beginner coil

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

Original poster: "Chris by way of Terry Fritz <twftesla-at-qwest-dot-net>" <chris-at-atomic-pc-dot-com>

Hi everyone,

Just for fun, I'd like to share the specs of our first working coil with
the list...

--Transformer: 10 KV, 20 (?) mA Oil burner trans.  My friend used to use
it for a Jacob's ladder.
--Capacitors: 7 Snapple bottles, foil on outside, salt water on inside
--Spark gap:  2 large bolts PC-7'ed onto wood block (from my first
attempt at a coil)
--Primary:  Inverse conical of 8 turns of 3/8" copper refrigerator
tubing, zip tied to 3 wooden stakes, looking sort of like a stove burner
bent into a wok shape.
--Secondary:  440 turns of #24 enameled magnet wire.  (This was the
whole roll that we had, so that was our limit)  wrapped on a 3" (inside
dia) PVC pipe, winding length 10 inches
--Top load:  brass drawer pull knob from hardware store, but we made a
toroid out of duct tubing and it makes the sparks shorter but brighter /
louder... also more "sting" to them, even though I already know you're
not supposed to touch it....
Alternatively, we top the secondary with a clear light bulb for a plasma
globe...

The coil throws sparks about 4 inches long, maybe 4.5;  we've found it
gets a little better when we put a ca. 6000 pF capacitor (homemade also,
rolled from PVC shower pan liner)  in *series* with the Snapple cap
bank... although we don't know the exact capacitance of the bank, I'd
estimate it to total around 5500 to 6000 pF (sound right for 7
bottles?)... I guess the series connection makes sense because the res.
freq. is so high for such a short secondary (less capacitance required)?

I know from reading the list and the web that this spark length isn't
amazing, but at least it's a start...  I just have to sit down and do
some actual math now...  for a pic of the coil's secondary and some
other junk, go to http://www.atomic-pc-dot-com/workbench1a.jpg
(see if you can pick out the "glue stick micro coil"... which threw a
decent spark for about 10 seconds before it arced through the hi-tech
bond-paper / scotch tape primary "insulator")

Best regards,
Chris