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Re: > Subject: Re: Flame Arc
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> From: Tesla List <tesla-at-poodle.pupman-dot-com>
> To: Tesla-list-subscribers-at-poodle.pupman-dot-com
> Subject: > Subject: Re: Flame Arc
> Date: Tuesday, January 21, 1997 12:25 AM
>
> >
> > Subscriber: tom_mcgahee-at-sigmais-dot-com Sat Jan 18 22:32:21 1997
> > Date: Sat, 18 Jan 1997 16:49:17 -0500
> > From: Thomas McGahee <tom_mcgahee-at-sigmais-dot-com>
> > To: tesla-at-pupman-dot-com
> > Subject: Re: Flame Arc
> >
> > [The following text is in the "ISO-8859-1" character set]
> > [Your display is set for the "US-ASCII" character set]
> > [Some characters may be displayed incorrectly]
> >
> > I received a note from Kevin <knardell-at-mailhost.accesscom-dot-net>
> >
> > >Fr. McGahee,
> > >
> > >I enjoyed your explanation there, it makes alot of sense. Could you
please
> > >explain what is going on when I put my caps across my neon outputs,
> > >everyone
> > >here has explained this to me but another view don't hurt. I have my
caps
> > >across the neon outputs and two dinky series gaps on each HV line to
the
> > >primary. I am getting results with this configuration but as everyone
has
> > >told me I will blow my neon. WHat is going to blow it, the caps are
not a
> > >dead short, when I move to the traditional method of putting the caps
in
> > >series on one sire and the gaps on the other I get zero results and
the
> > gap
> > >glows with a orange flame arc.
> > >
> > >Thanks
> > >PS by way of private mail (off topic here) I would really like to hear
> > about
> > >your lasers and other fun things:)))
> > >
> > >Thanks again!
> > >
> > > Regards,
> > > Kevin Nardelle
> >
> > To Kevin and other Flame Throwers,
> >
> > The fact that you are getting a FLAME instead of a regular Spark at
your
> > spark gap tells me that you have your circuit connected wrong. I bet
that
> > you have the transformer, capacitors, spark-gap and primary ALL
connected
> > in series. That won't work, because the Neon transformer is being asked
to
> > Charge the Capacitor(s) THROUGH the spark gap. The flame you are
getting is
> > virtually the same kind of flame you would get if you were to draw an
arc
> > Directly from the Transformer to it's Case.
> >
> > What you want to do is Charge the Capacitor(s) until the voltage
reaches a
> > certain critical value determined by the spacing of the Spark Gap. Then
you
> > want to DUMP all this energy through the primary.
> >
> > There are three basic ways that people have found to do this.
> >
> > 1) The method you were using previously. In this arrangement, the
Capacitor
> > is connected in Parallel with the transformer. The Spark Gap and
Primary
> > are connected in Series with one another, and then this series
arrangement
> > is Paralleled across the Capacitor (/transformer combination). The
> > transformer charges the capacitor. When the voltage is great enough to
> > break down the dielectric (air) between the spark gap, the gap fires.
The
> > gap switches to a heavily conducting mode, the stored energy from the
> > capacitor is delivered to the primary, and IF the circuit is properly
> > tuned, the secondary bursts into glorious resonance.
> >
> > This arrangement works fine IF your High Voltage Transformer consists
of a
> > SINGLE SECONDARY winding. Most Neon sign transformers are actually
> > center-tapped to the
> > Case of the transformer. Herein lies the problem! A Neon transformer
is
> > NOT a SINGLE SECONDARY, but Two Secondaries Center Tapped to the Case.
(See
> > my previous post for all the gruesome details). Remember all that
energy
> > that we dumped INTO the system? When you have the wonderfully
magnificent
> > lightning bolts hurling off of the TOP of your system, Guess What?
RIGHT!
