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Solid States Devices => Tesla Technologgy => Topic started by: Farmhand on October 26, 2013, 04:02:48 AM

Title: Tesla coil Build comparison. (Proof of ability)
Post by: Farmhand on October 26, 2013, 04:02:48 AM
Hi all, I propose that there be a comparison of the best "Tesla Coil" type resonant transformers, or "Tesla Transmitter" type resonant transformers, (same thing).

I suggest all those who have built or are building such transformers in the medium power range say from 400 Watts to 1000 Watts, should show pictures and schematics of their transformers and supply circuits, as well as explain any valid queries about them.

To my way of thinking this is one way of sorting the wheat from the chaff, and showing who can do what and who is all talk or have no will to show anything.

Any type of "Tesla" type transformer/Transmitter would qualify, eg, it could be a three coils design like mine or a regular Two coil arrangement like Tinsel has or a spiral type transformer also. All can do the same things.

We ought to have some basic requirements to qualify in the first place to take part in this comparison of a few of the different parameters, eg. the "Quality Factor" or "Q and input power, power factor ect. ect.

1) I say the input power " apparent" should be at least 400 Watts (real power could be less).
2) The elevated terminal voltage should at least reach the 250 000 volt area.
3) With a "break out point" or "leak point" the free arcs to air or to a grounded object should reach at least 200 to 300 mm and be frequent (seemingly continuous one after the other).
4) The transformer should also have an elevated terminal which is capable (without a leak point) of holding on it "without leaking off ", all or the vast majority of the charge placed on it, to show the transformer is more than a spark making machine.  ;)
5) The input power factor should at not point be less than 0.5 ,
6) Some kind of natural media energy transfer of single "man made wire" transmission line type power transfer ability would also be good to see, possibly using another transformer, I don't see this as necessary, but would be good to see, however not the point to the exercise.

In my opinion on many of the forums including this one I see far too many people claiming to know this and that but are mistaken or just plain wrong, making assumptions or misinterpreting Tesla's writings or quotes.

Let us see who can build the one thing most of this talk centers around, and not just toys, some powerful Transformers/transmitters.

I know of two of us that have transformers capable of entering already built and operational. One being of course the talented Tinsel Koala, and the other being myself.

None the less I will still need some time to put together a better video showing the (build, measurements of the L-C-R) and operating measurements ect.

I can say two things.

1) Any who are not comfortable building and using such device in my opinion have no call to be commenting on the subject so much and should not build if not comfortable with the energies and dangers involved.

2) Those of us participating in this comparison should discuss a reasonable and agreed upon set of measurements ect. to take and perform on the devices presented.

I say we should measure and show the values of the Primary and Secondary L-C and R, the resonant frequency, input power and power factor, as well as the calculated "Q", among other things, before even showing working demonstrations.

Any Takers, or shall I not bother with taking the idea/challenge any further ?  :)

Regards.

P.S. To clarify further, I would propose that there be discussion on a set of valid points or "requirements" for a particular entry to be a "valid entry".

Then, a start point. for entries or "exhibits' could begin, the intention being that it is not a competition as such but a comparison as well as a database, there would be no end point only a starting point, as well there would be no winners or losers, there would only be "valid entries" or "Non Valid" entries. Only valid entries should be seen as being in the comparison, those with invalid entries should be prepared to remove the posts or entries when the majority deems it best.


..

2nd, P.S.  :). Basically I am saying the devices compared should be pursuant to or "fit the bill of" the "Transmitting" devices described in any of these following Patents in reverse order of patent date.

1).  Patent US1119732 -  http://www.google.com/patents/US1119732

2). Patent US787412 -  http://www.google.com/patents/US787412

3). Patent US649621 - http://www.google.com/patents?id=CLJIAAAAEBAJ&printsec=abstract&zoom=4#v=onepage&q&f=false

Don't be fooled by the hype, all three transmitting devices can be used in the same ways, if designed to do it, they are resonant air cored transformers with elevated capacities.

..
Title: Re: Tesla coil Build comparison. (Proof of ability)
Post by: TinselKoala on October 27, 2013, 03:54:18 AM
Here's one I built quite some time ago, specifically as a power transmitting research station. It uses a small NST, 6 kV at a few mA, for the primary supply and a 3-element adjustable stationary gap. For transmission performance the gap is adjusted until it is just barely open, hardly any gap at all and very silent operation, so the input power stays very low, less than 75 watts from the mains, 40 being typical.

For more traditional "sparky" performance the gap is opened up quite a bit for a noisy spark, and the coil then makes a thick ropy blue power arc-spark between the top knob and the nearby grounded discharge electrode. I am sure that blowing the gap with compressed air would improve the performance in this mode, but the 3-element gap made from brass and stainless steel hardware works pretty well.

