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Tesla Coil Help!! Got only 3 days left to complete my project, plsss help

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ElectricalEngg.

Sat Mar 21 2009, 06:06PM

Registered Member #1946 Joined: Sat Jan 31 2009, 11:37AM
Location: India
Posts: 43

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.

TheBoozer

Sat Mar 21 2009, 07:24PM

Registered Member #1535 Joined: Wed Jun 11 2008, 11:37PM
Location: Northeastern Pennsylvania - USA
Posts: 117

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.

Steve Conner

Sat Mar 21 2009, 07:44PM

Registered Member #30 Joined: Fri Feb 03 2006, 10:52AM
Location: Glasgow, Scotland
Posts: 6706

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.

hvguy

Sat Mar 21 2009, 07:49PM

Registered Member #289 Joined: Mon Mar 06 2006, 10:45AM
Location: Conroe, TX
Posts: 154

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.

ElectricalEngg.

Mon Mar 23 2009, 01:11PM

Registered Member #1946 Joined: Sat Jan 31 2009, 11:37AM
Location: India
Posts: 43

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 :)

coillah

Mon Mar 23 2009, 04:09PM

Registered Member #1517 Joined: Wed Jun 04 2008, 06:55AM
Location: Chico CA
Posts: 304

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.

Andyman

Mon Mar 23 2009, 04:48PM

Registered Member #1083 Joined: Mon Oct 29 2007, 06:16PM
Location: Upland, California
Posts: 256

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.

ElectricalEngg.

Mon Mar 23 2009, 06:01PM

Registered Member #1946 Joined: Sat Jan 31 2009, 11:37AM
Location: India
Posts: 43

coillah wrote ...
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.

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 :)

Andyman wrote ...
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.

would surely try that :)

would post update tomorrow evening :)

TheBoozer

Mon Mar 23 2009, 09:58PM

Registered Member #1535 Joined: Wed Jun 11 2008, 11:37PM
Location: Northeastern Pennsylvania - USA
Posts: 117

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....

ElectricalEngg.

Tue Mar 24 2009, 12:32PM

Registered Member #1946 Joined: Sat Jan 31 2009, 11:37AM
Location: India
Posts: 43

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. :(

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