# Re: A few rules of thumb for the solid state crew.

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-----Original Message-----
From: Tesla List <tesla-at-pupman-dot-comTo: tesla-at-pupman-dot-comtesla-at-pupman-dot-comDate:
Friday, October 22, 1999 5:18 AM
Subject: Re: A few rules of thumb for the solid state crew.

>Original Poster: "Reinhard Walter Buchner" <rw.buchner-at-verbund. net>
>
>Hi "TFCG"
>
>Comm ents interspersed.
>
>> Original Poster: "The Flavored Coffee Guy" <elgersmad-at-msn-dot-com>
>
>Snip
> ;
>> There is a way to do this right, and in small versions I have seen
>> the same results but, I cannot afford wire that can handle a Megawatt,
>>let alone several.  The only way I have found to control this is the
>>fundimental oscillator frequency, and the tuned gang.  Basically, what
>>I am trying > relate to you is that I don't know how you can control
>>the energy > that I can get to pump through a circuit with not more
>>than the 5 volts that are driving the 1 to 100 step up arrangement in
>> <A href="http://members.xoom-dot-com/suckyfish/melissa/Resonance/Circuit.jpg
ACIAPg-http://members.xoom-dot-com/suckyfish/melissa/Resonance/Circuit.jpg
>> The turns ratio is providing the voltage but, the current provided by
>>the oscillator is a very small fraction of the power actually used by
>>the circuit.  So, when I take 3.488 amperes, and divide it by 8.743
>>mA a power gain ratio factor of 398.948.
>
>Huh??
> APA-BR>>I had a look at that schematic. Could you please explain how you
>can charge a cap with ~9mA and at THE SAME TIME discharge
>it with ~3.5A?

A mechanical example would be similar to a swing.  When the circuit first
starts it does take an equal amount of energy but, once the swing has built
momentum, that is between the capacitor, and coil.  So, you have two time
constants in the schematic, 1uf *2*pi, and 1uH*2*pi, with the inductor,
current flow will continue for that period of time, with the capacitor, it
charges, or discharges at.  On a watt volt time constant that short to
charge, and short to discharge, or is in joules.  So, the capacitor trys to
dicharge for it's time period, and then that's long enough for the coil to
have reached the equal value of impedance as the capacitor alone at that
frequency.  To find the capacitive reactance of a capacitor alone you use
this equation 1/(2*pi*f*C), and with an inductor which will object to a
change in current you use this equation to find impedance in ohms 2*pi*f*L.
What the impedance indicates is how long a coil needs current flow before it
will continue to provide current as a result for an equal time period as a
result of a collapsing magnetic field.  Now, on a transformer, when the
magnetic field build up as a result of current flow through the primary
there is a change in current flow through the secondary, and when the
current flow ceases, there is a change current flow through the secondary.
If current flow reverses, then there is a reverse of current flow in the
secondary as well.  With the capacitor charging, and the time constant for
the coil being equal, the current is then ejected from the capacitor by the
coil long enough for it to recharge in the opposite polarity.  So, when the
circuit starts it acts almost like a short circuit for the first few cycles
of AC applied but, as time progresses in the first few milliseconds, the
impedance cause by this charge recharge situation becomes absolute.

I´m afraid I can´t see any way that could possibly
>work. This circuit diagram does not represent your typical TC,
>because it is missing the switching device (spark gap, tube, or
>whatever).  Also, the energy conservation law states that output
>energy can NEVER be greater than the input energy.

It only utilizes the law of conservation an momentum.

>
>You say that you need wire that can handle megawatts of
>power. Are these values (meaning the wire and the values in
>the schematic) peak or continuous values? Continuous,

A spark gap driven
>TC (or any kind of pulse duty oscillator for that matter) can
>easily be built to achieve Mw of power on a pulsed basis. As
>the discharge time isn´t very long there is no need for a wire
>size that will handle Mw of power on a continuous basis.
>
>>Now, with a solid state oscillator this is possible but, if you
>>insist on using spark gaps then the means isn't effecient
>>based on certian basic principals of signal inputs, and type of
>>signal as to whether the proper circumstances exist for the
>>circuit to function properly.
>
>I think I can agree that a solid state oscillator might well be
>more efficient than a simple spark gap driven one. However,
>to this day, I have never seen a solid state device that will
>handle both high voltage AND high current at the same time.

