Tesla's Magnifying Transmitter "Replications"

[dR-Green]

P.S. Here is a chart for AWG approximate weight, resistance ect.
Copper Wire Properties Guage Size AWG - RF Cafe

Nice. Shame all the boxes from 1.8mm up are blank

[dR-Green]

If the coils aren't properly matched to the input signal, then you won't get the results.

Just about everything Telsa did falls under the category of telecommunications. A Tesla coil is a radio broadcast antenna, which is why standing waves can be detected near them. It's really easy to get lost when it comes to vectors: they're not very straight forward ( no pun intended). The most common use of wavelength is in antenna calculation and with regard to radio.

It seems quite possible to get satisfactory results with relatively random lengths. My primary, secondary and extra coils are all matched by copper weight but are all different gauges, the "tuning" (getting the best output) is done via adjusting the spark gap and the primary capacitor, and I can't say there's a great amount of difficulty involved in getting a nice output. It's just not necessarily tuned for the best possible output.

One question though, are you of the opinion that the energy is transmitted through the air - the output is the terminal at the top - or do you consider the output to be the grounded end of the coil?

[LetsReplicate]

It won't be the same diameter. The extra coil will be at least 1/2 or even 1/4 the diameter of the secondary. By "3 times the length of the secondary" I assume you mean "winding length", like "coil height"? How would it be 3 times though if I have 13m in the secondary and 26m in the extra coil if they were wound the same diameter? That would be twice the length/height of coil if I used double the wire

You lost me a bit with the last part. I'm guessing calculating the relative wire lengths of secondary and extra coil falls under basic antenna design. Unless someone can shed some more light on this, seeing as I'm not going to be using 1/4 or 1/2 wavelength of any particular anything, and the frequency will be whatever it ends up as being best, then I'll just go with double the wire length in the extra coil relative to the secondary and test it.

Smaller diameter means more inductance so the wires will have to be spaced out more to counter for that, or use a shorter wire length. The main issue is that there is no predicable way to calculate a coil's self-capacitance from wire space. That means you'll have to build the coils using a guess, then drive the coil at the frequency (the full electrical length of the coil) you want while adjusting the coil until the phase angle between the voltage and current at the frequency is 0, or a multiple of 180. That would have to be done for both of the coils. If the coils aren't properly matched to the input signal, then you won't get the results.

If the diameter and wire spacing are the same, then 3 times the wire length will result in 3 times the "coil height". If a 13m secondary "coil height" has an electrical length that is 1/4 of the wavelength (it's self-resonant frequency is the receive frequency times 4) then a 26m coil on the same frame will have twice the electrical length (having a self-resonant frequency that is double the receive frequency), which it 1/2 the wavelength. So if we want the extra coil to have a wavelength of 3/4, then the "coil height" would have to be 39m.

Just about everything Telsa did falls under the category of telecommunications. A Tesla coil is a radio broadcast antenna, which is why standing waves can be detected near them. It's really easy to get lost when it comes to vectors: they're not very straight forward ( no pun intended). The most common use of wavelength is in antenna calculation and with regard to radio.

[Farmhand]

For bulk copper, you might look in to home improvement or roofing suppliers. They sell rolls of copper flashing. One home improvement place in particular has 8in by 20ft for $43

Awesome tip. I was planning to go to a plumbing supply store to get some
pre-coiled copper tubing, so I will ask about the strip (flashing).

I'll have to do some calculations to match the weight of my planned
secondary to an appropriate copper strip thickness if the length and thickness
are fixed we can trim the width or (height) a bit to get the right weight but if
the copper strip is too thin or too short maybe it would need two layers in
parallel like two turns used as one. 8 mm copper tubing would be fairly heavy
and we could use two turns of that as one alternatively. I must admit a wide
strip of copper over the secondary would look very cool.

So much info and so short a time to read before my eyes go blurry. I
don't think reading for long periods from the computer screen is good for me.

I think I will go with 0.71mm wire for the secondary and extra coils, I think it's
about 3 Kg per Kilometer.
Being Christmas time I won't order anything online till after the new year. I've
got 110 meters of 0.71 mm wire already. I should have about 150 meters of
0.5 mm wire left after winding the other three transformers on my steel ring.

I'm hoping that transformer can give me 500 or 600 volts AC on two phases
with good current, a couple of hundred watts I hope.

Cheers

P.S. Here is a chart for AWG approximate weight, resistance ect.
Copper Wire Properties Guage Size AWG - RF Cafe

..

[QuarterPole]

For bulk copper, you might look in to home improvement or roofing suppliers. They sell rolls of copper flashing. One home improvement place in particular has 8in by 20ft for $43

[dR-Green]

I think your right, I think I remember reading that. But then he does a lot of stuff which is a bit confusing. It doesn't make much sense to me for him to be able to impress the vibrations of the extra coil directly on the ground through the condenser unless the extra coil was a 1/4 wavelength electrically.

