Manufactured in https://jlcpcb.com/ Manufacturing this type of board is not easy.
Boards form JLC works without problems and additional payments.
- Input power 24V - 35V from 5V USB powered step up converter or notebook 19V power supply.
- Frequency 2Mhz - 4Mhz
- No special components, just LED, BD243 transistor and 82K resistor
- v1 7/7mill almost not working
- v2 on video working, 100turns, no visible sparks
- v3 on pictures 160turns, works much better but no sparks
- v4 ready for manufacture 150x150mm PCB, 240 turns, I hope it can work much better