Help with LabCoatz's Staccato QCW DRSSTC Tesla Coil

[hal7rr]

Hi everyone!

I'm a second year electrical engineering student and I'm new to everything high voltage, so please excuse my lack of knowledge. I am however eager to learn and will take any advice to heart. I've been fascinated by Tesla coils recently and want to take a stab at building one when the semester ends this month. I'm going for Labcoatz's design as it looked relatively easy to solder and build. I do have a couple of questions about the parts.

1. For the 12 VAC transformer, there are so many to choose from. some have 6 pins and others have 8 pins, which one should I go for? I looked at the PCB design and I couldn't figure it out.

2. In the instructions it says that the MMC Capacitor bank has to be at least 1kv 100nF. does he mean each capacitor has to be 1kv or the total voltage of the bank has to be 1kv? I know that connecting capacitors in parallel equates to the sum of them and that connecting them in series equates to the inverse sum.

3. Lastly, for the top load, how doing figure out the size of the topload? The secondary coil I ordered is 75mm in diameter. Do I go for about 1.5x the diameter?

Link for the video I'm referencing

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Please let me know if any information is missing. I'm here to learn and I'll be as cooperative as I can.
Thanks!

[NyaaX_X]

I think it's may be hard to build a "Quasi Continuous Wave" "Dual" resonance variant of a SSTC as your first tesla coil. So maybe you would like to build a simple SSTC first.?

Whatever, here is some informations for your example:

https://www.stevehv.4hv.org/SSTC5.htm
https://www.loneoceans.com/labs/sstc3/

And for your questions:

(1)_usually that kinds of 110VAC to 12VAC or 220VAC to 12VAC transformer are basically have a pair of input pin for utility power, and 2 or 3 pin for output 12VAC or +6 to 0 to -6 VAC. You need to observe them for more details.

(2)_http://www.hvtesla.com/mmc.html or https://deepfriedneon.com/tesla_f_mmc.html or else... Somebody use only one pcs of a high-voltage rated, high voltage changing rate capacitor (snubber capacitor) for a small size tesla coil.

(3)_I don't know much about the Top load and the behavior of discharging. The top load can change the parasitic capacitance and change the resonant frequency of your secondary LC circuit.

For your informations Please getting more help from the other members on the forum

[Michelle_]

I'm building the same design. Good luck, this is optimistic for a first build however it's well documented and already has a PCB so as long as not much goes wrong it should work out. It sounds like it's too late now but I would have recommended starting with a SGTC, then building a regular SSTC first to build your understanding because now you will be lost trying to troubleshoot a far more complicated system. Also building your own secondary instead of ordering one would have also been an incredibly valuable learning experience but I guess it depends on whether your goal is learning more or just building a tesla coil. Anyway I digress.

1.) The number of pins is irrelevant as long as you get the input and output voltage you need. The reason there are different amounts of pins is because some of them accept and output different voltages depending on how they are connected.

2.) I'm sure he means the whole bank because the individual capacitor voltage rating is meaningless since they can be connected in different ways and numbers in a MMC.

3.) You can go by various rules of thumb (google them) but one of the most important things is making sure your resonant frequency will be in your target range (the coil with the top load) - just use javaTC to estimate it if you don't have it on hand to test with a signal generator and oscilloscope. I would suggest making the toroid easy to remove and change out so you can try different sizes. Generally AFAIK smaller ones store less energy before the spark breaks out so a bigger one will have bigger sparks, up until the point it is too big and strains the drive electronics or can't break out anymore.

[alan sailer]

Good luck to all. I had built about seven tesla coils (including two QCW coils)and the LabCoats PC
board proved my undoing. After blowing up several sets of IGBJTs and learning nothing I threw
the whole project in the trash.

To be clear, I am not saying that there is a fatal flaw in the board. I just could not get it to work well
at all.

Cheers.

[Michelle_]

Good luck to all. I had built about seven tesla coils (including two QCW coils)and the LabCoats PC
board proved my undoing. After blowing up several sets of IGBJTs and learning nothing I threw
the whole project in the trash.

