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Tesla Coil Build Thread

Crazlaser

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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.
I didn't think about denting the topload. I'm just curious what the cap in front of the NST does.

I also need to get the right value caps rather than six bottles, I need less wire to reduce inductance.

I'm probably going to be building this coil on a larger platform. Then I will be able to choose the height of the cool to change the tightness of the coupling.

There is sometime arcing from the primary to secondary wire after the last wind on its way to the ground wire so I'm going to put hot glue or something over that.
 



Down with Umbrella

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Google "Power factor correction for inductive loads."
Read up on it.

Cut that first primary turn off or bend it down! Give yourself an inch, inch and a half on each sides. Incorporate a method to adjust coupling. You have to protect that secondary. That's possibly the most time consuming aspect of a tesla coil.

Run a thick wire to that 3/4" copper tubing. Not sure where you are but the ground could be frozen:/

I have a 10' copper coated stake pounded in the ground with a double 00 welding lead to ground my secondary. Hehe. Read far enough back in this thread and you'll see my struggles. (Pages in the 70s I think)
 

Seoul_lasers

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Google "Power factor correction for inductive loads."
Read up on it.

Cut that first primary turn off or bend it down! Give yourself an inch, inch and a half on each sides. Incorporate a method to adjust coupling. You have to protect that secondary. That's possibly the most time consuming aspect of a tesla coil.

Run a thick wire to that 3/4" copper tubing. Not sure where you are but the ground could be frozen:/

I have a 10' copper coated stake pounded in the ground with a double 00 welding lead to ground my secondary. Hehe. Read far enough back in this thread and you'll see my struggles. (Pages in the 70s I think)

yup, indeed. The larger connection one can make to RF ground the better.

Just like to add that most modern XMFR based NSTs are PFC'd already. Some even have GFIs which make them useless in TC application.
Normal PFC = no PFC

Normal PFC / no GFI



@Crazlaser Have a look at the VA rating as it'll give a good idea about whether or not the XMFR
is PFC'd or non-PFC'd if it isn't already explicitly
written on the transformer case. As stated above.


As Down with Umbrella is suggesting, any part of copper primary elevated above the height of the primary turns is a recipe for a direct primary strike.
Too close to a secondary and you also risk a discharge between sec. and Primary.

-- This can be fatal to your tank circuit and transformer not to mention damage your secondary. :(

Additionally, the strike rail must never make a full loop as you'll be essentially creating a shorted turn. This will pull energy away from the primary.
 
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Crazlaser

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yup, indeed. The larger connection one can make to RF ground the better.

Just like to add that most modern XMFR based NSTs are PFC'd already. Some even have GFIs which make them useless in TC application.
Normal PFC = no PFC

Normal PFC / no GFI



@Crazlaser Have a look at the VA rating as it'll give a good idea about whether or not the XMFR
is PFC'd or non-PFC'd if it isn't already explicitly
written on the transformer case. As stated above.


As Down with Umbrella is suggesting, any part of copper primary elevated above the height of the primary turns is a recipe for a direct primary strike.
Too close to a secondary and you also risk a discharge between sec. and Primary.

-- This can be fatal to your tank circuit and transformer not to mention damage your secondary. :(

Additionally, the strike rail must never make a full loop as you'll be essentially creating a shorted turn. This will pull energy away from the primary.
Thanks guys. The coil I've built is really junky. I am not going to invest more money building. I'm working on a slightly bigger one with a 14inchx3inch secondary. Everything on the current one is jury rigged even the wires are just taped with aluminum tape so I'm building another in which I can change the coupling. I'm using the same transformer and topload, however I do have an old topload made of duct and aluminum tape from a few years ago but it's 14 inch which may be too big.

If any of you tesla coil builders have Instagram and wanna see mine run pm me and I'll send you mine.
 
