Ground current experiments

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Jon Rosenstiel by way of Terry Fritz <twftesla-at-qwest-dot-net>" <jonr-at-pacbell-dot-net>

The past couple of weeks I've been helping my grandson, (age 14), build a
small battery powered TC for his school science fair. The coil we built is
based on John Couture's 70kV model as described in his "Tesla Coil
Construction Guide".

The purpose of this TC project is to determine if wireless power
transmission is possible.

I did a search of the list archives and found a post by Richard Quick
describing some ground current experiments he performed with a medium sized
Tesla coil. I kind of doubted that we would be able to perform those
experiments with our battery powered TC.

Before we were too far along with the construction of the coil I lashed
together the various components with alligator clip leads to see what we had
for spark length, (around one inch), and to see if the ground current
experiments were possible.

I had already ordered and received 3, 4, and 5 inch copper spheres from
McMaster-Carr. I poked around the loft and found an old 4x21 inch, (#22
wire), secondary.

The 4x21 secondary topped off with a 5-inch sphere just happened to resonate
pretty well with our TC's 3.5x13 inch secondary, (#28 wire), topped off with
a 3 inch sphere.

I covered the top of our work table with aluminum foil to act as a
counterpoise and placed the 4x21 coil with it's 5 inch sphere about 1 foot
from our lashed-up TC.  Both the "transmitting" coil and the "free" coil had
the bottom of their secondaries connected to the counterpoise.

When I fired up the transmitting coil I was totally amazed! The experiment
worked beautifully! We were getting ½ inch sparks off of the free coil's
sphere! With the free coil placed 15 feet away from the transmitting coil,
(it's base still connected to the counterpoise), we were able to easily
light a neon tube and could draw a tiny arc to a ground rod!

So, if you're looking for some TC entertainment, (and education), I highly
recommend Richard Quick's ground current experiments. Search the archives
for "Tesla Experiments", December 1994.

I don't know if what we did qualifies as "transmitting power", but we did
manage to produce a spark from the free, "receiving coil" solely through the
action of ground currents.

My grandson plans to show that although power can be transmitted using Tesla
coil ground currents doing so in this age of electronic everything would be
completely out of the question. Using a AM radio he is going to show just
how much interference a small Tesla coil, (around 18 watts), can generate!
If this Tesla coil can drown out stations on the lower end of the AM dial
100 to 200 feet away, (it does), just imagine how much havoc a TC the size
Tesla was constructing at Wardenclyffe would cause!

Our coil did scramble, (temporarily I hope), my WWVB wristwatch! I had
better bury this watch in a copper lined lead vault when I fire my 10 inch
pig powered coil. Just happens to resonate at 63kHz! Might be too much for
the 60kHz watch receiver!

Ok, enough for now.

Jon Rosenstiel