Tesla's Bifilar Pancake Coils

[Jiffycoil]

I made a post remarking to Crackahcrackah's reply and after reading it I realized that I'm wrong to be posting this coil in this thread. The thread is for replicating Tesla's bifilar pancake coils and this is clearly different. He is telling me how he believes Tesla would build a pancake coil. I would like to say Crackahcrackah:

If you read my post I say I'm going to put the coil in dialectic oil just like Tesla says to do. If you read through the references you sited he's speaking of insulating coils by sealing the wire and then the wound form with melted wax. He then goes on to say "It may be found convenient to immerse the coil in paraffine oil or some other kind of oil; it is a most effective way of insulating, principally on account of the perfect exclusion of air, but it may be found that, after all, a vessel filled with oil is not a very convenient thing to handle in a laboratory." Given the quality of todays dialectic oils I feel that the immersion of this coil in oil will give it an air fee environment.

We will move the discussion of this coil elsewhere.

[7imix]

You don't have to move discussion about non bifilar coils out of this thread. It would be very interesting to use this thread to also discuss regular pancake coils, and where tesla used them instead of bifilar coils. One thing I wonder about. Most of tesla's wireless patents show non-bifilar coils. However it is sometimes the practice of inventors to not put all of the details for constructing a working system in a patent, but rather spread all the component parts and techniques across many patents, to hide trade secrets of construction a little better.

Could tesla perhaps have actually been using bifilar coils as one of his secrets to getting better performance out of his devices? From the theory side, what would be the difference in effects?

In his magnifying transmitter replication video, Eric dollard mentions he uses a bifilar pancake coil, with one winding going one way and the other winding going the opposite way on top.

I'm grateful for the reference to the 1891 lecture. I just finished reading it a few days ago and studied with interest the quoted part about coil construction and paraffin.

[xee2]

I think everyone should remember that Tesla built his coils over 100 years ago. He used wax and oil because that is all that was available then. I think that today you are better off using normal hookup wire which can be found with ratings of 500 volts or test lead wire which has rating of 1000 volts. This may not seem like much but if there are 100 turns in the coil, then the voltage between turns is only 1/100 of the voltage across the coil. Thus 500 volt wire (which is 1000 volts between two wires since they each have insulation) would work for 100 turn coil voltages of 100,000 volts. And using test lead wire would double that to 200,000 volts. I suspect the wire insulation works better than wax for the same thickness. If you need higherer voltages, higher voltage wire is also available.

[Mike2kt]

I think everyone should remember that Tesla built his coils over 100 years ago. He used wax and oil because that is all that was available then.

I am in 100% agreement with you. Quality magnet wire today is going to contain PTFE (aka Teflon). PTFE insulation is orders of magnitude better insulation than what Tesla had available.

[thenetprophet]

Bifilar Construction Ideas/Questions

Folks,

First, I am an amateur at all this, so pardon my ignorance. I have been trying to follow several threads/subjects, but this is my first post.

I am wondering whether one could use bi-metallic bifilar elements in such a coil, if that would enhance the voltaic performance from the standpoint of any galvanic effect that might be had. I.e., if I were to use Cu and Al for element A and element B in the Tesla bifilar pancake coil?

Second, I am going to be getting some samples of Cu and Al tape w/non-conductive adhesive on each. I believe these are more than 1/2" wide tapes. The Al is 50 micron thick and w/adhesive, just over 80 micons. The copper is 25 micron and w/adhesive, 50 microns. This is a free sample of about 18 yards of each. I am planning on possibly leaving the adhesive backing on the tape, and rolling both into a spiral around say, a 25-50 mm spool or dowel.

Third, I am wondering whether there would be any advantage to have a ferrous disk vs. air as the central core?

I am investigating whether or not I can get my hands on some rolls of bare Cu (or w/insulative or conductive coating) and bare Al (or likewise, w/insulative or conductive coating), that is a little thicker at the expense of some width, as I believe, if this approach is reasonable, it would be better to have some thicknesses that give the geometry some electrical and mechanical "meat."
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Another thought I am having, is purchasing some bifilar magnet wire and even though in parallel, wrap both in parallel as a spiral pancake (see attached drawing). The attached drawing shows the two magnet wires as Cu and Al, although it might also be done w/regular Cu bifilar. I am not even sure there is such a beast as bi-metallic bifilar magnet wire available. Might be possible if the two metals are separate magnet wires but combined that way?

Please also note the possibility of the internal series connections.
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Now on to other questions:
1) If one were to connect an antenna to this would there be any output from this coil? I.e., passive reception that generated a voltage or current reading?
2) If so, what would happen if I were to connect pancakes in series and/or parallel?
3) If any of these combinations were frequency dependent, due to the number of turns, would connecting them in series and/or parallel cause the output to be additive (i.e., make it act more broadband w/re to frequency AND w/re to voltage/current)?

