Re: winding lathe built -> Enamel-coated copper wire on PVC water pipe - PVC cement to hold the windings
Dago, Wed Oct 08 2014, 05:49AM

Umm why would you use PVC cement to glue the wire to the PVC pipe?

AFAIK PVC cement is solvent cement so it just melts the PVC pipe itself, so you basically need two surfaces made out of PVC for it to do much.

Just use epoxy...

Re: winding lathe built -> Enamel-coated copper wire on PVC water pipe - PVC cement to hold the windings
Graham Armitage, Wed Oct 08 2014, 08:02AM

First off, you should start with doing a lot of research and reading old posts on this forum. There are many other factors to consider before deciding on the size and winding of the secondary. Whether you are building a DRSSTC or a Spark Gap tesla, you should understand the rest of the circuit parameters first before winding the coil. Once you have the rough design figured out, you can use something, like JavaTC to model your coil. That will tell you how many turns and length of secondary to use. Do the math before winding and you don't have to measure the resonant freq as you work - this would be difficult! For your first coil, you may want to consider purchasing some TC plans to get you going. At least you know it will work.

As was mentioned there is no reason to use PVC cement. Tape the one end of the wire to the PVC, wind the coil and tape it off. I use super glue to anchor the two ends for safety, then while rotating slowly, coat the entire coil with several coats of polyurethane gloss. That will hold everything together nicely.

Good Luck

Re: winding lathe built -> Enamel-coated copper wire on PVC water pipe - PVC cement to hold the windings
Dr. Dark Current, Thu Oct 09 2014, 09:54AM

Just use JavaTC to calculate the resonant frequency (be sure to add a few percent (usually around 5-10%) to the bare wire diameter when calculating the number of turns, due to the enamel coating)
Then just get your wire and wind the coil. Do not calculate or measure anything during the winding process. After the coil is finished, just measure its DC resistance and compare with JavaTC output. If it's all right, you're done. If there is some difference, modify the number of turns in JavaTC until the resistances match, this will slightly change your resonant frequency.

Re: winding lathe built -> Enamel-coated copper wire on PVC water pipe - PVC cement to hold the windings
tarakan2, Fri Oct 10 2014, 03:09AM

Thank you.
I am looking at the Java Script Tesla Coil program.
It has a lot of strange things to it such as "Height 1(LV end)" and "Height 2 (HV end)" variables.
May I remove the Toroid from my calculation?

I wish I could see the formula or a train of formulas that are used to estimate the Secondary resonance frequency.
I am planning to wind some 1" PVC pipe coils for my experimental purposes and some 4" PVC pipe coils for a traditional Tesla transformer.

I may end up using TeslaMap, but I would prefer an Excel spreadsheet where I can see what came from where.

Re: winding lathe built -> Enamel-coated copper wire on PVC water pipe - PVC cement to hold the windings
tarakan2, Fri Oct 10 2014, 05:04AM

Based on what I read, the secondary has to have a self-frequency so the wavelength is 4X the winding length.

Are we STILL using speed of light to convert one to another?

Re: winding lathe built -> Enamel-coated copper wire on PVC water pipe - PVC cement to hold the windings
tarakan2, Fri Oct 10 2014, 05:53AM

Based on what I read, the secondary has to have a self-frequency so the wavelength is 4X the winding length.

Are we STILL using speed of light to convert one to another?

Re: winding lathe built -> Enamel-coated copper wire on PVC water pipe - PVC cement to hold the windings
Dago, Fri Oct 10 2014, 06:45AM


If I recall correctly this theory has been proven wrong.

I think Steve C. or someone more knowledgeable of the theory can tell more.

Re: winding lathe built -> Enamel-coated copper wire on PVC water pipe - PVC cement to hold the windings
Andy, Fri Oct 10 2014, 07:01AM

Hi
I thought it would be 1/4th, based on antenna dipolar antenna, but longer wave lengths can work, 1/8, 1/16(maybe) can't remenber others but, sorry is it a E filed or B Feild, big difference?

Re: winding lathe built -> Enamel-coated copper wire on PVC water pipe - PVC cement to hold the windings
tarakan2, Fri Oct 10 2014, 09:46PM

So there are many "schools of thought"?
I guess I will wind several transformers of different proportions to see.

If the coil is 1/4 the wavelength, than the wave is X4 the coil length. Am I correct? :)

I firmly believe that there is something behind Tesla physics that requires a lot of attention.
It is not obsolete and should not be retired for decorative purposes only.

A veil of inert gas, sandwiched between two conductive plates does not behave like a dielectric in a capacitor. I had proven it experimentally.

Re: winding lathe built -> Enamel-coated copper wire on PVC water pipe - PVC cement to hold the windings
Hazmatt_(The Underdog), Sat Oct 11 2014, 04:43AM

Okay...

1. Why a quarter wave? Simple, draw out a sine wave, 90 degrees is the first peak, this is quarter wave. YOU COULD drive the coil at 3/4 wave, which is the second peak, 270 degrees of your sine, and right at 180 degrees, or HALF WAVE, you have a NULL, just like your sine wave picture.


