Re: Tesla Coil Help!! Got only 3 days left to complete my project, plsss help
Tigeris, Mon Mar 09 2009, 05:11PM

The glass bottle thing i cant help you with much...im using the same thing and not getting good results with them. As far as the Xformer, do you have any pictures of it you can upload? The outputs on the transformer are both hot ( + ) there is no real "neutral". Try googling "tesla coil plans"

Re: Tesla Coil Help!! Got only 3 days left to complete my project, plsss help
LithiumLord, Mon Mar 09 2009, 06:37PM

so, first of all - 1.05uF?! Either there is something wrong with your measurements or that beer bottle is more of a beer storage facility ;)
The xformer usage schematic is not really any good at all btw - not only there's no RF filtering to protect the NST against any primary currents, but also the capacitive secondary feedback current is cut off-ground with NST acting as a choke. Any primary strike means a certain death of your NST in this case, without those strikes it will not live any long either however.
For your xformer, just ground the neutral output to a good RF ground, bypass it to one or both primary inputs with a cap, set up a protective gap across the NST output and, preferably with an RF-filter, rig it to the coil circuit.

Re: Tesla Coil Help!! Got only 3 days left to complete my project, plsss help
Ultra7, Mon Mar 09 2009, 06:38PM

Problem 1.
You didn't make just one beer bottle cap did you?
Read this.

Pay close attention to the part where he describes the salt water capacitor.

Problem 2.
The Neon Transformer you have should have two small insulated terminals labeled L and N.
Those are for Line and Neutral.
Then it should have two larger insulated terminals without any labeling = These would be your HV out.
Finally there should be a threaded bolt attached to the outer case = this would be ground.
Remember: Not all NST's are created equal though, so we should have a picture of yours to find out what you have. For instance, if you have a Switch mode NST, then you may not ever get your coil to work.


Problem 3.
You probably should do some more reading, as building a Tesla Coil can be very dangerous.
Here are some good sites.
Safety


Deepfried Neon


Tesla map

Re: Tesla Coil Help!! Got only 3 days left to complete my project, plsss help
ElectricalEngg., Tue Mar 10 2009, 11:01AM

Now I am scared
Just when I thought I have everything under control


@Tigeris:I will get the pics of the transformer as soon as possible but I guess probably on day after tomorrow coz its in my college where I work on it and it will be closed tomorrow due to local festival.

LithiumLord:I have been reading on internet that the capacitance should be very low but well this is what I got :(
1.05 checked with various instruments even with a LCR meter.
and for the RF filter thing can we just use an MCB or fuse?
rest I am a bit confused right now with what to do and I have to finish it within 10 days from now :(

Ultra7: I am not sure now :( but well I can get the bottle capacitors not that tough, I can make them at home :)

and for transformer, well all the terminals have threaded bolts :(
There are total 4 terminals , 2 on input and 2 on output
Ill post the pics you mark what is what for me thx
and Ill also confirm the supplier if possible on phone, cant visit him, he lives 7 hours away from me :(

and yeah I already read all those sites :)
I have collected too much data on the internet and well now just have to put it into practical use :)

I operate stuff only under my teachers supervision just to be safe :)



Edit: Ok I thought I cant wait for that long coz my teachers will get angry if I will not work on day after tomorrow on my project.
so here I found an exact transformer shape as mine and well showed how terminals of mine are :)



Now ok just to make it easy for me
can someone roughly make the diagram using this transformer and tell me how to connect this in circuit. :)

so help me , I am really too scared now, if I don't make it now then I am like dead as just about 15 days ago when I explained the project properly to my teachers, they not only said me to build it in fact I am not gonna represent my college in tech-fest(just like a science fair) in like first week of april.

so basically if I am unsuccessful, then I am doomed:-((

Re: Tesla Coil Help!! Got only 3 days left to complete my project, plsss help
LithiumLord, Tue Mar 10 2009, 11:32AM

Of course it may be 1.05, but surely not uF ;)
As for the xformer, the "IDK" (XD) input to the left goes to your RF ground, the one to the right goes to the neutral mains terminal, bypass them with a 0.1-1uF cap mains-rated or bigger (500v feels right) so any stray inductance will not cause any spikes across the windings. Now just rig a protective gap (no midpoint) across the secondary (left "IDK" to live output) - and rig the rest of the coil circuitry across the output. As for the filter, the most simple one is just a choke to be added into the coil's live wire, in this case also a small cap across the NST output is highly recommended.

Re: Tesla Coil Help!! Got only 3 days left to complete my project, plsss help
Steve Conner, Tue Mar 10 2009, 12:31PM

If the transformer only has one HV output terminal, then it isn't "mid point grounded". A mid point grounded transformer would have two HV terminals with large insulators.

If we assume that it only has one HV terminal, and the other end of the HV winding is connected to the case, then the way to hook it up is like LithiumLord said. The two terminals on the left are the HV output, and the two on the right are the mains input.

The schematics posted here are terrible, the transformer should connect across the spark gap, like so: And when wired like this, a small coil may be OK without a safety gap.

