An expanded, more stable version of the half-bridge build above. The topology is the same self-oscillating one, but a full bridge of HGTG20N60A4D IGBTs replaces the single half-bridge leg, roughly doubling available power at the same bus voltage. He chose IGBTs over MOSFETs to avoid the parasitic inductance of the external fast-recovery diodes a MOSFET bridge would need. The driver stage credits a separate forum contributor, "sifun," for its design. A UCC27425 feeds three gate-drive transformers into low-voltage buffer transistors, which then drive the bridge. Ward's own Universal DRSSTC Driver uses the same two-stage split for the same reason, keeping the GDTs' own capacitance off the high-current path. It reached roughly 50 A and 4-5 kW in continuous-wave operation, with streamers to about 60 cm off a saline-wetted terminal from an 11 cm resonator and a 6-turn primary. An NE555-based interrupter adds burst-mode operation on top of plain CW.
Schematics and photos
schematic (Zerg, UCC27425 full-bridge)
Sources
This is the card from the driver tree, written from what the builder published. Send corrections through the forum.