2. Why is it not exactly one quarter of the wire length? Capacitence. The winding proximity of each turn next to the other is a fraction of a pico-farad. Tesla realized this when he had to tune his close-wound coils to a greater degree than his space-wound coils. Turns have a proximity capacitence which lowers the resonant frequency. A 4.5" coil with H/D of 4 can have 12pF or more of self capacitence from the winding and coil form contributions, I know this, most of mine are of this sort.

That capacitence, which you overlook in your calculations, is why you see a lower resonant frequency then calculated.

3. The full wavelength or transmitted frequency should be 4x or nearly 4x the winding length.
Just for fun I verified the NULL on a coil by exciting one end and probing the other, there was nearly no voltage at the probe! It's neat when the physics proves the theory.

4. A gas dielectric will reach a breakdown voltage sooner than a solid, unless you have some SF6 lying around.

Re: winding lathe built -> Enamel-coated copper wire on PVC water pipe - PVC cement to hold the windings
tarakan2, Sat Oct 11 2014, 06:44AM

Quarter of the wave for 1000KHz is about 28000 cm.
Are we talking about the wavelength of electricity in copper at this frequency?

Or do we have Tesla Transformers that run at GHz?

Re: winding lathe built -> Enamel-coated copper wire on PVC water pipe - PVC cement to hold the windings
GrantX, Sat Oct 11 2014, 08:55AM


The little stubby output antenna of a microwave oven magnetron (the ceramic thing with a metal hat) is essentially a 2.45GHz "Tesla coil" since it is a 1/4 wavelength antenna. If your microwave oven is particularly old and greasy the magnetron can actually achieve "breakout" like a high frequency VTTC (I think this occurs due to gunk building up in the waveguide and causing the antenna to flashover to ground - my mate's ancient oven went to a fiery grave).

Re: winding lathe built -> Enamel-coated copper wire on PVC water pipe - PVC cement to hold the windings
Andy, Sat Oct 11 2014, 04:11PM

If it was B field theory it would be 28000 cm(assuming accurate haven't checked), if its E field it would be smaller, as B is large in amplitude based on time, and E is lower in amplitude based on time.

I think

Re: winding lathe built -> Enamel-coated copper wire on PVC water pipe - PVC cement to hold the windings
tarakan2, Sat Oct 11 2014, 06:44PM

Not sure what B and E fields are. May I ask you to elaborate, please.

Speed of light in vacuum: 299,792,458 M = 29,979,245,800 cm

29,979,245,800/1,000,000 = 29979.2458 cm

29979.2458/4 ~= 7494cm
Not possible because the bigger the coil gets, the lower the frequency is. For that reason even Wardenclyffe Tower could not function at 1/4 wavelength.

What other theoretical 3D wave forms do we have that may be around 30cm X4 at 1MHz?
So it may work for a microwave wave guide but not for Tesla coils since they work in the range of 10^4 to 10^7 Hz and are impractical above and beyond this range.

Re: winding lathe built -> Enamel-coated copper wire on PVC water pipe - PVC cement to hold the windings
Andy, Sat Oct 11 2014, 06:56PM

Hi

Re: winding lathe built -> Enamel-coated copper wire on PVC water pipe - PVC cement to hold the windings
tarakan2, Sat Oct 11 2014, 07:31PM


OK.
So I have my frequency.
In this case I care only about the length (1 dimension)
So each of these fields will produce a wavelength that will somehow have a relationship with the frequency (1,000,000Hz)
Are there any formulas that tie E and B fields with a specific Tesla Coil of a specific geometry?

Re: winding lathe built -> Enamel-coated copper wire on PVC water pipe - PVC cement to hold the windings
Dr. Dark Current, Sat Oct 11 2014, 08:51PM

Its not true with the quarter wave, simply adding a topload will decrease your resonant frequency (relatively a lot) while the winding length remains constant. And the resonant frequency can be even higher than 1/4 wavelength in some cases, but most often its lower.

Re: winding lathe built -> Enamel-coated copper wire on PVC water pipe - PVC cement to hold the windings
tarakan2, Sat Oct 11 2014, 10:56PM


So in the f = c/ lambda formula, c is not speed of light in vacuum. It is some other constant. Am I correct?

Numbers get more realistic if we use Fermi velocity in copper instead.

Re: winding lathe built -> Enamel-coated copper wire on PVC water pipe - PVC cement to hold the windings
Hazmatt_(The Underdog), Sun Oct 12 2014, 05:05AM

tarakan,

IF YOU DO THE RESEARCH... you will find that transmission velocities in coaxial cables is often 0.86 x c

But this varies depending on the medium.

The propagation is also on the surface of the medium, this is the skin effect, which is another headache!

AND if the copper is silver plated, now you're dealing with an extremely conductive medium plated onto a second medium, whereby most of the RF energy, if not all, is inside the 3 mils of silver, and the copper is just acting as a mechanical support.

AND ALL OF THIS... goes right out the window with Tesla coils because they are NOT IDEAL antennas, so antenna theory doesn't really matter at this point.

