| HDMI
October 24, 2009 at 8:00 pm
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If you've shopped for an HDTV, a PlayStation 3, or an HD-DVD
or Blu-ray player, you've probably heard about HDMI. It can
seem like just one of many connections on televisions or
home-theater receivers. But HDMI is more than a port on the
back of a TV (and the often expensive cable that fits inside).
It's a set of rules for allowing high-definition electronic
devices to communicate.
Before the development of high-definition televisions, most
TVs displayed pictures in what is now known as standard
definition. The picture was roughly square -- its aspect
ratio was 4:3. Its resolution, or the number of dots that
make up the picture on the screen, was about 704 x 480 pixels.
The picture was interlaced -- each piece of the moving image
was really half a picture, but the pictures changed quickly
enough that the human brain didn't really notice. Finally,
older TVs relied on analog signals, which travel as
a constantly varying electrical current.
HDTVs, on the other hand, are digital. They use information
in the form of ones and zeros. This information travels
through cables as distinct electrical pulses. HDTVs have
an aspect ratio of 16:9, so the picture is rectangular. They
also have a higher resolution -- current HDTV standards allow
for resolutions of up to 1920 x 1080 pixels. HDTV signals can
also be progressive, meaning that the each frame of the
moving image is a whole picture rather than half of one.
So, compared to standard TVs, HDTVs have a wider screen, more
pixels and a faster refresh rate. Often, HDTVs can display
more colors than older sets. This means that HDTVs need more
data and need it a lot faster than standard-definition TVs
do. If an HDTV can receive this information digitally, it
also doesn't have to spend time or processing power
converting the signal from an analog format.
This leads us to HDMI. Created by a group of electronics
manufacturers, the HDMI standard is a set of guidelines for
creating high-bandwidth connections between digital devices.
With the right setup, HDMI can make a significant difference
in a home-theater system. The current standard can carry
1080p high-definition signals, and it supports eight channels
of uncompressed audio, enough for a 7.1 surround-sound
system. HDMI can cut down on the number of cables required to
connect components, and it can even reduce the number of
remote controls needed to watch a movie.
But there's a catch. In order to take advantage of
everything HDMI has to offer, all of the components of a home
theater have to be compatible with them. Some of the features
HDMI touts also don't yet exist in the consumer marketplace.
In addition, there's a limit to how long an HDMI cable can
be, and some users complain that the limit is too short to
support convenient setups.
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| How to Build a DVR
October 24, 2009 at 7:59 pm
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The digital video recorder (DVR) is a wonderful piece of
modern technology. While the VCR may have freed us from the
rigid schedules of TV programming, the DVR has freed us from
having to learn how to program our VCRs, not to mention
trying to figure out what's on that pile of unlabelled video
tapes.
But DVRs have two major flaws -- you have to pay for the
privilege of using one, and you're stuck with whatever
capabilities the DVR you purchase happens to come with. If
you want to expand the space on your DVR for storing
additional programs, or want to tweak your user interface,
there isn't much you can do about it.
If you build your own DVR, you sidestep both problems. You
won't have to buy the hardware or sign up for a contract with
your satellite or cable company for the device, you won't
have to pay for the service, and you can modify and expand
your DVR all you want. And it turns out a DVR isn't very
complicated -- you can easily build one with off-the-shelf
technology. That's because a DVR is basically a hard drive
with a way to interface with your TV signal, plus some
software to control it. If you have an old desktop computer
lying around, you're already halfway there.
Laying the Foundation for Your DVR
The most basic element of a homemade DVR is a computer. You
could technically use any computer for this, but you'll be
installing some new internal components, including a new hard
drive, so a desktop is a better bet than a laptop. You could
use a Mac, but you'll generally find that you have more
options with a PC.
How powerful of a computer will you need? Well, that depends
on what you want to do with your DVR. If you're just
recording TV shows and movies in standard definition, then
you don't need anything very powerful. If you'll be recording
and playing back high-definition (HD) programming or want to
watch Blu-ray discs, then you're going to need a computer
with a little more horsepower. There are five things to watch
for when buying or setting up the computer that you'll use
for your DVR:
Processor - You don't need a top-of-the-line quad-core
processor to run a DVR. In fact, for basic DVRing, older and
slower processors will work fine, especially since the
encoding will be handled by a separate component (the TV
capture card). The bottom line here is that the processor
should be powerful enough to run a modern operating system.
If you're stuck running Windows 95 or earlier, you may have
a harder time finding compatible software.
Hard Drive - You'll be surprised how quickly hard drive space
gets eaten up by recorded TV shows. A single movie in HD can
use up several gigabytes of drive space by itself. Hard drive
prices have dropped considerably in the last five years, so
if you're repurposing an old computer, you'll want to swap
out the old drive for something larger. Remember, you can't
have too much hard drive space, so buy as much as you can
afford. You'll want a speedy drive to avoid problems with
video quality. Keep in mind that you can always expand later
by adding an additional drive.
