Tesla Coil Build Thread

[Sigurthr]

Yeah, that level of output looks reasonable. It depends greatly on your grounding.

 

[USAbro]

I'm just grounding to the wall outlet.

 

[Sigurthr]

I'm just grounding to the wall outlet.

Yes, let me elaborate:

Depending on how effective your wall outlet is at conducting RF energy to earth, you will see better or worse performance.

Not all household installations are of equal RF performance.

 

[USAbro]

Transformer is now 60 miles from my home and will be delivered tomorrow, is what Fedex tracking says.

Here are some shots of my coil. You can see it is tapped at about 5.3 turns.

And sorry the beer bottle capacitor image is upside down. When I flip it, it doesn't allow me to upload it because of dimensions problems. :thinking:

And the tissue box is my quenching contraption. Basically just a 12v computer fan taped into a tissue box, with a paper towel role acting as a duct out of a hole. The strange thing is, the Radio Shack box that I bought it in, said the fan was a 6v fan. But a sticker on it said it was 12v, and 6v was running it fairly slowly. So now I'm running it off of a 3S 3200mah lipo venom flight pack. I had bought a sealed lead acid 4.5ah 6v, and wasted $21 so I guess I'll just have to use it for something else.

Also, does anyone know how to cut down on RF interference. Mom is always watching TV, and hates the interference I'm causing. "It's getting to the good part. Stop doing whatever your doing! Are you playing with that thing of yours?" Talks to dad-"He's gonna burn down the house! Can't you make him do more constructive things!?"

P.S. How do I put the images in my post?

 

[Sigurthr]

RF Interference... there's really no cheap way to fix that, haha, not for a spark gap tesla coil. The better the grounding, the shorter the wires, the less the interference and the better the performance... that's about it.

Later on when you have a real budget ($$$) and electronics equipment you can try moving on to Solid State tesla coils, when done well they have a very short radius of interference, often ten feet or less (my kW-class coil is about 8ft from my PC).

 

[Down with Umbrella]

Talks to dad-"He's gonna burn down the house! Can't you make him do more constructive things!?"

Ohhh tell me about it. I'm too old to even be living in my parents basement but it's where I have the best access to building materials and space.

My tesla coil is about 95% complete. I'll post pictures and a few questions later. Today I'm hitting the slopes!

Keep up the work USAbro! I like to monitor your progress as well!

 

[nospin]

A piece of advice

Don't use the house ground for an RF ground!

Get a ground rod And as big a conductor as you can to connect
The bottom of the secondary to it and as short as possible
I blew out my vonage unit with mine.
Even with that the TVs were unwatchable

 

[USAbro]

Oh guys I feel so sick I could throw up. I got my NST today, powered my TC and it was cool. It wasn't shooting any streamers off the topload, so I put on an aluminum foil light bulb. Streamers shoot out!

But now my NST isn't working! And it hums, and only sparks when I touch the two secondary wires. What is wrong? Can it be fixed?!?! No arcing now. Could it be a temporary shutoff? AHHHHHHHHHHH! Is $40 and a week of waiting wasted?

 

[USAbro]

Oh crap. It smells burnt. I unscrewed it, opened it up, plugged it in, powered it on. And a small stream of smoke rises from inside this thick layer of orange hard muck. Is it burnt?
Is a tesla coil bad for it? Is the secondary damaged, or is it something to do with the insulation needing to be melted out?

I feel really bad wasting this much money. I just feel sick. I was so excited, showed my family it working and now I don't even have it for a day before this. Really?

I kinda feel like I'm never gonna end up with another, this is really bad. Maybe it's time for some microwave transformers, but where to get them?






Edit: Guys I found the problem! After opening it up I found a burnt connection between the secondary thin wire, and the big thick wire that connects to it. Now there's just about 1cm open before it goes into the goop and I have to solder it to the wire and then shrink wrap it. But it still arcs to that point! Yippee, tesla coil streamer images will be upload in the next week (if my soldering skills don't fail me)!

P.S. And they say, "no user serviceable parts inside." What a bunch of crap.

 

[Down with Umbrella]

Photo update of my tesla coil progress.