1.05nF is about right for a beer bottle cap. 1nF = 0.001uF

Re: Tesla Coil Help!! Got only 3 days left to complete my project, plsss help
ElectricalEngg., Sun Mar 15 2009, 01:13PM

sorry for late reply firends :( was having probs with internet lately

and yeah sorry again I just want to confirm the final reading for the capacitor
Its 1.05 pF
not uF sorry for that confusion :(


and yeah I cleared the confusion of transformer terminals

here are the final terminal configuration



and the circuit diagram I made acc to these terminals, friends pls confirm this circuit diagram for me :)




@LithiumLord would a safety gap be better than a choke?
and the small cap across output you said, whats that for? pf improv?



and yes The Capacitor

Friends I wanna ask if a capacitor made with MMC capacitors of TV will better?
They are pretty cheap but I have one problem, those have high capacitance value, but I read abt tesla coil that the capacitor should have low capacitance value:-((



and yes I was making a spark gap like this



the real one will have screws infront of eachother and not at any angle like in the pic lol

is it ok?
the screws are of copper and are adjustable. :)
I know might not be as efficient, but easy to make:-p

My current configuration of Tesla Coil Is:

Transformer: Neon Sign Transformer, 220/6kV, 30 mA, mid point grounded to case.

Secondary Winding: 28 Guage Wire wound on a 2 inch dia PVC pipe. 1050 turns.

Primary Winding: Not wound yet but to be wound on 4 inch dia PVC pipe with a 14 Guage Copper Wire.

Capacitor: Still to decide between the bottle capacitors or MMC capacitors. Made one bottle capacitor and got a capacitance reading of 1.05 pF

Spark Gap: Static Spark Gap(adjustable screws type)

help me guys I only got this week left :(

I am happy that I finished secondary ^_^

Thanks again for your help friends, you all are great:-)

Good Day
Kashish Malhotra

Re: Tesla Coil Help!! Got only 3 days left to complete my project, plsss help
TheBoozer, Sun Mar 15 2009, 04:10PM

1.05pF ????

1000 times that would be 1.05nF, and that's still so little bang energy. :(

Re: Tesla Coil Help!! Got only 3 days left to complete my project, plsss help
ElectricalEngg., Sun Mar 15 2009, 05:40PM



Yeah I know thats why I thought I was looking for MMC capacitor bank

Re: Tesla Coil Help!! Got only 3 days left to complete my project, plsss help
ElectricalEngg., Tue Mar 17 2009, 01:36PM

friends I only have 3 days left help :(
any suggestions on mmc capacitor bank will be very helpful thx again ^_^

Re: Tesla Coil Help!! Got only 3 days left to complete my project, plsss help
Sulaiman, Tue Mar 17 2009, 06:13PM

You can use almost ANY kind of non-polarised capacitors to make your MMC
Some types are excellent, some are really poor.
Provided the overall capacitance and voltage ratings are ok it will work.
A quick guide, best to worst for commonly found types;

KP Polypropylene foil/film
KP/MMKP Polypropylene foil/film and double metalised film internally in series
MKP Polypropylene metalised film
MKT Polyester/plastic/mylar/PET metalised film
Ceramic, first letter X, Y, Z.

You must run at home for longer than the time you intend to demonstrate the coil
to ensure the capacitors don't overheat or EXPLODE during your demo .... not good.

Blowing air through the spark gap makes a HUGE performance difference,
use a small fan/blower etc. or a vacuum cleaner on 'blow'. (or 'suck' even)

You really should have a safety gap to protect the transformer in case of
failure or wrong setting of the main spark gap.
It doesn't need to be efficient, just present.
With just the transformer and safety spark gap connected, adjust the gap so that it just fires with full ac input voltage.
For the main and safety spark gaps don't use sharp points,
the larger and smoother the surfaces the better.

Re: Tesla Coil Help!! Got only 3 days left to complete my project, plsss help
Plasma Lover, Wed Mar 18 2009, 12:23AM



Please trust me, the capacitor you made is rated at 1.05nF, if the 1.05 part is right, at all. Unless, of course, the bottle you're using is one of those little bottles you get on airlines, in which case, it would be in the order of from one to fifty picofarad.

If you are planning on making an MMC and only have a few days left, just make more beer bottle caps. They're easy to make and cost almost nothing. They aren't very efficient, but, then again, neither is your secondary coil. The beer bottle caps can be put in parallel, as explained later in this post.

The reason the high capacitance capacitors work well for TC caps is that, when put in series, a capacitor's voltage rating will go up (because of the new voltage rating of the one before it, plus it, when wired in series) and put in parallel the capacitance goes up (because they share current).

When put in parallel, a capacitor's voltage remains the same, and its capacitance doubles as the number of capacitors doubles. If you have three 2µF caps in parallel, you will have a 6µF capacitor when ran in a tank circuit.

Just keep these things in mind. My recommendation is to put fifteen of the bottle caps in parallel and try that, then adjust it for best performance, tuning for best performance in between capacitor changes.

By the way, people have used bottle caps with 15KV transformers and had no problems...just make sure you don't seal the bottle like so many people foolishly recommend. If you do seal the bottle, it may explode due to internal heating. Also, don't quite fill it to the top, or the oil will spill over due to thermal expansion.

Good luck!

Re: Tesla Coil Help!! Got only 3 days left to complete my project, plsss help
ElectricalEngg., Wed Mar 18 2009, 02:42PM

@Sulaiman, I got this ceramic capacitor
rated 8200 pF (8.2nF) and 2000 Volts



would they be good enough?
or do I need to buy any other one?

and I wanna know how to add resistors I mean what quantity and hot to connect them I mean in series caps and in parallel caps

and should I operate them inside some oil
coz I heard that they only have half their rated voltage when operated in open air, but full when operated in oil having a good dielectric strength. but I am not 100% sure abt it

and ok Ill make sure that I run it more than demo time at home first thx

and I am using a computer fan attached to a heat sink for the spark gap :)

and is the spark gap as given in the diagram above be good enough?




