Eric Dollard

[dR-Green]

Ok I am going for a little less rigorous earth. I have one copper tube in the ground now and I will add three more to start with in a sort of circle. Now I have to make a doghouse to cover the coil under it.

I'm aiming for transmission/reception for the CRI and other experiments, so I plan to use the biggest area I can get from the garden. This is not least due to doing experiments in the past and observing how the received power is directly affected by the depth of the receiver earth terminal.

[dR-Green]

I have one question. Did anyone measure the magnetic field on the secondary coil and was it maximum at the top? It should be if the longitudional network is right but I never measured. Thanks.

Ok done a measurement and indeed the magnetic field is stronger on the last loop of the coil

Design frequency = 3670 kc

New Extra Coil #3 + 20% 20 turn secondary









New Extra Coil #3 + 15% 17 turn secondary

Tuned secondary



Free secondary

[orgonaut314]

That is strange. In your case the magnetic field is lowest at the top of the secondary coil.

I restudied the longitudional simulation and it shows the current is most at the last coil. For details I had to multiply the coils current by 1/2 exept the last coil because the simulation did not allow two equal coils parallel. So you see in the picture a rising current from L2 till 2*L5. I zoomed in on the highest resonance.

[orgonaut314]

When I measure the magnetic field on the secondary like this it rises from bottom till the top ring. Could you confirm this?

[orgonaut314]

Another two pictures. This time a simulation of the Tesla coil as a network. Eric calls it the shunt concatenated network. You see the mutual capacitances on top and the mutual inductance as the first coils left. The rest is the transversal transmission line. Don't mind the resistors they are there for the simulator only.



The voltage seems stronger with 4 elements and the same 0,7V input. It has the same type of resonance as the longitudional network.



Looks like this one:


Has someone measured the complete frequency spectre with his Tesla coil? DrGreen?

[dR-Green]

When I measure the magnetic field on the secondary like this it rises from bottom till the top ring. Could you confirm this?

Is the secondary grounded? In 1/4 wave resonance the current and voltage distribution should be like this. Maximum potential at the top, and maximum current at the bottom.

[dR-Green]

Has someone measured the complete frequency spectre with his Tesla coil?

From http://www.energeticforum.com/203695-post7.html

And http://www.energeticforum.com/204220-post12.html

[orgonaut314]

Hi drGreen I just did a complete measurement of resonance of the secondary. I measured with only the primary as a loop to my solid state frequency generator no tank capacitor.


very small peak at:
0.925MHz
something bigger peak at:
1.390MHz
I measured the very large peak at
2.766MHz

There is no resonance above this. I cannot plot the vallues because my nanoamp meter goes over the max when I have amplification that I can only just see the other peaks.

So they rise like the longitudional network just like Eric said. I included the tekst where Eric says literally that the Tesla coil is the shunt concatenated line (point a) that I simulated in the earlier post.

This is very strange. Your resonance seems a typical transversal resonance where current and voltage are out of fase, a halve wave resonance. Strange I have no explanantion. My coil is grounded and has an elevated capacity.

[orgonaut314]

I measure the resonance with the meter on top, metallic connection. The argon tube works like an elevated cap. I found it very easy to pick up the wrong radiation in the past during measurements.

[dR-Green]

This is how it was determined that the coils are not in concatenated resonance at the design frequency (or thereabouts). The 3095 kc distribution shows a typical 1/4 wavelength over both coils as one.





The spectrum isn't the same as the coil's resonant frequencies. The spectrum shows the harmonics that are produced when the coil is driven at a certain frequency. There's another set of harmonics if you drive it at another resonant frequency.

Spectrum when primary is driven at 3892 kc



Spectrum when primary is driven at 1742.5 kc

[dR-Green]

I measure the resonance with the meter on top, metallic connection. The argon tube works like an elevated cap. I found it very easy to pick up the wrong radiation in the past during measurements.

Yes isolating measurements from each coil when they're both in use is tricky/impossible, but you might want to switch to the extra coil non-contact measurement approach for the secondary too, because even the distance between the pickup and the secondary has an observable effect on the resonant frequency, especially with high(er) frequency coils. That's why I had to start making note of the distance as well. The natural resonant frequency of your secondary will be much higher without the meter connected.

[orgonaut314]

Yes true the resonance was 3,2MHz without the contact measurement but this way I am sure I measure the right point on the top of the coil for maximum radiation. I do not completely understand your spectrum and I do not think measuring without contact will change my spectrum. Perhaps with the extra coil you have a halve wave resonance with different harmonics?

[dR-Green]

Yes true the resonance was 3,2MHz without the contact measurement but this way I am sure I measure the right point on the top of the coil for maximum radiation. I do not completely understand your spectrum and I do not think measuring without contact will change my spectrum. Perhaps with the extra coil you have a halve wave resonance with different harmonics?

Measuring without contact won't change the spectrum (much), it will change the resonant frequency.

https://en.wikipedia.org/wiki/Frequency_spectrum

Like a piano note playing, you hear the pitch as the fundamental frequency, or the strongest frequency. But the "sound" which you recognise as a piano note consists of countless different harmonics/frequencies. If you remove all the harmonics from a piano note, or any instrument playing a continuous note, then you essentially end up with a pure sine tone at the fundamental frequency which sounds nothing like a piano. So a spectrum analyser simply shows you all the frequencies that combine to make up that sound, or whatever it is you are measuring. You can then reconstruct the sound simply through putting sine waves together in the same frequency relationships and amplitudes as was originally measured.

Harmonics - Sine, Square & PWM - YouTube

[orgonaut314]

Hi did you see this video where Eric explains transversal and longitudional analoques and how the harmonics are reversed in longitudional and how electric and manetic field are in fase?
https://m.youtube.com/watch?v=6BnCUBKgnnc


I have the feeling you don't understand what I tried to say?

[dR-Green]

Hi did you see this video where Eric explains transversal and longitudional analoques and how the harmonics are reversed in longitudional and how electric and manetic field are in fase?
https://m.youtube.com/watch?v=6BnCUBKgnnc


I have the feeling you don't understand what I tried to say?

Yes I understand. The resonant frequency and the spectrum are two different things.

The spectrum produced by the coil(s) is the spectrum measured and shown. They are different when the coils are tuned differently and have different resonant frequencies.