First off Im afraid to turn this thing on. ehhh what if it catches fire and 4 months worth of work goes up in flames. Maybe i'm being pessimistic.
here is the coil how it sits right now. the primary isn't connected yet I still have to cut the excess and secure it to the clamp.


The Power supply section. that switch box is on a 10' whip with an AC line filter.


The RF ground bus goes directly into a grounding rod buried in the back yard.
the Terry filter has an damn built around it with oil to keep the components from arcing.


Tungsten series spark gap. 6 awg wiring.


Here is my issue, the Flexible(ish) 4awg is too stiff. also is the lead too long? it should be able to reach anywhere on the primary right? also I think I need to build a plexiglass sheet above those caps so the primary lead doesn't touch the capacitors.


Secondary connection to the top load. how do you guys keep that magnet wire tight to the conform? tape?

 

[USAbro]

Output sucks right now. 1.5" to the air, 3" to ground. The reason may be I'm not using a ground. The ground wire is just hanging off the desk.

I breathed ozone and now I feel shaky.

I don't have any filter do I need one for the NST?

Also, there are lots of small streamers. How do I smooth the topload for one big one?

 

[Down with Umbrella]

Light! + rep USAbro when I can. Is it constant?

 

[USAbro]

Yep it's constant. Will post a video if I find out how. Now I'm getting longer streamers. I found that reducing the tank capacitance, and smoothing out the toroid, along with quenching the gap harder, makes longer arcs.

Edit: After grounding to a metal shelf, outputs are even a little longer. 2.5" to air. Almost 5" inches now to ground.

And @Sigurthr. I must say, at exactly 5.3 turns, it gives the best output. Hurray for javatc!

But now I need a smoother toroid.

Also maybe a small faraday cage, as my mom complains about TV interference.

I'm wondering if I should bring this to my science fair at school, it would be awful cool, but my dad thinks it might be a bit dangerous. He freaks out and says all kinds of jokes, about me being electrocuted, and how he hopes he doesn't find me dead when he comes home, and how I should look into how dangerous high voltage is and all this other stuff.

If I ever stop posting immediately, for ever, you'll know what happened. As none of my family members know my credentials now.

 

[Sigurthr]

Output sucks right now. 1.5" to the air, 3" to ground. The reason may be I'm not using a ground. The ground wire is just hanging off the desk.

I breathed ozone and now I feel shaky.

I don't have any filter do I need one for the NST?

Also, there are lots of small streamers. How do I smooth the topload for one big one?

Bah, you risked destroying your coil right there. Never leave the secondary ungrounded. Ground that immediately before the next run. If you're stuck only using the wall outlet to ground then go throughout the house and UNPLUG any electrical device you can't afford to replace. Yes, it is a pain in the ass, but it is the right thing to do.

Get some fresh air, you'll be fine. Yes, they put out tons of ozone.

Good job on the NST repair. Generally NSTs from eBay tend to be a gamble, you never know how badly it was mistreated before.

DO NOT CONNECT THE GROUND ON THE NST TO THE SECONDARY. THIS MEANS IF YOU USE THE WALL OUTLET FOR GROUNDING THE SECONDARY DO NOT GROUND THE NST. Connecting these two points will usually burn out a NST. Also, grounding the NST but not grounding the secondary, but a much lesser chance of catastrophic failure.

Search the grounding tips throughout this thread, tons of info there. You should hit 6" when grounded well. Even if you just buy an extension cord of around 30ft or less and lop the ends off and connect all three wires together, then connect one end to a piece of scrap metal pounded into the dirt, and use that cable as your ground, you'll be doing alright. Then you shouldn't have to unplug the whole house either, as long as the coil isn't physically near anything.

It takes a bit of first hand experience and finesse to get JavaTC to output info that is useable as is, but that's what I'm here for. That's why building tesla coils is as much of an art as it is a science... even aside from all the RF "magic".

Photo update of my tesla coil progress.

First off Im afraid to turn this thing on. ehhh what if it catches fire and 4 months worth of work goes up in flames. Maybe i'm being pessimistic.
here is the coil how it sits right now. the primary isn't connected yet I still have to cut the excess and secure it to the clamp.

Yeah, the flame test is always the most nerve wracking part. At least it is just a SGTC. Can you imagine how I feel plugging in $600 worth of high end electronics directly to the mains with no current limiting or line isolation? Heh.