@PlasmaLover: Yeah I checked that today it was the one you told
bottle cpas are not looking good enough to me as I will not be able to know what is the voltage rating of them :(
and in case they fail, I mean they get damaged while demo or just before it, I wont have another way :(

but if I am able to successfully make MMC, I can make 2 of them before I go to the tech fest for showing demo and I can replace in case it gets any problem :)

and I got the calculation system thx
and can you tell how will the resistors go in the circuit, they stable the circuit right? and they also discharge cap when switched off :)


thx for your help guys, can you guyst confirm me if the capacitors I am using top build the tank circuit are Ok??

Thanks again :)

Re: Tesla Coil Help!! Got only 3 days left to complete my project, plsss help
Plasma Lover, Wed Mar 18 2009, 06:23PM

Well, i suppose it would be completely possible to make it using those capacitors, but then you would need to have at least five in series to get you a voltage rating of 10KV which would be suitable for your transformer, and then you would need to get enough rows of these to make 15nF.... That would be 10KV at 15nF, or a total of 0.75 J. That means that, since each capacitor is rated at 0.0164J, you would need 46 caps, at least to get 0.75J; you would use five in series and, since that would decrease capacitance, you can measure that by taking the total energy in J per cap and multiplying it by the number of capacitors, then figuring out the needed capacitance by squaring the capacitors' rated voltage (after putting them in series) and then dividing the J expected by the voltage rating. The equation would be -

0.0164J*5(caps in series)=0.0825J; 0.0825J/10,000V^2 = capacitance = 0.000000000825F = .825nF

To make .825nF into 15nF, you need to divide 15 by .825 to get 18.18, or, in other words, to get a near-resonant capacitor (as my own estimate) you would need eighteen rows in parallel of five caps in series, which equates to 90 capacitors. Better buy 100 in order to be on the safe side, if you're only going to make one MMC.

On the other hand, the voltage rating of bottle caps are actually quite high. You can make extras and switch them out much more easily than you can an MMC's caps, as well. It would be a much more simple design, even if not as pretty. Just keep them in some kind of dish to contain any spilt liquid, just in case. Really, i advise bottle caps, having done those equations.

Good luck,

Christopher

(fifteen years old and fighting myself for life and happiness)

Re: Tesla Coil Help!! Got only 3 days left to complete my project, plsss help
Arcstarter, Wed Mar 18 2009, 08:33PM

Actually, for a lond lasting capacitor, i would go with at least 15-20kv rating. CDE capacitors for example are only 500vac rated, yet we abuse them with around 2 times that voltage.

Basically, for a dc rated capacitor, you want 2 times there rated voltage, plus a few kv for a safety margin. The cap bank voltage on my 12kv 60ma NST is going to be rated 32-36kv for example.

I would suggest you spend some real money, and buy some of the .15uf 2000vdc CDE capacitors, and use a larger than resonant value. In other words, just put 8 of them in series, for 18.7nf and a 16kvdc rating (this is absolutely perfect for a 6kv 30ma nst).

Re: Tesla Coil Help!! Got only 3 days left to complete my project, plsss help
ElectricalEngg., Wed Mar 18 2009, 09:51PM

omg 100 caps hm.. 1200 rs., I can manage that :)
and well still havnt got the bottle cap out of mind due to some of the positivie comments :)

I wanna know if I could use less mmc caps and keep the capacitance less and instead increase the capacitance through the torroidal and spark gap?

our main motive is to use the resonance for that we can adjust Xc from capacitor, spark gap, torroidal.
what you say would it be possible?

say I use 6 in series and 6 in parallel


and for bottle capacitor, as per my calculations, 15 bottles should give a capacitance of around 0.0285 micro farads

what should I do?? :(

Re: Tesla Coil Help!! Got only 3 days left to complete my project, plsss help
Fraggle, Thu Mar 19 2009, 02:34AM

All of the information you could possibly need is available from Google, I think you ought to spend a few hours reading and you`ll be sorted.

Re: Tesla Coil Help!! Got only 3 days left to complete my project, plsss help
Plasma Lover, Thu Mar 19 2009, 04:29AM


.0285µF? That doesn't work out right. Are you thinking that each bottle is 2nF? It seems that you are, since you said yourself that your one cap is about 1nF. So, if you have 1nF and you put fifteen in series, you get 15nF. But, if you're making the caps yourself, I suggest you test them with a meter (if you have one on-hand) in order to make sure that they capacitance is right. The meter on a multimeter will work fine, just get wires small enough to stick into the holes on the meter. That's the tough part! =) It takes a little while to get it all set up.

Keep us updated!

By the way, in the future, I recommend using the CDE caps, as well, but since you don't have much time, that wouldn't work well.

Re: Tesla Coil Help!! Got only 3 days left to complete my project, plsss help
LithiumLord, Thu Mar 19 2009, 12:32PM

Well, in fact a bottle is around 1-2nF, however I don't like bottle MMCs due to higher loss factor and really heavy weight.

>fifteen in series
In parallel (I know this was a typo as I kept sometimes mixing words myself like this - but just to make it more clear)

>and the small cap across output you said, whats that for? pf improv?
Nope, I mean one between the neutral terminals - it will exclude the chance that some ground faults would cause RF to form up against the coils of the NST, eventually heating it or causing a damage or internal flashover.

