Tesla Coil Build Thread

[Sigurthr]

I'm sorry to hear that, it's a shame. I remember my first few coils were huge disappointments and frustrations. I wish you all the luck with future ones!

 

[DashApple]

That does suck , My first PLL coil was horrible to get working , mainly due to bad phase locking , But many MOSFET's gave there lives for it and in the end it worked well .

just the getting from Not working , to working is worst part of it all . Good luck to any future ones you try



new secondary on VTTC using GU81m , Outputs over 12 inches from a 5 inch secondary , coils running a 10 Hz mains synced .


SAM_1042 by TwirlyWhirly555, on Flickr


SAM_1054 by TwirlyWhirly555, on Flickr

 

[Atomicrox]

I didn't think it'd be easy but TBH I didn't expect it to be this hard either. I've already spent at least some 15 whole days working on the coil, not to mention all the money and waiting for international shipping.

But what pisses me off the most is that it's very hard to debug... I mean, how am I supposed to know what went wrong and how to avoid it?

As of right now I see a couple options:
-Recycle the bridge and try again with some reused MURs/slightly damaged silpads. Will most likely blow up again.
-Order some IGBTs and in a couple months try Po210's or oneTesla's design. Will probably blow up but I might get some bigger sparks with voltage doubling. Not to mention they don't use all the diodes, which makes the bridge easier to make.
-Buy a oneTesla kit. Pity I hadn't seen it before starting this.
-Lay low for a while, slowly buy parts and go the opposite way Sig went - build a big ass dual MOT SGTC when I get on vacation. At least it doesn't have as many failure points and will produce 1m sparks.
-Give up coiling.


Great results as always, ion!

 

[Sigurthr]

The main downside to SGTCs is that they are freaking deafening. I mean jet airplane LOUD. My ears were ringing with 120dB reduction ear plugs, and I only ran it for 90sec intervals because my spark gap kept overheating. That was with only 300W of input power.

If you had a scope I'd say go for a PLL driver as they run way better (if you can dial in the phase lock correctly).

I think what killed your bridge was cross conduction (aka. shoot through). High side fets tend to blow in cross conduction scenarios (from my own tests anyway) and leave everything else intact. I may be quick to point my finger but the elephant in the room is RF getting back in to the driver causing a false HI signal in your drive train which turned the high side fet on when it should have been off. Nothing else would cause it to suddenly blow without taking anything else when the coil was not on start up and when no thermal issues were present. RF can couple across normal circuit "barriers" and it makes it hard to control.

There is another option all together you know; go Twirly's route and start a VTTC. They are robust as hell, the hardest part is tuning the three resonant circuits to work together.

 

[Hydroas]

I want to show my VTTC:
große VTTC testaufbau - YouTube
If I get better caps I test it again and show the results.
The tube is a swiss T 380-1 and I know it isn't a good idea to lay it on the side...
It run on a 2kv MOT stack and the coil is 35cm high.

 

[Atomicrox]

The main downside to SGTCs is that they are freaking deafening. I mean jet airplane LOUD. My ears were ringing with 120dB reduction ear plugs, and I only ran it for 90sec intervals because my spark gap kept overheating. That was with only 300W of input power.

If you had a scope I'd say go for a PLL driver as they run way better (if you can dial in the phase lock correctly).

I think what killed your bridge was cross conduction (aka. shoot through). High side fets tend to blow in cross conduction scenarios (from my own tests anyway) and leave everything else intact. I may be quick to point my finger but the elephant in the room is RF getting back in to the driver causing a false HI signal in your drive train which turned the high side fet on when it should have been off. Nothing else would cause it to suddenly blow without taking anything else when the coil was not on start up and when no thermal issues were present. RF can couple across normal circuit "barriers" and it makes it hard to control.

There is another option all together you know; go Twirly's route and start a VTTC. They are robust as hell, the hardest part is tuning the three resonant circuits to work together.

Do you have any clue of how to debug that? I'm out of ideas here..

No way I can do VTTC. Regular electronics are already hard to come by around here, tubes will be pretty much impossible.

I want to show my VTTC:
große VTTC testaufbau - YouTube
If I get better caps I test it again and show the results.
The tube is a swiss T 380-1 and I know it isn't a good idea to lay it on the side...
It run on a 2kv MOT stack and the coil is 35cm high.

Nice coil!


Edit: a friend of mine recorded some videos of my coil while it was still alive:

 

[MrMcChicken]

Hi all,
after a long time of building nothing special, i thought i's about time to start a bigger project.
Well I decidet to build my first SSTC. The Desings isn't from me. Here is the link where i got the shematics from. SSTC Solid State Tesla Coil

Actually the TC is the same as the one on this site.
There are just some little differences like the gate resistance, the GDT, capacitors an a few other small things I changed for finetuning.
The secondary is a bit bigger too.

Well, here is a pic of the whole setup.

Here is a pic of the gate signal. You can't really see the rise and fall time an this picture but it is about 150ns.

I think the sparks are really impressive. They're about 20cm long.

And finally here is a picture of an arc against a screwdriver:

Cheers :beer: MrMcChicken

 

[Atomicrox]

Great work!
What's the secondary length?

 

[MrMcChicken]

The secondary is 22cm long and 7.5cm width.

 

[Atomicrox]

Cool. A video would be nice

 

[MrMcChicken]

Cool. A video would be nice

Ther will be a small Video. I just had some problems to make it, because my camera start to go crazy if I was to near to the coil.
Finally I could make one. I will upload it as soon as possible.

 

[Sigurthr]

Excellent work! REALLY clean gate signal, is that just gate drive without being hooked up to the gates?

 

[MrMcChicken]

Excellent work! REALLY clean gate signal, is that just gate drive without being hooked up to the gates?

:thanks: No that is the Signal connected to the gates loading them.
While building I tested the signal after the GDT and there was some ripple on the secondary. This part is cut off by a bunch of zener diodes at the gates.

Edit: Here's a short video:

 

[DashApple]

Nice Coil , Nice output .

I should try and find a ceramic tube to make my secondary to remake my audio sstc .

 

[Sigurthr]

Looks really great! Could you draw up a quick schematic of your gate side subsection? I've never heard of zeners being used to clean up the gate signal. Most zener diodes are considered too slow for common TC frequencies. Judging by your secondary size you've got to be around the 400kHz+ neighborhood.

Really makes me want to finish my mini halfbridge SSTC. I've got the secondary, toroid, GDT, and a decent driver (but I really -should- make a better one) all done for nearly a year now. I just need to get around to making a new primary and bridge.

 

[benmwv]

Ive been wanting to make a small (like desktop size, maybe 6inches tall) sstc, but I just dont know where to start. Audio modulation would be nice. Can you guys link me to some good drive circuits and info about secondary size, topload size, etc?