The bottom is the metal plate. There is no top plate. The cage is
grounded to NST and mains earths but there should not be much current
flow in these.
It is probably best to regard this not as a Faraday cage but as
1 A spark shield for (some) personal and viewer safety.
2 A safety gap. by allowing a spark from the toroid the voltage on the
toroid doesn't get to build up as much and interference is less.
I've seen it happen with news cameras on a small coil. Stop the spark
and they get hash on their $100k cameras.
3 As an earth. This is probably the most important as you do not want
stray high voltages on mains earths.
4 To prevent voltages developing on nearby conductors such as people
or equipment (by capacitance with the toroid).
None of these really need the top plate.
I really have no idea about EMI other than my wife doesn't like it.
(Interferes with the TV when I use the big coil outdoors)
Peter
-----Original Message----- From: Jim
Sent: Monday, June 17, 2013 6:48 PM
To: Tesla Coil Mailing List
Subject: Re: [TCML] Faraday Cage
Hi Peter,
That's a nice looking cage. I noticed that it did not have either a top
nor a bottom. Are you using the cage for EMI shielding? Also, do you
have the cage grounded at the same point as the coil?
Thanks,
Jim
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