Re: Tesla Coil Help!! Got only 3 days left to complete my project, plsss help
ElectricalEngg., Thu Mar 19 2009, 01:21PM


no actually I did spent a few hours looking for capacitor banks and similar terms on google, but all I found was the already made pics etc. and no real knowledge on how to make them, or abt the resistors and all :(

can u guide me to article or any useful pice of information thx:-)



oops sometime I scare myself too with the silly mistakes I make
Oh well Ok, the 15 nF will be equal to 0.015 mF. still awesome enough I guess :)

I have a digital LCR meter at college which i use to measure them :)

and well I just took the permission of my teacher and wow you wont believe but I just came across one of those caps (the CDE), one of my classmate bought one of them for his own project, and I saw I calculated and I found that using them will be more cheaper than MMC cpas and more reliable too :)
and now you also recommended them :D

The caps I found were rated at
4mF

and 440 V AC

if I connect 27 of them in series, I get 12 kV voltage as required
and also 0.148 mF capacitance

wont that be awesome?
coz that will look good too and I guess more efficient than the bottle caps right?

I have a full tomorrow, whatever I have to do, I have to do tomorrow, the saturday as my teachers said is reserved for testing or maybe small work but not for a full fledge work day
so Ill have to be very quick tomorrow

I now wanna know how to add resistors

Like this??



and can you tell me how to calculate the value of resistor across each capacitor??

pls tell me as soon as possible, ill check ur msgs before going to college tomorrow :)

and yeah I measured the inductance of secondary today
it's 25.1 mH :)

is it good enough??


thanks again guys
you guys have been very very helpful without you I would not have reached even till here, I hope to finish it tomorrow

Re: Tesla Coil Help!! Got only 3 days left to complete my project, plsss help
ElectricalEngg., Thu Mar 19 2009, 01:36PM



wow so even just one bottle capacitor is good enough as per voltage? and we need multiple just for the capacitance?

and I am sorry I feel dumb to ask this
but can you mark the position of the capacitor you were asking mew to add pls thx


400 pixels max image width, it's the board rules d00d!
thx again:-)

Re: Tesla Coil Help!! Got only 3 days left to complete my project, plsss help
Corey, Thu Mar 19 2009, 04:14PM

cool got any pics yet? =D

Re: Tesla Coil Help!! Got only 3 days left to complete my project, plsss help
Arcstarter, Thu Mar 19 2009, 04:26PM

It is not absolutely required, but it seems that people say to switch the capacitor and spark gap position. It will be so that the primary and capacitor are in series, connected parallel with the NST, and the spark gap is parallel with the NST.

Re: Tesla Coil Help!! Got only 3 days left to complete my project, plsss help
Herr Zapp, Thu Mar 19 2009, 06:30PM

Kashish -

It's pretty obvious that you do not have even the most basic understanding of what a Tesla coil is, how it operates, or how a Tesla coil circuit is configured. Without gaining some understanding of these topics, your chances of getting a Tesla coil assembled, tuned and operating are just about nil.

For a start, go to Richie Burnett's extremely informative Tesla coil website (still the world's best) at: and read up on Spark Gap Tesla Coils. Richie's site will explain the purpose and function of each component in a Tesla coil, what their electrical characteristics are, and the theory of operation. Without gaining at least a minimal understanding of what a Tesla coil is and how it operates, you won't be successful in getting one running.

A few other comments:

1. With your 6KV @ 30ma transformer, you need a tank capacitor value of around .018uF. Your 4 microfarad @ 440 VAC capacitors are unsuitable because their capacitance value is far, far too large. You would need over 200 of them connected in series to achieve your target capacitance value. Do you understand how to calculate the value of series and parallel connected capacitors? If not, you absolutely need to gain some knowledge of basic electronics.

See:

for info on series and parallel connected capacitors, and how to calculate their values.

2. Your best option for a low-cost, readily available tank capacitor will be to use an array of salt-water bottle caps. A typical beer-bottle salt-water capacitor will have a capacitance value of around .0007uF to .001uF, and will withstand 20KV. If you assemble an array of 15-18 of these bottles connected in PARALLEL, you will be near your target capacitance value. Empty beer bottles and a few meters of scrap copper wire can be salvaged or obtained at very low cost.

3. Your sketch of your MMC shows the bleeder resistors in SERIES with the capacitors; this is incorrect. If you understood that a Tesla coil tank circuit has to carry large pulses of current, you would immediately see that your sketch is completely wrong, and that the high-value resistors would effectively prevent ANY useful current from flowing in the circuit. In an MMC tank capacitor array, each individual capacitor has a bleeder resistor connected in PARALLEL with it, not in SERIES between capacitors. The value of a bleeder resistor is based on the time constant of the circuit (how rapidly you want the capacitor to discharge). For typical MMC capacitors used in Tesla coil circuits, a value of 10 megohms (10 million ohms) works well.

4. Your sketch of the Tesla coil circuit shows the tank capacitor connected across the HV transformer. This arrangement may apply higher stresses to the transformer's secondary insulation than if the spark gap were connected across the transformer. Interchange the positions of the tank capacitor and the spark gap, and your transformer will have a better chance of surviving.

Really, your best option at this point is to spend some MORE time reading up on Tesla coil design and theory of operation. You absolutely MUST have some basic understanding of what a Tesla coil is, what the various parts do, and especially about how a coil is "tuned" to achieve resonance. A Tesla coil may appear to be just a few coils of wire, a spark gap, a capacitor, and a transformer, but in actuality the operation is a quite bit more complex. It's absolutely essential that you understand what RESONANCE is, and how the primary and secondary circuits are "tuned" to achieve resonance, to be able to get your coil operational. Richie's website provides a very detailed but easily undestood explanation of what resonance is, and how it is achieved.

(Also, it's OK to just say "Hello, I'm Kashish, I'm 14 years old, I live in India, I saw a Tesla coil on the Internet and now I want to build one." Telling us that you are just about to "graduate" from Electrical Engineering college, and need to build a Tesla coil as a condition of graduation, doesn't seem to be truthful. The people on this forum are very willing to help you in any way possible, regardless of your age, location, schooling, or background.)

