Dan's Data letters #61
Publication date: 5 September 2003.Last modified 08-Mar-2015.
Suspiciously simple
I was interested in your thoughts about this power supply tester (reviewed here).
Any merit in the concept? Could it substitute for a real PSU test rig?
Rob
Answer:
Well, it'll tell you whether a PSU is dead or not. It'll also probably start
smoking if left plugged in for a long time, since I see no heat sink for
its 25W resistor - that'd explain the second warning on its label. But it
won't load a PSU significantly.
The part in the review where it says an unloaded PSU will burn up is incorrect. Old switchmode supplies do have that problem; they needed a load for more than one reason, which is why antique hard-drive-less PCs often had a power resistor heating up one drive bay to keep the PSU happy. Modern PSUs will, however, generally work pretty much perfectly if you just connect the green wire on the ATX connector to any ground to turn them on (which a PSU test rig will also have to do, of course).
This tester's load resistor does make it more valuable than a paper clip from green to black; a bit of load may give you output voltages that're closer to spec. It might also make voltage probing easier, though I've never had much of a problem with that either (multimeter probes fit nicely into the tubular contacts in PSU plugs!).
If a PSU is delivering OK voltages when unloaded but going haywire when powering a PC, though, this thing won't come within a mile of truly simulating the operating load.
HD Quest
I am looking at buying the DGTEC DH-2000A DSTB (HD) you reviewed, and connecting it to a three year old 109cm rear projection Samsung TV. The TV has S-Video inputs, but no YPbPr or RGBHV.
Will I still get HD quality via the S-Video connection? If not, I am better off just buying a SD Set Top Box?
What does a digital input look like for a HD capable TV? What are the connections called? Is it a standard RGB input just like a computer?
I had a look at several new TV's for sale and only saw the normal composite and S-Video connections.
George
Answer:
No, S-Video can't manage HD resolution, but neither can your TV. The current-model
Samsung 109cm would probably be the
SP43T5;
that's a nice 100Hz line-doubled SD screen, but its real resolution is unlikely
to greatly exceed 640 by 480. Yours won't be any better.
If you don't envisage upgrading to a real HD display device, then yes, you might as well get an SD box.
In the Know Your HD Connector department, check out some big pretty pictures in the one-page Acrobat document here.
Big screen HD-capable sets are still pretty excitingly expensive. Even little ones are pretty pricey. You clearly didn't see any of either when you looked around the TV shop.
If you want a cheap HD-capable display, you either need to put up with a pokey little computer monitor (mind you, a 17 or 19 inch monitor makes a fine bedside HDTV!), or buy a video projector. There are plenty of relatively affordable LCD and DLP projectors that qualify as real HD display devices.
Digital Broadcasting Australia has some pretty up to date lists of widescreen TV products in Australia (all HDTVs are widescreen, but not nearly all widescreen sets are HDTVs) in PDF format here.
Look for the ones that support better-than-576i resolution. 576p is progressive scan (100Hz) standard definition; 1080i and 720p are true HD.
It's glow time!
I got a new Casio watch that I think is pretty nifty for $30. It has a electroluminescent (EL) light in it which is quite bright. I wanted to rig it so the light stayed on all the time. I would just try to short the light button, but if you hold the light button down for two seconds it beeps and shuts off.
I know keeping it on would kill the battery, but I'd be willing to change the battery every week or so, since the light is cool looking.
Brian
Answer: I don't know how EL backlights compare with the old teeny-tiny-light-bulb technology, but neither is at all kind to watch batteries. The watch's own current draw will be way down in the microamps, but the backlight probably draws a few milliamps, which'll whip the flat coin cell in the watch to death surprisingly fast.
You may be willing to change batteries every week, but what about every day? Or every five hours? This is quite possible, depending on the backlight current draw and the kind of battery the watch uses.
Another problem is that EL material has a lousy lifespan - commonly only about 3000 hours. So even if the battery life was a week, the backlight would be substantially dimmer, if it worked at all, after about four months.
Stupid Proprietary Format?
How do I convert .spf files to .jpg or .tif in order to upload photos to a photo center?
I've purchased a (cheap) digital camera from Wal-Mart that only allows me to save the digital pictures in .spf format, and now when I try to send them to the Wal-Mart photo center they say that the pictures have to be saved in .jpg or .tif.
Pamela
Answer:
Quick answer: Try just renaming them from picname.spf to picname.jpg, and
see if they work then.
As per my old piece here (and other pages, like this one), SPF images are just JPEGs with extra info (maybe just in the header; you can stick as much data as you like in JPEG headers, and various people have made semi-proprietary JPEGs-with-sound, for instance, by doing just that). So just renaming them may solve the problem.
Tastes great, less charging?
What are your thoughts on rechargeable alkaline manganese batteries? I was looking at NiMH batteries (I already have a charger and a few NiMH cells) on flEaBAY, and saw someone selling them:
"All the great advantages of alkalines (full 1.5V and years-long storage capacity) without the drawbacks of NiCad/NiMH rechargeables (only 1.2V and poor storage, especially in heat)."
Are alkaline rechargeables better than NiMH, or is this just marketing?
Matthew
Answer:
Rechargeable alkalines aren't a very exciting product. Yes, they behave
pretty much like regular alkalines (not necessarily good news, for high-drain
applications like photography), and yes, you can recharge them a reasonable
number of times. But the flatter you run them before recharging, the less
capacity you'll get from that charge. Run 'em flat and they'll be pretty
much dead right there.
This makes rechargeable alkalines a lot less practical. Who cares how much capacity they have, or how low their self-discharge is, if you're going to have to charge them as often as a low capacity NiCd anyway?
