I'm not an expert in pulse transformers but the idea of a zener sounds like a good one.
It is strange, but when I've disconncted zener diode (I belive in) connected to AC mosfet switch gate (I had only one zener so far and it worked with 4VDC Vgs ) now it works fine with 1k load @ 4Vcc

-mosfet-switch-directly-from-mpu-using-gdt/?action=dlattach;attach=860670)
Even with 100k resistor on mosfets gate we have nice ~20kHz output on AC mosfet switch, but this is not supprise, since we have a few mA gate current for sure.
It is strange why this zener diode, which I'll remove from this PCB to examine, makes GDT not working at all as gate driver?
Maybe we need two as suggested in antiparallel, to provide the same GDT secondary load in full period?

Anyway, now we drive AC mosfet switch directly from MPU using GDT, however it will be interesting to see what happends with this 80W 230VAC infrared light bulb, since at 4Vcc and 1k load resitor we had 2V on AC mosfet drains shown by this YATO multimeter, so probbaly it was fine, but this blood zener diode tried ruin my night today

Any ideas, why this zener diode sucks in this AC mosfet switch when we use GDT as gate driver @ eg. 20kHz?