The Power supply section. that switch box is on a 10' whip with an AC line filter.

Yeh, you're gonna get zapped holding that. Ground yourself to ground with a wrist strap before operating the switch.

The RF ground bus goes directly into a grounding rod buried in the back yard.
the Terry filter has an damn built around it with oil to keep the components from arcing.

Looks good.

Tungsten series spark gap. 6 awg wiring.

Looks good.

Here is my issue, the Flexible(ish) 4awg is too stiff. also is the lead too long? it should be able to reach anywhere on the primary right? also I think I need to build a plexiglass sheet above those caps so the primary lead doesn't touch the capacitors.

Yep, heavy gauge is a bitch. Yeah lay some plexi or PP sheet over the caps to prevent catastrophic failures. Lead length looks fine, you can trim once you know your tap point.

Secondary connection to the top load. how do you guys keep that magnet wire tight to the conform? tape?

You coated your coil with polyurethane, right? It kinda looks uncoated there. Never run a tesla coil that has an uncoated secondary, the insulation of the wire isn't enough to prevent a total melt down. If you didn't coat it go out and buy a pint of fast drying polyurethane and a good brush, disassemble then apply it on thick and make sure it dries well. Put as many coats on as you can bare to do.

 

[USAbro]

Bah, you risked destroying your coil right there. Never leave the secondary ungrounded. Ground that immediately before the next run. If you're stuck only using the wall outlet to ground then go throughout the house and UNPLUG any electrical device you can't afford to replace. Yes, it is a pain in the ass, but it is the right thing to do.

Get some fresh air, you'll be fine. Yes, they put out tons of ozone.

Good job on the NST repair. Generally NSTs from eBay tend to be a gamble, you never know how badly it was mistreated before.

DO NOT CONNECT THE GROUND ON THE NST TO THE SECONDARY. THIS MEANS IF YOU USE THE WALL OUTLET FOR GROUNDING THE SECONDARY DO NOT GROUND THE NST. Connecting these two points will usually burn out a NST. Also, grounding the NST but not grounding the secondary, but a much lesser chance of catastrophic failure.

Search the grounding tips throughout this thread, tons of info there. You should hit 6" when grounded well. Even if you just buy an extension cord of around 30ft or less and lop the ends off and connect all three wires together, then connect one end to a piece of scrap metal pounded into the dirt, and use that cable as your ground, you'll be doing alright. Then you shouldn't have to unplug the whole house either, as long as the coil isn't physically near anything.

It takes a bit of first hand experience and finesse to get JavaTC to output info that is useable as is, but that's what I'm here for. That's why building tesla coils is as much of an art as it is a science... even aside from all the RF "magic".

Okay thanks. The NST is working, but the last bit of wire is too short to solder but is hard so I'm figuring out how to scrape away the orange hard muck.
And I temporarily grounded to a metal shelf.
But I have some 12 gauge wire left, and a 2' steel pole. I'll run that out of the garage and into the ground.
How does it damage the coil if you leave it ungrounded? Just wondering.

I had decided not to use the wall, using simple logic.

Dad is watching TV.
TV is connected to house ground.
Tesla Coil would be connected to house ground.
High voltage enters TV.
TV turns off.
Cause is determined.
Tesla Coil project leaves house immediately.
All summer funds replace $500 TV.

I'm feeling better now. I've gotten cramps before and the chills after breathing ozone. Now I'm doing it in the garage, rather than my room, which allows for better ventilation.

 

[Sigurthr]

How does it damage the coil if you leave it ungrounded? Just wondering.

Well two reasons:

1) the resonator is basically a transformer, and normally one end, the end that is closest to sensitive parts (capacitors, primary, nst connections) is grounded, so it is designed with only seeing a relatively low voltage difference between it and the sensitive parts. With it ungrounded the bottom of the secondary reaches the same voltage as the top of the secondary, and the nearby parts are not designed to withstand that kind of voltage.

2) the RF current wants to connect between the topload and the bottom of the coil. Grounding the bottom means that anything grounded in the environment is now a suitable path for that current without causing damage. With it ungrounded now a large voltage will develop across anything in the environment and little current will make it back to the bottom of the coil, resulting in high voltages and stray currents forming.