The capacitors are 400 pF, 30 kV strontium titanate doorknobs arranged in a series-parallel arrangement that can be easily configured for a few different total capacitances, and the primary tap can also be adjusted. This allows the coil to be tuned to different top capacities and spark-gap settings. The coil typically operates at about 1.8 MHz, iirc. (It's up there on a high shelf in its box, I haven't had it down to run it in years.)

The whole thing breaks down easily and packs into a 13 x 13 x 28 inch wooden box I built for transport.

I know this coil doesn't fit into some of the power parameters you listed, and I don't really intend it as an "entry" in your comparison, I'm just putting it up here for the record, and perhaps to inspire others to build more powerful coils.

Title: Re: Tesla coil Build comparison. (Proof of ability)
Post by: Farmhand on October 27, 2013, 05:21:23 PM
Another very nice transformer Tinsel, Nice piece of work. I hope when i get well I can put more time into "Period" presentation of some devices.

I think that coil would fit most parameters.

Anyway I'm in no hurry like I never am. But I do intend to set up my big coil and some smaller receivers for a BBQ demo/entertainment, I don't drink so no drunk operation of deadly equipment problems there.  ;D When I do I'll get some pics and video.

I intend to prepare a bit by allowing more power and going to maybe 1200 Watts input, I may possibly increase the terminal capacitance as well and tune the rest accordingly, most likely resulting in an increase of the primary capacitance and a decrease of frequency, hopefully both allowing for increased streamer length with a break out point and streamer suppression without one.

One thing I may have left out is the transformer should be at least able to operate for about 1 minute continuous at any power it is capable of. And show some form of other usefulness such as power transfer, power supply or in my case my transformer can be used as a "spark gap transmitter" to send Morse code with a Morse key installed..

Also the comparison should allow for entries that cannot show input power well, but can show a well measured output within the power range.  ;)

Thanks for the reply Tinsel, I hope you can maybe show the Tinsel coil at a later date as a solid state entry ? If you can control the streamers that is. heheheh, gotta love them streamers though.

The hope is that maybe more people will put in the effort to actually build a powerful transformer and find out what is actually involved in getting one to work well.

Although the fundamental principals between a Joule Thief and a fully fledged Tesla Coil in the 500 Watt to 1200 Watt range are the same/similar, building the latter to be reliable and somewhat safe and non damaging to sensitive stuff in the area is not so easy.

The transformer below is restricted to about 650 Watts input as the supply circuit stands.

Cheers

P.S. Just for the record and to show looks are not a big issue to me.  :-[
Here is a picture of my "Outlaw Coil" as I like to refer to it in spite of the Dollard crew.  ;D
And a Fine smooth looking Arc from it as well.

Oh and I guess I may as well include the supply circuit here now as well in blue.
Title: Re: Tesla coil Build comparison. (Proof of ability)
Post by: Farmhand on October 27, 2013, 05:55:13 PM
I guess one of the points to this thread is that I would like to see who has built something like this, who actually can build something like this, who is prepared to put in the effort to build one and run it at fairly high power.

Since this device or similar is the backbone or cornerstone of a great many Over Unity claims, and many claims by people on behalf of Nikola Tesla that this kind of device is a "free energy machine" or claims that these are something that "creates or amplifies Energy", I figured all those in future who make such claims should have a thread where they can point to the post number of the device they built that exhibits the behavior they claim or speak of.

I'll bet there are none of those posted here though.  :)

Cheers

P.S. I should also say that not fitting in with one or two of the valid entry points should not discourage anyone from posting what they think will come close when some of the finer parameters of the transformers are determined at a later date. The line is grey here and wide.  ;D

.
Title: Re: Tesla coil Build comparison. (Proof of ability)
Post by: TinselKoala on October 27, 2013, 07:20:16 PM
That's a nice setup, looks very "retro". I like the way you've spread out the upper windings on your secondary, to reduce arcing-over the last few turns. I've done this on my big 2kW SGTC as well. One of these days I'll have to get that sucker all dusted off and running again.

Meanwhile for the record, here's the TinselKoil 2.0, the solid-state TC. I don't have a complete schematic handy but the block diagram and the annotated board layout should give enough info for a builder to work with. This coil can work with around 1.5 kW input from the mains, and it makes scary big power psarks. It can also be audio-modulated. Unfortunately I don't have this coil with me at the moment, it is in storage in Canada along with a lot of my tooling and test kit.