I'll read some more when I get some time, I keep forgetting to take notes of the page numbers and so forth.

Cheers

There is also this from page 192, not quite sure what it means yet though. His "when a spark is used" comment suggests to me in relation to Fig. 2 and 3 of page 185 that he's not including the extra coil in this diagram or as a part of the oscillator. The way he speaks here is like the extra coil is a part of the structure, instead of a wire leading up, the wire is replaced with the extra coil

[dR-Green]

As long as the capacitance:inductance ratio and diameter remains the same, then doubling the coil length would be adding another 1/4 wavelength. The extra coil would be then be 3 times the length of the secondary if they were wound exactly the same. The part that makes this messy is the leads that run to the coils, and the spark gap all add capacitance which can be enough to mess up the whole effect if they are not accounted for.

It won't be the same diameter. The extra coil will be at least 1/2 or even 1/4 the diameter of the secondary. By "3 times the length of the secondary" I assume you mean "winding length", like "coil height"? How would it be 3 times though if I have 13m in the secondary and 26m in the extra coil if they were wound the same diameter? That would be twice the length/height of coil if I used double the wire

You lost me a bit with the last part. I'm guessing calculating the relative wire lengths of secondary and extra coil falls under basic antenna design. Unless someone can shed some more light on this, seeing as I'm not going to be using 1/4 or 1/2 wavelength of any particular anything, and the frequency will be whatever it ends up as being best, then I'll just go with double the wire length in the extra coil relative to the secondary and test it.

[Farmhand]

On page 186 (191) of the Colorado Springs Notes Tesla says, referring to Fig. 4, that the best results are with a 1/4 wave secondary and 1/2 wave extra coil. But I've noticed he also changes a lot within the next few pages and I haven't read very far beyond that.

I think your right, I think I remember reading that. But then he does a lot of stuff which is a bit confusing. It doesn't make much sense to me for him to be able to impress the vibrations of the extra coil directly on the ground through the condenser unless the extra coil was a 1/4 wavelength electrically.

I'll read some more when I get some time, I keep forgetting to take notes of the page numbers and so forth.

Cheers

[dR-Green]

I read there somewhere that the extra was a bit shorter, but then the sphere would slow it down a bit.

Are you sure that wasn't mine, because I currently have a 13m secondary and 8.25m extra coil? On page 186 (191) of the Colorado Springs Notes Tesla says, referring to Fig. 4, that the best results are with a 1/4 wave secondary and 1/2 wave extra coil. But I've noticed he also changes a lot within the next few pages and I haven't read very far beyond that.

Good point about the sphere, but again in Fig. 4 he also has a sphere on the top of the secondary to make up a condenser. I suppose I'd better read Eric's book as well then

I've started looking for materials already anyway, one obvious problem so far is a lack of easily sourced copper strip The biggest length that's easily available is 1 metre. Same with copper wire, 2mm is easily available, 2.5mm a bit more rare, and anything bigger can only be sourced from industrial suppliers. None of which seem to have the convenience of selling it on a web site to be able to know prices etc, they all want you to contact them for some reason.

Anyway at the moment I'm literally learning something new about the MT every day, so I reckon I'll just finish the spiral coils I was intending to make. I'll use 2x 1.5mm layered wire for the primary, and I haven't decided on the secondary yet. I'll also make another 2 or maybe 4 extra coils, 2 of which will be to test on the 30cm spirals with twice the length of wire than that of the secondary. And by then I should have enough information to get started on a proper MT type setup. Or that's the plan

[Farmhand]

I see. I'm assuming you could still use twice the secondary wire length to make the extra coil for a 1/4 and 1/2 wave combination, or would you need to do some calculations?

Fig. 4 is the one I mean as being the "best approach".

Hi dR, I think the extra should have the same frequency as the secondary, but I read there somewhere that the extra was a bit shorter, but then the sphere would slow it down a bit.

We really should refer to Eric's book,

http://www.tuks.nl/pdf/Eric_Dollard_Document_Collection/OCR_in_progress/Condensed_Intro_to_Tesla_Coil/Condensed_Intro_Tesla_Coils(OCR).pdf

It does look like the primary is wound below the secondary, cool. I'd like to go with a strip like Eric suggests but I'll probably use some tube, and weigh it all.

Cheers

[LetsReplicate]

I see. I'm assuming you could still use twice the secondary wire length to make the extra coil for a 1/4 and 1/2 wave combination, or would you need to do some calculations?

Also I should have been clearer earlier, by "spark gap" I meant what's going into the primary. In other words the tuning can be done by adjusting the input spark gap and capacitor to the right frequency, tuning the input to the coil. The other, probably more difficult way would be to aim for a specific frequency and building/tuning the coil to the power source.

Fig. 4 is the one I mean as being the "best approach".

As long as the capacitance:inductance ratio and diameter remains the same, then doubling the coil length would be adding another 1/4 wavelength. The extra coil would be then be 3 times the length of the secondary if they were wound exactly the same. The part that makes this messy is the leads that run to the coils, and the spark gap all add capacitance which can be enough to mess up the whole effect if they are not accounted for.

