Dan's Data letters #28
Publication date: 13-Feb-2003.Last modified 03-Dec-2011.
But I wanna shoot something!
I recently picked up a light gun for my Dreamcast, and after enjoying it thoroughly on my monitor, I decided to hoik it over to the olds place so I could enjoy some large screen shooting. Soon after I attempted this though, I remembered that light guns don't work on flatscreen TVs.
I've done some Googling and haven't found anything relevant, so I was hoping you might be able to fill me in on why light guns and flatscreens don't mix (and perhaps in a dreamy scenario, a fix for such a problem). With flatscreens becoming cheaper and slowly becoming the norm, will our gun toting enjoyment be left to the arcades?
Chris
Answer:
Light guns work fine on a TVs with flat screens - just
not on TVs that aren't normal 50/60Hz (depending on whether you're in a
PAL or NTSC country) cathode ray tube displays.
Light guns rely on the screen redrawing in a particular way. For ones designed to work with TVs, that's a 50/60Hz interlaced display. When the game system knows how the screen's being redrawn, it knows what's appearing on the screen at any moment; your high-persistence eyes can't see the fast-moving electron beam dot painting the screen over and over, but the low-persistence sensor in the light gun can. When the light gun's lens is pointed at the dot, the game system knows where it's aimed. Simpler light gun systems only track the aim when you fire (the whole screen, or the target, flash white then, and that's when the gun's aim is computed); fancier ones can track all the time, and thus display a crosshair.
LCD and plasma screen monitors or TVs don't have a scanning dot at all; neither do non-CRT projectors. De-interlaced CRT TVs that run at 100Hz or higher refresh rates do have a scanning dot, but it scans faster than the game system expects, because each of the interlaced fields of the image is doubled up into a whole frame, to create the low-flicker doubled refresh rate. This messes up the light gun tracking, too.
Conventional light guns will never work with non-CRT displays, but ones with cameras or otherwise improved position tracking could. Making them work with 100Hz CRT TVs is a lot simpler, but I don't think anybody's actually done it yet.
Light power
I loved the article about making your own caselight with Luxeons.
Quick question, does a computer power supply waste all of its power even if you aren't using it? In other words, does a 350 watt power supply always draw 350W even if you only have, for example, one hard drive, one CD-ROM drive and nothing special in your case?
The reason I ask is I want to hook up a long wire and use a few white Luxeons to light up my desk, from the ceiling, from the power supple to outside the computer. It would save on the electric bill, which in California is pretty dang high, and also give me free light. I want to just let them hang from the ceiling. Should look interesting to vistors if nothing else. A single switch and dimmer inline with 2 or 3 Luxeons is what I'm thinking. Any recommendations on resistors or how it should be wired?
Also, will the non-lensed version of the Luxeon be too wide angle?
Randy
Answer:
No, PSUs don't draw, or deliver, full power all the time.
Their rating is how much power they can deliver (well,
in theory,
anyway).
Running external lights from your computer PSU therefore won't actually give you "free" light, since the more stuff the PSU runs the more power it consumes. But a few watts of Luxeon light won't cost you anything significant.
The resistor(s) you use depend on the Luxeon array you build. If you want to run five watt Stars at or near their full power then you'll need the thick end of seven volts for each of them, so you can't have more than one in series, but you can have several in parallel hanging off the 12 volt rail from the PSU. Just work out the resistor value as described in my first caselight piece, but with rather larger numbers from the Star spec sheets.
You can find Luxeon product documentation, including those spec sheets, here.
If you want a no-calculating option, by the way, then a reader's pointed out to me that dedicated Luxeon driver hardware, suitable for hobbyist use, can be had for non-ridiculous prices. See here, for instance.
Lensless Stars probably will be too wide angle, but that depends on the effect you're looking for. If you want the lights to behave like regular downlights, then you want the lensed versions - Star/Os.
Powerless fan
I have an NB-101 fan [as reviewed here] but can't seem to get XP to recognize it. It didn't come with software. Where can I find a driver?
