ghostlocc, I may be able to help you on this one. Since your time is short you probably don't have time for a major build. It usually takes a month for me to get everything together. The following link
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http://www.freepatentsonline.com/3769575.pdf
has a PDF file of a detector that is ideal for a classroom demonstration. It works and it is as simple as you can get. You will need a DVM and a soldering iron. The coil I used was 3 inches in dia and had 40 turns. I built this as a probe and it has a sensitivity of about 2 inches for a penny. Not much good in the field but as a demonstration of the principle it will work. It uses one tranistor in a hartley circuit and a cheap AM radio as a reciever. you tune the am radio to the oscillator frequency and and wear the radio around your waist. It works better if you keep the radio and the coil at the same distance at all times. If it doesn't work the first time it is probably because the oscillator frequency is wrong or the oscillator isn't working. Buy 2 transistors and pay especially close attention to the pin out. If the first doesn't work replace it. One note of caution. When you are working with an AM radio on the bench the 60 cycle buzz from the house wiring will drownd out the oscillator. I suggest you wrap a wire around the radio several times and then wrap the radio in aluminum foil to block the buzz. run the wire to a battery terminal of your detector. After you are sure the oscillator is working, you can remove the foil and wire. (stay away from cfl bulbs they are noisy) Good Luck
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