Regards,
Herr Zapp

Re: Tesla Coil Help!! Got only 3 days left to complete my project, plsss help
LithiumLord, Thu Mar 19 2009, 09:06PM



(got a bit too creative, but still sure it will help ;) )

ps your NST is NOT mid-grounded ;)

Re: Tesla Coil Help!! Got only 3 days left to complete my project, plsss help
Steve Conner, Thu Mar 19 2009, 09:23PM

Thanks for the valuable input, Herr Zapp and LithiumLord. I'd have liked to help out too, but one of my New Year's resolutions was to ignore any thread with a smiley in the title.

Herr Zapp already said this, but I'm going to repeat it. Don't put resistors in series with your capacitors! It's completely wrong. Your coil will hardly work and/or the resistors will go on fire.

Tesla coils might be hard to optimize for ultimate performance, but it's pretty easy to slap together something that "kind of works". My favourite is the Trashy Tesla: If this guy can do it, so can you.

Re: Tesla Coil Help!! Got only 3 days left to complete my project, plsss help
ElectricalEngg., Fri Mar 20 2009, 10:44AM



I want t clear this out first
y birth date is
7th november 1990, I am in college - Mehr Chand Polytechnic College, I am final year electrical engg. student with 2 months to go before my college ends.
IDK where you read that 14 year old thing, but I am ready anytime to show myself on cam if you want, I would never lie in my life to people I am gonna ask for help.

and yeah thanks for your post mate, really very very helpful :)
Ill reply again in like half hour, I am reading the site articles and all you gave.

and yeah this is the first time I am engaging in any kind of practical job, that's why I am being very silly at some places, its just the study structure of our country, very theoretical, very few college gives good practical info. :)

Re: Tesla Coil Help!! Got only 3 days left to complete my project, plsss help
Herr Zapp, Fri Mar 20 2009, 05:53PM

Kashish -

Take a look at a new thread on this forum titled "Need your Help please", by Tareef.

He has constructed a very nicely made Tesla coil, using what appear to be all the correct components. However, has has not yet been able to get this coil "running".

It might be useful for you to take a close look at his coil design, and follow the steps as we help him troubleshoot this coil, determine why it will not run, and what needs to be corrected to get it running properly.

Regards,
Herr Zapp

Re: Tesla Coil Help!! Got only 3 days left to complete my project, plsss help
coillah, Sat Mar 21 2009, 05:39AM

not to thread jack or anything guys, but this has to be the nicest I have ever seen any forum be to a newb.

on the internet, this is simply unheard of. call me jaded, but that's just what I have seen...

you're one lucky dude kashish

Re: Tesla Coil Help!! Got only 3 days left to complete my project, plsss help
ElectricalEngg., Sat Mar 21 2009, 06:06PM

I made a huge update to my tesla coil and have 3 huge questions :(

@Herr Zapp: I read most of the articles on that site and wow now I feel like I really had no idea abt the working lolz. thx
a few one left gonna read them all tonight :)
and ill keep a very close look on the topic of taheer and saw the video, the connections and setup was really very clean :)

@LithiumLord: woot thanks for the sketch, makes it easy for me to understand. ^_^

@Steve McConner: lol sorry erased the smiley in title :)
and thanks for the support :)

@coillah: lolz yeah I feel really special when everyone helps in such a way, really thankful to all of them, they all have been just superb :)



UPDATE:
Yesterday my dad went to delhi and I sent the transformer with him back to the manufacturer and got it replaced and now finally I am confirmed that it is not a mid point grounded transformer. :)

the circuit diagram for my tesla coil remains the same now for me as in the richie's site, cox the mid point of the secondary of my t/r is grounded

this is the diag:



Q1:
now I want to ask that there is no safety gap in this diag except the mid point of secondary grounded, so how is that helping the transformer from those high frequency kickbacks and voltage spikes? I am really confused on it. :\

Q2:
is abt the winding style of secondary now I have seen the generator windings being done like, going up then continuing backwards but is it the same here too?
here I made this video with voice to explain my problem :)
I was too scared while recording my only second recorded video lol so I go like oo aa ii on some spots, dont mind pls :P
Video:



Q3: Will it be okay if I use an Isolation Transformer as a line filter?




and well I have one good and one bad news for me and my coil,

Good News:: we had a strike in college due to controversial umpiring in a cricket tournament of college so I got a few extra days, and using them
I contacted my retired college principle whom I have stuidied under too and shared the tesla coil project with him, and the only thing he said was

"Give me time till Sunday for studying this, and dont buy any material till that, whatever you have to make first get it done on paper with every calculation and blue prints before going towards practical building."


Bad News:: Had a fight with one of the teacher so on Tuesday if the strike ends, he is gonna go mad at me if I dont give him the project, so maybe he will fail me, but really I dont care now, I just want to make it now, dont care abt college now,
I have been in this project long enough to love it more than anything at the moment.

Re: Tesla Coil Help!! Got only 3 days left to complete my project, plsss help
TheBoozer, Sat Mar 21 2009, 07:24PM

Winding up the secondary, adding an insulation layer, winding back down the secondary, adding an insulation layer, winding up the secondary again, it seems so wrong...

The primary coil will be inducing upon the base of the secondary which is normal, but then again, at the same time, inducing on the second layer which, at the base is 2/3 along the total length of the secondary coil.

This seems so wrong. Clash. I don't know how to properly word this. This goes against my understanding of how a classic Tesla coil should work. I would have just stopped at the 500 to 600 turns at the top. You'de have a higher frequency coil, but it would be a standard setup.

