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Thread: Lighting a LED lightbulb using electromagnetic Induction.

  1. #1 Lighting a LED lightbulb using electromagnetic Induction. 
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    Well, I have technically two questions and they are as following.

    1.) I found this diagram which I'm sure many of you have already seen, but it's a diagram of Nikola's Tesla's famous no wire light bulb.
    http://upload.wikimedia.org/wikipedia/en... the website for the picture. Anyway, I was just wondering if anyone could please explain the diagram and the parts and of course if anybody knows, how it works. As I am a student trying to research upon this topic, I was wondering if anyone could please shed some light upon whether this could be easily built and if so how, and any tips or experiences.

    2.) A PHD student at MIT (which im sure many have also heard of) has done the wireless levitating light bulb. I am trying to research that and on his website
    http://bea.st/sight/levitation/
    There is a few schematics, primarily this one as following,
    http://bea.st/sight/levitation/resonantT...
    Could any please explain the diagram and instructions in colloquial terms? Thank you very much.


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  3. #2  
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    The way it works:

    It's basically a big transformer. One coil is hooked up to an AC source, and the other one (resonant) is placed some distance away. The coils working together act as a transformer, and the LED lights up (acting as a diode, and a lamp).

    The "levitating" bit is probably a bit of string doing its thing.


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  4. #3  
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    The second link you posted doesn't work.

    I don't think it could be easily built. The LED part wouldn't be too hard. Basically, it is an air core transformer with the LEDs connected to the secondary. Most transformers have an iron core to couple the magnetic field of one coil (the primary) to the secondary coil. By coupling the coils through air, it make it look like the bulb is glowing without a power supply. But without the iron core to couple the magnetic flux, the coupling is inefficient so the two coils have to be close together and tuned to a resonant frequency. The current is relatively weak so he used LEDs, which don't use much current.

    The magnetic levitation part is the hard part. The current in the coil makes an electromagnet and the repulsion of this electromagnet with the permanent magnet is what keeps it levitated. It's unstable which means that the control system has to keep making minute adjustments to keep it from either flying off or falling down. Tuning that conrtrol circuit would be very tricky.
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  5. #4  
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    Transmitting power is inefficient. The aerials or coils required tend to nearly as big as the gap they are trying to bridge.
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