Tesla Coil Build Thread

[Seoul_lasers]

One of the reasons you lost output moving up toroid size is because you don't have enough turns on your secondary. The effects the magnetic fields characteristics and as such fails to energize the full winding length.

So I was right in thinking this secondary is too small then! Good to know. What size would you recommend for a larger coil using the same MMC/NST? Is 3"x15" going to be big enough to get ~1ft streamers? I'd rather not go so large that streamer length exceeds secondary height, because then I need to do serious primary side strike protection.



One word; AWESOME. How the heck do you wind such large secondaries? I assume you have some kind of motorized jig?

Woops... I ment primary. Your secondary is fine for now. You don't have enough power for anything too much larger. 3" coil is probably the largest you can use.

Big secondaries require a motorized or (I prefer) hand cranked jig. Reason is that you want to slowly turn the wire onto the coil form as perfectly as possible. At larger powers, a small break in the insulation on the wires can lead to a breakout or racing arc.


Just to clarify the SSTC thing. small DIY SSTC, are quite inexpensive, but when I consider TCing I like anything that can give +70" discharges. SSTCs that can deliver this kind of power are $$$$'s! Those are usually DRSSTCs, ones that utilize huge IGBTS. Oh yes, they are REALLY expensive.
DRSSTC that produce the shows seen in Vegas (singing coils) are $10,000s each or more.

 

[Sigurthr]

Ahhh, gotcha, thanks! That makes more sense then, too small of primary and the magnetic field can't energize the much larger secondary very well.

I had to change out all the smaller gauge wire I was using today as after a 3 minute run the insulation melted off them. :crackup: I replaced it all with 14ga stranded high dielectric wire sold for use in Ham dipoles. Runs cool now! I also fine tuned the primary a bit and gave quenching another shot, this time with the fan up as high as I could make it go and as close as possible to the gap... wow it really makes a difference now! Before I guess I just didn't have enough air flow to make any difference. Unfortunately the new increase in power came with a downside... racing arcs again. I was getting up to 6" streamers now but the racing arcs were persistant. One even blew off some insulation at one point in a turn on the secondary. I turned it off as soon as I could and inspected it, it appears to not have shorted any turns so I got lucky. I had to readjust the spark gap so no more racing arcs appeared, but this lost some output power. I'm getting 5.5" streamers at best now, with most around 4". Next week I'll go out and buy more electrical tape and wrap the entire secondary in multiple layers and give spark gap readjustment another shot.

Also I shot some more video.


One thing I noticed is that the spark gap frequency is not very stable, and directly relates to the output power. When the sound of the gap takes a lower pitch the streamers grow, and when it raises in pitch they shrink and stop dancing. This would be evidence of a quenching problem, right? The gap is staying "on" too much causing a perceived raise in frequency and not letting the caps charge up to full, right?

 

[Hiemal]

Next week I'll go out and buy more electrical tape and wrap the entire secondary in multiple layers

Be careful about what kind of tape you use.

Alot of black tapes use carbon in the colorant and are more prone to dielectric breakdown as a result... Try using Kapton tape, if you can get it cheaply.

Alternatively, 3M makes some really nice stuff that would work too.

 

[Sigurthr]

Hmm, thanks for the reminder. I don't know what I'd be able to get really, up here in the middle of no where WalMart is the main source of anything. Aside from shopping online, if WalMart doesn't have it, we can't get it.

Today I went to the only local "hardware store" to see if I could find 1/4" copper tubing and PVC pipe. Neither were available. Tons and tons of PVC fittings... but no actual pipe. My face did irl. Sometimes I really miss living in the city. Unfortunately I forgot that I was out of electrical tape.

I wonder if acetyl packing tape will work....

 

[brtaman]

One of the reasons you lost output moving up toroid size is because you don't have enough turns on your secondary. The effects the magnetic fields characteristics and as such fails to energize the full winding length.

Woops... I ment primary. Your secondary is fine for now. You don't have enough power for anything too much larger. 3" coil is probably the largest you can use.

Big secondaries require a motorized or (I prefer) hand cranked jig. Reason is that you want to slowly turn the wire onto the coil form as perfectly as possible. At larger powers, a small break in the insulation on the wires can lead to a breakout or racing arc.


Just to clarify the SSTC thing. small DIY SSTC, are quite inexpensive, but when I consider TCing I like anything that can give +70" discharges. SSTCs that can deliver this kind of power are $$$$'s! Those are usually DRSSTCs, ones that utilize huge IGBTS. Oh yes, they are REALLY expensive.
DRSSTC that produce the shows seen in Vegas (singing coils) are $10,000s each or more.

