Dan's Data letters #141
Publication date: 24 February 2005.Last modified 03-Dec-2011.
Free car! No engine!
I recently got given an old HP e-vectra (model p2025a) but it didn't come with a power supply. On the side of the machine it has: "INPUT 19V - 3160mA".
Could I find a generic power supply from, say, Dick Smith Electronics that would work, or would I need to source one from HP?
whoisthatguy
Answer:
Browsing through the quick user's guide (PDF)
confirms what the sticker says. Actually, that guide says 19V at 40 watts max, which is only a couple of amps; perhaps
it's for an older, lower power model. But even if you need three point something amps at that voltage, you'll still
have no trouble finding a cheap generic adapter, even
here in Australia.
The input connector could be more of a problem. I don't know what size it is, and it may or may not be dangerous if you get the polarity wrong. But there'd be no problem with toting that little machine to an electronics store to check such things, and if you need to change the plug on the adapter cable, that's a trivial soldering job.
Not even filled with cream
I went to JB Hi-Fi to buy an optical interconnect for Dolby Digital sound recently. I paid $AU25 for one that looked to have decent build quality (and it seems to work fine). However the more expensive ones were boldly marked as having gold plated plugs. The sales assistant told me it was for better electrical contact but this seems to be garbage - it is an optical connection right? It even glows red on the end when it's unplugged from the receiver.
Michael
Answer:
Actually, the very cheapest made-by-unwashed-peasants-in-Elbonia
optical cable you could find would probably also work perfectly well. But yes - there are build quality issues,
especially if you're plugging and unplugging the cable often, or if your cable-mess results in some other cable hanging
off the middle of the optical lead and bending it.
As you say, though, there is no electrical contact in an optical lead. And yet you can get gold-plated plugs.
I'd never noticed this before, but apparently it's something of a plague.
Making these connectors out of metal is vaguely justifiable for durability and alignment reasons, but in the real world supercheap plastic connectors really do seem to work just fine, and it's not as if the metal versions are any more resistant to some crud getting in between the fibre and the diodes, which is a common cause of optical cable problems, and is curable by anyone who knows how to whistle.
Optical audio cables are straight bitstream connectors with no provision for error detection or correction, so they either work or they don't; either you get perfect sound or you get very obviously screwed up sound, or more likely no sound at all. People who're concerned that their $5 optical cable might wear out are best advised to buy another one and tape it in its packaging to the back of the component in question, just in case it's ever needed.
Oh, and Bill Hicks was right about marketing people.
Surf board
Do you have any idea where (preferably in the US) I can find bigger veroboard? I'm making an LED array that is to be 30" long, one LED wide, and need something that would work nicely for that.
Tyler
Answer:
I think the largest standard prototyping board sizes are 20 inches by ten, which you could cut down for your purposes,
and join end to end - all of the decent-sized proto boards I've seen are much closer to square than the ruler-shaped
board you're looking for.
If all you're making is one string of LEDs, though, then you don't really need any kind of plated board. You could just run a couple of wires if they're all in parallel, or solder them to each other for series.
If you need something straight and flat to keep the LEDs in order then, of course, getting some blank piece of fibreglass and drilling it yourself would be something of a pain for a zillion LEDs. But since they're going to end up a bit higgledy-piggledy anyway, it won't matter if you and your Dremel drill press don't quite manage perfect tenth-inch spacing.
Comfier keys
Does anyone make a true Internet keyboard? One that has the @ without a Shift, and switches the colon with the less-used semi-colon, and where $, ? and % are also Shiftless. If not, does XP allow you to remap the keyboard to eliminate the second "Windows key" etc?
The current keyboard is miserable for people like me with arthritis in my hands. The Shift key is a lot like forcing us to use manual transmission on our cars.
Jack
Answer:
There's no keyboard like that, but there are utilities
that'll do the job.
There are, of course, also about a zillion weird ergonomic keyboards out there that pretty much all claim to be useful to people in your situation. Many of them have accessory pedals that can be mapped to whatever you like - Shift, for instance - and some of the pedals are standalone devices. Take these, for instance. I think they're made by TypeMatrix, though, who don't seem to sell them any more. But you get the idea.
Brass monkey photography
I'm a landscape photographer exploring the switch to digital. One consideration is battery/camera usability in cold (-20 degrees C and below) weather. Is the cold weather issue really about the battery, and is it resolved by keeping say, your home made battery pack close (and warm) to your heart?
Jeff
Answer:
Yes, the battery's the big problem. There are other issues that can arise in very low temperatures - lubricants hardening
and causing mechanical assemblies to stick, plastic and rubber parts becoming brittle, and of course condensation
if you absent-mindedly carry your freezing cold camera straight into the toasty warm ski lodge. Batteries are a biggie,
though.
And keeping the battery close to the body is, indeed, a popular solution. If you've got a big pro camera, of course, then you can't keep the whole thing inside your vest when you're not using it, and swapping batteries in and out in subzero temperatures is not an elegant solution.
Alternatively, you could use batteries that actually work at that low a temperature. NiCd and NiMH cells will just barely work at minus 20 C (and give you about 20% of their rated capacity); some NiCds may be good down to -40, but that's for a pretty broad definition of "good". Lead acid and lithium ion also have minus 20 as their nominal lower limit. Lithium polymer and regular alkaline are useless below freezing (water-based electrolyte).