To be clear, I am not saying that there is a fatal flaw in the board. I just could not get it to work well
at all.

Cheers.

Any suggestions on an alternative QCW driver that could be a backup for this that can use the same secondary?

[ZakW]

Any suggestions on an alternative QCW driver that could be a backup for this that can use the same secondary?

Check out my ramped sstc thread in my signature. Full schematic on page 4.

Labcoats QCW coil has many issues and is not a good beginner coil. Good luck!

-Zak

[Michelle_]

Any suggestions on an alternative QCW driver that could be a backup for this that can use the same secondary?

Check out my ramped sstc thread in my signature. Full schematic on page 4.

Labcoatz QCW coil has many issues and is not a good beginner coil. Good luck!

-Zak

Thank you, your results and quality of work speak for themselves, I am inclined to listen to you and Alan so I will keep an eye on this thread (if it is updated) and as for myself most likely change directions and build your version of the QCW coil. At this point I'm only out a few bucks for the PCBs but I can always give it a shot down the road when I understand what's going on better.

[hal7rr]

Hmmm, it does seem that I'm in way over my head. I picked LabCoatz's cause he had a 240 VAC version which a lot of the designs I saw did not + the videos I saw and the comments all said it was relatively straightforward to build (tho they probably are more knowledgable than me lol). Can anyone recommend simple SSTC designs that can handle 240 VAC as I'm based in the Middle East.

[Michelle_]

Hmmm, it does seem that I'm in way over my head. I picked LabCoatz's cause he had a 240 VAC version which a lot of the designs I saw did not + the videos I saw and the comments all said it was relatively straightforward to build (tho they probably are more knowledgable than me lol). Can anyone recommend simple SSTC designs that can handle 240 VAC as I'm based in the Middle East.

It depends what your goals are. If you want the simplest tesla coil that can make decent sized sparks something like the ZVS flyback driven spark gap unit I made running off a PSU that converts to DC (That will accept 240 no problem) can get you pretty far and requires extremely little potential troubleshooting as long as it's been designed properly to begin with. You can also build a spark gap tesla coil with a neon sign transformer. There's a reason most people start off with these it's because you learn the fundamentals but there are no electronics to complicate them.

As for solid state I think most of them can depending on the voltage rating of individual components, but you should probably consider getting a variac either way so you can ramp up voltage for testing. 240VAC is pretty dangerous to play with for a first tesla coil and you also need to be aware of whether this is single phase or not, etc... At least in America once you're talking about line voltages of 208, 220, 240, they don't always work the same way.

I would recommend looking here:

https://kaizerpowerelectronics.dk/tesla-coils/kaizer-sstc-ii/

Kaizer's designs are fundamentally sound and similar to the popular (for a reason) Steve Ward designs. The reason these designs are popular is because they don't have any funny business and contain the basics that are needed to have a reliable and functional tesla coil (interrupters, gate drivers, etc...). Things like QCW are similar in many respects but are more complicated. Even the basic ones like the steve ward SST5 will take quite a bit of understanding to build, but if you can build it and understand it you'll be way better off than blindly putting parts into a PCB that's not very serviceable or easy to trace, modify, repair, etc...

Also it’s ok to try things and make mistakes, I’ve made plenty so far and still have a lot to lean. but try to lean from them and know when to listen to people that know more. You don’t always have to do what they say but at least try to understand why they are telling you what they are.

[hal7rr]

As for solid state I think most of them can depending on the voltage rating of individual components, but you should probably consider getting a variac either way so you can ramp up voltage for testing. 240VAC is pretty dangerous to play with for a first tesla coil and you also need to be aware of whether this is single phase or not, etc... At least in America once you're talking about line voltages of 208, 220, 240, they don't always work the same way.

I would recommend looking here:

https://kaizerpowerelectronics.dk/tesla-coils/kaizer-sstc-ii/

Kaizer's designs are fundamentally sound and similar to the popular (for a reason) Steve Ward designs. The reason these designs are popular is because they don't have any funny business and contain the basics that are needed to have a reliable and functional tesla coil (interrupters, gate drivers, etc...). Things like QCW are similar in many respects but are more complicated. Even the basic ones like the steve ward SST5 will take quite a bit of understanding to build, but if you can build it and understand it you'll be way better off than blindly putting parts into a PCB that's not very serviceable or easy to trace, modify, repair, etc...

