|MadSci Network: Engineering|
I bet you can't use the Nintendo Zapper Gun on a "Lap-Top" computer. Back in the olden days, when there were real TVs (no not the program), they had electron guns and Cathode-Ray-Tubes. And this is what was inside the TV, shooting stuff back at you, and you didn't know it. 1) Here is how it works: In the older TVs (Non-LCD screens) there is an "Electron Gun" that looks like a big light bulb. The function of this electron gun is to use electricity and heat up an element, and boil off electrons. A set of electro-magnetic coils then repel and direct the flow of these loose electrons at a very high speed towards the inside of the TV screen. This is all happening behind the TV tube glass. These electrons are being generated in the back of the TV tube, and are shot directly out towards you. What stops most of these loose and high speed electrons is the front of the tube which is made up of very tiny capsules of phosphorous material that momentarily give off light as they are hit by these loose high speed electrons. You can actually see the tiny capsules that look to be red, yellow, and blue. Your monitor is rated at xx dots per inch, which means that there are xx of these clusters of red, yellow, and blue capsules (called pixels - short for picture elements) in each linear inch of the front of your computer monitor. If you look close enough, you can actually see these pixels. Well, as you guessed it, some of those nasty loose high speed electrons make it past the phosphor screen and come straight at you. And you didn't believe your mother when she said sit back from the TV screen or you will … Inside the Nintendo Zapper Gun or any such device (like a "light pen") is a "detector". That's right. The Nintendo Zapper Gun does not actually shoot anything out, but it actually gets hit by the TV's bullets that are the loose high speed electrons which are generated in the back of the TV where it gets really warm. 2) How does the Zapper Gun know where you aimed? The electrons are boiled off. The magnetic field on the back repels and accelerates the electrons towards the front. And then, there are guide electromagnets on the side and the top/bottom of the tube. With precise timing and monitoring, these guide electro-magnets can direct a very fine beam of loose electrons to each of the red, yellow, and blue pixels. The back electro-magnet determines how much energy that electron has when it hits the particular pixel. By controlling and mixing the amount of high speed electrons going into each of the primary color pixels, different colors can be made. This beam is controlled to sweep from left to right horizontally, then go down one row, then start the horizontal sweep from the left to the right again, and so on. The exact location of the beam at any given time is known by the TV circuitry. When you pull the trigger on the Zapper Gun, the Nintendo system, then reads this information from the TV circuitry, and checks to see if the gun has been hit by an electron beam or bullet. If the Zapper gun has been hit by the electron beam, that means you were aiming at the right spot when the sweep was going through, and you have a direct hit. If the zapper gun is not hit by the electron beam, that means that you must be aiming elsewhere on the screen, and it is considered a miss. 3) The reason it will not work with LCDs: Liquid Crystal Displays, such as those used on Lap-Top computers use a different technique to get light out of pixels. They do not shoot high-speed electrons into your face, which is what the Zapper Gun needs to function - and so the Nintendo Zapper Gun probably will not work on your Lap-Top. Yes I still sit too close to the TV screen. Let me know if any questions arise, Abtin Spantman SPANTMAN@EXECPC.COM Ollie Strickland adds: Mr. Spantman, I was cruising through the mad scientist web page, and saw your response to the kids question regarding how the Nintendo zapper gun works. I believe your answer is partially incorrect. The explanation of how the CRT works, fine... but then you went on to say that the NES reads the TV circuitry to get beam information, then checks a sensor in the zapper for a "bullet" or electron beam. Well, 1st of all, the communication between the NES and the TV set is unidirectional, not bidirectional. It can only output data to the tv, not "go in" and get any from any circuitry. Secondly... there is no correlation between the gun being pointed at the correct target on the screen (a hit) and an electron beam being sensed by the zapper. So... how does it work??? When the trigger is pulled on the zapper, the NES tells the tv to momentarily not draw the numerous targets on the screen, but instead an object of a specific size and color, maybe even blink at a specific rate. This all happens very fast, but if you look in the popular game Duck Hunt, you will see that right when the trigger is pulled the ducks disappear and white rectangles appear. This is what the sensor recognizes. The sensor sends data about what was in it's field of vision, and the NES looks for that special target data (flashing box, whatever). This solves the unidirectional problem between the TV and NES. Cheers, Ollie
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