In theory, if you build this system tuned to a natural signal: then it becomes the primary and all the energy you receive is free. I always run my "electricity from radio" ideas on the premise that there is no transmitting primary. The difficulty is in the design of those coils is it tends to require an RF antenna tuner like the MFJ-259B to make the coils perfectly resonant (which I don't have yet, but it's on my equipment wish list).

Assuming that diagram 4 is being built, the ideal amount of capacitance for the condenser should be enough to cancel 1/2 wavelength of shift. What you will be receiving then is both peaks of the wave (magnetic and potential) at your receive point at the same time. This will effectively be making your secondary -1/4 wavelength long (negative elements do exist in antenna design), and the extra coil 1/4 wavelength long. Honestly, this concept is a step beyond my understanding of radio and worthy of investigation. Umm, thinking about it, you might be able to replace the condenser with another half-wave coil and accomplish the same effect (educated guess, by no means certain as it would make the secondary both 1/4 and 3/4 long while making the extra 3/4 and 1 1/4 long, all of which are viable receive lengths).

[dR-Green]

The physical length of the wire is not important at all. The electrical length of the coil is the critical factor. Electrical length is a factor that is just as much connected to wire spacing of the coil as it is the physical length of the wire.

I see. I'm assuming you could still use twice the secondary wire length to make the extra coil for a 1/4 and 1/2 wave combination, or would you need to do some calculations?

Also I should have been clearer earlier, by "spark gap" I meant what's going into the primary. In other words the tuning can be done by adjusting the input spark gap and capacitor to the right frequency, tuning the input to the coil. The other, probably more difficult way would be to aim for a specific frequency and building/tuning the coil to the power source.

Fig. 4 is the one I mean as being the "best approach".

[LetsReplicate]

As far as I can make out, then, a particular length of wire isn't important to plan out in advance unless one intends to use a particular frequency, and I'm guessing the best results in relation to the input rate will be obviously visible by adjusting the spark gap. But these are the main design criteria whatever the scale.

The physical length of the wire is not important at all. The electrical length of the coil is the critical factor. Electrical length is a factor that is just as much connected to wire spacing of the coil as it is the physical length of the wire.

The vectors of a transverse wave are only in phase with each other at multiples of 1/4 of the wavelength. While at a multiple of 1/4 wavelength the wave will either be entirely potential, or entirely magnetic. Since we can only receive the potential portion of the wave only half of the 1/4 wave points are suitable for receiving. That means the receiver (secondary) should optimally have an electrical length that is either 1/4 of the full wavelength, or 3/4 of the full wavelength.

The extension of that is that if we are receiving potential at the end of a 1/4 wavelength antenna, then at the far end of the antenna, the wave will be entirely magnetic. In the 3/4 wave "extra coil" we are also receiving and far end of the coil is entirely magnetic. So in these diagrams we have just the magnetic portion of the wave pressing on the spark gap. The metal balls on the spark gap in diagrams 5 and 6 should allow the magnetic wave to pass freely across unless they are shielded (the capacitors in the diagram) making this circuit a full wave electrical loop for a wave of one frequency where the phase of the wave is set by existence of the spark gap to ensure that you're only receiving potential where you want it. Diagram 4 would would the best because the capacitance of the condenser would also act to shift the phase magnetic wave back to potential.

Fascinating.

Great info, thank you.

[dR-Green]

Excellent info, thanks for posting There is also this from page 185 (190)



So it looks like the best approach is to make the extra coil double the wire length of the secondary, with the extra coil (frame and actual winding with extra spacing) being as wide as it is high (long). The primary and secondary copper mass should be equal, but apparently this doesn't apply to the extra coil.

As far as I can make out, then, a particular length of wire isn't important to plan out in advance unless one intends to use a particular frequency, and I'm guessing the best results in relation to the input rate will be obviously visible by adjusting the spark gap. But these are the main design criteria whatever the scale.

And it looks like the secondary is wound above the primary?

[Farmhand]

Here is a plan for the winding's of Tesla's Colorado Springs coil, the second arrangement I believe.

October 3rd, 1899 Page 198 of the PDF



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And here is how he wound it on the fence former.
September 22nd, 1899 Page 188 of the PDF


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Here are the objects near to the coil for consideration of the effects on the main oscillator.

October 3rd 1899 Page 198 of the PDF


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Further on pages 188,189 and 190 he explains about the windings.

I dare to say that this was still not a perfected system, in fact it appears to
be far from perfected. He was experimenting after all. And the experiments
didn't stop there so I imagine he made further improvements to his methods
and theories.

Tesla seems to have determined the secondary resonant frequency by the
period of the primary circuit and observing the effects from the secondary
when adjustments were made.

Cheers

P.S. Colorado Springs sounds like a wretched place with a good view, much
like where I am located, at altitude on a big pile of rocky dirt.

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