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Tesla Coil Build Thread

Down with Umbrella

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Gahh, look at this waveform. Is this typical for a VTTC or should they be a nice clean sinusoidal wf?

 



Down with Umbrella

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Here's a quick photo run with a short power up. Might need to consider a duel 833c configuration. I have a blower wired in for forced air & post flow cooling.
Grid leak: Right now I have a 5k variable rheostat. I might add a fix 5kohm in series then just use the rheostat to trim. Tube seems to run healthier with greater grid resistance and there is a negligible difference in streamer length.


 
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Polonium210

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Was the scope probe just hanging beside the coil for that ugly waveform?

I'm still waiting for a few parts then the build starts.

I have a few tricks I'm going to try out. I will keep you posted.
 

Down with Umbrella

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Yes the probes just hanging. Approximately 2m away.
This coil should run cooler at 120vac input. More tuning tomorrow.

Do you have a plan for a secondary or target parameters?
 
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Sigurthr

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Odd about waveform. Make sure the scope has good RF grounding. Maybe there's actually harmonic content in it from low resonator Q, though this is unusual. Keep watching that plate glow, hehe. It doesn't really need to be a clean waveform, btw, vacuum doesn't care!

Excellent results though!
 

Crazlaser

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So I got a new 15kv 30ma NST on ebay cause my last 9kv one burned out, and I've thrown away the beer bottle caps and want to make my sgtc run again.

I remember beer bottles being annoying because they could spill and weren't compact and just need some help. I've looked at the deep fried neon calculator and it says I would need 0.0053uF for those specs. I'm looking at these but I don't know exactly how many I need. I would put them in 9 rows just to have a buffer of 3kv. Thing is, the deepfriedneon calculator says even 2 columns of 9 rows is more than was is necessary. Can someone help me figure out how many I need?
I really know barely anything of tesla coil tuning or the such. When I built mine I just did my best to follow instructions online.

Thanks in advance.

edit: Does it effect the tc if I have a higher capacitance? Or I see from the calculator that if I use about 28 of these caps in one row, I will have the correct capacitance but the voltage will be 54kv. Plus that is quite expensive. Any other ideas? Obviously for a cheaper deal I can go back to the beer bottles but I prefer not.

edit #2: these capacitors are cheaper.

It looks like I only need two strings of five caps with the 15kv 30ma nst, is that correct?

edit #3: Actually it appears I would only need 4 of these in parallel. That seems really small compared to the bottles. Something seems wrong.
 
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Down with Umbrella

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Abandon the beer bottles. Buy the trusted MMC Capacitor - Cornell-Dubilier CDE 942C20P15K-F. http://www.easternvoltageresearch.com/flexibrute_capacitors.html



These capacitors are rated for 2000volts. String 17 in series(you should series/parallel this configuration for head room for your nst's peak voltage but you're on a budget)
For 15kv/30ma .15uf /17= .0088uf. This should put you in the ballpark.
Don't forget the bleed resistors soldered across each cap! A ten meg ohm value should suffice.

Here's another resource if you're looking to build a basic coil.
http://www.teslacoildesign.com/design.html
 
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Crazlaser

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A little too expensive at the moment. I could spend $40 tops on capacitors. And I won't forget those resistors! I don't need to be electrocuted! :p

The coil is already built, it's just been sitting in the garage for over a year since I burned out my last NST. We were having a groundhog dig up under our front porch threatening a cave in so I built an "electric fence," composed of some thin multi-use wire suspended on pvc, out of the way where the rodent was entering. Apparently it overheated and arced through the potting material. Only outputted about 1mm sparks after that so I through it away.
 
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Down with Umbrella

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Lol you built an "electric fence" out of a 9kv nst for a ground hog attack on your front porch?
Did you get him?!
I'll rep that.
Did you ever see the taser glove built? Momentary switch in the palm.

I don't think it would drop a human. Maybe a small mean dog.

Anyways, can't get too far off topic.
Your nst doesn't have a GFCI does it? What the brand? Have you tested it with a chicken stick?
Ask for capacitors for Christmas
 
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Crazlaser

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Nope, it never got the ground hog. Came back two hours later to a burnt out NST. Ended up catching it in a metal trap dad bought a few weeks later.

