Things Newbies Should Know

[djb28]

Lol. I read all over these boards and then after i made a post i saw this. If i only read a little longer and not gone from back to front.. lol

My pics are still there for the viewing and i would love some input any way.. My topic once reviewed is Video Projector Project. Thanks everyone!

[verbose mustafa]

I have created a dictionary with many of the diy words we use.

Click Here To Browse Or Search The Dictionary For A Specific Term

[snootch]

I figured i'd post this in case anyone had trouble searching the net for information, the best search engine is Dogpile. It searches something like 14 search engines. I always return more hits than just by using Google, or Yahoo search. My first couple of posts, no one answered, because I hadn't searched in-depth.

www.dogpile.com

[bitbyter]

When doing research on the forum make sure you note the date that the information was posted. A lot of progress has been made in the last year and our diy projectors have moved from lcd projection panels as being the standard to lcd monitors. Also the standard light source has moved from 400W or 1000W large metal halide bulbs (& their huge reflectors) to the much smaller and point source 150W/250W double ended metal halide bulbs. Generally these changes have made the alignment of the light sources MUCH easier but the lcd monitors require a bit of luck, electrival knowledge and the right monitor for the project to be a success. Personally I am waiting to find the holy grail of lcd's, under 15" with a good resolution, contrast ratio, response time and most importantly cheaper than an arm and a leg.

[ace3000_1]

A Small Glossory For The Noobs

Trev

Contents:

Active Matrix TFT
Audio In (Stereo input)
Audio Out (Stereo out)
Ceiling Mount
Channel (source)
Compressed Resolution
Contrast Ratio
Diagonal Screen
Distribution Amplifier
Digital Light processing (DLP)
Halogen Lamps
Inverted Image
LCD (Liquid Crystal Display)
Light Valve
Long Throw Lens
Lumens (ANSI Lumens)
Metal Halide Lamp
Overhead Projector (OHP)
Panel
Polysilicon LCD
SVGA Resolution
XGA Resolution
SXGA Resolution
VGA Resolution
Zoom Lens Ratio

Active Matrix TFT
Most common type of LCD. Used in most laptops, and most projectors. Has fast response times allowing the display of animation, full-motion video (30 frames per second), and an excellent color saturation.

Audio In (Stereo input)
The jack used to plug in sound coming from the computer or video source. Most projectors have more than one.

Audio Out (Stereo out)
The jack used to hook up external speakers or a Public Address (PA) system. Most projectors allow their remote control to adjust volume. Not all allow the direct connection to a pre-existing sound system.

Ceiling Mount
A projector that is rated acceptable for ceiling mounting. They have the ability to invert the image (because they are typically mounted upside down), and have remote control ability. Our recommended ceiling mount projectors also have power zoom and focus, the ability to power down completely when the lamp is extinguished, and may have a lens that shifts to minimize keystoning.

Channel (source)
Switchable sources that have been connected to the projector. The typical projector can switch between one computer channel and one video channel.

Compressed Resolution
Most all projectors offer compressed resolution for handling higher resolution images than their true resolution. There are a few different ways a projector processes the image to compress it. Some will simply drop every other line of image, while others go through complex programming to accomplish the same effect. The quality of the compressed picture can vary greatly. Typically, a projector that "scales" the image, rather than "compressing" it will do a much better job projecting an image from a source that has a higher native resolution than the projector.

Contrast Ratio
A method of measuring dynamic range. The higher the contrast, the more detailed the image. Blacks will be blacker, whites will be whiter, and particularly text on a projected image will be more vivid. A typical projector will have a contrast ratio of 200:1 to 400:1.

Diagonal Screen
The standard way a screen is measured. It measures from one corner to the opposite corner. For example: a 9ft high and 12ft wide screen has a diagonal of 15 ft. Most projection systems have a 4:3 aspect ratio, meaning the height of the image is proportional to the 3/4 of the width of the image, there has been a recent emergence of projectors that will also do 16:9.

