Tesla Coil Build Thread

[Sigurthr]

12" - 3" x 12" Toroid Tesla Coil for Neon Transformer | eBay



I think im gunna change my Onetesla toroid to the 8" one above, the onetesla toroids are shit.

Putting the 4" one on my nano spark gap coil.

Eww... don't spend that much on toroids!

High Voltage Products - Toroids & HV Terminals - Information Unlimited $80 for 3"x12". It's the one I use on my 3kW coil.

It is my formal opinion that OneTesla is a waste of money given the wide array of problems that have cropped up and the lower standard of quality of the parts used/offered.

Btw, I never got around to telling you guys, but if you're ever designing a secondary for audio modulation go with a rather high Q secondary design (small L, large C) as it enhances the slope detection effect in converting the FM to AM. I found out that is why I couldn't audio modulate my 3kW coil properly, I used a very low Q design for easy tuning.

 

[Speedy78]

Its not showing any products under toroids. Maybe its because im on my phone. Definitely want to build a larger coil than my onetesla.

 

[Fiddy]

While in the little conversation I've had with them they were exceptionally helpful and polite, the culture there is not as... forgiving to newcomers who haven't done tons of research as we are here on LPF. If I were in your shoes I wouldn't want to impose with a direct question.

I've dug up a pertinent thread for you. I *think* you can view it without being a member. Forums / Tesla Coils / DR tank impedance, lower vs. upper pole - 4hv.org

Let me know if you can't see it.

I see ill have a read.

Eww... don't spend that much on toroids!

High Voltage Products - Toroids & HV Terminals - Information Unlimited $80 for 3"x12". It's the one I use on my 3kW coil.

It is my formal opinion that OneTesla is a waste of money given the wide array of problems that have cropped up and the lower standard of quality of the parts used/offered.

Btw, I never got around to telling you guys, but if you're ever designing a secondary for audio modulation go with a rather high Q secondary design (small L, large C) as it enhances the slope detection effect in converting the FM to AM. I found out that is why I couldn't audio modulate my 3kW coil properly, I used a very low Q design for easy tuning.

yeah i saw the 12" was a bit of a rip, have you ordered from that mob before?

When you say audio you mean CW right? like plasma speaker or you mean our interrupted midi style coils?

I bet thay would drop my secondary resonance a good bit. Has a lot more surface area. Would I be able to build a larger coil with this new board and utalize that 12 inch one?

yeah it would, just add more turns to primary to counter it!

 

[Sigurthr]

Some more DRSSTC "required reading". Fair warning; this is a thick soup to swallow.

Forums / Tesla Coils / Tuning tricks, poles etc. - 4hv.org

Forums / Tesla Coils / A dynamical arc model - 4hv.org

By now you're starting to see how Dynamic Plasma Physics starts to really play a role, and you thought the electronics-only side of the engineering was rough!

Here's a quote from the master, Mr. Steve Ward, about what it can do when you understand it all though:

Im using my new digital drivers so i can do tuning tricks* and primary current regulation. The coils are 30" tall secondaries, running ~50khz. They have made 11.5 foot arcs to the ceiling so far, with 350V-560V bus and 600A peak in the primary with a 0.3uF primary cap. They have a generous 78pF of secondary capacitance (they use a secondary-side MMC at 300kV). These coils managed to essentially "drill a hole" in a concrete floor when it found some rebar just 2" below the surface. There was a 1/4" diameter hole after the ground spewed orange sparks. These coils make incredibly bright arcs to ground. A pair of them will throw 10 foot arcs (each) with a 10kW power supply thats shared. Might be some of the best coils ive ever worked with, mainly because they maintain better tuning with big spark loads. The low primary amps is mainly due to this good tuning effect, the streamer resistance is reflected to the primary side as a significant resistance which keeps the primary amps reasonable with very long pulses. And if that doesnt work out, the driver knows how to step on and off the gas to keep it going at whatever primary amps we want.

edit: I mean CW for plasma speaker type performance. Oh and I've ordered many times from Information Unlimited. These days they're a rip for most of the stuff they sell, still a good source for toroids though.