Title: Re: Tesla coil Build comparison. (Proof of ability)
Post by: Farmhand on October 27, 2013, 08:23:26 PM
As far as Topload materials and construction goes, I was thinking of using some "ribbed" aluminium ducting or some copper tubes arranged on a wooden bracket to form a virtual large capacitor from smaller bits. My thinking is the ribbed ducting will not hold charge so well. Making larger top loads is a bit of a pain. I know I can tune around it, but I want to increase the size and capacity by a bit more than double what it is now and be able to change out the topload and switch the primary cap bank capacity, then a quick tune and run at a different frequency.  ;) I want the Maximum  primary capacitance to be about 40 nF. And if charged to 7500 volts 800 times a second that would be about 1.1 joules x the break rate of up to over 800. So Maximum input should be in the range of around - 880 to 1200 Watts. I hope.

I do have more topload rings the same as the one on it but when added on top of each other the capacitance secured is not so great, I don't think. Anyway, BBQ is a ways off yet.

Cheers
Title: Re: Tesla coil Build comparison. (Proof of ability)
Post by: TinselKoala on October 27, 2013, 09:17:19 PM
The topload on the TinselKoil 2 is two big "baby moon" hubcaps taped together with aluminum duct tape. It is very smooth, being bright chrome plated, and it's steel so it's easy to stick a breakout point to it with a magnet. I got a dozen or so of the Chinese baby moons from Active Surplus in Toronto for a couple of dollars each. I also use them on my big Van De Graaff machines as toploads and bases. They work great! A set of four, put together into two flattened spheres and stacked, would come very close to your desired 40 pF capacitance, I think.

Four for 68 dollars from JCWhitney:
http://www.jcwhitney.com/baby-moon-hub-caps/p2031512.jcwx?filterid=u0j1
Title: Re: Tesla coil Build comparison. (Proof of ability)
Post by: Farmhand on November 02, 2013, 10:10:58 PM
Hi Tinsel, Yes I like those hub caps they look real nice. I'm sorry did I say 40 pF toplaod ? I meant 40 nF primary capacitance, maybe I'm confused. 40 pF top load might just correspond to 40 nF primary capacitance with my transformer. I think you get what I mean anyway though, I could stack two top loads and have a primary bank that can be changed from say 20 nF to 40 nF with a switch, then I could operate at one lower frequency with the two top flat spheres and 40 nF primary capacitance or whatever it takes and then remove one top sphere and switch to 20 nF in quick time and with a bit of a tune it could then operate at the higher frequency. If I could get 600 Khz or 400 Khz or something like that with a simple change it would be cool. I can also adjust the resonant charging coil inductance.

That makes the baby moon hub caps look really appealing over and above the aluminium ducting, which would be "electrically" smooth as you say, but not adjustable without more trouble.

I fear that if I up the power input too much my diodes will give out. If I heat sink the diodes with some simple wrap sinks might that help I wonder ?

And what is your opinion on a ground plane just under the platform the coil sits on ? I did have an aluminium sheet just under the platform and it was connected to ground but I removed it, not sure if it made much difference except maybe to tuning, if the grounded plane was too close could it drain power from my primary coil ? I was about 20 mm below the primary with 12 mm of plywood between. I can draw a simple sketch to show it if my description is not clear. I thought it was a bit close and increased input but decreased performance.

Cheers
Title: Re: Tesla coil Build comparison. (Proof of ability)
Post by: TinselKoala on August 07, 2014, 04:36:39 AM
Look! A ONE MILLION VOLT Tesla coil! !!!! (sic)

http://www.youtube.com/watch?v=-qKl_JhNVWM
Title: Re: Tesla coil Build comparison. (Proof of ability)
Post by: Neo-X on August 07, 2014, 02:00:44 PM
Hellow 2 all.. I have a question, is it possible to make 100,000 sparks in 1 second?
Title: Re: Tesla coil Build comparison. (Proof of ability)
Post by: TinselKoala on August 08, 2014, 02:34:43 AM
Hellow 2 all.. I have a question, is it possible to make 100,000 sparks in 1 second?

Yes.