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Crazlaser

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So I have been working on construction of this slightly larger coil. I built a multiple spark gap with copper tubes on a plastic sheet from home depot but it arced over so I build a slightly different multiple gap on the outside of 3" pvc pipe. Still 450va and the secondary I wound got scraped a damaged so it arcs across. I plan to just buy a 20 inch one on ebay. The one I made had 27 awg wire and was 14 inches tall. Would 30 awg wire at 20 inches tall work better? The height is adjustable so coupling can be changed. I'm still temporarily using the broken secondary and getting about one foot arcs to air with a breakout point. I have a lot of work to do and I don't have a line filter or pfc cap yet, nor a safety gap. I'll be constructing those soon.
 

Crazlaser

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Messages
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So I have been working on construction of this slightly larger coil. I built a multiple spark gap with copper tubes on a plastic sheet from home depot but it arced over so I build a slightly different multiple gap on the outside of 3" pvc pipe. Still 450va and the secondary I wound got scraped a damaged so it arcs across. I plan to just buy a 20 inch one on ebay. The one I made had 27 awg wire and was 14 inches tall. Would 30 awg wire at 20 inches tall work better? The height is adjustable so coupling can be changed. I'm still temporarily using the broken secondary and getting about one foot arcs to air with a breakout point. I have a lot of work to do and I don't have a line filter or pfc cap yet, nor a safety gap. I'll be constructing those soon. Right now grounding is to a metal door frame outside or a downspout. I'm using a coaxial cable I found laying around that's like 20 feet long. Remember I'm working on a very limited budget so right now I can't afford better capacitors but I will probably add more as I'm only using 6 beer bottle caps. The strike rail is connected via the bottom of the secondary and the ground wire comes off the strike rail. And yes, the primary coil supports are made of wood against recommendation. Hopefully they won't get wet but right now I can't afford more cutting boards or plastic.
The arcing on the bottom right of the secondary is where some of the wire got pulled of into a loop. I secured the toroid with a plastic bolt I found in the plumbing section.
I used to touch the streamers but now I'm not anymore as I fear a streamer will hit the primary and connect me to the 60hz side of this thing.
The top platform can be raised up and down to change coupling and the secondary is mounted on a flange that is supported on 1/4 inch bolts, about 6 inches about the bottom platform. Everything is wired with low voltage 12-14 gauge wire and insulated with fish air tubing, for pumps, I think it's made of vinyl. Nearly all the connections are soldered and have heat shrink tubing on them. The legs of this thing are made of 1/4 inch threaded rod which is a bit too thin so when my budget allows I'll get 3/4th inch rod to make this thing a bit more rigid. I really should have built the entire thing on 1/2 inch plywood but I used 1/4 inch and it's pretty week. I may end up changing the bottom platform to 1/2 inch when I have the time and when funds allow but that wouldn't really be possible on the top platform because the primary coil supports are wood glued down with wood elmers glue.

edit: after running the coil for a while tonight it suddenly stopped. No hum of the transformer. My heart immediately sank and I took the coil inside for the night. I disconnected the capacitors are tried arcing the NST and it worked! I thought it was burnt out. After some troubleshooting I narrowed the culprit down to a shorted beer bottle cap, which after replacing, fixed the problem. A thing to note: an NST won't hum when it's shorted.
 
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Seoul_lasers

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So I have been working on construction of this slightly larger coil. I built a multiple spark gap with copper tubes on a plastic sheet from home depot but it arced over so I build a slightly different multiple gap on the outside of 3" pvc pipe. Still 450va and the secondary I wound got scraped a damaged so it arcs across. I plan to just buy a 20 inch one on ebay. The one I made had 27 awg wire and was 14 inches tall. Would 30 awg wire at 20 inches tall work better? The height is adjustable so coupling can be changed. I'm still temporarily using the broken secondary and getting about one foot arcs to air with a breakout point. I have a lot of work to do and I don't have a line filter or pfc cap yet, nor a safety gap. I'll be constructing those soon.
hmm...
With the secondary arc breakout...
have a look at where the breakout is occurring and cover with several coats clear epoxy, then apply an overhead projector (clear plastic/usually PE) sheet overtop. This will arrest the sec-Primary discharge.

Hopefully the arcs have not carbonized the plastic underneath. :undecided:

Edit:
To me this looks more like inter-arcing caused by an overlapping turn.
Please don't turn it on again without really having a good look.
 
