First sstc is not working

[davekni]

he circuit I made is not working properly. I have been dealing with this for about 3 months.
It only works when I touch the interrupter with one hand and bring my other hand closer to the coil.i think i will copy another design

Sounds disappointing!  Sometimes starting over is the easiest.  However, I don't think there is any inherent issue with the circuit you are using.  Now that you have a scope, debugging should be possible.  It will take some time to step through the circuit scoping signals at each point.  If you want to continue, I'd suggest testing entirely in interrupted mode with duty cycle set low.  That minimizes risk of part damage as average power remains low.

[Mads Barnkob]

Sounds like you need to find the fault in the feedback circuit. The gain is not high enough, there must be some faulty or wrong component. You are basically acting as a large antenna and amplifier, when you can make it work by touching it.

I have also started over completely on some projects, it happens to all of us, do not loose hope

The schematic seems to be a run of the mill version of Steve Wards Mini SSTC, which is really one of the simplest to get running, I would recommend to still go with that schematic. I built 3 of them myself: https://kaizerpowerelectronics.dk/tesla-coils/kaizer-sstc-i/ and https://kaizerpowerelectronics.dk/tesla-coils/kaizer-sstc-ii/ and https://kaizerpowerelectronics.dk/tesla-coils/kaizer-sstc-iii/

[NyaaX_X]

My half-bridge SSTC is still been tested too. My experiences may not be helpful. 

The wiring might be as short as possible. But the primary coil leads be stranded and make the tesla coil tower far away from your driver at least about 15cm (for me) might be better. And away from interrupter like 30cm up and make the interrupter connect to power V- or ground. I saw many people put all the circuit under the tower but their circuit might be finished. And that position seems also have low EMI.

The unuse "input" pins of 74HC14 are better to be connected to ground or 5V.

And you can make a 200k ~ 500k Hz oscillator with ~50% dutycycle 5V squarewave output directly go into UCC "in" pin and catch the GDT waveforms with oscilloscope. I think here do not have to  power the half-bridge power stage while testing.  To test if your half-bridge driver working fine. (Also maybe disable the interrupter so driver run in CW mode. Watch out the UCC temperature)

[Recep talip]

Thank you all. I'll fix the feedback section soon and fix other issues. thank you all  for inspiring me
I will follow all your advice,

[Recep talip]

  hello again i'm back with more problems. I rebuilt the driver circuit, and I changed the UCCs and 74hc14 and to test gdt I  bought a signal genenator 
N30 material 10 turn CAT5 wire





driver output



interrupter output


my first problem is: a ringing comes from the bridge and comes a tittle from gdt. Trying to reduce the number of turns of the primer didn't help.I changed the direction of the primer but nothing changed.
all unused pins of 74hc14 connected to gnd. bus voltage is 80v dc   I still can't get this project working.

[davekni]

all unused pins of 74hc14 connected to gnd.

Only unused inputs should be connected to ground.  Leave unused outputs unconnected.  With inputs grounded, outputs will be high.  Grounding them will short outputs and make 74HC14 chip get hot.

interrupter output

I'd suggest testing at much lower duty cycle than shown 50%.  Reduces risk of something burning out.

Then scope GDT inputs (driver outputs) while trying to run in feedback mode.    Scope antenna too.  These scope traces should give some idea of what the issue may be.

[Recep talip]

Only unused inputs should be connected to ground.

yes that's how i did it

Ringing coming from primary and gdt in interrupter mode
No output in CW mode,touching the antenna did not work. This is the signal on the input pins of the uccs

[NyaaX_X]

If there are mistakes in my saying please check and correct them for safety, thank you very much

Here I have a few questions. Where do you connect your secondary coil ground to? A big piece metal or something else? And how much is the k-factor in your coil. The javaTC might help you to calculate the parameters of tesla coil. Sorry for I don't know how to use it.. Here is the url https://www.classictesla.com/java/javatc/javatc.html . And in your post the "driver output" 80V waveform seems to be measured from the half bridge? without secondary? If that's right I think the GDT is working. Maybe you can catch a VGS waveform and post it in the future. Here I don't recommend you probe your live wire connected circuit with a non-isolated oscilloscope. And the ringing may caused by the parasitic inductors and oscillation. You have to optimize your power stage wiring and also can add a capacitor between Vbus +- near your half-bridge transistors as near as possible to  absorb some switching ringing.

And you can also read about Steve ward's articles like https://www.stevehv.4hv.org/SSTC5.htm or the transformer feedback type from the left-up side of
https://www.stevehv.4hv.org/DRSSTC.5.htm, you can ignore the JK flip-flop part, focus on the 74HC14 and current transformer part. I'm shocked you buy a function generator.. But not bad if you like to play with electronics and you have enough resource 

Pay attention while playing with AC live wire...

[davekni]

This is the signal on the input pins of the uccs

That looks like a great 671kHz square wave.  As NyaaX_X said, JavaTC can tell you if that is expected frequency for your secondary and top load.  If so, then coil is running, just without enough power.  If JavaTC indicates a lower frequency, then the antenna is picking up the wrong signal and/or phase is inverted.

[Recep talip]

  Hello again, I'm back with some good results
I connect the secondary to the building ground line. there is a bus cap 1500uf 450v

when it started to work at first, the length of the arcs was short, I set the primary as 4 turns and it looks like this at 80v dc. but the coil sometimes doesn't work when playing with the interrupter.
the coil  not working in CW mode. I think what Davekni said is not true for my 671khz coil
 I will review and share when I have time
I am grateful for your help, thank you all

I don't know much about how to use javatc. need to do some research

[NyaaX_X]

So how do you get that 631kHz? Feedback form coil or function generator?
If you want to boost up the Vbus voltage then you might have to decrease the ringing on your power stage half bridge.