> > There has to be Another End experiencing the Opposite Side of all this
> > Electrical Activity. It's the BOTTOM of the secondary (Which Right Now
> > would be safest if it was connected very solidly to Good Old Mother
Earth
> > (Ground)). The only way you can accomplish that is with your current
wiring
> > arrangement is by (ultimately) tying
> > one of the Neon windings directly to Earth Ground. BUT, if you do THIS,
you
> > actually have the AC Primary and One Side of the Neon connected
TOGETHER,
> > because One Side of the AC Line is NEUTRAL, and that means Connected to
> > Ground. So you're thinking to yourself: "OK, so the case of the 12KV
Neon
> > is now floating at 6KV. The transformer was DESIGNED for that amount of
> > voltage." NOPE!!!! It was Designed for That Kind of Voltage between the
> > CASE and the HV electrode, NOT between the Case and the PRIMARY!!! Now
> > let's assume that Sooner or Later there is arcing between the primary
and
> > the case. Yeah, well, THAT is actually a SHORT between the Case and the
> > Lower HV winding. POOF! You now own HALF of a Neon transformer! By the
way,
> > if you own a Single Secondary Transformer, please DO Connect the Case
to a
> > good solid AC Ground if using the kind of circuit currently being
> > discussed. Otherwise Transients and Electrostatic Effects can
> > raise the Case to quite large potentials and cause arcing between the
> > Primary and the Case.
> >
> > OK, so you see the problem with Floating the Case and decide to Ground
the
> > Case. Now you have a DIFFERENT problem, but Still a PROBLEM. You see,
you
> > have the Primary of the Tesla coil Directly connected to ONE of the
sides
> > of your Neon transformer. Which is Grounded at its Center Tap. You Fire
Up
> > your Tesla Coil. It hurls huge lightnin' bolts off into the sky.
Meanwhile,
> > at the Opposite End of the Tesla Secondary, the Bottom of the Secondary
is
> > frantically trying to find a Really Good Ground. But you aren't
connected
> > to any Earth Ground THERE, because YOU have the CASE of your
Transformer
> > Grounded. Not To Worry. Your Monstrous Tesla Coil just Happily Blasts
> > through (or Around) your Neon's Insulation... and another one of your
pet
> > Neons just went Belly Up. Ain't it DISGUSTING?!!!
> >
> > 2) To get around the problems associated with method #1, you COULD
decide
> > to TOTALLY ISOLATE the secondary and only have the secondary hurl
electrons
> > from one end of the primary to the other. This works. It isn't as
SPIFFY as
> > having a coil that hurls the lightning right out into the open air, of
> > course, but it Does Work. It is also AWFULLY Wimpy. And the Tesla
Secondary
> > has this AWFUL tendency to spark over to the Primary. Sigh. So you make
the
> > Beast into a Half Wave Resonant Coil in which the Tesla Primary is
located
> > in the CENTER of a Dual Secondary. NOW the Two Ends of the Opposing
> > Secondaries work Against One Another, and there is No Sparking between
> > Tesla Primary and Secondaries, because what you REALLY have here is a
> > Modified AutoTransformer. Both Ends send out Beautiful Long Streamers.
Life
> > Seems Good. Until Something gets closer to one Secondary than the
other,
> > that is. Then the OTHER Secondary will retaliate by changing its tuning
and
> > going Wimpy on you. TOUCH one end, and YOU become the nearest thing to
a
> > ground point. If You or the Approaching Object is Grounded, then a
spark
> > reaches over, establishes a Ground Reference, and POOF! You have
recreated
> > problem #1 and Destroyed yet ANOTHER Neon Transformer. There has to be
a
> > Better Way.
> >
> > There is.
> >
> > 3) Take a Neon Transformer and connect it in PARALLEL with your Spark
Gap.
> > Note that if you turned it on now, you would get nothing but that
> > disgusting 12KV Flaming Arc. FLOAT the Neon Transformer (Do NOT Ground
it).
> > Floating a Neon transformer is ALWAYS somewhat IFFY, but this time it
is
> > going
> > to be a Calculated Gamble. We are going to do Everything we can so that
> > Even Though it IS Floating, we don't Unnecessarily Stress it. We aren't
> > going to Completely Remove the Danger, but we ARE going to MINIMIZE it
as
> > much as we can. Life is imperfect, but if all else fails, do something
> > else.
> >
> > For this Method you will Need TWO Capacitors instead of One. Connect
One
> > Side of Each Capacitor to a different Neon Secondary. Connect the
OTHER
> > side of Each Capacitor to a different side of the Tesla Primary. The
INNER
> > side of the Primary SHOULD NOT BE CONNECTED TO THE BOTTOM OF THE TESLA
> > SECONDARY. It should be INSULATED from the Bottom of the Tesla
Secondary by
> > a distance capable of insulating at least three times the rated
capacity of
> > the Neon Transformer. If "retrofitting" a previously built coil, you
might
> > want to wind several layers of good insulating material around the part
of
> > the Secondary that comes nearest the Inner side of the Primary. The
Next
> > Thing is VERY IMPORTANT! GROUND THE BOTTOM OF THE TESLA SECONDARY TO A
GOOD
> > SOLID EARTH GROUND. If you forget to make this connection, the Coil
will
> > SPEW Sparks all over the place until it MAKES its Own Connection (And
burns
> > down your Tesla Coil, giving a whole New Meaning to the phrase: Firing
Up
> > the Coil!)
