File information: | |
File name: | tv_generator.rar [preview ] |
Size: | 406 kB |
Extension: | |
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Descr: | CCIR PAL TV GENERATOR |
Group: | Electronics > Measuring equipment |
Uploaded: | 21-09-2004 |
User: | toltec |
Multipart: | No multipart |
Information about the files in archive: | ||
Decompress result: | OK | |
Extracted files: | 1 | |
File name videoi.pdf Video pattern generator Introduction The objective of this project was to construct a Composite Video Pattern Generator, which can be used as a teaching tool in the video field as well as a laboratory instrument, useful for repairing and adjusting television receptors. This instrument is in no way intended to be a commercial set, because I cannot guarantee all the specifications that a professional tool must have. However, the result is a high quality video equipment. Specifications Patterns: Color Bars, Raster, Cross-hatch, Points Controls: independent R, G, B, luminance, chrominance and color burst Video output: composite video, 1 Vp-p at 75 ohms load Color system: PAL-N (option PAL-B/G/I, changing chroma oscillator crystal) Scanning system: Interlaced (Bars and Raster), Non-Interlaced (Cross-hatch and Points) Power supply: 12 Vdc (8 x AA alkaline batteries) Power consumption: 70 mA maximum (White Raster) Applications: television receptors adjustment (purity, convergence, linearity, etc.), troubleshooting of video section in television sets and video recorders, teaching of video generation techniques General overview The human eye is capable to "see" images using "receptors" located on the retina. There are two types of receptors, classified by function: the Rods, in charge of black and white perception, and the Cones, responsible for color discrimination. If we concentrate only in the cones, we will discover that there are three types of them: one type reacts to Red light, another to Green light and the last group reacts to Blue light. We only "catch" three colors; however, we actually "see" all the colors. Here comes a basic rule of color generation: to know the color information of an object, we only need to know the relative amount of the three basic colors: Red, Green and Blue. By this reason, these three colors are known as Primary Colors, because we can make any other color by combining them in the adequate proportion. Now, let's think for a moment. When we learned the colors at school our teacher probably told us that the primaries were Red, Yellow and Blue. Another strange fact: if we observe the way in which ink printers create colors, we will notice that there are only three color cartridges, Magenta, Yellow and Cyan. But they print in full color. Someone must be wrong... This "confusion" results from the existence of two groups of primary colors: the Additive Primaries and the Subtractive Primaries. In order to understand the difference between them let's see a couple of examples. Suppose that we illuminate a white wall with a green light. Obviously we will see green, because this is the color reflected by the wall. If we now turn the light into red, again we will see red. But, if we illuminate the wall with both colors (green and red) at the same time, the resulting color will be yellow, which comes from the sum or addition of the two original colors. As we can observe, the sum of this colors gives a new, secondary, color. By th |
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