anyone know how diodes are made?  Yes,  I'm serious!?
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yes. diodes are essentially one way valves for electrons. a discreet diode (a single diode in a package) is created by "doping" a small piece of silicon- the dopant chemicals introduced into the silicon semi-conductor cause a migration of charges away from the center of the chip, positive (holes- actually a deficit of valence electrons)  to one end, and negative (excess valence electrons) to the other causing a depletion region in the center.
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City and Guilds in electronic engineering, at a guess?\n\nOnly a guess mind - why dont you call the local company that installs them, or even ask your local fire brigade?\n\nHope that helps.
25404
See "How Light Bulbs Work":\nhttp://science.howstuffworks.com/light-bulb.htm\n\nThe full answer is:\n\nLight bulbs have a very simple structure. At the base, they have two metal contacts, which connect to the ends of an electrical circuit. The metal contacts are attached to two stiff wires, which are attached to a thin metal filament. The filament sits in the middle of the bulb, held up by a glass mount. The wires and the filament are housed in a glass bulb, which is filled with an inert gas, such as argon.\n\nWhen the bulb is hooked up to a power supply, an electric current flows from one contact to the other, through the wires and the filament. Electric current in a solid conductor is the mass movement of free electrons (electrons that are not tightly bound to an atom) from a negatively charged area to a positively charged area.\n\nAs the electrons zip along through the filament, they are constantly bumping into the atoms that make up the filament. The energy of each impact vibrates an atom -- in other words, the current heats the atoms up. A thinner conductor heats up more easily than a thicker conductor because it is more resistant to the movement of electrons.\n\nBound electrons in the vibrating atoms may be boosted temporarily to a higher energy level. When they fall back to their normal levels, the electrons release the extra energy in the form of photons. Metal atoms release mostly infrared light photons, which are invisible to the human eye. But if they are heated to a high enough level -- around 4,000 degrees Fahrenheit (2,200 degrees C) in the case of a light bulb -- they will emit a good deal of visible light.\n\nThe filament in a light bulb is made of a long, incredibly thin length of tungsten metal. In a typical 60-watt bulb, the tungsten filament is about 6.5 feet (2 meters) long but only one-hundredth of an inch thick. The tungsten is arranged in a double coil in order to fit it all in a small space. That is, the filament is wound up to make one coil, and then this coil is wound to make a larger coil. In a 60-watt bulb, the coil is less than an inch long.
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Diodes convert ac to dc.  You need an inverter to convert dc to ac.  That's done with a timer circuit and powerful transistors.
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By Lance Ulanoff  \nImagine a world where all your portable devices can be charged and powered simply by placing them on a desktop. Chip manufacturer MobileWise has gone well beyond imagining such a world and this week unveiled "a conductive solution" that it believes can make it all possible.\n\nDuring a mid-day press conference in chilly New York City, MobileWise showed off a handful of functioning prototype powerbases and retrofitted mobile devices that all use the company's new MobileWise chipset and enable "Wire-Free" electric power. One chip, the tiny Adapter Controller, goes inside the mobile device and the other, the Contact Controller, gets built into the power base station. These power bases, which were shown in a wide variety of shapes, sizes and colors, are each covered in an array of gold-plated contacts. The retrofitted mobile devices also have a pair of contracts. With properly configured handheld devices, the bases can, according to company CEO Andy Goren, change any flat surface into a charging/power station.\n\n \n \n \nThe patent-pending technology behind the MobileWise is, on the surface, quite simple. The adapter chip inside the handheld device will, when placed on a base station, receive a very small electrical signal and message from the base controller chip that will power up the adapter chip. The base controller chip will sense for polarity. If there is none (say you place your hand on the base) then it does nothing. If it does find polarity and then a signal from the adapter chip, it will then read information about the voltage level necessary to run the mobile device and begin charging and powering it. Because of the array of contacts—from dozens to hundreds, depending on base size—there's no need to place the device in a special spot or position on the base. In fact, during the demonstration we saw the bases accept multiple devices, charging and powering them all at once.