It doesn't have a gfi. I know what to look for in an NST. It's an Actown. I don't have it yet. It's coming priority mail from CA. I searched for hours for a 60ma one but couldn't find one in my budget. Ended up asking the guy for $100 shipped down from $140 shipped. He said, "You had me at tesla!" when I told him that's what I wanted it for.

I would really like to know if these might suit the purpose. http://www.ebay.com/itm/172415526357

edit: one other question. Two years ago my dad had a concern about one month I used my sgtc and the power build increased from the average 280 to 500 dollars. He thinks the radio frequencies messed with the power meter on the side of the house. Is this actually possible? It doesn't effect anything else except the tv and radio while they're running. For that reason he will only let me use it far away from the house which is quite annoying.
 
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Crazlaser

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Sorry for the double post, here is my coil with 6 beer bottle caps. I just received an 8x2 inch spun toroid from information unlimited and now I'm getting about 6-8 inch streamers. Very impressive to me! 15kv, 30ma.

edit: I resized them




 
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Down with Umbrella

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Hey, there ya go! Do you have a fan to quench that static spark gap?
Try adding a break out point like a piece of wire or something to the top load...preferably pointing away from the wall Look for any racing sparks on the secondary.
Consider a terry filter if you don't have one. Also have you got a PFC capacitor? They are fairly cheap you need a RUN type not a motor start.

What's securing your top load down to the secondary?
 

Crazlaser

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Right now the top load is just sitting on the secondary. I am trying to find a way to bolt it down without creating a breakout point. I could use hot glue.

I have access to many PFC caps because my dad does HVAC, however what would I use it for?

And I use to have a computer fan cooling that gap but that didn't seem to help so I removed it and I think I broke one of the blades a while back. No I don't have a terry filter.

Right now I have it on my patio and have been grounding it with some cheap coaxial wire to the downspout on the side of the house. It seems to work. What would you recommend for grounding wire that would be more professional.

I tried a breakout point but it doesn't seem to work, in fact it seems to make the arcs shorter and split into many tiny ones off the same arc to air.
 

Down with Umbrella

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Ok Sean, you need to secure the topload to the secondary. I don't know how, you're going to do it but it needs to be done. God forbid the thing falls off while running...I used 3/8th nylon all thread with the magnet wire pinch between a brass washer and the aluminum tl.
Pfc- this will correct the AC sine wave coming from the mains. (Most use spade connections) Put this right in front of your NST to improve efficiency. Read up on that. The value isn't critical but there is a formula for optimal capacitance.
Dedicate a special earth ground for your secondary. This will improve performance. Your dad works in HVAC? Scavenge a piece of 3/4in x 3' copper tubing pound it into the ground and ground to that. Thickest wire you can find. Coax might be fine. I used a 00welding lead.

Fiddle with the tuning.
It takes me months to build a coil, some of the vets here be like: look what I found in the pahts drah... and the damn thing will work marvelously. Haha
 

Crazlaser

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Ok Sean, you need to secure the topload to the secondary. I don't know how, you're going to do it but it needs to be done. God forbid the thing falls off while running...I used 3/8th nylon all thread with the magnet wire pinch between a brass washer and the aluminum tl.
Pfc- this will correct the AC sine wave coming from the mains. (Most use spade connections) Put this right in front of your NST to improve efficiency. Read up on that. The value isn't critical but there is a formula for optimal capacitance.
Dedicate a special earth ground for your secondary. This will improve performance. Your dad works in HVAC? Scavenge a piece of 3/4in x 3' copper tubing pound it into the ground and ground to that. Thickest wire you can find. Coax might be fine. I used a 00welding lead.

Fiddle with the tuning.
It takes me months to build a coil, some of the vets here be like: look what I found in the pahts drah... and the damn thing will work marvelously. Haha
I don't see any problem if the top load fell off besides it making some sparks on the primary circuit. I didn't think of the nylon threads I'll look for some. I have a piece of pipe 3/4 inch pounded into the ground on the side of my house but I'm going to try to pull it out and use it somewhere else. It's six feet long so that might be hard.

Most of the caps my dad uses are for 440v. Won't the NST damage the cap?
 
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Down with Umbrella

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Yeah if your topload falls off it could possibly dent the nice aluminum spun torrid. If it falls on the primary and touches the secondary which is ground it will fry windings.
I can't be sure, but this might damage your NST as well.
You put the PFC CAP INFRONT OF YOUR NST. Low voltage mains. Not across the NST output.
 
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