Akula eternal lantern 4

[kEhYo77]

ferroresonance? 

[d3x0r]

Adding a diode between the collector and coil stops perpetual(or even secondary) oscillation ;  extra oscillations are real power draw, and are not free... they trick the transistor into conducting. 
scope shot is really that the pulse happens when the gate goes off.  It can be higher amplitude, have the pulse width about as short as I can get it... a longer lead time to conduct allows more energy to be stored; (up to saturation?).
Extra ringing on the circuit is induced by the scope probe having a capacitance.

[d3x0r]

a few incarnations of akula devices... maybe demo by akula... https://www.youtube.com/watch?v=NnFgr9eu7bAand a TPU device

Looks like the version 4 (attached, cut from schematic)

[d3x0r]

That video was privated here's another upload http://youtu.be/w_WCcUXvZK8


english translation of original lantern 4 video https://www.youtube.com/watch?v=rbyJKRuzFLw

[TinselKoala]

Lots of room inside that big electrolytic capacitor can.