The driver is based on an UC3844 current-mode controller. It runs the transformer in flyback mode. The driver output feeds into a beefy IGBT, an IXGN200N60. The IGBT has a snubber network and a bunch of shunt resistors measure the emitter current.
There's also a big decoupling cap to smooth things out.
The driver was tuned to about 25kHz (ideally it would be a tad lower, around 21kHz) and the gate drive looks quite decent.
The nice thing about the driver is that the power output can be set with a simple trimpot.
Hi there! Where did you get your flybacks?? I bought a dud awhile back. I tried building from scratch, but have only found moderate success