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Re: My First TC

At 07:55 AM 10/07/1999 -0600, Tesla List wrote:
>Original Poster: "Spud" <spud-at-wf-dot-net> 
>
>Hey, I have been searching the web relentlessly for information on Tesla
>coils for about a week now.  What I have found, basically, is that there is
>no common set of plans, but you pretty have to create your own.  I can do
>that, but I just don't know the basic construction.  Things like how the
>primary is connected to the secondary. (Or does it just spark through the
>air? How is the secondary grounded?)  Things like that.  I'd love to know
>even the most basic information that you could provide.  I am astounded by
>these Tesla coils, and am very excited to learn about them.  Thanks to
>anyone that will share their knowledge.

No, there is no specific set of plans for a Tesla coil. I wondered the same
thing when I first started a few months back. :-) 

There really couldn't be since tesla coils are built in different sizes. There
are
other factors such as the type and voltage rating of the transformers involved.
The most common transformer type used in tesla coil construction is a neon
sign transformer. 

A good coil for a beginner is a 4" diameter, using a 12-15,000 volt neon sign
transformer. The most common coil form is PVC pipe. I believe from memory,
a 4-4.25" secondary coilform should have about 20-22" of winding length. 
A 4" secondary is more than capable of putting out 4-6 foot streamers, with
a 15kv, 60ma neon sign transformer (NST).

The primary is not connected in _any_ way to the secondary. The primary
tank circuit causes resonance in the secondary, which creates streamers
and arcs off the top of the secondary terminal. There's only two connections 
on the secondary - at the base is a connection for a dedicated RF ground, 
typically flat copper strap which is run to ground rods. The grounding strap 
works best if kept short as possible (less resistance). This is to move the
heavy 
currents away from the base of the coil. The second connection is the top
terminal, most typically a toroid or doughnut shape is used. The most common
toroid type is corrugated aluminum ducting. It works well. 

You can find neon sign transformers at sign shops. Check the yellow pages
for your area. Do not, I repeat, do not, buy a *new* neon transformer. They
will cost you $400-500, easy. Look for used. You want at least 12kv, 60ma. A
15kv 60 would be better. If you ever come across a 15kv 120 ma unit, you're
_real_ lucky. More current is better. Figure on anywhere from $10-75 for a used
unit.

You can find magnet wire used for the secondary at most electrical motor
re-winding shops. You can use AWG 22 for a 4-6" secondary. If you buy
a spool, it will run you anywhere from $30-45, but will have enough wire
to do at least 3 secondary coils. 

Some coilers use heavy guage wire for the primary, but 1/4" refrigeration
tubing is probably the most common, and durable.

A good sparkgap unit for a beginner is the Richard Quick Cylindrical
static gap. This is a length of 6" diameter PVC pipe that holds a series
of copper pipes. I used 12 - 1" pipes in my unit for 11 gaps. It has a 5"
muffin fan on top to exhaust the hot ionized air out of the unit and for
better quenching or extinguishing of the spark. Think of the sparkgap
as a real fast switch.

You will need to build a jig to wind the secondary. You can visit my page
and see a quick jig setup. Some people use a lathe, if available, others
have used a drill with a variable speed. The wire needs to be closely
wound, with no overlaps or breaks. Practically all coilers have read or
know of the Richard Quick articles on winding a secondary. These are
the text files you will need to read and study.

Above all, you will need to read the Safety Sheet at http://www.pupman-dot-com
since you're dealing with high voltage. The toroid produces a copious amount
of ozone, is extremely loud and can be considered a health hazard.

I've only been doing this myself a few months, but following RQ's articles,
reading LOTS of other coilers' sites, pestering a few people in email and
reading the list here and in the archives have achieved 53" streamers
with a 6" coil, 15kv 60 NST and a commercial .01 capacitor. 

If you have a garage and an electric door opener, and plan on running
a coil in the garage be careful. Tesla coils and garage door openers
do NOT mix. I already took mine out with a strike. You will need to unplug
anything connected to the opener. 

Hope this helps,

Don



http://www.fwpd-dot-net/dona/tesla/teslacoil.htm