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Thread: Need help with microwave transformer-- for experiment

  1. #1 Need help with microwave transformer-- for experiment 
    New Member
    Join Date
    Jan 2009
    Hi. Iím doing a science project in high school, in which I dismantled a microwave, and took the microwave magnetron, capacitor (no need to worry; the capacitor was discharged) and transformer out.

    Before I go on, the premise of the project was to get a magnetron to emit a microwave, which would be received by a rectenna (composed of an isolated microwave antennaóin this case a wi-fi antenna, connected by wire to a Schottky diode) which rectifies the AC current and turns it into DC current. In other words, wireless power transmission.

    Now, Iím particularly having trouble with the transformer. Iím planning to hook up the apparatus to a variable power supply, in which in the science classroom, has an outlet that you can put wires into. One hole is for positive current, another is for negative current.
    The variable power supply is in one room, the outlet for the two holes is in another.

    This poses a problem, as I have a normal electrical plug (you know, for common household electrical outlets) for the microwave (which is connected to the control board AND eventually to the transformer). The transformer is a step-up transformer. The input has two flat knobs (almost like those on an normal electrical plug), and the output has other knobs that I was able to connect to the capacitor and the magnetron via wire. I supplied the link to a diagram of the transformer at the end of this post.

    Iíd like to bypass the controls and be able to directly wire the transformer to the variable power supply via the two holes (+ and -) instead of plugging it into the electrical outlet, that way I can directly control the voltage of the current going into the transformer, instead of having a steady voltage from the normal electrical outlet.

    How can I make this possible? I donít know how to distinguish between the two input knobs on the transformer (where to plug into positive and where to plug into negative).

    I was wondering if it was possible I can use 18-gauge wire to connect into the two variable power supply holes, and connect it to the two input knobs on the transformer via alligator clips.

    Here is the link to a diagram of a transformer that is extremely similar to mine:

    Pardon me for the extremely long explanation (more info is better than less).

    I would greatly appreciate your help.



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  3. #2  
    Join Date
    Apr 2007
    Yikes! That doesn't sound safe at all. You know, when they came out with microwave ovens there was quite a bit of concern about safety. Your oven has a number of safety features, like the electromagnetic shielding provided by the metal oven enclosure and the metal mesh in the oven door. The oven shuts off when you open the door. All of these safety features are bypassed when you take the guts out of the microwave oven.

    You could boil your eyeballs or something.

    Heed this FDA warning:

    Much research is under way on microwaves and how they might affect the human body. It is known that microwave radiation can heat body tissue the same way it heats food. Exposure to high levels of microwaves can cause a painful burn. The lens of the eye is particularly sensitive to intense heat, and exposure to high levels of microwaves can cause cataracts. Likewise, the testes are very sensitive to changes in temperature. Accidental exposure to high levels of microwave energy can alter or kill sperm, producing temporary sterility. But these types of injuries - burns, cataracts, temporary sterility - can only be caused by exposure to large amounts of microwave radiation, much more than the 5mW limit for microwave oven leakage.
    FYI, there is no plus and minus polarity to alternating current. It seems your lab may have a variable d-c power supply. If you connect that up to a transformer, you will get no output and most likely fry the transformer.

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  4. #3  
    Join Date
    Jan 2008
    From the standard of your English, which is extremely high, I'd say you are probably not a high school kid. I reckon also that no high school tutor would allow such an 'experiment' to be performed in anything like the manner you describe.

    If I am wrong, and you are a high school kid then stop right there and go make some corn dollys instead, otherwise you are likely only to receive the 2009 Dawin award.
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