Gus
Answer:
I don't think you can, because there's no way for the
laptop to tell the difference between the slot with the fan in it, and a
slot with nothing in it at all. The fan just uses the power pins on the
PCMCIA connector, nothing else. This wasn't a problem when I reviewed the
thing back in 1999, but recent laptops with recent Windows flavours don't
energise the PCMCIA slot power pins if they don't think there's anything
there.
If a port's not being powered up when an actual proper PCMCIA card is in there, there are things you can do; Microsoft's page here talks about the problem, which ought not to arise with later Windows 2000 Service Packs, or with WinXP. But, otherwise, I don't think there's a solution, unless your laptop's BIOS setup provides an option, which it probably doesn't.
I've updated the review (which was written before Win2000 came out) to mention this problem.
Console cables
Recently, I bought myself a Zenith HD-compatible TV for Christmas. I have no particular interest in trying to watch over-the-air HDTV signals at the moment; I chose it over its low-def competitors to use the 480p [480 line, non-interlaced] outputs from my DVD player, my XBox, and my just-acquired GameCube.
It does an entirely adequate job of displaying 480p, but it has an annoying quirk. There are two sets of component video inputs on the back of the TV: one only works with 480i signals, while the other only works with 480p and 1080i signals. (Why the 480p/1080i jacks can't accept 480i input is entirely beyond me.)
In my current configuration, I have connected the component video lines from the three 480p sources to an inexpensive Radio Shack passive source selector that was originally designed to carry a composite video line and two audio lines. This selector is then connected to the 480p/1080i input of the TV. I have heard that using a source selector with a bandwith smaller than 30 MHz can cause a degradation in picture quality. At 480p, I don't notice any softening of the picture using my cheap selector. Will this crappy selector cause me problems if I try to route a 1080i signal through it?
While this works great for my progressive-scan DVD player, it poses a small problem for my video game consoles. All (or nearly all) Xbox games support 480p, but the front-end menus for the box are 480i. It's even worse with the Gamecube, where many games don't even support a progressive-scan output. So, if I want to look at my Xbox menus or play a 480i-only game on the 'Cube, I need to reach around the back of the TV, pull the cables out of the 480p/1080i jacks, and move them to the 480i jacks. As some folks from the American South might say, that ain't no way to live.
The easiest solution to this problem that I can see involves buying Y-cables and sending the component video lines into both sets of component video inputs. Thus, my second through fourth questions: Will this work? Will my picture quality suffer as a result? Do you have any better ideas?
Nicholas
Answer:
Switching high resolution component video through a box
that has the right connectors but isn't designed for that job can, indeed,
be a bad idea (oh, and the bandwidth-and-resolution question can be
curlier than it looks). A cheapo switcher may work just fine; if it
clips off the top end of the video bandwidth, though, you'll get a fuzzy
picture. Reflections from bad connections can also cause ghosting, though
that's unlikely to be very noticeable at video bandwidth, even if it's high
definition video. These problems are generally more visible in really high
contrast, high detail images, like black-on-white computer text displays;
console games tend to be made with the expectation that they'll be displayed
on a fuzzy screen, so they deliberately avoid that sort of stuff.
Y-cabling your component (or Y/C, or composite) video may work OK, provided your TV doesn't have a conniption over getting two signals at once, but your picture quality probably will suffer. Video cables have a set characteristic impedance, and Y-cabling them puts two loads in parallel, which can screw up your picture. Commonly, the result is a dark picture; sometimes, weird and wonderful other things happen.
If the destination components go open circuit on the inputs they're not using then there ought not to be a problem, but I think that's unlikely to be the case.
You can deal with the problem, by using a proper video splitter, preferably with an integrated amplifier, instead of a plain dumb Y-cable. Fancier models are often known as "distribution amplifiers", but you just need a two-output unit.