 

[Fiddy]

Interesting read lol at found some reo bar in the concrete lolo.
Ahh yeah i saw some of their stuff before.

here's a quick drawing i did of what i mean by the ring down im seeing on my scope when the coils running.

 

[DashApple]

@ Twirly: use two non-inverting chips and just run the signal to the second gate drive IC through a single pass of the Schmitt Trigger Inverter to make it inverting. Why do you need TO-220's anyway? I've never had any heating issues with the 8-dip ones.

Thanks , just prefer the 220's ones , I've used both 220 and DIP8 though .

 

[Sigurthr]

Interesting read lol at found some reo bar in the concrete lolo.
Ahh yeah i saw some of their stuff before.

here's a quick drawing i did of what i mean by the ring down im seeing on my scope when the coils running.

I first need to know what I'm looking at; is that primary current, secondary base current, primary voltage, secondary voltage, BUS voltage? Is your OCD set at your desired current level? Were you hitting OCD limit or not? Does the driver control burst length (how many cycles per burst)? Does the driver have a phase shift control?

 

[Fiddy]

I first need to know what I'm looking at; is that primary current, secondary base current, primary voltage, secondary voltage, BUS voltage? Is your OCD set at your desired current level? Were you hitting OCD limit or not? Does the driver control burst length (how many cycles per burst)? Does the driver have a phase shift control?

Secondary volts im assuming as im getting large voltages on the scope leads near the coil when running.

yeah OCD is at 350A the limit as advised in the microbrute manual.

You hit OCD quiet easily if your out of tune.

I can only control PRF and PW from the interrupter.

 

[Sigurthr]

Ah. No wonder... blind interruption and no phase delay adjustment. That is an old school DRSSTC!

Do you have a dual channel scope? I assume the circuit uses primary current feedback via a current transformer? Scope the current transformer output on one trace and secondary voltage on the other trace; when they're 90deg out of phase you're in perfect resonance. Note though; this CAN cause hard switching of the IGBTs/MOSFETS depending on the driver topology, so monitor junction temps of the switches.

I'm trying to find the 4HV post tailored specifically to tuning old DR coils... not having much luck.

 

[Fiddy]

Alright sweet!

Also im making a Spark gap for my small SGTC (9kV @ 20mA), which electrode material is the better between the following: alumimium, stainless steel, titanium, brass, mild steel. I know tungsten is best but wont get any before xmas

 

[The Lightning Stalker]

Definitely not aluminum. The titanium should be interesting to experiment with. I would say try them all
and see which one has the best SigNature. I would think it would be between the brass and titanium, but
who knows?

 

[Sigurthr]

Brass and aluminium ablates away widening the gap which can cause resonant rise destruction of your transformer. Mild steel will have pronounced corrosion and will undergo thermionic emission causing quenching problems if you let it get hot. Stainless will do that too but less so and won't corrode as badly so that's what I'd use. Never tried titanium but I suspect it will behave similarly to aluminium. Copper works great if you can use that.

 

[The Lightning Stalker]

Yeah, you're probably right. I didn't realize that titanium burns before it melts, so it will probably just blow
away in the wind. It would still be in interesting (and expensive) experiment.

 

[Fiddy]

i made some aluminium ones to try out, its a low power transformer so ill see how it goes

I thought copper would die easily?

here's my attempt at a static spark gap:

 

[Sigurthr]

Either that fan is tiny or that gap is freaking huge. On my 300W SGTC using a 7.5KV NST the gap distance for proper tank charging was something like 0.117 inches. JavaTC has a spark gap tool, use it.

 

[Fiddy]

its a 80mm fan, gap is like 12mm!

thats like 3mm gap for 7.5kV?