\n\nThe solution is not actually entirely "wire free", however. The base station is plugged into an AC adapter and can deliver up to 30V DC to an individual device. It's also, according to Goren, completely safe, and if any charge were delivered to a person, it would be at the level of a low-voltage battery, virtually imperceptible to humans and certainly not harmful, he added. The final base units will also, he said, be waterproof and protected from electrostatic charges. \n \n \n\n\nDespite calls for MobileWise to manufacture the bases, Goren said the company plans instead on delivering the chipsets to partners who will likely build the adapter chip and proper contacts into their products and OEM the power base manufacturing to another company. MobileWise showed a variety of colors and form factors for the bases.\n\n \n \n \nAcer has already partnered with MobileWise and, according to Goren, may ship a MobileWise-enabled notebook by Q1 of next year. But MobileWise has, it seems, even more intriguing plans on the horizon. The company is already in discussion with a couple of major office furniture manufacturers to build the power array bases and controller chips into furniture. Apparently, these bases are for more than just mobile devices. Properly-equipped televisions, lamps and more could be powered by the bases—Goren even had an HDTV that worked with one of the larger ones. Later next year, MobileWise expects to add data handshake capabilities to the chipset, allowing, once the signal is split, data delivery over the same contacts.\n\nWhile no shipping units currently exist, MobileWise said the adapter chips run roughly $1.25 a piece adding, it said, just a few dollars in manufacturing costs to mobile devices and the base stations could, in units of 100,000 cost roughly $11 to manufacturers. Goren said he expects a mid-sized base (roughly 12 by 18 inches) to sell for $160 street. Not every mobile device will have to be retrofitted, by the way. MobileWise says it expects to see a ha
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I would guess it is made from rapid prototyping:- Fused-deposition modeling.  It technique is call Extrusion of melted plastic. there is more information that you can find. Just keep looking..
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maybe this would help\nhttp://encarta.msn.com/encnet/refpages/search.aspx?q=semiconductors
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I have been taught by my old-timer physics teacher that an SCR is a diode with an insulating space between the P and N layers.  This insulating space is the gate.  An electric field exists when no voltage is applied to the gate, keeping the forward-biased diode from conducting.  But a small current injected into the gate breaks down the field keeping the diode off.  An avalanche between the P and N junctions then commences and the SCR is ON.  The feild cannot reestablish itself until the SCR is REVERSE biased and the gate current is brought to Zero.
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The ones i've seen are a diode with 1 or 2 little arrows pointing out, indicating radiant light.  The circle is optional.\n\nSimilarly, photodiodes have the arrows pointing in.
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I think what you might be looking for is on Compfused.com\nThey had a tutorial about how 2 make little lights.\n\nOkay I found a site that tells you how 2 make led throwies(that is what they call them)\nGo 2 www.instructables.com they r right there.\nI understand this might not be what you r looking for but it might help:)
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i think that you should try to make some working models of semi conductors and and their use in the LED as you will search for the led then you will find that how semi. cond. helped to enrich the fields of leds . and i think that either you can go with the working projet of radar and how they used . or on lasers. lasers is really an interestin field. and i don't have any idea bout the chems. go to the discovery kids.com site and you will thousand of project reports.
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There are several ways to do this:\n1. thermocouples\n2. thermionics\n3. thermophotovoltaics\netc\n4. thermal diodes
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Are you asking how a laser is made, or what sort of things can be made to lase?
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This gives a detailed explanation of how they work.\n\nhttp://en.wikipedia.org/wiki/Bubble_light
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In electronics, pure crystals of silicon (for example) are DOPED with IMPURITIES such as arsonic and selenium to create desired electrical charactoristics. These are called P-type and N-type materials.\n\nWhen there is a junction between P and N materials, electrons can only flow in one direction.\n\nSo you could say the effects of a diode are caused by the IMPURITY ATOMS in the structure of the two materials at the junction. \n\nIn general, it might be better english usage to say ATOMS of an impurity. But the scientific meaning would be the same.
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Try Edmund Scientific on the web..but if you want to make your own try the link provided.\n\nGood luck!
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I don't think it would work. A diode works on principles of quantum physics that require the internal junction to be manufactures according to certain specifications. Putting a copper conductor on between the junctions would destroy all the effects that make it a diode; that is assuming you managed to cut it exactly at the junction. \nBy the way what where you planning to do with such an idea?