> >
> > OK, so what has all this stuff done for us? Well, by Isolating the
Tesla
> > Secondary, we removed One of the Major Sources of Inductive Voltages
and
> > Currents from the Power Supply Loop. The voltage difference between the
> > Neon Primary and the Bottom of the Tesla Secondary now approaches Zero
> > Volts. Our Trade-off is that now there may be a large voltage
difference
> > between the inner winding of the Tesla Primary and the Bottom of the
Tesla
> > Secondary, but at least we can gain ACCESS to this area and Beef Up the
> > Insulation. (We can't too easily Modify the inside of the Neon
Transformer,
> > now can we?) Another Wonderful Side Effect is that since the Tesla
> > Secondary is connected to EARTH, the Spectacular Effects caused by the
Top
> > of the Tesla Secondary are Enhanced since the Really High Voltage At
The
> > Top want to Reach Out and Touch EVERYTHING that is Connected to Earth.
> > How Cool!
> >
> > Why did we use TWO Series Capacitors? To keep the Power Supply Unit
> > BALANCED, of course! If you draw the Schematic for this arrangement,
you
> > will see that it is symmetrical. Which means that ideally it should
have
> > Equal things happening at BOTH sides of the Neon Transformer. If ALL
the
> > capacitance were on ONE side, the circuit would "Work" the same as far
as
> > frequency, power, and all those things go, but the STRESSES in the
circuit
> > would be out of balance. By BALANCING the circuit we HOPE that we will
not
> > stress One Side of the Neon Transformer MORE than the Other Side.
> >
> > WAIT A SECOND: in this design aren't we Charging the Capacitors THROUGH
the
> > Tesla Primary? Yep. It doesn't matter at all really, since the Low
> > Frequency Charging Current sees the Tesla Primary as an Extremely Low
> > Resistance. The effects are so small I doubt if you could measure them
even
> > if you wanted to.
> >
> > YEAH, BUT WHAT ABOUT THAT SPARK GAP ***RIGHT ACROSS MY NEON
SECONDARIES***?
> > First of all, the time that the Spark Gap spends Conducting is only a
Small
> > Percentage of the Total Time. MOST of the time the Transformer is
CHARGING
> > the Capacitors. The DISCHARGE Time is measured in microseconds.
> >
> > ONE More Issue Needs To Be Dealt With. Even with all the Good Stuff
that we
> > just outlined, there are still Nasty Little Transient Voltages that we
> > would like to halt in their tracks. For this reason the Secondaries of
the
> > Neon Transformer should should have some sort of filtering... at Least
a
> > Coil, and Even Better, a Coil/Capacitor arrangement. There are really
two
> > issues here. There is the need to SHUNT excessive stuff AROUND the
> > Secondaries. This can be done with a small value HV capacitor directly
> > across the two Neon HV terminals. (We are assuming that you have
already
> > included the afore-mentioned filter Coils!) The Safety Gap can be
placed
> > directly across the Neon transformer Secondaries, but in Parallel with
the
> > Tesla Spark Gap is probably Preferable. The other issue has to do with
the
> > Floating Case. I am inclined to NOT connect ANYTHING to the Case, and
just
> > let the fact that there are balanced secondary windings force the case
to a
> > midpoint voltage. Attaching a capacitor to the case, for example, would
> > tend to ANCHOR the supposedly Floating Case, and I'm really not sure if
> > that's a good idea. Just my own opinion. If you want to reduce any
effects
> > caused by electrostatics, etc, then build the FLOATING Transformer into
its
> > own little Faraday Cage. Actually good for safety too, especially for
those
> > people out there who are in the bad habit of touching their
transformers
> > while they are running. This is Definitely a No-No when running a
Floating
> > Coil!
> >
> > Just a little Side Note. The Original Tesla Coil Circuit had no
electrical
> > connection between the Tesla Primary and Secondary. A French guy named
> > Oudin patented the concept of tieing the bottom of the secondary to
the
> > primary. Tesla had DONE that, of course, as many of his handwritten
notes
> > of the time show, but Oudin is the guy that rushed out and got the
patent
> > on that little aspect of Tesla Coils. The advantage that the Oudin Coil
has
> > is that it does not NEED an Earth Ground. Almost all modern Tesla
Coils
> > use the Oudin configuration, even when the Secondary is grounded.
