Desktop Coil ground? (fwd)

From: 	Jim Lux[SMTP:jimlux-at-earthlink-dot-net]
Sent: 	Tuesday, January 20, 1998 10:24 AM
To: 	Tesla List
Subject: 	Re: Desktop Coil ground? (fwd)

> ---------- Forwarded message ----------
> Date: Mon, 19 Jan 1998 08:27:36 -0800 (PST)
> From: baumann-at-proton.llumc.edu
> To: tesla-at-pupman-dot-com
> Subject: Desktop Coil ground?
> I am in the process of designing/building a desktop coil for a friend
> that is a physics teacher. Can you think of a better way to get kids
> interested in science that arcs? :)
> Anyway: It is pretty obvious that said coil must be small,and that is 
> not really a problem. What is a problem is how to ground the beast.
> The instructor is not allowed to do little things like pound 8ft rods
> into the ground outside the class.
> [Proposed coil would be: 1"x10" 28awg, with a 2-3" spherical topload`
> I will have to find ferrite toriods or sticks to build the protection
> circut. At this frequency, he will be able to use a small cap, and yet
> still get 5-6" arcs at least.

The ground is just to make an approximation of the infinite grounded plane
for the top of the coil to work against. For a small coil, a small ground
plane is good enough. Why not a 1 meter square board with foil or hardware
cloth. Sure, for a multi foot coil with multi foot sparks, you need a multi
foot ground plane, but not for a desktop unit. Just roll out some
conductive cloth and use that (ground it to the third wire for safety,
though, you don't want it to float up.).