The Tesla Project

[Charlie_V]

@ wattsup,

Lets assume we have a simple primary circuit with a capacitor thats 0.1F and an inductor that is 1μH.  We charge the capacitor up separately, disconnect the power supply, and then discharge the capacitor into the inductor.  When the capacitor discharges into the inductor, it will electrically ring, similar to how a bell mechanically rings.  We want to calculate the period of the oscillation in seconds:

T = (2Ïâ,¬/10?)*(L*C)^0.5
T = (6.283/1000)*(0.000001*0.1)^0.5
T = (0.006283)*(1x10^-7)^0.5
T = (0.006283)*(3.1623x10^-4)
T = 1.98692x10^-6 (sec)
frequency (f) = 1/T
f = 503.3kHz

The ideal secondary circuit would then be an inductor with 0.1H inductance and a ball on top with a capacitance of 1μF (with respect to ground).  The length of the wire in the secondary inductor should be a quarter wavelength of the oscillation frequency.

wavelength (λ) = 300,000,000/(4*f)
λ = 300,000,000[m/s]/(4*503,300[Hz])
λ = 149m or 489ft

This length assumes your secondary coil has no distributed capacitance.  Unfortunately it will, so the length of the wire will need to be slightly shorter.  According to Tesla, the more distributed capacitance, the shorter time the circuit will ring.  Reduction of the distributed capacitance can be accomplished by the coil's geometry. 

As a side note, its very interesting that this is the exact opposite of what you do to make a modern antenna.  If you look at the Tesla primary circuit, the characteristic impedance will be (L/C)^0.5 = (1μH/0.1F)^0.5 =  0.003Ω, where as the secondary's characteristic impedance is (0.1F/1μH)^0.5 = 316Ω.  They are greatly different.  This means that the energy will be reflected back to the source.  If you wanted to turn Tesla's magnifier into a modern day antenna, you would make the primary circuit's characteristic impedance be as close as possible to 316Ω.  Then, energy wouldn't return, instead it would radiate away like in modern day radio transmitters.  So, Tesla's magnifier is really like a single edged knife, one dull side and one sharp side.  Unfortunately, modern radio chose to use the dull side. 

[Grumpy]

The "mass matched" primary/secondary may have been for "efficient excitation" of the secondary by the primary.  I have searched for a long time to explain why Tesla stated this.  Eric Dollard modified this from matched mass to matched surface area in his work and states that with impulses, the skin effect is "total" - implying that the surface area is what matters.  I am building a MT now and I did match the mass of the primary/secondaries (it double ended) - just in case.  (surface area is proportional with each secondary 4 times the primary).

Tesla magnifier is not a resonant-coupled system, per se.  It does not use resonant rise like Tesla's two-coil transformer.  In the magnifier, the "extra coil" is an independent system that is excited by the primary/secondary.  I use the term "independent" loosely since the coils are related and tuned.  there are many many ways to make them and so long as they are balanced, people get fabulous results.  Richard Hull worked a great deal with several different arrangements and used rather large inductance values for primary and secondary and got monstrous sparks out of the extra coil.  Hull's approach is very different than that of Eric Dollard.  Dollard recommdends a single strap primary, and secondary or large surface area with maximum self-capacitance, and then the extra coil is wound for max self-inductance and min self-capacitance.  Hull did not tune for resonance or even wavelength at all, where as Dollard tuned for 1/2 primary (times an even integer and harmonic of secondary), 1/4 secondary, and 1/4 extra coil while calculating propagation rates which far exceded light in the extra coil.  Dollard connected all three coils directly.  Hull coupled the primary and secondary and would detroy them when they shorted together.  Tesla mentions when expalining his disruptive discharge coil that the primary can be connected to the secondary to prevent arcing between them - nice tip.

Hull got monstrous sparks which was all he was after.  Dollard got much more interesting effects such as a conductive field extending from the top load of the extra coil that was not "ionic" in nature (he doesn't say what it was), "explosive phenomena" when driving the system above resonance, superliminal velocities (phase not group velocity), and other effects that Tesla  mentions regarding radiant energy.  This is what prompted me to follow Dollard rather than Hull's work.

