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Messages - mrsebe

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Spark Gap Tesla Coils (SGTC) / Mini spark gap Tesla coil

« on: April 28, 2021, 03:16:00 PM »

I made a mini sgtc, with a 4x1” secondary, with 32awg. It’s not a finished product, as I’m still having issues with primary to secondary arcing, however when this happens, the frequency of the spark gap increases significantly, and the arcs from the top load get significantly larger, to the point where arcs break out from the top without putting an object near it. Why is this? I’ve attached a video below. The power source is one of those high voltage generators from eBay (linked below), the black ones potted in resin. They are powered from 3v. I’m not using a capacitor since measuring across the high voltage output of the module reads a capacitance of 1.8nf, which seems fine. I'm assuming the coupling coefficient is too high, would I be able to use javatc to tune this small of a tesla coil?
https://imgur.com/gallery/6by9Da7
https://www.ebay.com/itm/303851604694?hash=item46bef78ad6:g:Gg8AAOSwWnBgBPHq

Dual Resonant Solid State Tesla coils (DRSSTC) / Re: Some questions about DRSSTC's, and guidance to build one.

« on: April 20, 2021, 01:54:01 PM »

Quote from: AstRii on April 19, 2021, 08:48:07 PM

Hello!

To answer your questions:

1.)
Very few DRSSTCs use their very own driver, and if so, it's usually based on Steve Ward's driver anyway. I think the best thing to do is to buy a plain driver board and solder your components by your own. This way you get some sense of how it works by looking at the traces and ICs on the board and you do not just blindly use an existing driver.

2.)
I don't really think that's the case. I would say that most DRSSTCs operate in the range of 1000 - 1500 wingings. It's always a compromise... More windings = higher windings ratio which leads to higher voltages. But lower amount of turns usually coresponds with a thickness of the wire. The thicker ther wire, the lower its resistance and thereore higher Q factor which again leads to higher voltages...

3.)
If this is your first DRSSTC i would probably go for half bridge as this way the IGBTs will operate at lower voltages which means less likely to blow up.

4.)
You usually design your secondary first. Don't go too crazy with height/width ratio. I would say that 3:1 - 5:1 is the optimal ratio. Then you usually make your topload minor diamater to match the diameter of the secodary and topload major diameter to match the height of the secondary.

5.)
DRSSTC drivers always have a feedback system, usually a feedback transformer sensing the current on the primary coil. Lower resonant frequency is usually better as you can push your IGBTs further, but the frequency depends on the size of your coil, a small table top DRSSTC will have a frequency in the range of few 100kHz while a large IGBT brick coil will be in the range of 30-70kHz.

Good luck with your DRSSTC and dont forget to share your results with us!:)

Thanks for all of this information, I don't think I could ask these questions anywhere else on the internet haha.

Dual Resonant Solid State Tesla coils (DRSSTC) / Some questions about DRSSTC's, and guidance to build one.

« on: April 19, 2021, 04:36:43 PM »

I have a couple questions since I am looking to make a drsstc. I have been building and tinkering with electronics for several years, and have built a small sstc and sgtc before, so I have a basic understanding. Where should I start with building a drsstc? They seem very complicated, and I can’t find any guides online that show a step by step process.

A couple questions off the top of my head that I couldn’t easily find on the internet:

1. Do all drsstc’s use a dedicated driver board, such as Steve wards universal driver? Could I build my own, or should I buy a driver board?

2. Most of the drsstc’s I’ve seen online have ~2000 turns on the secondary, as opposed to the ~1000 that sgtc’s have. Why is this?

3. Should I build a half bridge or full bridge? I am planning on using to-247 igbts, as the big “brick” ones seem a little too expensive for my first drsstc. What are the best IGBT's (to-247) to use? I'm looking to make one similar to this one: https://www.loneoceans.com/labs/drsstc1/

4. Since the primary and secondary tank circuits have to be in tune, what is the circuit designed around? Put another way, do you create a secondary coil first, then design the rest of the primary tank circuit based on the resonance of the secondary? How do you decide the number of turns for the secondary, and is there a height/width ratio that gives the best performance?

5. Does the driver switch the IGBT's at the resonate frequency? In some videos I see that the driver board has an antenna or some sort of feedback device, is this to determine the resonant frequency? Is lower resonant frequency better for drsstc's?

6. This question is pointed towards sgtc's: I'm having trouble finding an nst that does not have secondary ground fault protection. Does anyone have an nst that they'd be willing to sell, or where to source one?

General Chat / Re: Welcome new members, come say hello and tell a little about yourself :)

« on: April 17, 2021, 07:56:07 PM »

Hello, my name is Sebastian and I'm from New York. I'm a senior in highschool and am going to study Mechanical engineering (most likely) in college. I have been building and tinkering with electronics since I was a 6th grader, and give all credit to YouTube for learning everything, haha. I have built a couple small tesla coils, a small SGTC and some SSTC's, however I want to build a DRSSTC and need some guidance as to where I should start, hence me joining this forum.