Mystery BNCs
I have recently purchased a monitor with 5 BNC connectors at the rear. Are there any video cards on the market that actually use these? Can you connect other devices through these directly to the monitor (Philips 109P)? I have read that these connectors are supposed to improve picture quality over the standard connector.
Michael
Answer:
You can plug your video card into the BNC connectors with
an HD15-to-BNC lead, which'll have a normal VGA plug on one end and five
BNCs on the other (find more info about what it means when a monitor has
fewer BNCs than that
here). A good BNC lead will give you a sharper picture at very high
resolutions; a bad one won't do anything worthwhile.
And yes, you can probably use the BNC inputs for a second input device. Many monitors make it quite easy to select between HD15 and BNC input, which gives you a cheapo video switcher function so you can run two PCs on the one screen.
Hush, little server
I recently purchased a cheap case advertising a 300W PSU and it looks like I was accidentally given a 450W power supply.
Anyhow, this thing is being used as a fileserver, and I am going for the silent system. The computer has two hydraulic bearing HDs, a 1333MHz Thunderbird Athlon, two CD burners (usually idle) and an Asus A7V motherboard. No video card.
Since the PSU is so underloaded (surely no more than 200 watts) would it be safe to remove its fan altogether? If not, how would I go about slowing it to the point of being noiseless? Could I simply attach the fan's 12V lead to a 5V line?
When I remove the fan, it is nearly silent, but when it is reinserted, it becomes irritating and loud again.
Also, can you recommend a material which will absorb vibrations? I find the slight vibration of the box seems to resonate through the surface it is on, which is really irritating if one pays attention to it. I've tried a towel, foam, and corrugated cardboard, all with no luck.
Sean
Answer:
All things being equal, an underloaded high rated PSU
will run just as hot as would a lower rated PSU under the same load.
You could replace the standard fan with a quiet, low speed one; many 80mm fans will start OK from five volts, but at that voltage will move considerably less air than the quietest common 12 volt 80mm units. If you greatly reduce the PSU's air moving power, though, you'll probably need to add another fan or two to the case to keep a decent amount of air flowing through it. It also helps to have some redundancy, to avoid killing the server by heat stroke if its only fan fails. I've seen single-fan PCs with stalled fans that get too hot to hold - all over - before crashing. It ain't pretty.
Outfitting the case with two or three low power 80mm fans may leave you with an acceptably quiet server, or may not. Hacking a big hole in the side of the case and installing a 120 or 150mm fan, run at low speed, may be a better solution. Unfortunately, 1.3GHz Athlons do need air flow.
For vibration absorbtion, Dynamat is the big name, but there are lots of cheaper options. If you tried foam and it didn't work, you probably didn't have enough foam. Silicone sealant, or some similar sticky-putty-goop, may also do nicely.
Overseas overvoltage?
Been thinking about moving to a different country for a few years and I was curious how my collection of computer hardware would make the trip. No I'm not asking how to take a supercomputer to questionable areas, but rather about the power.
I suspect that I should be able to swap PSU with a PSU from the host country and have the rest of my hardware work, except my monitor or wall packs. Am I right, or is there some other nefarious scheme that would conspire against me?
Davin
[whose e-mail address bounced, by the way. Hello, Davin, if you're out there...]
Answer:
You won't even have to swap PSUs, if your existing PSU
has a 110/220V switch on the back of it. As long as you're not going to
Elbonia (where
they probably use 80VDC, or something), you'll be fine. Your imported PSU
may or may not meet local electrical regulations, but people only generally
care about that if you're selling unapproved gear, not if you're using it.
If it's US-approved, it should be safe enough. But the management declines
all responsibility for cartoonish singing or non-cartoonish death.
If you don't have a voltage selection switch, and the local voltage isn't the same as that where you came from, then you can swap in a PSU from a local vendor. You can also use step-down and step-up converters for gear that you don't want to buy locally, but that's only sensible for small things. Given the hassle involved in moving most large-ish pieces of computer hardware from country to country, you'd do better to sell or give away your old gear, and buy a new monitor/laser printer/whatever in the new country.
