within two weeks of moderate use. Using your educated judgement (or a guess) do you think rechargeable batteries would work all right in this mouse, and if so would I be better off with NiCd or NiMH?
I was considering one of these relatively cheap chargers from Jaycar with suitable batteries. The bottom of the mouse has spec ratings of 3V 0.1A, which I guess rules out rechargeables, but your thoughts would be appreciated.
I don't know whether rechargeables would be OK, but they probably would. Kensington "recommend" you use alkalines, but don't say that you shouldn't use rechargeables. There's a good chance that the mouse'll be happy from 2.4V, but the only way to be sure is to try.
NiMH is definitely the way to go; you can't get anything like as much capacity from NiCd cells, especially in small sizes.
You might like to try this charger, by the way. Decent price (because it uses USB power rather than having its own plugpack), and some cells included. It only charges a couple of cells at a time, but whaddayawant for this kind of money?
Can you explain Australia's funny automobile laws? What is "rego"? I've figured out right hand drive.
Australian vehicle laws aren't a lot stranger than anyone else's. Well, as long as you stay away from Melbourne, anyway.
You can read all about Aussie road rules here.
"Rego" is vehicle registration, abbreviated the Aussie way with an O on the end. Similarly, "worker's compensation" for on-the-job injuries becomes "compo", "afternoon" becomes "arvo", "bottle shop" becomes "bottle-o", "journalist" becomes "journo"...
The further away from a major population centre you get in this country, the more optional vehicle registration and driving licenses become.
Just read your Shot-Blade review, and I was intrigued enough to contemplate buying. That is until I started doing so from Backyard Artillery, and found the total for one unit would be just over $US50, which would be roughly $AU70-$AU80 down here. I might still get it if I could just figure out one thing about it, and I am hoping you can answer this question:
What happens if you make your own ammunition for the Shot-Blade? Say, out of steel? It would obviously cease being a toy at that point, but I am quite eager to find out just how far it can fire such types of ammunition. Any ideas?
Yeah, the shipping's a bit steep, but it's not actually outrageous, considering the size of the box. Aussies buying from any RLT site will do well to order a selection of toys, which'll reduce the shipping price per unit to something less painful.
RLT's the only real retailer of Shot-Blades that I know of, by the way; there are a few other penny-ante dealers, but I don't know whether any of them even ship outside the USA.
Regarding steel ammo - sure, you could do that, and it'd probably work passably well. The launcher apparatus would chuck a 1mm sheet steel shuriken quite happily, I think.
If you didn't give the projectile an airfoil profile then it'd have a pretty plain ballistic path, mind you, and the muzzle velocity of the Shot-Blade is, as I said, not terribly high; it expects lightweight high-lift ammo that'll pretty much float away, so its range with heavy ammo won't be thrilling. But you certainly wouldn't strain that giant launcher spring by feeding it ammo more than ten times as heavy as its plastic shots, and you'd probably be able to plink throwing stars at a target at normal dartboard ranges with reasonable accuracy.
As a regular reader, I was a bit taken back by your advice to the guy with the lightly salted Canon camera - "You could play dumb and try to get a warranty repair; Canon may not bother to look hard at the camera and just give you a new one. If they don't, though, I doubt there's an easy way out of this."
This just seems so uncharacteristic!
Or have I just had too long a morning tea?
While I don't think it's entirely upstanding behaviour to try to get a free warranty replacement for something that's not really eligible, I also don't think it's a very big deal, and feel quite comfortable saying that it's a good way to pay large companies back for the marketing tricks they use to get you to buy crap you don't need in the first place.
If a gadget's toast through no fault of your own (or, at least, through no intentional fault of your own), you are not in my opinion committing much of a sin if you manage to score a new one from the manufacturer.
I think there is, however, a definite line between trying it on with the manufacturer when you know the gadget's actually been damaged in an un-warranty-covered way, and deliberately destroying the gadget yourself in what you hope is an undetectable way, so you can get a new one.
It's also, in my opinion, Not Cool if you get an undeserved warranty replacement from the small retailer you bought the gadget from rather than from the giant corporation that made it, and then leave the retailer stuck with a busted gadget that it turns out they won't be compensated for. This happens from time to time, when a retailer accepts a dud device in good faith and then finds out the manufacturer doesn't want to know about it, because they can see the salt crystals around the shutter button, or whatever.
Most retailers are hip to this sort of thing, though, and make darn sure that all "warranty" cases are acceptable to the next rung of the RMA ladder (which probably isn't The Manufacturer; it'll usually be the distributor that wholesaled the device to the retailer) before they hand over a replacement.
And often, of course, the retailer's not involved in the warranty return process at all; the consumer talks directly to the manufacturer's local branch.
Also, regarding my opinions vis-a-vis The Man, I refer you to this.