But there are pitfalls. If you are trying to make a spark gap circuit controller that operates at that rate, like a rotary spark gap, or a fixed gap in a 100 kHz resonant primary tank circuit, you  must avoid the "power arc" that results when conductive gases/plasmas remain in the gap and short it out. This is not as easy as it might seem at first glance.
The reason my MOT-DC SGTC works so well with only one MOT and only 2kV in the primary circuit is because of the spark gap. I use an intense blast of compressed air to "blow out" the spark in the simple 2-element adjustable gap, and prevent the power arc from forming.

http://www.youtube.com/watch?v=yjc9ilOAaQU (https://www.youtube.com/watch?v=yjc9ilOAaQU)

This coil easily produces quasi-continuous (really split at line frequency)  18-inch high-energy sparks to ground or the conductive walls of my experimental chamber. The gap performance is probably the most critical aspect of this kind of resonant system.

http://www.youtube.com/watch?v=tTLFlRhsa5U
Title: Re: Tesla coil Build comparison. (Proof of ability)
Post by: Farmhand on August 08, 2014, 05:17:07 AM
Look! A ONE MILLION VOLT Tesla coil! !!!! (sic)

http://www.youtube.com/watch?v=-qKl_JhNVWM

Looks like it's barely putting out a inch or two spark at quite low frequency, not nearly 1 million volts. Theoretically my transformer
could develop 1.7 million volts but the charge leaks off way before then. I can run it at about 300 Watts input without it sparking
or leaking any carona, but without any load more power causes leaks as it must.

Neo-x, my coil used a rotary spark gap that could run up to a couple of thousand breaks per second, but it makes best sparks at
a lower break rate of like 400 BPS, a faster break rate supplies the energy more consistently and less abruptly if the input is
restricted.

Solid state arrangements that work at the actual resonant frequency and input power with every half cycle or every cycle produce
a different type of discharge which is like a spray rather than quick violent jets (sparks) discharge.

I just realized I didn't link to my clip where I vary the break rate of the rotary gap. In this clip I vary the break rate up to over
1000 BPS. It shows the difference between regular sparks and a "rope" like discharge to ground, like a slow motion lightning
strike to ground. The sound is from the terminal sparks the spark gap is fairly quiet.

Varied break rate.
https://www.youtube.com/watch?v=1nkJtrKCdFg

..

Title: Re: Tesla coil Build comparison. (Proof of ability)
Post by: Neo-X on August 08, 2014, 06:00:02 AM
Thanks Farmhand and Tinsel your comment helps me alot. Now i can start to build my own tesla coil.  ;)
Title: Re: Tesla coil Build comparison. (Proof of ability)
Post by: TinselKoala on August 17, 2014, 08:53:49 PM
TinselKoil VII first light.

http://www.youtube.com/watch?v=t2sldgRoZqU (http://www.youtube.com/watch?v=t2sldgRoZqU)

I just built this one over the past two days. I was inspired by Tommy Reed's simple flyback driver "Tesla coil" and so I wanted to make a complete Tesla coil using one for the primary supply. I used a more efficient oscillator geometry and made a matched primary and resonator according to the calculator linked below.

This is a hybrid ss-sg coil powered by 24 VDC input. It uses a ZVS oscillator with 2 ea.  IRFP260N mosfets to drive a TV flyback transformer through a 10 turn, centertapped primary winding on the ferrite, which produces the HV for the primary tank circuit. The ZVS cap bank is about 1.4 uF and it drives the flyback at around 30 kHz which is the best output frequency for this flyback. The Tesla tank capacitor bank is 10 ea. 400 pF 30 kV strontium titanate doorknobs in parallel for 4 nF roughly, the primary is 9 turns on a 4 inch diameter form for 9 microHenry roughly, the secondary resonator is about 975 turns of #27 on a 1.68 inch diameter paper mailing tube, soaked in polyurethane before winding, then coated with several coats after winding. The coupling is about 0.12, quite loose. The spark gap is a 4 element parallel-tubular type of brass tube bits. The top capacity is a couple of 5 inch cake pans taped together and the sphere with breakout point is a Chinese chime exercise ball.

I used the calculator here:
http://www.classictesla.com/java/javatc/javatc.html (http://www.classictesla.com/java/javatc/javatc.html)
to calculate the basic dimensions and values. The coil isn't completely tuned and there are still some problems with the gap, but I think it is decent, so far. When it is completely tuned and I bump the input up to 48 volts... look out!

Ah, I love the smell of ozone in the morning.

 8)
Title: Re: Tesla coil Build comparison. (Proof of ability)
Post by: Farmhand on August 17, 2014, 10:03:25 PM
Wowsers, I like that one too ! How many is that now and are they all in some significant way different to each other ?

Stand back.  ;D
..

Oh can you get a still image if you get the time/chance, please ? I like the stills. Fascinating. I use some for background images for
the computer desktop, and I should make a Giff. screensaver or something. Anyone know how to do that already in Gimp 2 ?
.
And a tip from one of the guys posting in the Figuera thread about solving the over sized images problem. There is a "ADD ON"
for Firefox browser which allows us to resize images on the web page and if we do all the images on a certain page then we can
read the words without scrolling sideways. It's a really handy Add on.