This series of transformers, and style of circuit design was intended to get
you around that but, it will cause a large arc, then require power from the
oscillator.  Every time you disturb the load, or change the load by any
factor on the secondary it shows as a change in resonance.  When the
secondarys load increases, the inductive reactance of the primary increases,
and the frequency of the resonant circuit decreases.  When this happens, the
tank circuit acts like a tuned notch filter, and shorts power at any other
frequency rather than the new resonant frequency caused by the change in
power demanded by the load.  Now, on a resistive load, and very high amount
of energy can be converted to heat as long as you can tune the primary to
the frequency of the loads resulting change of inductance on the primary.
So, if the coil is designed for a constant arc it will function as soon as
an arc is started and several milliseconds later the whole circuit will be
at resonance.  Then the demand for power on the oscillator will decrease to
a very low value as shown in the schematic.

The primary coil acts like a lever, and the core of a transformer acts
like the fulcrum when using this resonant style of high output.  So, if we
went back to the mechanical swing What I changed was the rope, and place an
axle, and weight that extended beyond the top of the swing, placing the seat
underneath it.  Now, that weight could be held with a minumum amount of
mechanical energy balanced above me as I sat in the chair.  Once I start
building up momentum, that wieght will help me go up farther each time I get
pushed.  Now, it takes less energy from the pusher to push me higher.  Now
the swing is acting more like a see saw, or a lever, eventually if the
pusher keeps pushing I will all the way over, and the weight will come
around, and he can push me again.

>
>The reason (I think) that SGDTC (spark gap driven TCs) get
>such great spark length results is because of the peak(!) power
>they can supply. Although of very short duration, this peak
>power is gigantic, which results in impressive sparks. This is
>also the reason (I think) why tube TC´s will always give less
>spark length than a comparably sized (VA) SGDTC.
>
>>This means that at 5 volts you would have a impedance that
>>when the circuit started was only 1.433 ohms.  With each
>>successive cycle from the oscillator the impedance of the
>>tank circuit goes up, and eventually reaches 571.886 ohms
>
>Hmm. The only way I can see how the impedenace will change
>is by altering the supply frequency. The impedance (=R on an
>AC basis) is directly dependant on the frequency. If your L is
>changing, your frequency must be changing. This, however,
>means you will no longer be resonant, which in turn will change
>the behavior of the circuit (i.e: in your case the 3.4xxA will drop)

Take out a cheap audio transformer, and get a variable resistor.  Now
make the output variable with that resistor using the transformer as a step
up.  Find the frequency that the primary equals 50 ohms with the output
shorted,  then increase the load to half of the value of the pot you are
using, and then measure again the impedance of the primary.  It went up, and
the inductance of the primary went up to cause that change in impedance.
That is because the inductance of the primary is a result of the shared
inductance of it and the secondary being wound on the same core...

>
>>If the resonant frequency were 159 KHz for the primary of the
>>oscillator driven tank circuit then the second stage would be
>>at 318 KHz.  Now, if you were building a Tesla coil the output
>>of the second transformer would be fed to the primary of the
>>Tesla, and it's resonant frequency would need be 318 KHz, or
>>636 KHz which would be experimental beyond the scope of
>>the circuit I have found appropriate
>
>Well looking at your circuit (if there is an analogy to what you
>are saying), how are you back-feeding the circuit? Your
>connection from the secondary to the primary is grounded, so
>it will reside at zero volts (= no power feedback), unless your
>ground is of high impedance, that is.
>
>
>a bit puzzled in Germany,
>Reinhard
>