r/highvoltage

I’m working on an asynchronous rotary spark gap tesla coil. I was hoping to get a sanity check on my plan, since this is my first time making a medium-size tesla coil. I’ve been using JavaTC to design it around a secondary coil I got on aliexpress. Here’s my current plan:

Primary Coil:
flat spiral
10.3cm inner diameter, 26.3cm outer diameter
1/4” copper pipe, about 4.7 turns. About 8.8uH

Secondary coil:
44cm length, 11cm diameter, 1800 turns of 0.21mm magnet wire. About 79mH

Top load:
toroid with minor diameter of 12cm and major diameter of 52cm. About 21.3pF

Tank cap:
MMC made up of 20x 2kV 0.33uF CDE capacitors; 4 parallel strings of 5 caps. Each cap will have 4 series 1W 250kOhm resistors, which are rated to ~1kV each.

Power supply:
Line filter on fused mains input, Ballasted MOT fed by variac (Planning to use a MOT with its secondary removed as a ballast), RF choke (please let me know if you have tips for this, I plan to make a pancake choke with high voltage cable but have been struggling to find much information online), MMC and then rotary spark gap in series with primary.

Rotary spark gap:
small/medium size angle grinder, G10 epoxy fiberglass disk 20cm diameter, 1/4” bolts for electrodes (2 on disk, 1 stationary set). Should give me ~260bps and ~150us dwell time.

Does this seem like a reasonable setup? I’m sticking with just one MOT for now, I don’t want to risk overheating my caps or have any issues with spark gap quenching. Please let me know if I’m missing anything significant or if you have any tips.

I used a 2000W 48.8V 40.98A powersuply with a 2000W zvs Driver from ebay I already knew the Flyback probably wouldn't survive what's the best flyback to use with my setup ? I thought abbaut building my own but idk for information i got abbaut 20cm I think but I didn't measure

Last month, we use acoustic camera to detect Partial discharge in a substation, we found corona discharge and surface discharge, I believe the surface discharge should be a broken or a dust on the isolator.

My last post here was about my zvs driver not working. I made some changes to the circuit like using solder traces with some thick jumpers instead of just aluminium wire, got some irfp260n mosfets, rewinded the choke and got some better heatsinks. https://youtube.com/shorts/VOyg821d8Ok?si=EPSfy\_1gklwxujmy (link of it working) 28v 10A

Running a customized ZVS driver using 400 V IGBTs at 60 V input, driving a huge projection CRT flyback that came out of a 60 inch TV. The primary is hand-wound litz wire. The system produced arcs exceeding 12 inches in length, making it the highest-output flyback transformer I’ve worked with so far. Output frequency was about 50khz.

I have improved my crt flyback driven tesla coil yet again! The new driver is a 555 and mosfet circuit, while the old one was a transistor self-oscillator. I am pretty satisfied with this, and it is very tunable with the spark gap size. I can get more pulsed/branching arcs, or nice continuous tendrils with different distances. Pulling 28 watts.