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[TCML] Building a medium sized Tesla Coil - (This is my first post)

Hi Tim,

Your story sounds very much like mine.  Like you, I was in high school 
that issue came out.  I had the advantage that my dad was an electrical 
contractor so I had access to neon transformers.  So I got one and built 
our garage a very nice coil suitable for display.  I was getting 12" 
from the point electrode at the top with lots of corona around the glass
capacitors. Being a contractor my Dad had stored in the open attic of the 
garage lots of florescent bulbs that would light up the whole space when I 

fired off the coil.  I remember trying to increase the capacitance by make 
layers of glass and metal.  The result was that I shattered the glass with
the most beautiful french curves.  For some reason that impressed me.  The 

other thing that sticks in my mind was the winding of the secondary coil.
I lived in Miami at the time and I loved the outdoors so I sat on our 
one afternoon and wound the coil by hand.  I was apparently facing north
because after I was finished I was tanned only on the left side of my face
and chest. Quite comical I suppose as I got a lot of ribbing for a few 
I do know what happened to my coil.  My Dad had read somewhere, or so he
said, that high frequency would sterilize you so he made me dismantle it.

A number of years ago I started collecting parts to make a static gap 
I have several matched 30 mA 15k transformers and even a 15k 120mA beast
along with MMCs and I have two wound coils.  Well, I wanted to make really
nice metal spheres and other metal parts for the project and started down
the road to having a machine shop.  Well, a 12x36 engine lathe, milling 
machine, surface grinder, etc. have side tracked me for about 5 years all
based on those spheres.  I am sorry to say that since the 90s I have just
been a lurker and dreamer on this forum but I have ever intention to get
back into coiling.  I can make spheres now!


All - This is my first post:

When I was 15 (35 years ago) I saw in a magazine (Radio and Electronics?)
and article about how to build a Tesla Coil. It used sheets of glass and
aluminum foil for the capacitor and explained the details. I thought this
was amazing! Initially I was able to locate a Model T Ford spark coil for
$5 as the HV transformer. I used an old Lionel train set variable voltage
adjustment (like a variac might be now) transformer used for speed control
on the train - as AC input into the Model T Ford spark coil. I found some
wood in my dad's garage for the base and used a PVC pipe and 8 guage
primary wire and 28 gauge spooled secondary wire I had gotten from a
friend. I pieced everything together and turned it on and figured out how
to tap the primary turns (on wooden dowel rods as per the magazine
instructions). I saw 4-5" sparks and held a florescent tube nearby. I was

I brought it into school to show my shop teacher. He told me about a city
wide Industrial Arts show and contest and thought I should re-build my
tesla coil and have it properly stained and got everything looking really
sharp looking for the contest. I was able to locate a more powerful neon
sign transformer of perhaps 15 or 30 mA. We fired it up and tuned it and
got 9-12" sparks out the single wire of the top of the primary. I did not
know about toroids/spheres for capacitance back then. I entered the 
and won first place for the research and development category.

>From this point forward I read as much as I could about Tesla from the
library and later bought many books about him and his work. I wrote a term
paper the following year about Tesla. I don't know what became of my
original Tesla coils but I have been reading online the last couple of
months about various tesla coils and modern ones and the latest
advancements with calculation software.

I found about about the GFI issue and was lucky to find on eBay a "France"
neon sign transformer 15kV 60mA used (no indication on the label about GFI
or UL 2161) for $45 + $58 shipping which is a bargain for some of the
prices I've seen online at over $300. I ordered plans online for $14 for
several tesla coil designs and I'm hoping to get 3-4' sparks using the 
60mA neon sign transformer. I remember hand winding my secondary coil as a
kid and I should be able to find a 4" PVC 26 gauge 22" long secondary on
Ebay. I also bought some HV 15kV connection wire (25') and a primary 
tubing frame holder to make it look nice and evenly space the primary 
- online. I will not use sheets of glass or make my own HV caps but will
purchase MMCs and make a bank of them with 10M resistors. I hope to spread
out the cost over the next few months and have a finished medium sized
Tesla Coil by late spring. Getting Excited! - Tim

Russell Thornton
Engineering Specialist
Spacecraft and Systems Engineering
The Aerospace Corporation


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