Re: HV wiring
Tesla List wrote:
> Original Poster: "Kent & Kim Schaffer" <santoken-at-bright-dot-net>
> Hello everyone!
> Just to let everyone know, my step son received first place at his science
> fair and is advancing on to the regional science fair on March 27th. We'll
> keep you posted.
> Also, what is it that most of you use as HV leads and wiring on your TC's?
> Like the lines runnig from your Xfmr, etc. On my step son's coil I used 12
> ga stranded, insulated wire fed through vinyl tubing.
What you have will work..
Other popular things (i.e. real HV wire) are:
Neon Sign Wire (GTO-15) a polyethylene jacket on a 14 ga stranded
copper wire. About $.10/ft in quantity. Good to 20 kV without fear
Solid core spark plug wire (not the supressor kind) (good to 40 kV)
Coaxial cable that doesn't have the foamed dielectric. RG 58/59 (if, and
only if the dielectric is a clear plastic and not white (the white is
actually foam) works fine for Neon Sign transformer voltages, the
thicker RG-8, RG-213, RG-11, etc. (about 1/2 inch in diam) works up to
around 30-50 kV.
I personally leave the shield on coax and ground it. It works to a
higher voltage because the shield makes the field even and it provides a
safety factor if the dielectric does break down, it breaks down to a
grounded cover, so you don't get shocked. There are those that have had
trouble with using long runs of coax in a TC because of transmission
line effects (the travelling waves can cause voltage spikes which
destroy neon transformers, caps, and/or cables).
take a look at http://home.earthlink-dot-net/~jimlux/hv/hvwire.htm for more
discussion of the above. For the lowest cost option, I'd look for old
RG-58 network cabling being ripped out somewhere. Most cable TV coax is
foamed dielectric (lower loss, good for TV, worthless for HV
Finally, I also do a lot of wire inside plastic tubing or pipe for
> Another question I have is how do most of you run the wire from the top of
> the secondary to the toroid? How do you attach it? Is each case
> different? The reason I ask, on my step son's coil we used a brass coated
> door knob, the wire ran from the top of the form right to the center of the
> upper cap and attached to the door knob. The only problem was the corona
> and arcs off of the wire before it got to the knob. Is this a sign of
> something else?
You might try a bigger top electrode so that it "shields" the top
windings. Think of a small donut shape that mounts on the top of the
coil (or just sits on top of the existing doorknob). ALmost anything
will work. Try some of that foam pipe insulation bent in a ring and then
wrapped with aluminum foil tape. You'll need to retune a bit (you'll
need more turns on the primary, or to move the tap out, as the case may
be). And, if the new top load is big enough, you won't get sparks out of
it unless you give them somewhere to start. A thumbtack stuck to the
electrode with tape works nicely (poke the tack through the tape so the
point sticks out).
Jim Lux Jet Propulsion Laboratory
ofc: 818/354-2075 114-B16 Mail Stop 161-213
lab: 818/354-2954 161-110 4800 Oak Grove Drive
fax: 818/393-6875 Pasadena CA 91109