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Basic faraday cage questions

  1. Apr 9, 2015 #1
    I hit a 1:40 ratio pulse transformer with a 1000V (100mA) sawtooth pulse and it creates a spark gap. Unfortunately it also creates a lot of EMI and my micro-controller and power supply has problems because of it. How do I stop this? How do I know what the wavelength is of the EMI field so I can figure out what size copper-mesh to get? I don't have a spectrum analyzer. I pulse the coil from anywhere from 10Hz to 400Hz if it matters.

    Will any mesh diameter work?
    http://www.twpinc.com/wire-mesh-material/copper

    How about a metal box? Would that be more effective?
    http://hollandshielding.com/324-EMI_enclosures

    Should I not bother trying to shield the transformer, and instead only shield my micro-controller? I must tie the shield to earth ground, and the easiest way to do that is just my ground plug in my electrical outlet correct? I tried creating a silver box with 100oz pure silver bars, it did nothing. I though that would at least reduce it somewhat.

    Thanks for any help.
     
  2. jcsd
  3. Apr 10, 2015 #2

    Simon Bridge

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    The EMI from the pulse will not have a single wavelength: it's a pulse.
    You should discover (i.e. from the manufacturer) what frequencies your equipment is sensitive to and protect against those.
    Of course, you could just try putting the equipment in a solid metal box and/or putting a grounded metal wall (or a full water tank) between the equipment and the pulse source.
     
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