Yes to have someone like Steve Ward build it for you. Trust me...they are not 10k if you know how to build.

The mid size DRSSTC I had time for, which has a midi input as well...uses bricks, high quality components...cost me less than 300EUR, to build everything. Including MMC, controller everything. Maxed out at 1.2m spark length, because I ran out of time.

Don't know where you are pulling these numbers from man. Perhaps retail of a built coil? Because if you can shop around and you pay 10k to build such a coil I have some land in Fiji to sell. Trust me I have all the parts needed for a 2m Secondary coil laying around in my lab including industrial 1000V 4uF caps ready for a MMC that can handle 4k Amp pulses and imense siemens bricks, as well as all other parts needed and it cost me all together 400EUR...

 

[AUS]

Be careful about what kind of tape you use.

Alot of black tapes use carbon in the colorant and are more prone to dielectric breakdown as a result... Try using Kapton tape, if you can get it cheaply.

Alternatively, 3M makes some really nice stuff that would work too.

You can usually find someone selling Kapton tape on ebay, I have got it (For example).
You can also use rubber self amalgamating tape designed for water proofing RF connections, its good for up to 69kV, I have used it up to 15kV or so. 3M make it as do a few other companies.

 

[Seoul_lasers]

Yes to have someone like Steve Ward build it for you. Trust me...they are not 10k if you know how to build.

The mid size DRSSTC I had time for, which has a midi input as well...uses bricks, high quality components...cost me less than 300EUR, to build everything. Including MMC, controller everything. Maxed out at 1.2m spark length, because I ran out of time.

Don't know where you are pulling these numbers from man. Perhaps retail of a built coil? Because if you can shop around and you pay 10k to build such a coil I have some land in Fiji to sell. Trust me I have all the parts needed for a 2m Secondary coil laying around in my lab including industrial 1000V 4uF caps ready for a MMC that can handle 4k Amp pulses and imense siemens bricks, as well as all other parts needed and it cost me all together 400EUR...

Again, I'll repeat, the large demo coils that are used for the large shows in vegas and trade shows are most certainly 5 figures. --70" sparks are not big enough for +1000 person crowds. I'm talking about +10KW DRSSTC coils. I have looked into smaller 35" output DRSSTCs before and the cost of the kit was around $700, and that did not include the variac, wiring, nor the secondary or toroid... So by the time you're finished yes, +1000USD starting for all materials. Eastern HighVoltage research also produces a larger coil but it is for renting.
Remember I have built coils for galleries and exhibitions. I have looked into building DRSSTCs before, but the acquisition for parts and all the extras for set up was
cost prohibitive at the time. Basically anything under 70" of spark and I won't use it for an exhibition.



About the tape and coil performance. Virtually all black tape has carbon as the colorant. Stay WELL away from using it anywhere on your secondary.
IF you must use tap. Teflon or winding tape for xmfrs better.

 

[Seoul_lasers]

Ahhh, gotcha, thanks! That makes more sense then, too small of primary and the magnetic field can't energize the much larger secondary very well.

I had to change out all the smaller gauge wire I was using today as after a 3 minute run the insulation melted off them. :crackup: I replaced it all with 14ga stranded high dielectric wire sold for use in Ham dipoles. Runs cool now! I also fine tuned the primary a bit and gave quenching another shot, this time with the fan up as high as I could make it go and as close as possible to the gap... wow it really makes a difference now! Before I guess I just didn't have enough air flow to make any difference. Unfortunately the new increase in power came with a downside... racing arcs again. I was getting up to 6" streamers now but the racing arcs were persistant. One even blew off some insulation at one point in a turn on the secondary. I turned it off as soon as I could and inspected it, it appears to not have shorted any turns so I got lucky. I had to readjust the spark gap so no more racing arcs appeared, but this lost some output power. I'm getting 5.5" streamers at best now, with most around 4". Next week I'll go out and buy more electrical tape and wrap the entire secondary in multiple layers and give spark gap readjustment another shot.

Also I shot some more video.


One thing I noticed is that the spark gap frequency is not very stable, and directly relates to the output power. When the sound of the gap takes a lower pitch the streamers grow, and when it raises in pitch they shrink and stop dancing. This would be evidence of a quenching problem, right? The gap is staying "on" too much causing a perceived raise in frequency and not letting the caps charge up to full, right?

