Silkscreened on the stacked green PCBs: "GaN DRSSTC: GaN Full Bridge Dual Resonant Solid State Tesla Coil. Niklas Fauth 2019. Open Source Hardware & Software." Both the primary and the secondary are etched PCB traces, not wound wire. It is one of the few entries on this tree where the coil itself, not just the driver, is the original part. The bridge uses two TI LMG5200 GaN half-bridge modules (gate drivers integrated, about $9 each at the time). It switches at 2.6 MHz, two orders of magnitude above a typical DRSSTC's tens of kHz. GaN makes that practical because its switching losses stay low at that frequency. An STM32F072 enumerates as a USB-MIDI device (crystalless, with the clock recovered from the USB bus). It also generates the PWM for a flyback boost stage that steps 5 V USB power up to the 40-50 V bridge rail. The rail is software-adjustable, and the project notes this could extend to QCW-style ramping. A dedicated dead-time generator (dual triple-input AND gates with cross-blocking logic, opto-isolated) prevents shoot-through between the GaN switches; a simpler approach would not keep up at that speed. Sparks are modest, about 3 cm off a single PCB coil and a bit more with two stacked. The validation is thorough for a hobby project: six board revisions to reach stability, 69 of 70 fabricated PCB coils working correctly, and several independent rebuilds by other people confirmed before he called the design finished.
Schematics and photos
schematic: dead-time generator + feedback recovery (KiCad)
Sources
This is the card from the driver tree, written from what the builder published. Send corrections through the forum.