Re: Tesla Coil Help!! Got only 3 days left to complete my project, plsss help
Steve Conner, Sat Mar 21 2009, 07:44PM

Yup, a multi-layered Tesla coil is a really bad idea.

The whole point of the Tesla coil was to make insulation easier by raising the frequency so high that you could get a high voltage with only one layer of wire, and a good coil puts out so much voltage that it's already almost flashing over from the top of the secondary to the bottom. If you added a second layer, it would mean instant disaster.

Re: Tesla Coil Help!! Got only 3 days left to complete my project, plsss help
hvguy, Sat Mar 21 2009, 07:49PM

Q1:

A safety gap can be placed across your transformers secondary with out the need for a mid point ground. The only thing a safety gap does for you is short out any high voltage spikes that would appear across the secondary. If you use the schematic you have shown you DO NOT need a safety gap as the main spark gap will serve the same purpose.

Wire your circuit as show below.

Q2:

You should only use one layer of wire. Two layers will flash over and ruin the secondary unless more complex measures are taken to insulate it. Bottom line; ~500 turns is just fine, use only one layer. If you want more turns make the secondary longer. Remember, Tesla coils do not work like conventional transformers, more turns only means a lower frequency, not more voltage. (Edit: Steve said the same thing while I was typing :)

Q3:

Iso transformers work fine. I don't think you need an iso transformer or a line filter. Their usefulness is generally overrated.

Re: Tesla Coil Help!! Got only 3 days left to complete my project, plsss help
ElectricalEngg., Mon Mar 23 2009, 01:11PM

OK guys I got a new secondary, with 1500 turns :)
and a new primary wire too, its a 8 gauge copper wire :)

These are the calculations I got from Tesla Cad

Secondary Coil Design:

Diameter of secondary coil : 2.00in
Winding height of secondary coil : 22.641in
Wire diameter for secondary coil : 28 gauge or 0.0149in
Spacing between windings : 0.00in
Secondary turns : 1519.00
Secondary wire length : 795.62ft
Secondary inductance : 9.81mH
Approximate resonant frequency : 628.27kHz
Secondary quarter wavelength resonant frequency : 309.27kHz
Secondary self capacitance : 6.54pF
Toroid capacitance required to form quarter wavelength coil : 20.46pF

Primary Coil Design:

Primary capacitance : 0.0159uF
Primary resonant frequency : 309.27kHz
Secondary coil diameter : 2.00in
Primary conductor diameter : 0.16in
Primary turn to turn spacing : 1.00in
Spacing between the secondary and the inside turn of the primary : 2.00in
The primary will need to be tapped between turn 7 and turn 8 to form a resonant circuit at 309.27kHz

The approximate inductance at each turn is :

Turn 1=========0.36uH
Turn 2=========1.22uH
Turn 3=========2.64uH
Turn 4=========4.73uH
Turn 5=========7.59uH
Turn 6=========11.35uH
Turn 7=========16.12uH
Turn 8=========22.02uH
Turn 9=========29.15uH
Turn 10=========37.64uH
Turn 11=========47.61uH
Turn 12=========59.17uH
Turn 13=========72.43uH
Turn 14=========87.51uH
Turn 15=========104.53uH

Neon Transformer / Primary Capacitor Matching:

Transformer secondary voltage : 6.00kV
Transformer secondary current : 30.00mA
Number of transformers : 1
Primary capacitor required to form a resonant circuit at 50Hz with neon transformer(s) : 0.0159uF

Capacitor Bank Design:

Individual Capacitor Rating: 440V, 0.5mF
No. of Capacitors connected in series: 32
Total Voltage Output: 14080 Volts
Total Capacitance: 0.015625

Toroidal Design:

Dt, Diameter of Toroidal Tube: 3.20 inches
Dtc, Diameter of Toroidal 22.75: 22.75 inches
Capacitance of Toroidal: 24.45 pF

Ill be testing these calculations practically tomorrow, and well even if these are wrong, I will build my tesla coil around my secondary myself, I have a good guiding teacher now and got all formulaes to manually calculate them ^_^

Now I only need to get the Toroidal made, and them assemble everything, I am hoping to finish it tomorrow, but seriously, I will go for best even if that takes me 1 or 2 more days :)


so guys can you please confirm me the design please :)

Thanks :)

Re: Tesla Coil Help!! Got only 3 days left to complete my project, plsss help
coillah, Mon Mar 23 2009, 04:09PM

Your primary wire, seems a bit small to me, is it solid copper?

Ideally you want to use a hollow copper tube for primary's because of the skin effect.

Also, the primary has to handle huge peak currents, so you might want to lookout for that when selecting you primary material.

Re: Tesla Coil Help!! Got only 3 days left to complete my project, plsss help
Andyman, Mon Mar 23 2009, 04:48PM

Everything looks good to go, however, I would suggest one thing. You might consider decreasing the turn to turn spacing on your primary, 1 inch is pretty large. 0.25 inches would be plenty of space, especially considering your wire size.
You could always just use what you have for now, and then at a later time, experiment with a more closely spaced primary coil winding.

Re: Tesla Coil Help!! Got only 3 days left to complete my project, plsss help
ElectricalEngg., Mon Mar 23 2009, 06:01PM


Yeah its a solid copper very solid lol
I studied a lot and I am very sure that it is very much good enough for primary, not only it fits theoratically but also the pics I saw uses same or very near to this size of wire :)



would surely try that :)

would post update tomorrow evening :)

Re: Tesla Coil Help!! Got only 3 days left to complete my project, plsss help
TheBoozer, Mon Mar 23 2009, 09:58PM

A 2 inch diameter secondary with a 22 inch wind length?????

