Big Coil (DRSSTC v2)
Big Coil has been an ongoing long term project, with a bit of recent research into the optimal ways to get phase lead compensated feedback working within a half cycle at the start of each pulse. It is trivial to get a phase leading signal a cycle or two from start, but it has proven relatively difficult to get it immediately.
The project has also gone through a number of gate drive revisions. I’m currently using optically signaled drivers on each brick with a 60hz iron isolation transformer powering the board. It pulls the gate +20V/-5V, capable of about 30nS switch time with minimal gate resistance, although I put an ohm or two in to help limit any ringing that could occur both on the gate, and more importantly voltage spikes that could form from emitter to collector.