Re: [TCML] New 3.5" Coil - A kick in the right direction please!

["Grant Visser" <freeekyg@xxxxxxxxx>]

Dr, Resonance, many thanks for your reply!

Agreed! I will be switching over to using JAVATC instantly. Following
another recent post I had no idea that there were any issues at all
with WinTesla and that aside, I think that at least some of the
insanity of last week was caused by me trying to come up with a
working model for a coil which I liked AND which ALL of the available
TC Sims and Calculators agreed with! ......... LOL I'll take my
beating like a man! Lesson learnt.

Yes, although my current gap works "nicely" I am going to have to
upgrade it soon as it is almost impossible for me to accurately
measure the gap which is going to make documenting results etc. later
difficult.

I would also like to switch it from a suction based system to a blown
gap! Assxuming that I am right in my understanding of low vs high
pressure zones and how this affects the quenching! Erm, come to think
of it, this is another area I must research better!

(Not sure how much has been done or how feasible it really is but I
did have it in mind, as a future project, to have a good look at the
SSTC designs and try to come up with a simple, inexpensive, yet
efficient and reliable electronic spark gap that leaves the rest of
the system untouched....... *shrug*)

Antonio's oscillator and your RF probe ............. Thank you for
mentioning those!!! I had not come across them yet! *hangs his head in
shame!*

Yours, forever on the quest for knowledge ......... and TOYS! *g*
Grant Visser
Randburg, South Africa


