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My first tesla coil (SGTC)

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LAN_403

TeslaCoil

Fri Jul 22 2011, 06:09AM

Registered Member #4020 Joined: Thu Jul 21 2011, 06:40PM
Location:
Posts: 30

Hey everyone! I will soon be beginning the building of my first ever Tesla coil! I recently went to a local neon sign shop and asked them if they had any old transformers laying around they'd be willing to part with. They gave me their umber and told me to call the next day. I called them and they told me to come in and pick up my new 15Kv 30Ma NST. Below are all my calculations that I did while following the guided and using the calculators on deepdriedneon.com. I was really hoping you guys could look over my work and tell me any changes I can make. Thank you so much!! Please post if you need ant clarification!! Based on my transformer 15kv and 30ma (450watts) the secondary coil PVC pipe will have a diameter of 4 in and a length of 22 in (20 for coil and 1 in clearance top and bottom) 20 in divided by 1000turns equals an approximate wire thickness of .02 in multiplied by 1.1 to allow for enamel thickness (10%) Using the helical coil calculator with input values being as follows Diameter(D): 4in Number of turns(N): 1000 Wire Diameter (W): .0201in (24gauge wire) Turn spacing(S): .002in Produced these values Height(H): 22.1in Length of wire: 12566.359in Inductance(L): 16736.401uH ( Self Capacitance: 8.294pF ) Discharge terminal 4in aluminum Ducting Overall diameter of 15 in Gives us a capacitance of 16.6 pf Resonant Frequency of LC Circuit: Inductance (L): 16.736401mH Capacitance (C): .000024894uF Will give us 246.571 kHz Multi Mini Capacitor: Capacitors per String: 15 Strings in Parallel: 6 MMC: Capacitance: .006uF Voltage Rating: 30Kv Number of caps: 90 Using the lc calculator we find that the primary coil needs an Inductance of 0.06944mH/69.44uH to get a resonant frequency Of 246.569 kHz Using the spiral coil calculator I find that a 13 turn primary coil with a 6 in inner diameter using .5 in copper pipe spaced at .5 in, will give me the desired 69.644 uH Deep fried neon also said: "To allow for variations in component value and for experimentation, increase the number of primary turns by about 50% (7 turns goes up to about 10)." So should my 13 turns go up to 17 or something similar?? Thanks for all the help!!
!

Mads Barnkob

Fri Jul 22 2011, 08:58AM

Registered Member #1403 Joined: Tue Mar 18 2008, 06:05PM
Location: Denmark, Odense C
Posts: 1968

Please dear god what a wall of text to run into!

deepfriedneon is a good guide to build a SGTC, so I am confident in the numbers you show without doublechecking them.

Which capacitors will you use?
90 capacitors sound somewhat overkill depending what your goals are for this coil. Is it a run once in a while for friends for a couple of minutes or a longer run times show coil. You could possible save some money on the MMC by lowering the voltage rating.

You primary coil should be able to be tuned for a lower frequency than the secondary coil, its a well accepted method to tune your primary circuit at a lower frequency than the secondary circuit as the streamer loading pulls down the secondary frequency when blasting out large sparks.

Quick advice: structure your post much better to give the reader a chance of getting a overview.
Make a specifications "box" with all facts about the hardware that you will use, part numbers, ratings etc.
Pictures are always helpful.

TeslaCoil

Fri Jul 22 2011, 04:11PM

Registered Member #4020 Joined: Thu Jul 21 2011, 06:40PM
Location:
Posts: 30

Thank you for the tips!! I'll make sure to do that!!

These were the capacitors I found that if put in the previously mentioned setup, would give me 30Kv and .006 uF(a bit above the calculated .0053 uF)

And also, I'm doing my best to get the full 36 in sparks this transformer is capable of, how much of a difference would using 800 turns of a bit thicker wire make? Instead of the 1000 turns of 24.

cduma

Mon Jul 25 2011, 08:22PM

Registered Member #1822 Joined: Fri Nov 21 2008, 08:04PM
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Posts: 300

It would make a huge difference in operation but, as long as the inductance is the same it wont make or break it.

Dr. ISOTOP

Mon Jul 25 2011, 10:00PM

Registered Member #2919 Joined: Fri Jun 11 2010, 06:30PM
Location: Cambridge, MA
Posts: 652

At these power levels, I doubt you are bounded by secondary resistance.
The gold standard for secondary turns is 1k, as demonstrated years ago. I also remember reading something about secondary surge impedance being between 50 and 80 kOhms.

TeslaCoil

Mon Jul 25 2011, 10:09PM

Registered Member #4020 Joined: Thu Jul 21 2011, 06:40PM
Location:
Posts: 30

So I should stick with 1000 turns at 24 gaugel?

And how is my mmc cap? I was told by someone to go a bit higher that the computed capacitence, so instead of .0053uF I decided to go with .006uF. Is that good?

I also plan on using a tungsten tipped spark gap. Any other good suggestions? Can someone explain how a safety gap works and how to make one?

Dr. ISOTOP

Mon Jul 25 2011, 11:45PM

Registered Member #2919 Joined: Fri Jun 11 2010, 06:30PM
Location: Cambridge, MA
Posts: 652

Richie Burnett's page has all the details about optimizing coil performance. You *will* need a rotary for maximum spark length.

TeslaCoil

Wed Jul 27 2011, 05:00AM

Registered Member #4020 Joined: Thu Jul 21 2011, 06:40PM
Location:
Posts: 30

Would it be possible to audio modulate this?

Dr. ISOTOP

Wed Jul 27 2011, 03:41PM

Registered Member #2919 Joined: Fri Jun 11 2010, 06:30PM
Location: Cambridge, MA
Posts: 652

No.
Well, maybe if you used a triggered SISG, but otherwise, no.

TeslaCoil

Thu Aug 04 2011, 06:32AM

Registered Member #4020 Joined: Thu Jul 21 2011, 06:40PM
Location:
Posts: 30

Would I be able to use an old computer fan for a rotary spark gap? Or something bigger?
Also how do I set it at the right speed? I am assuming that the right speed is whatever will get the electrodes close enough to discharge the very moment the capacitors are fully charged. Is this right?

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