I finally got my first DRSSTC up and running and I'm very happy that it's working, but there are still some issues.
https://youtube.com/shorts/LW7HfMb8ZDw?feature=share

The OCD is currently set to around 350A but it gets triggered when the input voltage reaches around 130VAC yet the sparks I'm getting are still very short. To check if this was an issue with my tuning or not, I removed the secondary and replaced it with a solid piece of metal as the load on top of the primary coil. The OCD still got triggered at around 130VAC input.

I scoped the current waveform using a voltage probe across the 51ohm resistor and got following waveform. The peak voltage is 23.2V which translates to 284A in the primary (I'm using 1:625 reduction CT) Because the primary current looks good I thought I had just tuned it like shit. But I had calculated the secondary resonant frequency using a function generator and an oscilloscope and it came to be 153kHz. So I adjusted the primary tap till I could see the primary current having a frequency of approximately 143kHz (Detune of 10kHz) but still I was not impressed with my arc output. And I couldn't increase the input voltage cause then the OCD LED would be constantly on.


Then I proceeded to scope the comparator inputs for the OCD. The blue waveform is the set point, currently set to approx 2.8V which translates to 343A as the limit. The yellow waveform is the other input of the comparator coming from the feedback. Both of the waveforms have more noise than usual because I had to attach jumper wires to the header J9 so I can easily probe these voltages. The waveform is just when the OCD got triggered.


I'm not sure what the issue is, one possibility is that the ferrite cores I'm using for the CT are not good, as the N30 cores I had ordered were too small, so I had to use some other cores I had laying around. But I had tested them by making a GDT with them and connecting them to the output of the UD2.7C output while using a function generator as the feedback. The output waveforms looked good so I assumed the cores were good enough to use for the CT. (The core for the final GDT is big and of N30 material so that's not the issue)

Other than that I think I've done everything properly, maybe the primary tap is a bit janky but it hey it works. I've attached images so maybe you can figure out if I've done something wrong.

This is my first DRSSTC. I've built most of the separate parts, now I just need to assemble them together.

Bridge - SKM100GB12T4 in Full Bridge
Bridge Supply - 0-260VAC, 35A Bridge Rectifier, 4700uF 400V EPCOS Electrolytic Capacitor
Primary Coil - Spiral Primary - 7 turns of 1/4 inch OD copper tube with 10mm spacing and an Inner diameter of 150mm
Secondary Coil - 110mm diameter, 540mm long, 1350 turns, 28SWG enameled copper wire
MMC - 3 strings in parallel of 3 in series of Cornell Dubilier 942C20P15K-F for 0.15uF at 6000VDC
Snubber - 2uF 1kVDC 827V/us dv/dt (KEMET C4BSNBX4200ZBLJ)
Top Load - Toroid -  Minor Diameter-127mm   Major Diameter-490mm 
Driver - UD2.7C Thru Hole
Resonant Frequency - Around 150kHz

I don't have access to a tunable inductor, so I was thinking of making my own. The plan is to 3D print a screw and a housing. The winding will wound on the housing, and there will a ferrite core inside the screw which I'll be able to move up and down by turning the screw. It will be much bigger than a traditional coilcraft inductor, but should work I guess? What are your thoughts? Perhaps when I figure out the inductance value, I can remove it and replace it with a fixed inductor.

While connecting the grounds together, should the 24v supply case be connected to the mains ground or the common rf ground?

I noticed later on, that the skm100's I've bought have slower on/off times compared to some other models. So I hope that wont be an issue. I was planning on setting the OCD to 300A during testing, and increasing it to 500A after proper tuning. Can these IGBT's handle 500A?


I've made some annoying mistakes while building my inverter bridge. The IGBTs are too close together resulting in there not being enough space for the bus capacitor, as you can see it covers up the igbt screw terminals and the snubber capacitors cover up the wire connections. This means the bridge has to be assembled in a particular order, and if I need disconnect anything, I'll have to remove the IGBTs from the heatsink. The only benefit of this layout is lower stray inductance I guess.


I made the toroid out of 5 inch aluminium ducting. I wanted to ask, is the way I've connected the secondary to the ducting good or bad? The top of the secondary goes to a lug connection, connected to a threaded rod, which comes out the top, which is connected to the ducting using aluminium tape.

I was building the UD2.7 thru hole board but I ordered tantalum capacitors instead of ceramic ones. I wanted to know if they will work as well, as tantalum capacitors are polarized so that might be an issue. Also they are rated for 35V instead of 50V as mentioned in the BOM. I assumed the voltage on the board won't exceed 35V as the supply voltage is 24V. So are 35V rated capacitors enough or I need 50V rated ones at least? Thank you

So my sstc based on kaizerelectronics sstc1 stopped working probably when I increased the bus voltage too much but its not the mosfets that died but still i replaced them and also replaced the bus capacitors but still its not working Some observations are that when I turn it on nothing happens and theres not current draw from the bus capacitor and the ucc driver ICs also stay cold. So is it possible that something in the driver circuit got damaged due to the magnetic field of the tesla coil??because I hadn't shielded it, it was just sitting beside the secondary coil. I was thinking about building the driver circuit again with new parts. Unfortunately I didn't use sockets on the ICs otherwise I would have tried replacing them. If you have any ideas of how to fix it or whats wrong Ill be happy to hear it. Thanks for the help

I finished building a solid state tesla coil by using the schematics of Kaizer Power Electronics SSTC 1. Its working awesome except the enable pins of the UCC3732x are not working. I had bought them from Aliexpress. So the tesla coil always stays in continuous mode, even when I connect them to ground it still stays in continuous mode. I really wanted to use the musical interrupter. So is there anything i can do?