2008/9/20 DC Cox <resonance@xxxxxxxxxxxx>:
> A few more tips for Grant:
>
> (1) Use JAVATC for your entire design --- Bart's program is deadly accurate.
>
> (2) Use a 4.5:1 height/dia ratio.  Select the largest coilform size you can
> tolerate, then multiply by 4.5 to get the correct winding length.
>
> (3) Use a topload that is 2 to 3 times the dia. of the sec coilform.
>
> (4) Use an efficient sparkgap for good quenching (hyperbaric gaps work
> excellent with most NST powered coils.  Sparkgap shut off is particularly
> important to
> prevent sec - primary excessive energy translations.  The idea is to keep
> the energy in the sec as much as possible.
>
> (5) Use approx 1,200 turns on the sec.     divide the winding length by
> 1,200 to get the correct wire dia.
>
> (6) Then, select wire size from a wire chart --- use only double build
> insulated wire (very good insulation).
>
> (7) Coat your sec winding with 4-5 coats of Dolph's AC-43 or equivalent.
>
> (8) Use Antonio's very simple 555 oscillator to do the initial tuning to get
> the best possible setting without guessing.
>
> (9) Use my RF probe tuner to adjust coil for maximum output voltage.
>
> (10) John Freau's equation of D (inches) = 1.4 x SQR power (watts) will give
> you an accurate output estimate.  Yes, John uses 1.7 but
> he also used very large (40") sec diameter.   I use 1.4 and it's very
> accurate.
>
> Follow these rules, use good primary caps, and your coil will perform
> excellent on the first fire-up.
>
> Regards,
>
> Dr. Resonance
>
>
>
>
> On Fri, Sep 19, 2008 at 8:48 PM, bartb <bartb@xxxxxxxxxxxxxxxx> wrote:
>
>> Hi Grant,
>>
>> Something that caught my eye is that you "want" the secondary wire length
>> at 1/4 wave. I hope this is only a "want". A coil of course does not require
>> this for best spark performance. If you "really" want the secondary wire
>> length to be 1/4 wavelength (such as antenna theory, radio circuits, etc.)
>> then realize you can't use a top load. A top load will capacitively load the
>> secondary significantly and change the distributed capacitance affecting the
>> coils frequency (far from the wire length). Spark propagating coils are
>> tuned to their fundamental frequency which may be close or far away from the
>> 1/4 wire wavelength situation. The wire length has no bearing on the
>> resonant frequency. The resonant frequency of a coil is a composite of all
>> the capacitances (objects) which affect the coil as well as the inductance.
>> But it doesn't stop at simply object capacitances causing the change. With
>> increasing frequency and with coil geometry (h/d ratio, spacing ratio,
>> etc..), the currents along the length of the coil are also affected. This
>> causes variations in inductance along the coil. If you could measure the
>> inductance of each turn say on a 1000 turn coil, not all turns would measure
>> the same inductance (even though the wire size, geometry, and length are the
>> same). The current affects the emf and thus mutual inductance to adjacent
>> turns, which in turn affects the inductance of each turn itself. If the
>> current varies, so does the inductance. But if you calculate those currents
>> along the form at the fundamental and lump the inductances, you'll find the
>> "real" inductance at the fundamental frequency (which is different than say
>> a DC inductance or even 1kHz LCR inductance measurements). By the word
>> "real", I mean the inductance which is affecting the fundamental frequency.
>> This situation also affects the 1/4 wave wire length precursor because of
>> the inductance at high frequency (which is any frequency above DC which
>> adversely affects the inductance). So even our lowish frequency 100kHz coils
>> will have an effective inductance at the fundamental which will be different
>> than the wire inductance.
>>
>> By all these "words", I'm simply saying that to actually make a 1/4 wave
>> wire length equal to the fundamental is no small task. Wheeler and Medhurst
>> equations won't help here. To do this, you really need a bare secondary by
>> itself. Even a primary coil is seen as an object to the secondary that will
>> change the situation. Coil height to ground, walls, and miscellaneous
>> objects do the same. But to do it in a dual-resonant coil situation can only
>> be done best with just those 2 coils and nothing else. Even using a little
>> small sphere as a top load (to reduce Ctop) affects the coil a tad. It can
>> be done that way, but if you want a spark performing coil, then this isn't
>> the way to go about it. It causes many limitations to the coil design which
>> affects performance.
>>
>> If we ignore the 1/4 wave length wire theory, then we really only need to
>> worry about the fundamental frequency regardless of the objects on or around
>> the coil. This type of design makes for good sparking coils because we now
>> have freedom to play with primary LC values to match whatever fundamental
>> frequency the secondary coil ends up at.
>>
>> So it's hard to give advice. If your set on "1/4 wave wire length" as a
>> precursor, then you have your work cut out for you. Is this really your
>> train of thought on this coil?
>>
>> BTW, 9 to 12 turn primary? No. This is only a "common" value we tend to end
>> up at. Some coilers use over 20 turns and a few only use 2 or 1. What is
>> meant I think is that higher turns adds impedance which helps attenuate the
>> voltage on the primary for less problems and may even help with quenching.
>> But no one is saying this as though it is wrong to use less than 9 turns.