Non-rechargeable lithium cells, though, are still quite happy at minus 20, and have a nominal lower limit of -40. This includes regular camera batteries like the common CR123s and less common CR-V3 "double barrel AA" batteries, plus lithium AA cells, lithium button cells (many cameras have one of those, to battery-back their clock), and various other less-often-seen types. If you've got the money, and especially if your photography involves hiking around with your gear, then a digital camera that can run from AAs and/or CR-V3s will stop you having to worry about battery chill, and also let you tote a lot of spare batteries without much weight. You can also now get rechargeable Li-I CR123 and CR-V3 batteries, for when it's not freezing.
A more commonly seen solution, though, is a remote battery setup where the pack - probably a bunch of NiMH cells - is worn on the body somewhere and a wire runs to the camera. There are commercial products in this department to suit various cameras - any regular remote battery pack, like the various Quantum models, will do, provided it's not some 10 kilo monster or infested with razor sharp edges. But it's also seldom a big deal to hack something like this up from a bunch of loose cells and a spare AC adapter cable, which will terminate in a DC plug or dummy battery for the camera.
I've written about chilly batteries before, here and here.
(I pointed out to Jeff that, personally, I'd seriously consider shooting more landscapes in, say, Hawaii, Queensland or Brazil. He pointed out to me that "the number of photographers lined up shoulder to shoulder for that great shot is directly related to the temperature scale".)
ROYGBIVUVLED
I'm desperately looking for LED's in the 320-360nm range (UV). can you give me any leads to where I could find these? can you sell some to me?
Van
Answer:
Sorry; I don't think such things quite exist yet, though some experimental models
apparently do.
(Yes, faithful readers, there are lots of UV LEDs on the retail market now - but none at a short enough wavelength for Van!)
Needs more tinsel
I just got an e-mail from Corsair about their new "Bling Bling 2000" memory modules (or whatever they're called) and I noticed an interesting graph on their product spec sheet (PDF).
I love how there's only two numbers on the whole graph.
Krick
Answer:
I'm afraid I still prefer this masterpiece of informational illustration:
For my sins
i want to find a way to put a virus on my pc so the virus protecters
don't fnd it and let it slowly ruin it. can you tell me how,,i hate my
boyfriend and want to screw up this stupid toy he has,,,hope to hear
from you,,lisa
Answer:
Usually, when people read this and then ask me to help them commit fraud (or, in this case,
criminal damage), I let y'all see their e-mail address, and hilarity
ensues.
I think Lisa's been adequately punished just by, well, being Lisa, though.
And furthermore
Hey DAN!!!
If you got a need to help me kill my labtops CPU i would greatly appreciate it. I have a labtop that was leased through my college and its shit and every second year the new enrollment of people get a new labtop im stuck with a piece of shit that I have to pay 1300$ every year for four years. If anything else goes to shit on these labtops(ie hardrive) they replace it and ur stuck with it again. I really need ur help because u know how to kill these things. It has to be done in a way that they dont suspect a thing or a way which they wont be able to tell.
I need ur input later DANSlavik
Answer:
Oh, for God's
sake, college boy.
Another one fades away
Have you heard anything further about the Minato motor? The most recent thing I have seen is almost a year old. Is this a total scam?
Paul
Answer:
Needless to say, I, like everyone else in the world, have not received any more information about this wonderful
more-power-out-than-in revolution in science and physics.
The "40,000 units" allegedly sold "to a major convenience store chain" have, astoundingly, all vanished without trace - nobody managed to find just one of them and take it apart. And japan.com, the source of pretty much every story about this amazing innovation, has finally moved on to a new "technology" story, removing all mention of Kohei Minato from their site (that I can find, anyway). The Title tag on their Technology page still says "Japan.com - Technology - Magnetic Fan in Japan - Japanese Magnetic Fan", though, despite now heading a page about LED lighting.
Continuing another theme
I ran across this site in my search for reviews of various CD scratch removal products.
Little did I know that I was stepping into the realm of quack science.
It doesn't look like you've mentioned this site before. I just thought that it would be good for the usual yuks these things provide.
They even appear to run a music studio.
Nathan
Answer:
Well, voodoo products seldom actually hurt the sound; I dare say there are plenty of little boutique recording
studios out there that use one or another kind of "esoteric" equipment support (who knew putting
air-dried maple under your solid state amplifier
could do so much for it?), put heavy objects on top of components for no reason, apply anti-static treatments to their
power cables (as recommended here...) or employ
questionably engineered cables - though those unwieldy-looking
flat-conductor cables are a new one on me.
As are the tripod "cable lifts", and the gas-lighter
anti-static device.
I'm surprised that nobody seems to have come up with tungsten feet for audiophile gear yet. More than twice the density of the piddly brass that Maple Shade are selling!
(A reader's now pointed out to me the existence of various products like these. They're not solid feet - that wouldn't be expensive enough - and they're tungsten carbide, not plain metallic tungsten, but they fit the bill of being fancier, denser and even more stupid than brass feet.)
And, in closing
It's amazing to see so many excellent mods in one article. You owe it to yourself to have a look.
Tom