Video Card - It's going to take a fairly powerful video card
to process the video signal and send it to your TV. If we're
talking about HD and Blu-ray, the video card will need even
more power. This is the part of the DVR that's going to
matter most to what you actually see on-screen, so if you're
going to splurge on any part of your project, this should be
it. There are many video cards to choose from, with new ones
coming out all the time, so your best bet is to check
audio/visual message boards for tips on which card is best
suited to your purpose.
Memory - A minimum of two gigabytes of RAM will help your DVR
run smoothly, although upgrading to four gigabytes won't hurt
(and, again, might be necessary if HD is involved). Memory is
inexpensive these days, and more RAM is almost always better.
Power Supply - A high-end video card and an extra hard drive
can draw a lot of power, so you'll need a power supply that
can provide it. A good way to get a rough idea of how much
power you'll need is with an online power supply calculator
like the one Journey Systems provides.
Next, we'll choose and install a TV capture card.
TV Capture Cards
A typical computer doesn't have a video input that can accept
a signal from a antenna or a set-top cable or satellite box.
You'll need a TV capture card, which has its own tuner to
receive television signals, to take the incoming signal and
read it. Better capture cards have onboard processors that
handle the encoding of the signal into the digital format the
show will be saved as. A capture card that does its own
encoding takes a lot of stress off the computer's main
processor. In fact, if you use this type of card, you won't
need a powerful main processor.
One important thing to look for in a video capture card is
the ability to accept an MPEG-2 transport stream in both DBV
and ATSC, sometimes referred to as digital hardware cards.
That technical jargon simply refers to the format that TV
shows are transmitted in over digital broadcasting networks.
With the United States and many other countries switching to
all-digital broadcasting, you'll want to avoid older capture
cards that only accept analog signals. Many cards can handle
both analog and digital signals.
A typical capture card will allow a user to record up to two
programs at the same time while watching a third. If you want
to record even more programs simultaneously, you'll need to
install an additional capture card. But remember to make sure
your power supply can handle the extra load.
Installing a video capture card isn't difficult. Most cards
are PCI or PCI-Express cards -- they fit into slots on the
motherboard of your computer. After removing the cover of
your computer, the card is installed by pressing it firmly
into the appropriate slot. The card is then secured with
a single screw. There are also video capture devices available
that are even easier to install. They plug into to any
available USB 2.0 port. |
| Mesmerizing Tube Bender Looks Like It's Pooping Steel
October 24, 2009 at 7:56 pm
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Bent tubing is key. Roll cages need it. Tube frame chassis
need it. Even the storage arrangement for my welding clamps
needed it. There are a number of ways to go about bending
tubing. Rotary draw benders like the Hossfeld Universal
bender make a tight bend at one point. Three-roll benders
create more gradual curves. But none of them compare to this
automated CNC tube bender that just spits out steel in any
shape you want. I could watch it all day.
Information on this Nissin bender is a bit sparse, but I've
come across these two videos of it's impressive capabilities.
Tube to be bent is supported, lubricated, and driven forward
at a constant speed by the stationary part of the machine. As
the tube is pushed through the machine, it is forced through
the moveable die, which positions itself appropriately to
bend the tube as needed.
The bend is originally specified in terms of the geometry of
the desired part. That bend geometry is translated into a set
of instructions that control the position of the moveable
die. The die will be positioned in the right place at the
right time such that the tube is bent the right amount and in
the right direction to produce a finished piece closely
matching the original specifications. |
| High-Tech Glasses Beam Info Directly Onto Your Retinas
October 24, 2009 at 7:54 pm
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Office workers may never have to worry again about viewing
hilarious but NSFW images surreptitiously. A pair of glasses
developed by Brother Industries can project images or
documents directly onto a wearer's retinas.
The Retinal Imaging Display technology displays a small image
10 centimeters wide that appears to float about 1 meter (3.3
ft) in front of a user's eye. Images have an 800x600
resolution and refresh at 60Hz.
Each pair of glasses holds an optical scanner, eyepiece and
a light source that also contains a tiny power box. Brother
Industries derived its application from laser printing
technology, as well as piezoelectric technologies based on
inkjet printing.
Similar technologies have tried embedding heads-up displays
within the lens of glasses. Other heads-up displays have gone
for more specific applications, such as giving drivers
a safer experience on the road.
company has yet to announce how much the specs will cost when
it commercializes them next year. But reading those operation
manuals hands-free at your desk never sounded so exciting.
Those are operation manuals, right?
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