Yes, they'll stay charged on the shelf - but batteries that're sitting on the shelf (presumably in a seldom-used device) don't really need to be rechargeable anyway, since you're, you know, not using them.
Shoestring projector
My dad gave me a 3M projection LCD panel made in 1992, and I want to make a video projector out of it (see here).
The panel is compatible with a long list of obsolete systems - "IBM (VGA EGA CGA MCGA MDA), Hercules, Macintosh (512K, Plus, SE, SE/30, Classic), Apple 2 Family, Apple 2GS family, Olivetti, AT&T VDC400&600, NEC 9801 and DEC VT220."
Can I get a modification for windows 98 to suit one of the IBM ones?
Justin
Answer:
The best standard out of that list is VGA, and that's only 640 by 480, 16
colours. If you can get an appropriate cable (the panel probably expects
a nine pin mini-D connector, the same size as the current PC video card
14 pin connector but with fewer pins) and plug the thing into a PC running
640 by 480 at 60Hz, then it'll probably work. If it's got a 16 colour limit,
though, then it's likely to be insurmountable, so you'll never be able to
use the thing for movie projection.
Green beam
There are a few of us in the world who have been looking for a laser pointer that is useful in full sun. Red laser pointers show up as a tiny dot if the pointer is held an inch or two from the surface, but we need something that will reach out several feet and be clearly visible. Green laser pointers have been available, but cost $US600, and can only operate for two minutes on and 30 minutes off (for cooling).
I found one for only $US119, and bought it. There was nothing in the instructions about a limited operation/cooling cycle, so I used it continuously for two hours (on two AAA batteries) and it worked great. This must be a real step forward in laser efficiency!
Robert
Answer:
Green laser pointers have been rather cheaper than $US600 for a while, and
there are re-opticed hopped-up models as well.
This place is apparently a good source.
There are also lots of eBay dealers selling them; here, for example.
Only badly cooled green lasers should have Draconian duty cycle limits. With decent heat sinking, you can, as you say, use them continuously.
I don't think there's any big technical difference between the cheap(ish) green pointers of today and the expensive ones of a few years ago. It's still a high power IR diode, a frequency doubling crystal and an IR filter behind the collimating lens. The complexity of this assembly, by the way, makes green pointers a lot more fragile than red ones; they're far more likely to die instantly if you drop them. So don't do that.
Unfortunately, unlicensed lasers with a power rating above 1mW (Class 2) are illegal here in New South Wales, Australia. Green pointers are almost all rated at 5mW, and some of them even deliver it.
(And no, I haven't bothered trying to import one anyway.)
Superyum HappyFly Battery Corporation?
I'm looking at buying a second battery for my Canon PowerShot G3 and would prefer not to cough up the big bucks for Canon's "approved" offering.
By going with a "generic" or "third party" battery, do I risk damaging, incinerating, vaporizing or imbuing with demonic possession, my new camera?
Zed
Answer:
Someone somewhere probably makes a lousy clone of the Canon BP-511 used
by your camera (and by my D60), but third-party batteries
are usually fine, and often somewhat higher spec than the stock battery.
I've got two genuine BP-511s for my D60, and one clone. The clone works perfectly well, with no big difference in run time that I've noticed. It has a nonsensical "3000mAh" printed on the bottom - the standard BP-511 is an 1100mAh battery, and you can't actually pack much more capacity into this form factor. Real 3000mAh batteries with the same terminals as the BP-511 are the fat kind, for camcorders; they won't fit in an enclosed battery bay like the G3's or D60's.
The only problem my clone battery had was that it was very slightly larger than the genuine batteries, and so wouldn't drop out of the battery bay cleanly; I had to pry it out. I shaved its edges a bit with a pocket knife, and now it fits nicely.
Magnet hunting
I've only just discovered the lovely magnets in hard drives. I have been tinkering with an old PC and had two hard drives roll over and die. So I naturally decided to pull them apart. After pondering for a moment on what I could do with the magnets, I decided to screw them to the wall in my garage. Thus giving me a place to hang my hammers and screwdrivers.
Do you know where I can score some dead hard drives so I can collect more and more of these magnets?
Jarrod.
Answer: EBay's low-capacity hard drives category (Australian version here, US version here) is a good source. People regularly sell boxes of old drives very cheaply (though postage can cost rather more). If you want something really vintage, for whatever reason, then you'll pay rather more - but really ancient drives have stepper motors and no magnets, anyway.
This, that and radioactive the other
"...a heavy water ice cube will sink in normal water..."
Why do you know this?
Sincerely, FBI, CIA, NSA, ASIS...
Imagine if they used tritium, or if ice3 really existed (wasn't that some apocalyptic novel?)
Also, do you know of any Perth retailers who might stock one of your preferred IBM keyboards? I'm ready to give them serious (I had to retype the S and I then) money to get a real bloody keyboard instead of this $10 POS...
Nathan
Answer:
Why do I know heavy water ice cubes sink in normal water? Because I know
everything. Silly monkey.
Tritium, by the way, is heavy-heavy-hydrogen - two neutrons, versus deuterium's one. Water is dihydrogen monoxide, heavy water is dideuterium monoxide, and ditritium monoxide water exists (well, can be manufactured) as well.
It wasn't ice three, it was "ice nine", and it was a Kurt Vonnegut story. There actually is an ice nine form, but it's much less exciting.
Regarding battleship keyboards, I don't know if there's anywhere selling them in Australia. They're not too hard to find on eBay, though, if you craft a suitably counter-intuitive search string.
Or you could go to the source and get a shiny one. $US49 plus shipping for a non-Windows-key-polluted version!