Image Zoom 0.6.3 for Mozilla Firefox (web page image resizer)
https://addons.mozilla.org/en-US/firefox/addon/image-zoom/

..
Title: Re: Tesla coil Build comparison. (Proof of ability)
Post by: TinselKoala on August 17, 2014, 11:48:25 PM
@Farmhand:
My "grownup" Tesla coils, all different, all showing different principles:
#0: A 2 kW-class monster with rotary spark gap, big NST primary supply, safety gap, chokes, an Amplifying Transmitter (second secondary) coil, the whole nine yards. Haven't run it in years.
#1: A SolidState coil using TL494, a current driver, trifilar phase transformers, mosfet H-bridge.
#2: Major improved version of above with low-aspect-ratio resonator and double chromedome top capacity.
#3: SassyClassE SSTC: a low-aspect-ratio Class E single-mosfet DC-input SSTC, a real field-pusher.
#4: TKSlayer, my version of the Slayer Exciter simple low-voltage SSTC using NPN power transistor.
#5: MOT-DC Blown Gap SGTC, a unique single-MOT, HV FWB-rectified, compressed-air-quenched spark gap coil, 1 kW class, running at about 1.5 MV, actually.
#6: TKMiniSlayer, a bottom-loaded, tunable miniature version of the Slayer SSTC, using NPN power transistor, a field pusher.
#7: TinselKoil VII, the present design, a 'design proof-of-principle' built according to calculated parameters to see if they really worked, a hybrid SS-SG coil. DC input of 24 volts, ZVS dualing mosfet flyback driver at 30 kHz, flyback feeding traditional SGTC design with 4 nF SrTiO tank caps and 8-9 uH primary, ringing a loosely coupled secondary of 975 turns of #27 at somewhere between 600 and 800 kHz. The calculator used to design the coil says it should reach 1.15 MV at the top of the resonator (when fully tuned of course!)

 8)

ETA: Can you believe it? I forgot one, about #0.5, the portable transmitting plant that I use for a logo sometimes. It's in a crate on a high shelf.

Off to the bathroom to do some more runs... Coil runs I mean, silly!

How's THIS for "Overunity in VARs".....  ;)     The calculated theoretical VI profile of the 24-volt input TinselKoil VII:
Title: Re: Tesla coil Build comparison. (Proof of ability)
Post by: TinselKoala on August 19, 2014, 12:53:40 PM
Getting there:
http://www.youtube.com/watch?v=jsfW6tT3cQA
Title: Re: Tesla coil Build comparison. (Proof of ability)
Post by: TinselKoala on August 20, 2014, 07:59:09 PM
Making progress... this is just a test of the GIF animator... if it doesn't run inline please download and watch...

Not bad for 24 volts input, there are some streamers over 12 inches in there.

ETA: OK that didn't work, so here are some stills.
Title: Re: Tesla coil Build comparison. (Proof of ability)
Post by: TinselKoala on August 21, 2014, 07:10:11 PM
Erratum: At about 2:05 I say "drains" when it should be "sources" that the negative rail is connected to.
http://www.youtube.com/watch?v=d_VtbfhyvUU (http://www.youtube.com/watch?v=d_VtbfhyvUU)

 8)
Title: Re: Tesla coil Build comparison. (Proof of ability)
Post by: Farmhand on August 21, 2014, 09:12:11 PM
Nice, it has those smooth silky discharges like flames. I like it.

..
Title: Re: Tesla coil Build comparison. (Proof of ability)
Post by: Kamil on August 21, 2014, 11:16:40 PM
Hi Guys,
For last two years I have experimenting with Tesla coils but always kept them small size ,powered by flyback which was nice and fun but now I feel like I like to move forward and build some think bigger but relatively easy just to keep cost down.
I have few MOTs and thinking about useing them as a power supply for my new project.
Can you give me some advice plus schematic which will be best to start with building big Tesla coil ?

P.S. You can visit this website:
http://isparktube.com/ is really good and I have posted there few of my projects

Regards

 :D
Title: Re: Tesla coil Build comparison. (Proof of ability)
Post by: MenofFather on August 22, 2014, 09:46:06 AM
Making progress... this is just a test of the GIF animator... if it doesn't run inline please download and watch...

Not bad for 24 volts input, there are some streamers over 12 inches in there.

