How do the diodes protect the OT?

[trobbins]

On reflection, I think that the ringing portion of plate current also needs to describe the other half-winding, which would have a plate in cut-off and a voltage on that plate that is ringing as a result of the clamping action of the simmed plate at that time. The current that was in the cut-off plate's winding is resonating around the sim models LCR loop of winding inductance and parallel capacitance and winding DCR, with a coupled loading from the simmed plates circuit.

[Alan0354]

Guys, I am too busy buying fume filter and respirator because I have been coughing because of the solder smell and I need to resolve that. I come back when I have time.