> >
> > Hope this is useful to Somebody Out There, or I am wasting my time
writing
> > this stuff!
> >
> > If all else fails, try something else.
> > Fr. Thomas McGahee
>
>
> So what you are saying is the low impedence to high freq allows the
> current to pass through the caps and into the primary? If this is the
> equidrive circuit would'nt the the center of the primary be connected to
> ground?
Not necessarily. It helps a lot if you draw a schematic diagram first.
Neon Transformer HV Cap Toroid etc.
| | ***TOP***
s------*#RF Choke#-----*-----| |----- S
s | | | | | S
120 Hot-------p s | | | S
p s V O | S
p s--C safety gap SPARK GAP |__ S
p s ^ O P S
120 Neutral---p s | | P S
s | | | | P S
s------*#RF Choke#-----*-----| |-------P S
| | |
HV Cap |
RF GND
In the following discussion, it helps if you think of the lower HV
capacitor as alternately being fully charged and then ACTING LIKE A DEAD
SHORT. It is actually more complex that that, but using that Simplified
Mental Model will help you follow the discussion more readily.
Now DRAW A LINE from the 120 Neutral to RF Ground (because Both Eventually
connect to an Earth Ground, whether you like that fact or not) Failure to
ground the bottom of the Tesla Secondary will lead to almost certain
damage to the Neon's insulation, since any sparks coming off the TOP of the
Tesla Coil will attempt to drive the Bottom of the Tesla Coil to the
opposite polarity. If it is grounded, the Top gives off sparks. If it is
NOT grounded, it SEEKS ground... and because of the tremendous voltage
levels involved, it WILL find ground SOMEHOW! By connecting through the
Neon's insulation if necessary!
The problem with the circuit as shown is that NOTHING in the Disruptive
Discharge Circuit (Entire Tesla Primary Drive Circuit...
Neon/Gap/Caps/Tesla Primary) is referenced to Mother Earth. Ah, but when
the circuit begins oscillating, it will jump ALL OVER THE PLACE
(electrically speaking, of course). It is somewhat analagous to having a
mechanical oscillator suspended by rubber bands. When the mechanical
oscillator starts moving, it will jump wildly, because it has little to
push against. Thus the Neon's Secondary will see the Case voltage as a
wildly jumping Voltage with reference to its Neutral wire. This promotes
breakdown of the insulation inside the transformer. No Good.
Now, to see what would happen if you decide to ground the Neon's case, draw
a connection from the wire we Just Drew up to the Neon's Center Tapped Case
(labelled C in the drawing). Note that NOW there would be 1/2 the Neon's
voltage applied between the Tesla Lower Primary winding and the Tesla Lower
Secondary winding. This "works", but there is this primary/secondary
voltage present that necessitates insulating the two in some manner. (This
is exactly what many folks do. With a Neon Transformer, ALL connection
strategies involve a Trade-Off and a Calculated Risk. By being AWARE of the
Risk, we can at least take action to MINIMIZE the Risk!) By the way, note
that if a spark DOES jump between the Tesla Primary and Secondary, that
connects the Primary to THE SAME GROUND AS THE NEON'S Case for the duration
of the spark. So the spark will then FLAME. The FLAME type spark can VERY
QUICKLY do damage to the Tesla Secondary. Not to mention that the Neon is
NOW being effectively shorted out along the BOTTOM half of its secondary.
NOW do you see how the bottom half gets BLOWN?
To see what the OTHER Strategy is like, erase the line you just drew to the
Neon's Case. Draw a line connecting the Tesla Lower Primary winding to the
Earth Ground line we previously drew to the Tesla Lower Secondary winding.
As we eyeball THIS arrangement, we notice that NOW the Case of the Neon
Transformer is floating at 1/2 the secondary voltage. This is the voltage
between the CASE and the PRIMARY of the Neon Transformer. The Neon
transformer, she was NOT designed for such abuse! If you run the Tesla Coil
like this, it MAY run fine for many years, and it MAY fail within seconds,
depends on the way the primary wires INSIDE the case are arranged.
I hope this makes is a bit clearer.
If all else fails, do something else.
Fr. Tom McGahee