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Its working <VBG>



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Hi folks,
           well after all the trials and tribulations I have eventually got
the coil working.  The answer was, of course, the capacitor.  I eventually
tracked down the materials and got a half decent (two actually) cap built
and soaked.

This evening I have had the beastie working well and have 18 inches of spark
from same.  OK, sit down, take a deep breath or two, maybe have a cup of
coffee or stronger.  No big deal for this list maybe - but a very big deal
for me.  However, now that the beastie is going reasonably (well) it
actually poses many more questions than when it was just a mess of copper
and wire on some crappy plastic framing and wood stock.

Specifically :

Let me first start with what is running:

15000/60ma Neon

Quick gap using 1 inch copper pipe and 13 divisions -at- .028 inch gap each

Primary - Vertical 8 inch diameter 1.25 gap 9 turns tapped at 9

Secondary - 26 inch wound 2.25 inch poly pipe on varnish wound at 51 turns /
inch (I think I am using 24 gauge ? - but I don't know exactly as it was
brought as scrap)
Earth is  8 ft of 5/8 copper rod driven into wet clay.

8 x 3 inch torroid made of scrap plastic (with wire winding) exhaust ducting
from the tumble dryer covered in foil and thick aluminium sticky tape (bodge
tape).  None to smooth but the correct shape at least.

Caps -  I calculate my caps at 0.0105 uf using the Tesla software by Walt
Noon - circa 1993.  They are 450mm by 1800mm AL foil and 1.5 cm (sorry we
are metric here now) by 500 x 2000mm  low density polyethelyne sheet.  All
rolled tight and placed in 6 inch (150mm) plastic drainage pipe.  The fluid
is pure mineral oil.
This evening I had the caps in series and the all the gaps firing (I have a
jumper system on my gaps that allows me to select 2-13 gaps as required).

I started at 2 gaps and nothing happened, but you could see some small
corona around the top.  However this was to break in the caps (they have
been soaking for a week - 10 days) so no problem. After a few minutes
without cap stress I opened up the gaps.  As the gaps increased so did the
spark.  Initially I did not have the toroid on, just a 3 inch copper nail
that forms the top of the secondary.  By gap 9 there was a healthy corona
and sparks were starting to jump from the primary to the secondary.  I then
used some remaining 6 inch pipe to cover the secondary to within 2 inches of
the top.  This stopped the sparkover. By gap 13 (wide open) I was getting
some sparking through the 6 inch cover pipe and some small burning on the
outer edge, but no damage to the secondary.  Putting the torroid on stopped
most of this, but to get rid of all the primary / secondary arcing I had to
put extra metal on top of the torroid.  Actually it was rather interesting.
Tire irons, wheel braces, aluminium spirit level, wood saw, pieces of copper
pipe.  All provided a different set of spectacular (relatively speaking)
spark patterns (great photos - I hope).  I hung a grounding wire down from
the roof frame of the garage to provide a better earth. That was better for
a single spark, but played merry hell with the radio.

I then, (the caps being well exercised by now) tried one cap.  Very poor by
comparison.  What is happening?  In theory I need 0.0127 uf for my power
supply and here I am getting good performance (or am I?) off of 0.005 or so.
Or have I done the sums wrong again (fool that I am).

So question time please :

1.      Why does the torroid reduce primary / secondary arcing

2.      Why does more metal on top of the torroid get rid of it altogether 

3.      Why are my cap calculations all to hell (biggie )

4.      Why do more spark gaps inprove performance (I really feel I should
be able to answer this myself - but for the life of me I cannot.  I know it
happens, but not the why)

5.      Is my coil in tune - it certainly feels like it is - but then I am
easily pleased. (after a year of failure and balls ups and salt water /
glass caps I would have been pleased with the spark from an ignition coil <g>)

Sorry to put all this your way, but I am really pleased with myself today.
I have made a quantum leap (in my terms) and I would like to know what is
happening here.  One thing that is apparent is the popularity of the flat
coil.  The voltage buildup on the secondary is a major pain and covering all
that beautiful coil with plastic pipe is not the way to go <g>.  Next step
is a *flatty* I would guess...  But I will wait on any replies and insights.

Thanks in advance

Ken


To go up - pull back
to go down - pull back some more <anon>





Ken Smith
Weymouth
Auckland 
http://homepages.ihug.co.nz/~ksmith
ksmith-at-ihug.co.nz






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