That's a 1:11 aspect ratio. I'm no expert, but I've had very poor results going beyond typical ratios of 1:3 to 1:5.....

I've never seen a working coil with an aspect that high.

How about using a 3 inch tube, wind it 15 inch. That would be roughly the same amount of wire with a more common aspect....

Re: Tesla Coil Help!! Got only 3 days left to complete my project, plsss help
ElectricalEngg., Tue Mar 24 2009, 12:32PM

aspect ratio??
I thought the height will only affect the frequency :S

Tesla CAD says that the aspect ratio is= 11.32 : 1

pls explain how will the aspect ratio will affect it

winding again is not easy :(

I don't even have a machine for winding, I do it with hands and with very accuracy and that accuracy with hands is very hard or I should say very time consuming if not hard. :(

Re: Tesla Coil Help!! Got only 3 days left to complete my project, plsss help
Steve Conner, Tue Mar 24 2009, 01:33PM

It's common knowledge that tall and skinny coils perform poorly, because the high aspect ratio leads to poor coupling. In simple terms, a fat secondary coil can "absorb" more of the primary's magnetic field than a thin one.

It should still produce some kind of sparks, though, so if you can't be bothered to make a fatter secondary coil, you might as well just use the one you have.

I prefer an aspect ratio of 3:1.

Re: Tesla Coil Help!! Got only 3 days left to complete my project, plsss help
TheBoozer, Tue Mar 24 2009, 10:01PM

Steve certainly put it into better words than I could come up with at the time.

A 90 degree helix primary may offer better coupling for such a tall secondary. Two of my table top Tesla coils use 2.375 diameter secondaries and I use real right coupling on them without any troublesome racing sparks.

Winding secondaries by hand wore my hands out. I'de certainly make an attempt to use the one you made, I didn't realize it was already wound... My first few secondaries were wound by hand, but no more... :)

P.S. Secondary height versus coupling has only a fractional bearing on frequency. Wire length is the major contributor to frequency.

Re: Tesla Coil Help!! Got only 3 days left to complete my project, plsss help
ElectricalEngg., Wed Mar 25 2009, 04:01AM


I am not at all looking for long sparks while operating in tech fest
I will do that when I learn more and build more different types of Tesla coils(I am in love with them now):-p

would mine give sparks of say 3 to 4 inches??
thats all I need curently
and would there be enough Rf magnetic field to light up a fluorescent tube??



cool gained one more knowledgeable point abt wire length.:-D
thx buddy

I build a wooden stand which can like be made to change the side bars where the pvc pipe has to be placed

and now I can wind it with motor

I just need to add a counter on that motor now :)


edit: I will post my tesla coil pics in the evening. :)

Re: Tesla Coil Help!! Got only 3 days left to complete my project, plsss help
Plasma Lover, Wed Mar 25 2009, 07:22PM


I'm waiting to see the pictures. I'm wondering how you laid out your primary circuit.

You said "and now I can wind it with motor". What is it? And what do you mean by 'motor'? Are you speaking of winding a coil with the wire from a motor?

My bad. I didn't keep that part in context. I apologize.

Re: Tesla Coil Help!! Got only 3 days left to complete my project, plsss help
coillah, Thu Mar 26 2009, 03:13AM

no need for a counter kashish, your geometry should tell you how many turns you have. Just measure the length of your winding. Also, if you dont know the exact freq of your secondary circuit its no big deal, you can just adjust your primary to match it later.

Re: Tesla Coil Help!! Got only 3 days left to complete my project, plsss help
teravolt, Thu Apr 02 2009, 03:30AM

hello kashish0711, how did your project go. did work out with you and your teacher

Re: Tesla Coil Help!! Got only 3 days left to complete my project, plsss help
MRacerxdl, Thu Apr 02 2009, 01:55PM


It will light up a fluorescent tube even if there is no spark coming out from the secondary coil... Because, sometimes the voltage are no sufficient to cause the breakdown of the topload, but the RF Field is going out normally, The fluorescent tube is used much in Solid State coils, because if it has some output (small like 1mm or so) it will light a fluorescent tube for at least 5cm of the coil... So even if your coil is not tuned correct, it might light up the lamp.

Re: Tesla Coil Help!! Got only 3 days left to complete my project, plsss help
LithiumLord, Sat Apr 04 2009, 01:38PM

The main gap may be a rotary one, in that case I'd add a safety one anyway just to feel better ;) Btw that's a good idea to add another safety gap across the MMC.

Re: Tesla Coil Help!! Got only 3 days left to complete my project, plsss help
Plasma Lover, Wed Apr 08 2009, 06:08PM

Any news on the turn-out?

Re: Tesla Coil Help!! Got only 3 days left to complete my project, plsss help
ElectricalEngg., Wed Apr 22 2009, 04:11PM

hey guys
wow good to be back
sorry for not posting anything lately
I was on a college trip with no internet access

I completed my tesla coil and got the fluorescent tube glowing 3 feet away from tesla coil, but for some reason, no sparks :( there might be a few cm's but not big enough to be easily seen in daylight.

I think that is because the dia of secondary is small and the distance between primary and secondary is 1.5 inches more than desired and the no. of turns of primary are less.

I am taking it to tech-fest tomorrow and will post all the pics taken there, will return on 25th

and on the theory report, I will surely give credits to this site and you guys. without you I would have never been able to do it

Thank you so much guys

I love you all

You guys are great

Re: Tesla Coil Help!! Got only 3 days left to complete my project, plsss help
ElectricalEngg., Sat Apr 25 2009, 10:41AM

dudes final and awesome news, I managed to get the sparks too, not very long just about 2 to 3 inches but I found the mistakes why also

and I won gold in Tech-Fest

hehe

Thanks to you guys :D
pics coming in a couple hours

Thank you again guys :D

Re: Tesla Coil Help!! Got only 3 days left to complete my project, plsss help
coillah, Sat Apr 25 2009, 05:39PM

Won gold huh? That's awesome kash!

post pics so we can see the coil please!

