hello guys. fist i want to say i will pay
20 euros for a person who can help me sort this problem out
i can give more if you offer
extended helpshort about this project it is my graduation project that i cant get to work. I have to finish it as quick as possible that is why im offering money. I hope its enough because i have spent too much on this coil already. its almost 350euros for all the components that keep blowing or not working. im tired of wasting money on it and i need smarter people advise.
short about me and my equipment i have multimeter, clamp meter for measuring current ac/dc, osciloscope dso138 witch is good for 100khz at most. i can access a good one in my college.
i have decided to make drsstc TC for my finals that i kind of regret it, because it didnt turn out the way i wanted. im stuck with it and i need to finish it ASAP. i have electronics as a hobby and my speciality is electrican
short about my TC i decided to use already polished designs that are available on the internet. but it still doesnt work for some odd reason. i use DRSSTC design witch contain Universal driver UD2.7c full Hbridge bridge and an interupter. it seems easy at first, just order some pcbs, put it together and wuala. but i got stuck now. i think i have assembled my devices correctly. i got it working several times, but the result is not what i hoped.
UD2.7
http://www.loneoceans.com/labs/ud27/ H bridge design
https://github.com/profdc9/DRSSTC-PCB-Pack/tree/master/full-bridge-transistorinterupter
https://easyeda.com/stuarth/steve-ward-s-drsstc-interrupter-with-burst-modemy trial and error srory i goofed a lot of trial and error tries to get it working. i blew my transistors at least 4 times now.
on first try i can verify, my boards should be working to some extent interupter is definetly working. UD2.7 should be working because my gate drive transformer makes noise according to interupter pulses.
my h bridge should be working, verified with osciloscope, although the drive is not looking the best, at least on the first power up when i had a good osciloscope to probe around. on feedback i ran signal generator to check if it is working.
first i blew a single audyn brand polypropilene capacitor rated 550VAC 0.1uf i saw sparks of 1mm when metal object is near secondary.
then by grounding my primary coil i blew IGBT transistors
then i bought new audyn polypropilene caps, this time 4 in series making it 2kv ac capacitor close to 0.1uf i saw 1mm of sparks as well
then i blew transistors again, probably because my Gate drive transformer was 1:2 ratio making it 48v on IGBT gates
then i bought expensive snubber capacitors, they are called CDE capacitors 0.068uf, steve ward used them. it is 12 pcs bank, 3 series, 4 paralel, making it 0.09uf bank of caps
i changed up my primary design a bit, because it seemed that the most voltage is at the middle of the secondary. so i changed cylinder shape primary to pankake. my coil worked like a charm, except it was making sparks 3mm to air and maybe 3cm to grounded object. not the best result. the worst part i had to turn up my interupter and my variac. my variac was at maximum 250vac and my interupter was turned to pretty high pulse frequency and probably maximum pulse with. suddenly my apartments lights went black. i blew IGBTs again.

Now i found two older pair of transistors that seems to be ok, at least with multimeter diode test mode, so i was lucky and im left with two blown and two kind of ok transistors, so i slapped old pair and new pair of transistors, seems ok everything is working again, this time my GDT seems to change pitch quite differently. i kind of got it working with variac at 180vac, before last blow up by the GDT sound the circuit was geting into a working state as low as 90vac on variac, now it need at least 160vac to go to working state. this state is when the gdt is silent it means circuit is working. and then gdt is noisy it means the circuit is not working correctly.
so this circuit seems to go to working state. the GDT is silent, so my current transformers should be seeing current and giving it to the feedback. i can hear EMF disruptions through my PC speakers. but the
funny thing is, no sparks what so ever. i tried different MMC(capacitror bank) and the old one with no sparks this time
additional information my GDT and current transformers are ferrite toroids from car audio amplifier boost converter circuits. 500:1
the MMC capacitors is CDE cap bank with 6kvdc rating, i also have ceramic type mmc with 5kvdc rating, the little equipment i have says that they are good. transistor tester mk-168 and multimeter shows correct capacitance.
my tesla coil primary is about 3 turns, the secondary is about 1050 turns with former with unknown plastic. it has 0.4mm copper wire and former radius is 4.3cm and diameter is 8.6cm. winding height is about 43.5cm
i also have top load toroid that doesnt seem to affect things
there is optional resistor values on the Hbridge circuit that im not sure witch one to use and im using IGBTs that are suggested in base of materials list for the Hbridge circuit
couple of pictures of my project:
https://ibb.co/album/c7yhfa