If you really want to go down the rabbit hole, the secondary has multiple resonances which approaches a ladder network in simulation.

Honestly, just build your coil and be done with it, and stop worrying about minutia.
It takes about $20,000 in equipment to measure these small problems, and who has the time, seriously.

Re: winding lathe built -> Enamel-coated copper wire on PVC water pipe - PVC cement to hold the windings
tarakan2, Sun Oct 12 2014, 12:16PM



Tesla transformer is not wound with coaxial cables.
Proportions of height to width are also pure BS according to Tesla's own patents and drawings.

I am winding a long and skinny one 1" in diameter with a 36AWG.

Re: winding lathe built -> Enamel-coated copper wire on PVC water pipe - PVC cement to hold the windings
Dr. Slack, Sun Oct 12 2014, 02:36PM

Tarkan

I feel your pain and frustration, it's evident in each of your posts. You have a heard a lot of things about Tesla coils, and are having difficulty separating the true from the false. One of the joys of TCs is that they behave in such a strange, almost magical way. As they are complex, well, more complex than an antenna or an LC circuit, a lot of people think them magical. I forget who said that any technology with more than half a dozen variables is indistinguishable from magic.

Anyhows, there is a sizable body of people who think that the most efficient way to run a TC secondary is to have the wire length = lambda/4 at the resonant frequency. It has an emotional appeal, and it is possible to build or tune a TC to that relationship. However there is no emperical evidence to suggest that it's true. The fact that the wire on the secondary is close wound, and the nearest electrical things to each turn is the one above and below means you certainly cannot analyse it like an isolated wire.

Why do you want to build a Tesla coil?

If it's for the impress the friends and family stuff, then follow the well tried and well tested route. There are a great many rules of thumb that work quite well, ones like use 1000 turns on the secondary, or make it between 3:1 and 5:1 height:diameter ratio. You can't really go wrong following those. The secondary is the difficult thing, wind that, and then trim everything else to match. Forget Tesla's patents, the man was barking towards the end of his life, a pity really, but that's the way it goes sometimes. Read Hazmatt's posts, and Dr DC, you asked, and they are trying to help.

If it's to investigate electromagnetic theory, then you will need to know what B and H fields are, and a lot more besides. A TC is probably too complicated to attempt to understand all its behaviour from the ground up, but it is a lot of fun.

If it's to delve into the magical theory, then it will rapidly become a waste of time airing it on this forum.

It's a little disappointing to see a man on the one hand asking questions, but on the other dismissing height/wdith ratios as BS. If you have made up your mind it's BS, then you are uneducateable. The reason 4:1 is the ratio to go for is a complex mix of the conductivuty of copper, the typical frequencies TCs run at and so the skin depth, the impedance of free space, the typical coupling coeffieicnts that work well (so 8:1 is too long), the sort of trajectory a spark takes out of the topload towards a ground some distance away (so 2:1 is too squat), and a whole bunch besides. Most importantly, it's an emperical observation made by hundreds of people before you who have made sucessful Tesla coils. Don't follow it by all means, but expect to have to work harder to get a good result.

Re: winding lathe built -> Enamel-coated copper wire on PVC water pipe - PVC cement to hold the windings
Hazmatt_(The Underdog), Sun Oct 12 2014, 03:44PM

Spot on Neil.

Tarakan, pick yourself up a copy of "The Ultimate Tesla Coil Design" and let that be your bible.

Mitch Tilbury presents a very thoughtful analysis, But as a researcher and Electrical Engineer myself, I know that his numbers do not make much sense.
(In short his input power to output and wire considerations are way off.)

He had in the past downloadable spreadsheets to calculate every aspect. I am not sure if the website is still available, but if it is, it should be at

I have been researching this subject for over 14 years, I have all the books (Inductance calculations, Transient theory, Design of Inductance Coils, etc.), a bunch of equipment, and still no answer yet.

There are over 40 variables to consider, each related to another, including your friend H/D ratio.

H/D ratio determines the pitch of the winding, the TURNS!!!, RESONANT FREQUENCY, RESISTANCE DC AND AC, SKIN EFFECTS, HEATING, coil height like Neil said (you dont want it just arcing to itself) JUST TO NAME A FEW!!!

So no, its not BS.

And you totally missed the point of the transmission velocity, which cannot be measured in a single conductor. There has to be a return path. The point was that transmission IS NOT IN A VACUUM, it is in a conductor, so it can be close to 0.86 x c, so no, you cannot calculate the velocity based on the speed of light, there is a correction factor for the transmission medium.

PICK UP THE BOOK, WIND THE COIL.

Re: winding lathe built -> Enamel-coated copper wire on PVC water pipe - PVC cement to hold the windings
Andy, Sun Oct 12 2014, 04:10PM

Hi tarakan2
What I was meaning is that the primary is linked to the secondary by magtnic fields and the secondary is linked to the ground plane by static fields.
If I was going to build a Telsa coil I would find the secondary antenna length say 1km, then make the primary have 50% frequency of the secondary length, then build a top load to bring the thing into resonance.
A static field at 450-500V can in juice 5V at 100meters into a conductive object.