Re: Tesla Coil Help!! Got only 3 days left to complete my project, plsss help
Arcstarter, Sat Apr 25 2009, 09:18PM

Gold? Nice! I see tesla coils ARE good for somethign :).

The length of the secondary should not makes your sparks tiny. I am sure with it you could get at least 6 inches. The ratio is quite different than you want though. My 4.5 inch is about 1:5.33, and it works fine.

The length i like to go for with a 2 inch coil is 11 inches, because it smply looks right. Also, i would use 28 gauge double build wire that is thicker insulation and still gets about 1000 turns while somehow looking 'how it should'. That is one reason my 4.5 inch coil has a slightly high (or low, not sure what it would be called) aspect ratio, that and to give clearance from the primary for longer sparks without primary strikes!

Re: Tesla Coil Help!! Got only 3 days left to complete my project, plsss help
ElectricalEngg., Wed Apr 29 2009, 06:39PM

You had 1:5
but I had 1:13 LOL

people on this thread said that aspect ratio wil affect the output :)

and I won gold just because people there didnt knew much about tesla coil, and I told them one huge lie

I said I reduced the efficience so that sparks dont come out directly as I had to display it along with other people's electronic models. xD

and the best par was that they believed it :D

but I am gonna improve it and well soon gonna make that lie change to truth. :P

:D

I posted the pics here :)



mine is on the 11th page :)

Re: Tesla Coil Help!! Got only 3 days left to complete my project, plsss help
Plasma Lover, Wed Apr 29 2009, 07:45PM

For the size of your coil, your top load is far too large. I recommend making a smaller one and trying that with a similar setup to see if output improves.

Re: Tesla Coil Help!! Got only 3 days left to complete my project, plsss help
hotcrazyfruit, Wed Apr 29 2009, 09:30PM

your totally right, i think of it as being fascist, but a prime example would be youtube. say one thing someone doesn't like and its BANG YOU SUCK.

Re: Tesla Coil Help!! Got only 3 days left to complete my project, plsss help
teravolt, Thu Apr 30 2009, 02:31AM

don't listen to them! do you plan to make a larger one with a wider diamiter with what you have lerned

Re: Tesla Coil Help!! Got only 3 days left to complete my project, plsss help
ElectricalEngg., Thu Apr 30 2009, 05:19AM



Yes surely would be doing that

I am gonna increase secondary dia and get a ratio of like1:4 or 1:5
then reduce the torroidal size acc to that
and if needed, then increase no. of primary turns :)

gonna do that all soon ^^

Thanks for guiding me guys, you guys are the best :D

Re: Tesla Coil Help!! Got only 3 days left to complete my project, plsss help
Plasma Lover, Thu Apr 30 2009, 02:44PM


Well, it's always nice to see somebody's coil come together, whether it's as beautiful as Dr. Spark's coils, or as horrible as my own (the second reason I haven't posted pictures - first reason is that I have no camera).

We've all got to start somewhere and when your first coil actually works, when you're trying to build a Tesla coil, it's a miracle.

You've got a nice looking coil, and I'm sure it will continue to get better and better.

Eventually, you'll probably be able to source a nice transformer, possibly a potential transformer, to replace that weak little NST you're using. 6/30 isn't much, but I've gotten six inch streamers off of a 3KV 15mA NST (looks like a bug-zapper transformer, but has a luminous tube transformer sticker on it; looks like it's made to light up the tittle on a letter 'i', and that's it) and a 600 turn secondary. I'll post pictures if my friend lets me borrow his camera.

Anyways, I'm posting this to congratulate you, not brag. ;)

I look forward to seeing what you have to offer in the future.


Christopher Karr

Re: Tesla Coil Help!! Got only 3 days left to complete my project, plsss help
ElectricalEngg., Thu Apr 30 2009, 04:52PM



Yeah sure, I am gonna finish my college in around 1 month, then gonna get a job, then I will be independent financially, otherwise I had to borrow money from parents.

I am gonna buy a 12000 volts 1A t/r, which costs abt 10000 rs (200$)

AND THEN GO EXPERIMENTING :)

Idk abt anything else, but one promise that you will see at least one new properly and efficiently working tesla coil from me within next 3 to 4 months :)

Re: Tesla Coil Help!! Got only 3 days left to complete my project, plsss help
teravolt, Fri May 01 2009, 01:52AM

12kv@1a, 12kw, is monster transformer and a genral rule that I use is 2ft of spark per kw for a finely tuned coil. a transformer like that is deadly so coution is advisable

Re: Tesla Coil Help!! Got only 3 days left to complete my project, plsss help
ElectricalEngg., Fri May 01 2009, 12:49PM


Yup, I have seen people using them in big tesla coils :)

and yeah will keep the safety at priority
and gonna use it only after I correct my current tesla coil and make one more a bit more efficient tesla coil :)

Re: Tesla Coil Help!! Got only 3 days left to complete my project, plsss help
Steve Conner, Fri May 01 2009, 02:21PM


Well, b*tchslapping noobs is against 4hv rules too. The "OMG im a n00b plz help!!1 xD" thing is bad enough without a bunch of other one-liner "stfu noob" posts after it.

This thread is about as noobish as we would tolerate, any worse and it would probably just have got locked. It's good that it turned around into something constructive and Kashish got his techfest prize.