High Tank Circuit Q

 * Original msg to: scotty-at-wesnet-dot-com


I was thinking after our phone call about some of your recent
results, specifically your coil performance with various tank
circuit configurations. You remarked on the notable improvement
in your test setup when you used the balanced Tesla tank circuit.

No news to me, I have seen remarkable improvements in coil
performance when switching to the balanced Tesla tank.

For those out there who are not familiar with this circuit let me
diagram below:

    TESLA COIL SCHEMATIC                             ---------
                                                     |       | T1
         X1                              C1              O
                                         | |       L1    O  L2    
           O-----------------------------| |-------->O   O
         ||O                        |    | |         O   O
         ||O                        |                O   O
   -----O||O                        *                O   O
        O||O                                         O   O
   -----O||O                     G1 *                O   O
 Line >  ||O                        |                O   O
         ||O                        |    | |         O   O
           O-----------------------------| |---------O   O
                                         | |             |
                                         C1              |

Where:     X1 = Step up transformer
           G1 = Main system spark gap
           C1 = Matched pulse discharge capacitors
           L1 = Primary coil
           L2 = Secondary coil
           T1 = Toroid discharge terminal
          Gnd = Dedicated RF ground

This circuit is simplified: no safety gap, RF chokes, bypass caps
or step up transformer core grounding are shown.

It should be noted that this circuit requires two capacitors (C1)
each having twice the value of the actual system capacitance
required. What this means is that if you tune with a tank circuit
capactance of .0125 uF, and you switch to the Tesla balanced
circuit, you are going to need two .025 uF caps to get your tune
as these capacitors are in series. The capacitors must be
matched. The value must be very, very, close or a chronic
imbalance occurs which means kickbacks, heavy RF levels in the 60
cycle line, and frequent flashovers. Another note is that
shorting the circuit across G1 with a shunt wire does not safe
this circuit after shutting down. The caps will still be live. To
safe this circuit you MUST shunt between L1 and both sides of G1.
Now with that out of the way, let me proceed with the discussion.

This circuit is the highest performance Tesla tank circuit I have
encountered. We were discussing a few reasons for this on the
phone, but other reasons did not enter the conversation.

A big reason why this circuit offers such high performance is
that the tank circuit oscillation rings from capacitor plate to
capacitor plate without any arc in series with the primary coil.

Another reason is the ability of this circuit to utilize greater
break rates (PPS or BPS) because it is more responsive, sharper
discharging, and higher Q. This circuit can be shock excited more
frequently without "getting muddy". On a rotary gap system this
means your break rates can be comfortably increased 20-30%; on a
neon system this means you can add more transformer. What this
does is increases the amount of power that can be processed
through the system (longer sparks) without having to change out
your coil sets.

I am not surprised that Scott was able to hit four foot sparks at
1300 watts (neons are remarkably close to their plate ratings in
output, if the system sucks more RMS juice out of the wall it is
because it is not power factor corrected) using this circuit with
two of the Condenser Products capacitors. It just goes to show
that Scott watched me setting up the 10" coil on the video and
tried the same experiment scaled down a bit.

Richard Quick

... If all else fails... Throw another megavolt across it!
___ Blue Wave/QWK v2.12