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.