How Can I Shield My Circuit from EMI Caused by a High-Voltage Pulse Transformer?

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SUMMARY

The discussion focuses on mitigating electromagnetic interference (EMI) caused by a 1:40 ratio pulse transformer generating a 1000V sawtooth pulse. Users suggest using copper mesh for shielding, emphasizing the need to determine the effective wavelength of the EMI field, which varies due to the nature of the pulse. Recommendations include utilizing a solid metal box for shielding and grounding the shield to Earth, as well as considering the sensitivity of the micro-controller and power supply to specific frequencies. The effectiveness of pure silver as a shielding material is questioned, with suggestions to explore more conventional methods.

PREREQUISITES
  • Understanding of electromagnetic interference (EMI) principles
  • Familiarity with pulse transformers and their operation
  • Knowledge of grounding techniques for electronic devices
  • Experience with shielding materials and their effectiveness
NEXT STEPS
  • Research the properties and effectiveness of copper mesh for EMI shielding
  • Learn about the design and implementation of EMI enclosures
  • Investigate grounding methods for electronic equipment
  • Explore the use of spectrum analyzers for EMI frequency analysis
USEFUL FOR

Electronics engineers, hobbyists working with pulse transformers, and anyone involved in designing circuits that require EMI mitigation strategies.

kenw232
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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.
 
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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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