Am I crazy for thinking such possibilities might enhance performance?

Thanks in advance!

Pete
aka "thenetprophet"

[7imix]

Hi thenetprophet. Interesting suggestions. It will be interesting to hear if you get any unusual results.

Making a pancake coil out of metal tape is an excellent idea. That gives me an idea: I'm going to build a really nice primary coil with some copper tape I have.

[thenetprophet]

Re: Bi-Metallic Bifilar Pancake Coils

Thanks for the response 7imix,

W/re to the questions I had in the earlier post, I was just considering how I might go about testing. Wondering, if I want to see what sort of frequency response there is, I would almost have to utilize a spectrum analyzer or the like to see what the output of a pancake looks like. Anyone know of a reliable PC based oscilloscope, perhaps w/dual trace, that also contains a spectrum analyzer? Something for a poor man's budget?

Thanks guys!

Blessings,

thenetprophet

[thenetprophet]

Folks,

I would like to pose some questions that I hope some here may already know the answers to...

1) Does anyone know what the magnetic and electric fields around a tesla bifilar pancake coil look like without any power source applied?
2) If there is a DC power source applied, does the pancake coil output an AC voltage at a higher voltage/lower current at some resonant frequency?
3) If a DC power source is applied, does that change the magnetic and electric fields around the coil?
4) Could static/RF/cosmic ray energy and/or exposure to the planar magnetic field of the earth cause the pancake to be excited?

I know no one owes me any explanation, but I am pondering these things as it relates to some initial rudimentary design ideas w/re to either a static/atmospheric charge storage system, or an earth battery/earth energy receiver.



Thanks in advance folks!

Blessings,

thenetprophet

[morpher44]

wireless age - 1919

That's over a mile of wire man! Crazy!

On googles DOC collection I recently found a doc titled
"Wireless Age", dating from 1919.
During that year, the everyone was familiar with Armstrong
brilliant regenerative circuit, and the "wireless" hobby took off like crazy.
People were struggling with all sorts of LONG-WAVE technical challenges.
The radios of the time, many of them home-made, and quite creative, used various tricks to get LOWER frequency reception and transmission.
Some military gear would use TWO grounds, spaced a quarter wave or more appart from each other and these were the transmission lines, directly into the ground -- Stubblefield indeed. The "virtual" long-wave antenna is in the ground. Rocks and dirt is conductive and can carry a signal.

There was also an article where one "inventive" soul wrote up this amazing idea of using SEARCH-LIGHTs, but to replace the bulbs with UV bulbs. You could then use the light-beams as IONIZED air columns for long wave verticle broadcast or reception. This idea in 1919 -- well before so called PLASMA antennas being tinkered with today.

Another LONG-WAVE idea is not in the macro domain, but in the micro domain. Birds use magnetite for navigation. Long wave reception might be possible with the very small -- as it is in biology. Magnetic substances, that are free to float in liquids (or frictionless environments) are buffeted around and move with magnetic fields. Sensors for these moving materials can be made quite small.

And my last thought regarding looking to "the old days" is to see what the HAMs are doing. I recently found this amazing bit of software that a HAM wrote.

https://sites.google.com/site/sm6lkm/saqrx

This software could easily be adapted for use with "experiments" in these frequency ranges. Watch some of the youtube videos on people receiving VLF with it. A VLF radio completely in software. Brilliant!!!

[morpher44]

very cool demo

THE LENZ EFFECT DELETED....!!! - YouTube

[Farmhand]

THE LENZ EFFECT DELETED....!!! - YouTube

Neither coil he places near the rotor has a load, the different coils could be anything, the one that speeds the rotor is likely storing energy then exerting a magnetic field back on the rotor. Just like in Thanes acceleration video's.

Easy enough to do. Here's a clip with the wave form shown.

Acceleration under load effect ( 'Par-Petua' : ) Short clip.wmv - YouTube

Cheers

[jegz]

Yes. If you study william J hooper's patent on motional magnetic fields you will observe that he has several such 'BNC' coils in series to form a set..2 such sets are arranged in opposition ...he observed weight reduction in the space between 2 such sets...also he observed that while normal magnetic fields were not observeable there was another magnetic field that was existent and could not be shielded (similar to the scalar field of a caduceous coil?)...yet this field did produce some voltage when it passed a wire..he called them motional magnetic fields

[jegz]

the similarity is in the cancellation of the fields as a result of counterwinding as well as the inability to be shielded using conventional means such as a faraday cage