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Re: 24" secondary

In a message dated 9/2/00 2:52:21 PM Pacific Daylight Time, tesla-at-pupman-dot-com 

>     Do I need to space wind it? what does spacewinding achieve, voltage
>  insulation between turns?
>      What guage wire should I use (is 14g too lossy?)
>      And, should I wind it to around 1600 turns (John Freau? -- BTW, I have
>  noticed that John frequently mentions that more turns seem to be more
>  efficient, but no one else seems to acknowlege his claims or discuss 
>  with say a 5:1 aspect ratio or go for the traditional 900 or so turns?
>  also, if I do spacewind it, what if tightwound insulated wire is used 
> instead
>  of enameled wire to achieve the spaces?
>  thank you all for your advice
>  Dave


Thanks for your interest in my coil work.

That piece of pipe is a nice find for a large coil.  My work with
the 1600 turns was done at low power, so I'm not sure how much
benefit it will give in a large coil.  I can't see any reason why it
wouldn't work well though.  The main purpose of the 1600
turns is to permit more than the usual number of turns to be
used in the primary, which keeps the surge impedance higher
than usual, which keeps the gap losses lower than usual.
I first heard of this concept of keeping the gap losses low by
using a high surge impedance high from Malcolm a few years
ago.  Greg L, also spoke about it back then when he was
designing his fabulous Electrum TC.  Perhaps others spoke
about it too.

Clearly the same result (lower gap losses) can be obtained by
using a wider secondary with fewer than 1600 turns, but the
larger secondary prevents the proper voltage build up in the

There is one person (besides me) that I know of, who tried 
changing his coil from 1000 turns to 1500 turns, and that is
Richie B.   Richie reported on this list that his
sparks increased by 10%, and became more energetic when
he installed the thinner wire.  I think he also posted the 
results of the comparison at his website.

I think that many folks have a difficult time believing that thinner
wire can give longer sparks, because the old beliefs are so
strong and universal it would appear.  The concern that most
folks have is that thin wire will increase the secondary losses
..... it does of course..... but it reduces the gap losses even
more and gives an overall net benefit.  I keep mentioning it,
because I was surprised too when I first saw the benefit, and
I want to share my findings with others.  I know that the idea
is not well known on the list, because folks keep asking how
many turns are best to use.  It is possible too that some folks
may believe that the idea only works on my coil, and that it
is not really a universal concept, etc.  I have not tried it on a large
coil of course, but maybe someone will try that.

I've seen cases where a person reports that they used 900
turns (or whatever) and got excellent results.  This is expected
because the thin wire will only give a 10% benefit.  The only
way to judge, is to wind two primaries and secondaries; one
using 1000 turns on the secondary, the other using 1600
turns, then make a comparison.

I suspect that the reason so few folks talk about it, is because
basically no one else has made the comparison (except for 
Richie), so they can't really comment much.  I'm a patient
person, and I know that eventually more folks will try it.  For
anyone who doubts my claims, they can either talk to folks
who have seen my coils, or they can build a replica of my
coil at my website, or they can view my videotapes, or they
can rewind their coils to have 1600 turns and see the results
for themselves, etc.

I had to also post for a few months about the benefits of sync
gaps before they became more popular.  Others were using
them before me of course, but their use was relatively rare.
Change is very slow in any field.  Consider that surgeons saw
no reason to use anesthesia for 100 years after it was 
discovered (that's what I read anyway... whether it's exactly
true or not doesn't matter, I'm just pointing out the concept)

To answer your question, space-winding accomplishes two
things:  It reduces the proximity effect, and provides better
insulation.  Termin states that for lowest losses, the space
should be equal to 50% to 100% of the wire diameter.  In
reality however, it is doubtful that you'll be able to see a
difference in spark length which is why I don't bother with
space winding, although I want to try it sometime.  Generally
the insulation of magnet wire is *good enough* for use in a
TC secondary.  As long as you get enough turns in the
secondary, it won't make a noticeable difference if it's space
wound or not would be my guess.  In any case you'll never
know the difference in any benefit with any of the designs
unless a comparison is made with a different secondary.

Number 14awg wire will definitely *not* be too lossy for your

I'll give my webpage url again for those who have not seen it:


John Freau