I can hear the gap sputtering a little, so I may say your primary tuning is off by just a little.
Try increasing the turns 1 1/2 turns more and see what happens. Also, try adjusting the gap slightly, give it a very slight decrease in gap size.

 

[brtaman]

Again, I'll repeat, the large demo coils that are used for the large shows in vegas and trade shows are most certainly 5 figures. --70" sparks are not big enough for +1000 person crowds. I'm talking about +10KW DRSSTC coils. I have looked into smaller 35" output DRSSTCs before and the cost of the kit was around $700, and that did not include the variac, wiring, nor the secondary or toroid... So by the time you're finished yes, +1000USD starting for all materials. Eastern HighVoltage research also produces a larger coil but it is for renting.
Remember I have built coils for galleries and exhibitions. I have looked into building DRSSTCs before, but the acquisition for parts and all the extras for set up was
cost prohibitive at the time. Basically anything under 70" of spark and I won't use it for an exhibition.



About the tape and coil performance. Virtually all black tape has carbon as the colorant. Stay WELL away from using it anywhere on your secondary.
IF you must use tap. Teflon or winding tape for xmfrs better.

Oh, you meant kit buying...in that case probably. I am talking about building everything start to finish and designing the controllers or just replicating one of Wards designs.

You can do it much cheaper that way. Its all about getting the best deal but I suppose you have to be in the hobby and not a consumer. As I said the 50 inch coil, with midi capability set me back less than the cost of a semi-decent laser. But there was no kit nonsense. Besides EasternVoltResearch charges large amounts of money considering his designs are practically a direct copy of Wards work...

 

[Seoul_lasers]

Oh, you meant kit buying...in that case probably. I am talking about building everything start to finish and designing the controllers or just replicating one of Wards designs.

You can do it much cheaper that way. Its all about getting the best deal but I suppose you have to be in the hobby and not a consumer. As I said the 50 inch coil, with midi capability set me back less than the cost of a semi-decent laser. But there was no kit nonsense. Besides EasternVoltResearch charges large amounts of money considering his designs are practically a direct copy of Wards work...

Yes, I see what you mean.
Actually, that good advice. Thanks.

IF I had the set up to build DRSSTCs I would have tried, but I also know that they are quite finicky to deal with and really need an ocilloscope to iron out any issues with frequency and tuning. I know several builders who have blown gate drivers VIOLENTLY and IGBTs and when your building something pushing several KAs at ~650V into your primary, a single small flaw and KABOOM!
I am interested in Steve Wards 12KW singing coil. That's the size I am into.

 

[brtaman]

Yes, I see what you mean.
Actually, that good advice. Thanks.

IF I had the set up to build DRSSTCs I would have tried, but I also know that they are quite finicky to deal with and really need an ocilloscope to iron out any issues with frequency and tuning. I know several builders who have blown gate drivers VIOLENTLY and IGBTs and when your building something pushing several KAs at ~650V into your primary, a single small flaw and KABOOM!
I am interested in Steve Wards 12KW singing coil. That's the size I am into.

Oh yes, an o-scope is certainly needed.
Can't imagine building a DRSSTC without one. But they can be found quite cheap...like 200-300bucks for quite a decent one.

Even so exploding IGBT's are a given part of the game at least until a decent tune is set-up.

But really the whole DRSSTC system seems a lot more daunting than it actually is. It really is a very basic system, whose properties can be calculated with some very basic algebra.

Basically for another 100 bucks I could add a secondary 2 times as large onto the mid sized system (already have a large machined toroid), the bricks in there can handle a lot, would probably shoot output to 70-80 inches, but I live far away from my lab, I am home now for a month then off I go again, really with I could get back into the hobby it really is fun, but living in an apartment makes large DRSSTC systems impossible.

In terms of parts. Bricks can be had for peanuts on ebay, just have to know what to look for. IF you are contemplating a build, don't let the kit and pre-built prices hold you back. If you take the time shop around, they really aren't that much more expensive than a decent laser.

 

[Sigurthr]

About the tape and coil performance. Virtually all black tape has carbon as the colorant. Stay WELL away from using it anywhere on your secondary.
IF you must use tap. Teflon or winding tape for xmfrs better.

Righto. I just wrapped it in teflon tape (why didn't I think of that sooner!) and will report back on how it does.

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I can hear the gap sputtering a little, so I may say your primary tuning is off by just a little.
Try increasing the turns 1 1/2 turns more and see what happens. Also, try adjusting the gap slightly, give it a very slight decrease in gap size.