ETA: OK that didn't work, so here are some stills.
That curent is consumptio?
Title: Re: Tesla coil Build comparison. (Proof of ability)
Post by: tinman on August 22, 2014, 10:10:27 AM
Nice build there TK.
I bet that would light some CFL's.
Title: Re: Tesla coil Build comparison. (Proof of ability)
Post by: TinselKoala on August 22, 2014, 03:45:26 PM
That curent is consumptio?
I have not yet been able to measure the current draw because it makes my digital meters freak out and I can't seem to find my moving-coil ammeter in all this clutter, if I even still have one. I know several ways to do it but they require some setting up and I've been too busy and lazy to do it. Past experience says that the driver will draw up to 7 amps when a heavy flyback output is demanded. I am using 2 Sealed Lead Acid 12V batteries of 5 A-H capacity each and they are lasting a surprisingly long time so I think that the draw must be less than 7 A most of the time.
Title: Re: Tesla coil Build comparison. (Proof of ability)
Post by: TinselKoala on August 22, 2014, 03:48:09 PM
Nice build there TK.
I bet that would light some CFL's.
It does indeed, lights up the ones in the bathroom fixtures dimly. I haven't yet tried it with the bare bulbs and etc.  But I have found that big sparking coils aren't as efficient as what I call "field pushers" which don't produce visible psarks. By turning the spark gap down to tiny gaps (hard to do with this type) while avoiding power arcs, one can make a sparker into a field pusher and get more range on the E field effect like lighting CFLs with no circuitry at a distance.
Title: Re: Tesla coil Build comparison. (Proof of ability)
Post by: TinselKoala on August 22, 2014, 03:52:27 PM
Hi Guys,
For last two years I have experimenting with Tesla coils but always kept them small size ,powered by flyback which was nice and fun but now I feel like I like to move forward and build some think bigger but relatively easy just to keep cost down.
I have few MOTs and thinking about useing them as a power supply for my new project.
Can you give me some advice plus schematic which will be best to start with building big Tesla coil ?

P.S. You can visit this website:
http://isparktube.com/ (http://isparktube.com/) is really good and I have posted there few of my projects

Regards

 :D
If you are building a Big TC then Farmhand will probably be able to help you more than I can. Lately I have been going in the other direction, my next one will be tiny.
My MOT-DC coil is probably unique in that it uses a single MOT, a HV full wave bridge, and is able to make 18 inch streamers using only the 2 kV output of the single MOT. Most MOT coilers use two MOTs in series to get decent voltage output for the TC tank circuit and they don't rectify the MOT output, I think.
MOTs are far more dangerous than the Neon Sign Transformers, even though they are lower voltage, because the MOTs aren't current-limited. You can do a lot of damage in a hurry, with a MOT.
Title: Re: Tesla coil Build comparison. (Proof of ability)
Post by: TinselKoala on August 22, 2014, 03:56:40 PM
A couple more videos:

http://www.youtube.com/watch?v=T2JWGNCvh80

http://www.youtube.com/watch?v=SXsChNrBn5I

The spark gap performance is the key to success. Winding the coils is easy, tuning to resonance not too hard... but getting the spark gap to work properly is tricky. Each type has its own quirks. Much of Tesla's creative effort at one time was devoted to spark gaps and other kinds of circuit interruptors.
Title: Re: Tesla coil Build comparison. (Proof of ability)
Post by: Kamil on August 22, 2014, 04:36:33 PM
If you are building a Big TC then Farmhand will probably be able to help you more than I can. Lately I have been going in the other direction, my next one will be tiny.
My MOT-DC coil is probably unique in that it uses a single MOT, a HV full wave bridge, and is able to make 18 inch streamers using only the 2 kV output of the single MOT. Most MOT coilers use two MOTs in series to get decent voltage output for the TC tank circuit and they don't rectify the MOT output, I think.
MOTs are far more dangerous than the Neon Sign Transformers, even though they are lower voltage, because the MOTs aren't current-limited. You can do a lot of damage in a hurry, with a MOT.

Thank you TinselKoala for getting back to me. ;)
I visited your You Tube channel and I have to say that I'm impressed with your experiments.
Because you have experience with Bid TC  I will appreciate if you advice me on how to build spark gap for my MOT to make it right and SAFE , and how to protect my secondary from  over arcing because I heart that you can damage your coil in seconds if is not properly earthed .
Will you be able to give me schematic with good details or any from google will do ?
Thanks in advance . :)

Kamil
Title: Re: Tesla coil Build comparison. (Proof of ability)
Post by: Farmhand on August 22, 2014, 09:10:01 PM
Kamil, Very wise to be safe, I always consider safety first and every part of the primary circuit with MOT's in it is potentially
deadly. When I'm experimenting with anything to do with deadly charge on capacitor or high powers at dangerous voltages
I get myself into a routine where I turn off and disconnect the supply, then discharge all the capacitors and jumper them (shorted)
before even considering touching anything, distractions can be dangerous too.
I have 40 uF on my two MOT's to correct the power factor, which can be left with charge on them sometimes, they get 240 volts.
My primary capacitance is small because less than 20 nF due to my fairly high frequency around 760 kHz, that 20 nF gets charged
to almost double the voltage of the output of the two MOT's in series because I use a DC resonant charging circuit, without that
almost doubling of the 4000 v or so to about 7000 v my spark gap doesn't work so good, I think because of the low capacitance
and energy of the primary capacitor bank.   

