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• ## Describing the Inverted Center Tapped Resonant Transformer

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• Hi All, My name is Harvey D Norris and to start things off a breif history is in order. I am the Author of the Binary Resonant System with homepage at
Message 1 of 1 , May 7, 2001
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Hi All, My name is Harvey D Norris and to start things off a breif
history is in order. I am the Author of the Binary Resonant System
with homepage at
http://msnhomepages.talkcity.com/LaGrangeLn/teslafy/Homepage.html

I am interested in tesla coils, and adapting this special arc gap to
their operation. To describe this we must first consider the ordinary
center tapped transformer, which will be dealt with a little better
in the next post. The center pathway is shared by two 180 phases that
produce a net cancellation of current on that path, provided the
opposing sides of currents are equal. For the thing I am talking
about, the inverse situation applies where one resonant tank circuit
will be divided into two, with a center pathway shared by both
reactive sides from opposite directions, leading to the observation
that twice the current exists on that pathway than on the sides
alone. It is therefore a figure 8 tank circuit, that no one but
myself apparently is willing to work on. To make this into an arc gap
one merely needs the opening at the center of the 8. This opening
itself will procur a voltage rise, if the circuit is tuned to the
source frequency. The problems of this application to a tesla coil is
the fact that that circuit is not tuned to the source frequency, but
rather the secondaries resonant frequency. It is good now to explore
what Tesla himself invented, with some practical hints for a dual
spiral binary resonant arc gap.

The first record Of Tesla's high frequency coupled
oscillatory circuit with an air cored transformer is
to be found in patent 454622 of 23 June 1891 under the
title "System of electric lighting". The oscillator
converts low frequency currents into "currents of very
high frequency and very high potential" which then
supplies single terminal lamps. (from Aleksandar
Marincic's CSN preface)
The arc gap in this schematic is within the tank
circuit, something later abandoned as the best method.
On July 2,1899 Tesla notes the reasoning for this;
In a schematic showing the break within the tank
circuit he comments... "the scheme of connections has
the disadvantage that the primary discharge current
passes through the break hence, the resistance of the
latter being large, the oscillations are quickly
damped and there is besides a large current through
the break which makes good operation of the latter
difficult. To prolong oscillation in the primary and
increase economy one of the schemes before considered
may be resorted to." He then refers to the
conventional approach of allowing the break to be
shunted across the hv secondary outputs where he
comments.. "in this arrangement the currents through
the break device are much smaller and the oscillations
started by the operation of the break device continue
much longer."
Tesla makes no comment concerning the idea of placing
an inverse tank circuit on the other side of the break
in the first example for a center tapped high
frequency transformer. In that situation two (180
phased)primaries would recieve their oscillations from
a single arc gap. The problem of the arc containing
the entirety of the currents is then circumvented by
the pathway established along the sides of the newly
configured figure 8 LC quantities.

So here I am making some conceptual suggestions upon
implementing the "third schematic arc gap" apparently
neglected by Tesla as a possibility. This is described
using dual identical spirals. The usual reply that
this is already accomplished by a bipolar tank circuit
does not take into account the fact that in the
"third" schematic possibility there are two and not
one capacities involved.
I am still working to try a NST gap like that. Cant
take that much longer.
I have made some preliminary modeling ideas using the
dual spirals available at Radio shack as their flat
stranded 50 ft insulated for a mini-tesla coil
primary. I'm trying mine in a bipolar application for
a mini tesla coil one would suppose that length of the
wire is is small in comparison on the smaller mini
secondary, thus making the operation at a high
frequency. Since the duration of that rf burst is then
a very small time period,I am aiming for a very high
bps rate which this system should permit. Here are
some considerations of difference in tuning with a
single arc, oscillating two primaries 180 out of phase
as I have described as a Binary Resonant System,(BRS)
1)Because magnetic agreement between the primaries is
necessary for the maximum inductance, and the currents
on the primaries themselves are 180 out of phase, and
the further fact that the spirals themselves are not
themselves bifilar with respect to each other: to make
the fields in agreement means that opposite outer and
inner coil connections to the repective opposite hv
terminals is necessary. The inner and outer leads of
the dual spirals that remain are in turn connected to
capacities which connect in series with the opposite
hv potential. This then consists of two oppositely
phased series LC quantities in parallel which is the
current limiting condition before gap firing.
2) The arc gap is made from the connections at the
midpoints of the 180 phased series LC quantities, or
the ends of the inner and outer wire spirals that are
not connected to the hv secondary. Thus upon arcing
the resistance of the primary is on either side of the
arc: the arc is not directly shunted to the hv ouput.
3) The capacities on each side are NOT made from the
resonant frequency calculated from that sides L
quantity, but rather the quantity established by the
needed capacity to resonate with both L quantities in
mutual inductance where the primaries are in series to
determine this new L(total). A C(total) is then
matched to this new L figure to resonate, and each
side will recieve twice C(total). This is because
these capacities will appear in series when the gap
fires, thus to arrive at C(total) twice the value must
be used in series.
4) Because of the dielectric qualities of the
insulation between windings the spiral set also has a
internal capacitance, and adding capacitance on each
side of the LC quantites may not change the resonant
frequency as suspected. Since the set then has a
recorded C internal capctance of 220 pf, and a
measured .636 mh L quantity correctly wired in series,
a natural resonant frequency of 425,000 hz might be
suspected. A scope measurement of this frequency seems
to indicate 588,000 hz including the 25 pf scope
capacitance.
5) It may be possible to simply connect the inner and
outer spiral ends together at an arc gap and have the
primary resonate at its own natural resonant frequency
established by its internal parameters. Of course then
one would have no tuning and be limited to placing the
correct secondary to resonate in place.
HDN
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