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Crazlaser

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It is an overlapping turn. As I said, it's a junky secondary I'm just using for tests before I get another pre-wound one from eBay.
 

Seoul_lasers

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It is an overlapping turn. As I said, it's a junky secondary I'm just using for tests before I get another pre-wound one from eBay.
ah I misread the loop part. ..indeed an overlap as you indicated.
Good thing it is not a nice secondary and just for "testing purposes".

Good job on getting sparks.
At anyrate the next time you run a coil you'll know what to look out for... perhaps even try a homebrew MMC ?

:wave:

:D I love sparks and arcs!
 

Down with Umbrella

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Holy smokes we're tripping breakers.
Modifications:
Fixed 5khom resistor in series with a variable 5kohm rheostat to trim from 5-10kohm in the grid leak circuit for better tuning.

Item # 2. I added an ungodly large diode to the doubler circuit after the MOT. The little microwave diode was still kicking but could have given up the ghost any time.
Operation shunt punch commenced. I removed the shunts from an averaged size mot, No negligible difference except a higher current draw at the meter. :thinking:





Abuse. This poor tube should call a help line!




What this coil really needs next is not necessarily more power but a more adequate secondary as I just used this one because it was left over from a sstc project.
-2 needs a staccato!

-3 Drastically improve efficiency and investigate the high current draw.

No more time for experimentation :/ off to work I go.
 
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Seoul_lasers

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The mot without the shunts is what is pulling the large current here.

What you need is an inductive ballast on the primary side to limit your current draw like a smaller shunted mot
with the HV side shorted out. The power flows through the primary side of the windings. This should take your current draw down
to around 10-12A or so.

 
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Down with Umbrella

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Soooo, I was finally able to add the mot as a ballast in series with the HOT IN. This drastically reduced current draw (from>30A to 19A draw at 100% power)but also visible streamer output reduced.



 

Seoul_lasers

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you might be able to carefully knock a shunt or 2 from the mot to get the current up a little more. Say maybe, aim for a 23-25A draw.

Anyways... Great work with the VTTC btw!

I also like the shot with your argon ion laser in the background.
 
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Down with Umbrella

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I am officially classifying this VTTC as finished. I'd like to add a staccato but it's not a priority. Seoul laser, i do have a mot for that it's worth a shot for curiosity.

I still believe a DRSSTC is above my skill level but it's a possibility.
Next on the docket is a very large RSGTC. I want to acquire a damn Power distribution transformer but they're expensive and heavy.
Duel mots, meh. Maybe.
Tesla coil projects are on hold while I'm working in Panama. On more then one occasion it's been referred to as "brujos" witchcraft.
 

madskaizer

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I gave it a try to build a QCW DRSSTC that would operate directly from synced mains rising edge of the 50 Hz supply. A inherently bad idea due to reflected switching spikes directly into the mains supply. Which is also why I stopped the experiments after killing the voltage meter in my variac.

I achieved 50 cm sparks that would make the variac clunk loud and lights were dimming :whistle:

All can be found here: Kaizer DRSSTC IV | Kaizer Power Electronics

Also, some months ago I started up a new decicated high voltage and Tesla coil forum, I invite you all to come post and discuss your Tesla coils in greater details and with preferably a thread per Tesla coil instead of this huge 100+ pages long thread :)

Its at https://www.highvoltageforum.net
 

Down with Umbrella

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10kvA pole pig! 14.4kv for my next tesla coil :whistle:. I also have some massive transformer cores I might use for ballasting.

Questions for someone who has worked with these before. What's the best way to measure limited current on the output side?(target output would be 500mA) I'll be feeding it with 240vac 60 Hz with a thirty amp breaker.
This is the formula I'll be using to measure my ballast inductor. L = 1/((2 pi f)^2 * C. I have a signal generator and oscilloscope with a known resistor and capacitor circuit. Open to other recommendations
At this point in the project I'm just trying to work on the ballast values.

Salvaged cores:, one inductor and one large stepdown.
 

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