Building Tesla coils is kind of a very customized thing for most, people build them for different reasons.

Spark gaps are not a strong point for me as I lack a lot of equipment and live out of town. I had to build a wooden frame rotary
spark gap to get a good output from mine. As I just found out the rotor I made from a plastic cutting board for the spark gap is
cracked now so I'll need to make a new gap of some kind.

Almost impossible to build a "safe" Tesla transformer. It's the operator who needs to be safety minded and careful.
I've got my input power restricted by a coil in series with the MOT's that has a fair bit of resistance, my next play with it
will be to remove or reduce the power restriction and fix my spark gap or build a new one, it could do with a better frame
and rotor.

..

Title: Re: Tesla coil Build comparison. (Proof of ability)
Post by: TinselKoala on August 22, 2014, 10:47:16 PM
Yep, all of the above. Safety first, and a MOT is no toy, my small 1 kW MOT coil scares me even more than my full on 2kW NST coil.

Meanwhile, I really didn't like the look of TKVII with that white pvc form for the primary coil, so I made a more traditional "basket" form out of some mahogany plywood. It looks a lot better I think and is certainly  more  "classic" in appearance.

I also temporarily installed the ground electrode to see what kind of gap breakdown I would get. It spans the 15 cm gap easily enough, but not larger at the moment. So I am guesstimating only about 500 kV output.  :-[ Of course the electrode detunes the thing fairly drastically.

http://www.youtube.com/watch?v=aIZClhoU2Xk
Title: Re: Tesla coil Build comparison. (Proof of ability)
Post by: Pirate88179 on August 23, 2014, 11:07:47 PM
TK:

The photo above of your build is beautiful!  Everything is aligned and parallel and level and demonstrates your craftsmanship very well.  I do not have enough knowledge, or balls, yet to build a Tesla Coil, but I am enjoying your videos.

Bill
Title: Re: Tesla coil Build comparison. (Proof of ability)
Post by: TinselKoala on August 24, 2014, 01:00:37 AM
Thanks Bill! But... heh.... don't look too closely! Angles aren't too precise, dimensions vary, things only line up and fit one way... I'm working with an old small Ryobi bandsaw, a drill press and a T-square and that's about it. And I can't tell you how many times I've screwed something up by trying to make it just that little bit better.

Like that coil form. I should have made 3 rings instead of two and put one in the middle, because the coil wire pulls the "waist" of the thing in until it looks like a dress form or a dice cup or something. I finally broke one of the vertical pieces and had to re-glue it, while re-routing the wiring and adding a turn, after that picture. And I'm still not convinced that the 4 dowels in the corners of the base unit are actually vertical, my glasses distort so much the whole thing looks to me like it's leaning over.

But it's fun building and seeing something come together in reality as I envision it in my mind's eye. It is especially gratifying to me _under the circumstances_ that I designed the coil using a comprehensive Tesla coil calculator based on conventional electromagnetic theory, and the coil works as calculated. The tuning is so very narrow and precise that even the coupling of 0.122, set by the winding heights and spacing, is critical for it to work right. As I clean it up and get the spark gap working better it approaches the predicted performance given by the calculator.

The spark gap is critical, and this gap is now working well. I now set the 5 individual gaps with a 0.020 feeler gauge so that they are all even and all parallel. This gives a total gap of just 0.1 inch and gives great performance in streamer length, less noise in the audio frequency and greater spectral purity in the RF.

Did you notice? I have attracted the lone Drive-By Thumbs-Downer Troll, or another one, and some sock puppets. Of course they are too cowardly to leave any reasons for their droppings, knowing that if they don't have a cogent argument I will ban them at the first sign of trollery or insult. 
I am greatly amused by this activity. In fact I don't think I'm reaching my Target Audience unless little Trolly-poo wakes up one of his sock puppet accounts and leaves a little dropping.
Title: Re: Tesla coil Build comparison. (Proof of ability)
Post by: TinselKoala on August 24, 2014, 02:55:51 AM
 8)
Title: Re: Tesla coil Build comparison. (Proof of ability)
Post by: TinselKoala on August 24, 2014, 12:49:16 PM
Here's an interesting image.