[Charlie_V]

@Grumpy

where as Dollard tuned for 1/2 primary (times an even integer and harmonic of secondary), 1/4 secondary, and 1/4 extra coil while calculating propagation rates which far exceeded light in the extra coil.

Can you explain this a little more in detail?  What do you mean tuned for 1/2 primary? 

The way you've described Dollard's primary and secondary is the way Tesla describes it.  The secondary in his magnifier is only to transform things to a higher voltage, the same way a conventional transformer works, with turn ratios.  The extra coil is the free oscillator - developing a resonant rise, just as you've described, low distributed capacitance and high inductance.  This is still at the heart a coupled set of oscillators with mismatched impedances.  The thing I don't quite grasp is what does the standing wave look like with a quarter wave secondary AND extra coil.  This means the secondary circuit is a half wavelength.  So where will the voltage nodes and anti-nodes be?  For what I want to do this is critical.  This is the best I can imagine it, what do you think Grumpy?

Added After Posting - if the way I've drawn it is the way the standing wave develops on the secondary side, then this would explain why you want to connect the primary to the secondary, since its a good bet that the secondary "ground" terminal (which doesn't necessarily have to be connected to ground) will be at a much higher voltage than the primary.  Connecting them will put the primary at the same voltage level as that terminal. 

[Grumpy]

The primary is directly coupled - it would be at the bottom of you diagram.  The primary is 180 deg, the secondary is 90 deg, and the extra coil/lead is 90 deg = 360 degrees.

You need a half-wave in the primary.  Tesla mentions an equation: wavelength/2 = Kn (where K is any whole integer and "n" is a harmonic convenient for the size of the unit).  It works out that the primary length is 1/2, 1/4, 1/8, 1/16, 1/32, etc. of the length of the secondary depending on the harmonic selected.  This puts the nodes of the wave at the ends of the primary.  This means the nodes of the system are at the ends.  However, Dollard put a question mark for the phase effect of the top load.

Dollards explanation of the operation is brief and to the point - basically an energy field is collapsed and the shock wave moves through the system like something out of a horror movie.  Dollard also explains that the third coil can be tuned to move the max voltage point out of the coil and into the line or top load.  It is the lengths of the wires that is important along with several other things.  Amazingly Hull got excellent results just by tuning the coils with various tap points.  Rather than a transmission line, the magnifier is more like a special wave guide.

Tesla stated in an interview with his attorneys that the magnifier method was much more effective and easier than the resonant rise method and that turn ration did not even give an approximate indication of the rise of voltage developed in a few turns of the secondary.

Tesla went to great lengths in Colorado to get rid of the self-capacitance in the extra coil - saying it killed the effects.

It's my understanding that the top load of the magnifier is actually a "virtual ground".  Also, many think that there is no current in the output of the magnifier - Tesla stated he could easily pull 100's amperes off the terminal.  He also could diintegrate aluminum foil inside the extra coil - stating it was like a crack of thunder and the foil was vaporized.

Wonderful stuff.

EDIT:
Dollard specifically mentions that a "strong travelling wave is formed" coming out of the primary and he considers the secondary and the extra coil as 1/4 wave transmission lines.  In a travelling wave, the voltage and current are "in-phase" so it is "real energy" not "reactive energy".

[Charlie_V]

Coupling the secondary directly to the primary is what Tesla does to tune the extra coils, but in the Colorado notes he shows it the way I've drawn, disconnected.  Tesla also states in the Colorado spring notes that the length of the primary doesn't matter.  He used a 1/2 wavelength primary vs one that wasn't matched to the wavelength and he said he didn't get much of a difference.

I'll look for that equation with the Kn, I remember it but I thought it was with reference to the secondary, not the primary.  I know for fact he states that the length of the primary doesn't matter.  However, he does seem to change what he's doing throughout the notes so maybe I over looked that.  I'll go back and see.  I think this is going to be one of the things I just experiment with and see what happens. 

Originally, I thought the ground connection of the secondary was a voltage node.  In his notes he draws it as an anti-node (maximum point).  In the interview to his attorney he also says that you can connect the primary to the secondary, but it doesn't really matter.  He doesn't ever seem to make up his mind. 

Grumpy, is there free literature on Dollard and Hull and what they did?