Distribution Amplifier
Also known as a "DA", this device boosts a signal to maintain a clean, noise free signal over large distances. Without a DA, Video and computer signals are limited to a few dozen feet before they start to degrade. In addition, a DA can be used to split a source signal in order to allow the simultaneous viewing of an image on a monitor and projector, two projectors, etc.

Digital Light processing (DLP)
This technology was developed by Texas Instruments. Another name for it is "digital micro-mirrors devices" or DMD. A reflective approach to creating a projected image, this technology involves a tiny "wafer" about the size of a thumbnail, each with hundreds of thousands of tiny mirrors lined up in 1024 rows of 768 mirrors each. Each mirror is controlled and can tilt up to 20 degrees at incredible speeds. This allows the mirrors to modulate light from a lamp, and send the signal out through a lens on to a screen. Colors are added by putting a spinning color wheel between the lamp and the DLP before projecting the image out the lens.

Halogen Lamps
These lamps are mostly used in lower-end projectors. They last about 40 hours with constant output. Most projectors that use this type of bulb come with a spare bulb inside, since they blow out so frequently.


Inverted Image
This is used in ceiling mounted projectors. To make up for keystoning or the distortion created by pointing at an angle from the projector to the screen. Inverting the image turns the image upside down. Keystoning - Usually, the distance to the top of the image on the screen is greater than to the bottom of the screen (typically eye level). This often causes the image to distort and be wider at the top than at the bottom. This is called "keystoning" and many projectors have adjustments to correct it. The closer the projector is to the screen, the more obvious the effects of keystoning are.

LCD (Liquid Crystal Display)
This technology involves controlling the opacity of LCD "glass" by varying the electrical signal at each pixel. Each pixel acts as a shutter, to modulate light. This is a transmissive approach to modulated light as opposed to a reflective approach like Texas Instruments's DLP technology.

Light Valve
The projection technology usually found in "big" and expensive systems. These units start at about 2000 ANSI Lumens and go to 6000 or more. These are best suited for large stadiums. These units quite large and heavy, and not suitable for portable use.

Long Throw Lens
A lens designed for projection from the back of a room, or long distance.

Lumens (ANSI Lumens)
A standard for measuring light output. This method of comparison is used mostly to compare projectors. The ANSI lumen measurement standard was created by the American National Standards Institute to make certain manufacturers specifications could be easily compared. The ANSI measurement is independent of projected image size, and uses measurements from nine points around the screen to come up with an "average brightness". Previously, manufacturers would only take a lumen measurement at the brightest point on the screen which would be quoted, even if the rest of the image appeared dark.

Metal Halide Lamp
Type of lamp used in most new portable projectors today. These lamps typically have a "half life" 1000 to 2000 hours. They don't "burn out" all at once, they slowly lose intensity or brightness as they are used, and at the "half-life" point are half as bright as when they were new. These lamps put out an extremely white image, making halogen lamps look yellowish in comparison.

Overhead Projector (OHP)
A predecessor to today's projectors. They consist of a glass platform and a focusable lens assembly designed to project a transparent image upon a wall or screen.

Panel
Used in conjunction with a high-power (at least 3,000 lumen) overhead projector, panels consist of LCD display for projection, and are basically an electronic transparency. Flat panel projection systems have been replaced by self-contained projection systems, since projectors are brighter, easier to use, and sometimes even smaller than the older flat panel technology.

Polysilicon LCD
This is the small-format LCD panel that is increasingly used in state of the art projection systems. These panels are about the size of a postage stamp, and typically three are used inside of a projector, with one each corresponding to red, green, and blue. Projectors using these panels, as opposed to the older, larger-format amorphous silicon LCDs, typically have brighter images, more saturated colors, and best overall image quality.

SVGA Resolution
Refers to a 800 x 600 pixel display, regardless of the number of colors available. Most laptops purchased during 1997 and 1998 have these internal displays. Newer laptops incorporate XGA resolution panels, with diagonals around 13 or 14 inches.