The exposure was 1/13 second, or 0.0769 sec.
I count 31 individual psarks in that time, in that nice fan portion. This means that the spark gap is firing at a rate of (31/0.0769) Hz... or 403 Hz.

Coincidence?

 ;)
Title: Re: Tesla coil Build comparison. (Proof of ability)
Post by: Pirate88179 on August 24, 2014, 06:20:58 PM
TK:

I have never seen anything like that...totally cool.  Those fan like sparks are a work of art.

Bill
Title: Re: Tesla coil Build comparison. (Proof of ability)
Post by: Kamil on August 25, 2014, 06:00:52 PM
Kamil, Very wise to be safe, I always consider safety first and every part of the primary circuit with MOT's in it is potentially
deadly. When I'm experimenting with anything to do with deadly charge on capacitor or high powers at dangerous voltages
I get myself into a routine where I turn off and disconnect the supply, then discharge all the capacitors and jumper them (shorted)
before even considering touching anything, distractions can be dangerous too.
I have 40 uF on my two MOT's to correct the power factor, which can be left with charge on them sometimes, they get 240 volts.
My primary capacitance is small because less than 20 nF due to my fairly high frequency around 760 kHz, that 20 nF gets charged
to almost double the voltage of the output of the two MOT's in series because I use a DC resonant charging circuit, without that
almost doubling of the 4000 v or so to about 7000 v my spark gap doesn't work so good, I think because of the low capacitance
and energy of the primary capacitor bank.   

Building Tesla coils is kind of a very customized thing for most, people build them for different reasons.

Spark gaps are not a strong point for me as I lack a lot of equipment and live out of town. I had to build a wooden frame rotary
spark gap to get a good output from mine. As I just found out the rotor I made from a plastic cutting board for the spark gap is
cracked now so I'll need to make a new gap of some kind.

Almost impossible to build a "safe" Tesla transformer. It's the operator who needs to be safety minded and careful.
I've got my input power restricted by a coil in series with the MOT's that has a fair bit of resistance, my next play with it
will be to remove or reduce the power restriction and fix my spark gap or build a new one, it could do with a better frame
and rotor.

..

Hi Farmhand,TinsenKoala

Thank you for the advise on capacitance and safety ,
My flyback coils never scare me but MOT is different level but if I want to go bigger/stronger then I need to try it out and see how it goes.
Will start testing ASAP and if I will find questions and problems will come back to you guys ,lucky me that I have some body to ask :)
The schematic which I think should be appropriate for this build:
 http://isparktube.com/images/phocagallery/Schematics/thumbs/phoca_thumb_l_mot%20tesla%20coil.gif
Let me know what you think about this schematic?
Regards
Title: Re: Tesla coil Build comparison. (Proof of ability)
Post by: TinselKoala on August 27, 2014, 04:52:02 PM
@Khamil
Yes, that's a standard dual-series-MOT SGTC design. I'm sure it will work... but please be aware that this is a _very dangerous_ design and extreme care must be taken that the secondary output discharge cannot possibly reach the primary (MOT secondary) output wiring, or the mains (MOT primary) input wiring. Once a plasma forms it is highly conductive, and even though the secondary discharge might itself be "safe" because of the high frequency and spectral purity, the plasma will happily also conduct the mains frequency high current from the MOTs if you allow it to.  Distance is your only safe insulation, and plenty of it. Do not trust insulating materials when you are dealing with voltages over 5 kV. Distance is your only safe insulation. Keep one hand in your pocket when operating (not kidding, this will prevent you from taking a shock across your chest which might kill you). Always, always, discharge your capacitors before doing _anything_ to the circuit. The very first thing you should make is a discharge wand, that you can use to short the caps to discharge them. You can see me using a small discharge wand in my Jacob's Ladder Effect of Capacitance video, for example; and also a long screwdriver with a well-insulated handle can work well for this purpose, as I am using on my TKVIII work.
If this is your first large or mains-powered TC... you must be very very careful, because your first mistake will likely be your last one. The dual MOT-powered coil is much more dangerous than current-limited NST powered coils are, even though the NST makes higher voltage.

Distance is your only safe insulation. Keep one hand in your pocket. Make a discharge wand before you do any energizing of HV capacitors. And tell someone what you are doing and have them check on you while you are working with this kind of apparatus.

And be sure to take plenty of pictures of your build, and of the spark output! I wish you the best of luck, safety and fun! Distance is your only safe insulation!
--TK