Nathan Stubblefield Earth battery/Self Generating Induction Coil Replications

[protonmom]

@Iotayodi
This is probably the photo you had in mind.  (the first one)  The second picture shows that same Stubblefield large coil, alongside a picture of a coil made by a certain "Stephan of Germany".  Stephan's coil is just about the size I would love to see someone on this forum make.

[IotaYodi]

Hi protonmom. Glad to see your still around!
This is one of the pics but there was a closer one.
 

[tishatang]

Back in those days, circa 1902, capacitors were more difficult and expensive to build than inductors.  The variable cap was not invented until around 1910 and perfected around 1920.   

I am going to speculate that the layered stack on top of the old coils in the Stubblefield photos were open type capacitor banks.   They could be tuned to the coils by removing a layer or two of the metal plates and insulation between them.  Once you were close to resonance, then it could be fine tuned by external coils on the surface in series with the buried inductors.   Look at other photos of Stubblefield and the long open helix air coils connecting things together.   They look like coiled telephone receiver coils to keep things from getting tangled up.    But, it is a simple matter to tune these long inductors by simply removing coils and straightening the wire up.   So, rough tuning by removing plates of the open type capacitors and fine tuning by removing coils from the long helixes on the surface.

The large physical size of the components were probaly close to the Shuman resonance of about 8 Hz which some say is now closer to 12 Hz.
Now we have large capacity capacitors relative cheap and old variable air caps for fine tuning.   The large caps can compensate for small inductors to get the fundamental freq down to very low levels.

[protonmom]

Oh yes, I am still around, and will be, hopefully, for a long time. 
Iotayodi:
Back when we first started talking about Stubblefield, a couple of us made enlargements of all the coils we could see in that Stubblefield farm photo.  Perhaps you are thinking of one of the enlargements? I remember you asking once before about that picture of caps.  I don't recall any other photos except the ones we enlarged, unless perhaps you saw it on another forum or site?

I have a feeling that Tishatang is correct in that the stacks on top of the large coils are open type caps.  Thanks Tishatang for telling us about that!  It does make sense. 

[MW383]

Welcome back Tishitang. I had quit all of this business for a while but find myself back into it and constructing coils again. The coils are going together quite well. I have some really good wire materials and insulating layer materials which both make construction easy. Anyway, a few minor things I notice in construction....First, being generous in the insulation layer thickness between coil layers seems to be a good thing. As far as the outer winding (most call it the secondary), A true bifilar series winding produces better magnetic fields than something scramble wound in 'there and back again' manner. I will be taking my latest creation into work next week for some proper measurments. Resonant frequency and inductance will officially be measured on all windings in this system (the secondary, the iron winding of primary, and copper winding of primary). I work for a company that makes induction cooking devices so the project engineering leader has agreed to put my coil on some really good equipment to characterize everything. I am looking forward to the results. First, knowing the resonant frequencies would enable me to complete the rest of the system; capacitor sizing, and exact frequency to set my switching circuit. Who knows, maybe other useful information may be gleaned. I read the various links in ground antennas. Excellent stuff that plays right into this Stubblefield system. And in my opinion directly related to your earlier postings here. I have installed a ground antenna system to a radio I have in the garage and it does work quite well this way. So this is my current status these days. It is good to hear back from you Tishitang. I am getting close to testing these theories you have made. Resonance makes sense. I look forward to beating the hell out of my latest coil in this fashion. I will continue in my backwards operation of this thing. I will at first artificially power the secondary coil at a frequency, and use the primary coil like a ground antenna. My guess is that good power will be found and one that builds over time like Stubblefield indicated and the modern ground radio experimenters report. I'm after big power and the primary is obviously capable of high amperage. Doing it in opposite fashion is fine for play but limited in what it can do in my opinion. I have run them this way plenty and am quite done with doing it that way. More postings after I have coil test data. Oh, one more thing, I also remain wary of various - lets say - potential orbital type issues. Maybe more so in the coming weeks as earth passes through potential dustiness left directly in its path recently. Maybe no issues at all with this or maybe our satellites may not be to happy about it either. Time will tell.