I'm completely out of 12ga solid core wire and there is none to be had locally. I have dozens of feet of 14ga stranded though. Since we're ignoring the modeling program I can't just plug the gauge change in and see what the consequences are... - do you think 14ga stranded will be ok for this?

Likewise, remember I cannot put a flat sprial primary on this secondary - the coilforms are epoxied together and to the small rectangular base which holds the spark gap, which is also epoxied in place. So all primaries will have to be helical. Adding more turns of a small gauge helical coil may bring about racing sparks due to overcoupling. I'll give it a shot if you think it will work despite this but I REALLY don't want to blow out my secondary with a bad racing spark.

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Besides EasternVoltResearch charges large amounts of money considering his designs are practically a direct copy of Wards work...

Oh yes, an o-scope is certainly needed.
Can't imagine building a DRSSTC without one. But they can be found quite cheap...like 200-300bucks for quite a decent one.

I have been considering buying the EasternVoltageResearch MicroBRUTE DRSSTC kit because it says no oscilloscope required. $300 for an all-inclusive DRSSTC kit that is designed to not need a scope doesn't seem too bad to me. Am I wrong on this?

----------------------------------------------------

One thing to know is I'm not after super giant streamers feet in length. I'd like about 15 inches of branching, vibrant, white-hot looking streamer, that's all. Anything more than that and I don't have a place to put it. Do you think a larger secondary coil and flat spiral primary for my SGTC is capable of this? I'm open to suggestions. If it isn't realistic then I'll just save up for the EVR MicroBrute and keep my sgtc the way it is.

 

[Seoul_lasers]

I though I'd show you my airblast gap coil running 360mA @ 12kV. This is one of the medium power Tesla coil that ended being displayed at a school in Central BC.
Students of the Physics 12 class and woodworking and metal working built this coil.
The capacitors and secondary coil were all constructed in clean room.
Capacitor is a 100nF 36kVdc rated MMC. Gap is constructed from 5 ZrWo 1/2" arc cutter electrodes. There is a vacuum blowing air through the gap.

Output here is 80-85". The sputtering you hear is due to the Variac slowing being turned up.




No students were killed in the production of this coil.
Also made the local newspaper.

 

[Sigurthr]

That is a NICE SGTC!

It inspired me to search harder for new materials, which has paid off. Today I finally found some 1/4" soft copper tubing! I bought all I could afford to... 60feet of it. (I only expect to need about 20ft.) I also ordered a nice 1lb spool of 30ga enameled magnet wire. Now I just need to track down some damned PVC tubing for the new coilform.

I may be forced to move back to NJ in the coming weeks, so we'll have to see how much of this project I can get done before then. It all depends on where/when my next job comes from, really.

 

[Seoul_lasers]

Actually home depot is great for thin walled solid PVC.
I'd personally be aiming at doing 4" dia coil form for 50ft of copper tubing.
3". Better still is thin walled 4" acrylic tubing.
before using it youll have to sand it down.
Also you'll be wanting higher voltage and higher current.
12kV @ 180mA should be good for starters.

The coil in the YouTube video was tuned about 3 years ago
Winter to 92" sparks. To do this a 35" toroid and 13 turns were added.
There is no ground rail on the coil. The terry filter I butchered did its job.

 

[Sigurthr]

Terry filters don't protect the MMC though, I thought a primary strike can overvolt your MMC as well?

The same place I got the soft copper tubing at had some 4" pvc pipe (just not on display), so today I snagged two 22" long sections for $10 total. They couldn't cut it squarely though as their saw only cuts up to 3", so only one of the pieces has one square cut on it. I'll have to figure out how to fix the other should I ever need it as a coilform.

Yeah, there's no Home Depot or Lowes or equivalent up here, we have to make due with small businesses tailored to the normal needs of the community, which is mostly farmland. So if farmers or residential contractors don't need it, I can't get it locally.

That being said I have my new coilform and primary materials, and my spool of wire has been shipped. I'm not exactly looking forward to winding 1250-1500 turns by hand with no jig on such a large form, but hey, what can ya do? Lol. I don't have the tools (or money for them) to make a jig nor do I have the space to make it in. I don't even have a work bench, I use a 24" x 18" plastic folding table for all my projects. Sometimes living in an appartment sucks.

I'll worry about upgrading the NST/MMC later on, those are expensive upgrades. For now I have the daunting task of winding a huge (to me) secondary and making a base for the primary.