Noted. I'll have a look at the designs and I'll definitely invest in a variac! Quick question about the variac. Looking at the prices online, they range from about $50-$200+. Does it matter if I get a cheap one or should I invest in an expensive one?

[Michelle_]

As for solid state I think most of them can depending on the voltage rating of individual components, but you should probably consider getting a variac either way so you can ramp up voltage for testing. 240VAC is pretty dangerous to play with for a first tesla coil and you also need to be aware of whether this is single phase or not, etc... At least in America once you're talking about line voltages of 208, 220, 240, they don't always work the same way.

I would recommend looking here:

https://kaizerpowerelectronics.dk/tesla-coils/kaizer-sstc-ii/

Kaizer's designs are fundamentally sound and similar to the popular (for a reason) Steve Ward designs. The reason these designs are popular is because they don't have any funny business and contain the basics that are needed to have a reliable and functional tesla coil (interrupters, gate drivers, etc...). Things like QCW are similar in many respects but are more complicated. Even the basic ones like the steve ward SST5 will take quite a bit of understanding to build, but if you can build it and understand it you'll be way better off than blindly putting parts into a PCB that's not very serviceable or easy to trace, modify, repair, etc...

Noted. I'll have a look at the designs and I'll definitely invest in a variac! Quick question about the variac. Looking at the prices online, they range from about $50-$200+. Does it matter if I get a cheap one or should I invest in an expensive one?

It does matter, based on what I’ve read the cheap Variacs from China that you find in that price range can be potentially dangerous at worst and at best may not stand up to their rated current or long term use. Most people recommend looking for an older used unit from a good brand. Personally I’m a tool snob and am willing to spend $$$ to get things that will last and not fail at the worst possible time. It’s a habit that’s served me well as a technician and engineer and now I have a bunch of nice tools that still work and are worth something (can be a slight curse lol I can’t even lift up my sockets and ratchets section alone). So I’d google a bit then look on eBay or wherever you can buy used equipment and get something decent but I understand not everyone has an unlimited budget just be aware that with things like this they are not all created equal.

[alan sailer]

Michelle wrote,

Any suggestions on an alternative QCW driver that could be a backup for this that can use the same secondary?

At the risk of being a tesla pedant, LabCoats "QCW_ coil is not a QCW coil. It's a ramped, or RDRSSTC. A true QCW
coil uses  buck converter to generate a very long ramp. A RDRSSTC uses the leading edge of a sine wave to generate
a much shorter ramp.

A great description of the build of an RSSTC is by loneoceans,

https://www.loneoceans.com/labs/sstc3/

LabCoats borrowed this design for his own project. I am not sure if he even gave loneoceans credit. I also think he uses
the term QCW for his coil to make it sound like he has created a much more difficult type of device.

To answer your question, the ramp generation circuit in LabCoats in his design appears to work fine. It's identical to
loneoceans design.

Cheers.

[Michelle_]

Michelle wrote,

Any suggestions on an alternative QCW driver that could be a backup for this that can use the same secondary?

At the risk of being a tesla pedant, LabCoats "QCW_ coil is not a QCW coil. It's a ramped, or RDRSSTC. A true QCW
coil uses  buck converter to generate a very long ramp. A RDRSSTC uses the leading edge of a sine wave to generate
a much shorter ramp.

A great description of the build of an RSSTC is by loneoceans,

https://www.loneoceans.com/labs/sstc3/

LabCoats borrowed this design for his own project. I am not sure if he even gave loneoceans credit. I also think he uses
the term QCW for his coil to make it sound like he has created a much more difficult type of device.

To answer your question, the ramp generation circuit in LabCoats in his design appears to work fine. It's identical to
loneoceans design.

Cheers.

Not pedantic at all just facts! Thanks for explaining the difference. I think it’s crucial to rightfully call things what they are when it comes to things like this.