# Re: double wound secondary (fwd)

---------- Forwarded message ----------
Date: Sun, 30 Sep 2007 09:57:42 EDT
From: FutureT@xxxxxxx
To: tesla@xxxxxxxxxx
Subject: Re: double wound secondary (fwd)

In a message dated 9/29/2007 10:53:11 P.M. US Eastern Standard Time,
tesla@xxxxxxxxxx writes:

Hey  everybody,
I know, this topic has been covered an awful  lot in the archives, I
looked; but there seems to be some disagreement,  weather it is good or
bad.  It seems lately, everybody now thinks it  is not such a bad idea, as
it decreases the resistance, therefore  increasing output.  But, from what
I know of formulas and such, two  inductors (since a coil is essentially an
inductor) in parallel decreases  the inductance, which should decrease
voltage out?  Does this  situation not apply with a transformer, or does
the resistance decrease  make that much of a difference to make up for it?
Or, does nobody  actually know why it works so well?  Just curious (and
considering  double winding my 6-in secondary). Scott Bogard.

Scott,

A secondary wound with two wires in parallel is not the same as
two inductors in parallel.  When two wires are wound together,  the
inductance remains basically the same as with a single wire,
assuming everything else is the same.  I'm assuming here that  the
wires are the same thickness in both cases, and that the second
winding is wound over the first.  So the coil still has the same
number of turns.  The main advantage of the two wires in parallel is  the
reduction in resistance.  My guess is that it would be very hard
to measure an increase in spark lengths due to the double layer.
Some folks claim to have seen a benefit.  Since the expected
benefit would be very slight, the measurements would need to
be done very carefully to judge if there's any measurable
benefit.  I've never done that particular experiment myself.
If you do the experiment, I'd be interested in the results.
Possibly the sparks might be about 2% longer which may be
hard to measure.  If a coil produces 42" sparks, the double
winding might give another inch.  It might be possible to
measure the benefit if that is the case.

John

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