XGA Resolution
Refers to a 1024 x 768 pixel display, regardless of the number of colors available. Newer
laptops and projectors have all moved up to XGA resolution.

SXGA Resolution
Refers to a 1280 x 1024 pixel display regardless of the number of colors available. Currently the highest resolution available in a portable projector. This resolution is typically only required when using a projector with a high-end workstation such as a Sun, SGI, IBM RS-6000, etc. but is not recommended for the majority of PC and Mac applications.

VGA Resolution
Refers to a 640 x 480 pixel display, regardless of the number of colors available. Older laptops and projectors use this resolution, but VGA resolution is considered obsolete.

Zoom Lens Ratio
This is the ratio between the smallest and largest image a lens can project from a fixed distance. The higher the ratio the more flexibility a user will have when setting a projector up in a venue.

[DL]

Connection types & quality Post #8 About video quality depending on connection to LCD PANEL: 0. DVI conneciton -> LCD is by far, the optimal 1. HTPC->VGA cable is realistically the best 2. Svideo is OK 3. SCART is not so good 4. Composite is not so good

Just thought i'd point out that scart is actually a universal analogue connector used in europe,australia and other countries(and in a slightly different form in japan).It can handle rgb,composite,and in some forms s-video(depends on the tv,and the cable...usually one of the scart sockets takes s-video and the other takes rgb)
RGB is very much higher quality than s-video is,and is similar to vga but uses a lower scan rate and composite sync instead of seperate sync.I beleive can take non-interlaced signals as well,at least at low res anyway....but don't quote me on that.The reason you found that scart was poor,was probably because you tested with a cable and/or source that only use composite video...often for vcrs this is the case.RGB is actually the best possible quality you can get out of most older video game consoles and many of the newer ones as well...in fact only the dreamcast outputs vga natively but the xbox can do it with a modchip,and the gamecude has some sort of digital connector,I beleive.Most dvd players can output this is some form,even if it requires modding inside the player..particularly useful if the player does not output any from of digital or analogue vga signal.

[gregory27]

Just wanted to give some really simple advice for newbies
When planning to use an overhead projector, buy a nice one
My model of choice is the Dukane 4000, and has a triplet lens
this projector is so good, that I can see the flaws of the image very easily, it also is very bright, and I dont' see any reason to upgrad to metal halide bulbs, FXL is the bulb in this one, and it's bright enough to see with a small flourescent light on
Also when buying a projector panel, do some searching in this forum for that model, and make sure it's usable, or better yet buy a benq lcd and take it apart for hi resolution

[denun]

i have no instruments to compare s-video to SCART, but in europe SCART signal is really better the S-Video signal

[multiplexor]

From the stickied thread......

remp
Earthing and electrical safety Post #1

Grounding.
If you live in an area which uses 3 pin power points, anything you make, or purchase must have any accesible metalwork earthed by the ground wire unless the appliance is rated as double insulated. Double insulated means it is made of insulating plastic such as modern vacuum cleaners or any metal parts are connected to the appliance by plastic. eg the chuck in small electric drills is driven by plastic gears or the mains power transformer is rated as a double insulated transformer.
If you see on the power rating plate a square within a square it is a double insulated device.

If not double insulated there are stringent regulations and tests the device must pass to be sold to the public. One of these in 3 pin outlet areas is, all exposed metalwork must be grounded and holes in the device must be small enough so you cannot poke your finger in and get a shock.

In the USA or other areas using 2 pin power points I am not sure what the situation is but understand your outlet is regarded as the same as if you had an isolating transformer.

The point of these regulations are your safety and other people's safety especially children and from your point of view, when making things, to help stop you getting sued if someone gets electrocuted by failure to ensure safety.

[spawn]

Just to fill in the gaps:

How does one connect the video source to the LCD? I take it if your source is VGA (PC) then that is fairly simple as panels and LCD monitos come with VGA in. But what about if you're building a stand-alone projector and you need lets say an RCA video input?