>> Simply that "some impedance" has been noted to help with gap quenching.
>>
>> ALSO, coupling you mentioned. No, coupling is fully adjustable. It's just
>> that you "can" make a coils coupling to whatever you want and still have it
>> even with the bottom secondary winding. For example. Suppose a coil builder
>> is use to building a set distance from primary to secondary. And if the
>> primary is even with the base, he usually ends up about 0.13 k on the
>> coupling for the same coil size. Now say he lowers the primary to reduce the
>> coupling and ends up at 0.11 which he finds best. Well, the primary itself
>> could be redesigned so that when the primary is even with the sec base, he
>> ends up at his found 0.11 ideal value. Thus, he ends up not needing to
>> adjust the coupling. That's all there is to it. But adjusting the primary
>> height is also perfectly acceptable and usual (since coilers don't seem to
>> know what works best for a particular coil geometry).
>>
>> Best regards,
>> Bart
>>
>>
>>
>> Grant Visser wrote:
>>
>>> Hi there,
>>>
>>> Suffering from sleep deprivation or 18 hour research / calc / sim /
>>> research .... info overload at the moment, or BOTH! lol
>>>
>>> With my limited budget I am on a mission to get a solid base design
>>> into my head before I begin throwing things together as I did last
>>> time! *grin*
>>>
>>> The problem is that I have now done so much reading of content from so
>>> many different viewpoints (over the years) that I have confused myself
>>> COMPLETELY! Thus, I humbly beg your assistance ... or at least just a
>>> darn good kick in the right direction!
>>>
>>> I have in front of me 26.06" of 3.543" Plexiglass tubing with 3mm
>>> (0.1181") wall thickness (and don't want to waste a single mm of it!)
>>> lol
>>> Assuming 220V 50Hz mains and 2x 9KV/40mA NST's to power my new
>>> coil(/s) (could add another 2 very soon!!!)
>>> 3Kg of Double insulated magnet wire about to be ordered, ex works in
>>> either 0.335mm (0.013188"), 0.355mm (0.013976"), 0.375mm (0.014763"),
>>> or 0.4mm (0.015748") OD
>>> Have tried my best but am not going to be able to afford the (less
>>> than ideal) caps for a solid MMC so have decided that I will build a
>>> quality bank of vertical plate caps for this coil. They'll never go to
>>> waste!
>>> I have also decided (I think) to go for a balanced split cap tank design.
>>> Until I can find a decent blower I'll be using my current suction
>>> quenched adjustable 2 gap design.
>>> 1/4" copper tubing for the flat pancake primary coil
>>> Oh, and yes I do now have a SOLID and dedicated RF Ground.
>>> I do also have 3phase at my disposal .......
>>>
>>> Although it didn't even cross my mind initially, one of my biggest
>>> stumbling blocks at this point is at what frequency I am going to run
>>> this coil. This quandry started when I read a few posts from awhile
>>> back regarding the primary winding and that it should have no less
>>> than 12 to 15 turns and tuned at no less than 9 turns, and ensuring
>>> that the final diameter or the primary is the same or close to the
>>> winding height of the secondary! Apart from the fact that it actually
>>> made sense to me from a coupling point of view, it also meant that I'd
>>> be able to use a smaller main cap, so I was very happy right up until
>>> I started doing the math / sims and it meant that I was going to have
>>> to use a "SMALLER THAN RESONATE" capacitor which, seems to be an
>>> absolute no no if I have understood the numerous other posts and
>>> articles I have been reading!
>>>
>>> A further brainmangler that has crept in now is the other concept that
>>> I had forgotten about ..... and that is that I would want to design my
>>> secondary to have the length of wire I need to resonate with my
>>> primary at a 1/4 wave! ie. At 220KHz the 1/4 wave is at 1118.1818ft
>>> and I should thus use exactly that length of wire to coil my
>>> secondary. Again this all makes perfect sense ....... right up until I
>>> start doing the math and the sims ....... at which point, depending on
>>> which program I use to model my coil, either the program yells insults
>>> at me, or I simply cannot find a workable solution which allows me to
>>> use all of the data above AND have a resonate coil with a decent hd
>>> ratio! Going much below 220KHz means that I would have to increase the
>>> length of my coiling wire to seemingly crazy HD ratio's!
>>>
>>> Now I do absolutely want to achieve the longest possible sparks from
>>> this coil and I would like it to be an unstressed system allowing long
>>> run times. I would also however like to use this coil to begin
>>> demonstrating and researching the concepts of powering up light bulbs
>>> etc from the ground waves for which I am going to have to construct a
>>> top load with no breakout! With this in mind I was hoping to either
>>> split the 26" form in half allowing me to coil two seperate identical
>>> secondaries and use the second in a magnifier configuration. OR .... I
>>> was even considering (but had not yet begun much research) using the
>>> form for a BIPOLAR coil!
>>>
>>> I do realise that 3.5" is not exactly a MEGA COIL but it did seem to
>>> me that it could be a nice little testbed to get me started with some
>>> of the more interesting experiments! ???
>>>
>>> SO! Thats where I stand at this point! More confused than ever and
>>> really hoping that you will be able to help me back onto the straight
>>> and SPARKY!
>>>
>>> Grant Visser
>>> Randburg, South Africa
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