I certainly can't say that I know what happened. But I'll speculate that Tesla's purchase of 12 radio tubes and some wire in a Buffalo, New York, electronics shop was to hide what really went inside his mysterious box: a bank of parallel capacitors precharged overnight at his hotel room with whatever voltage he needed to provide sufficient torque to run the A/C motor in his EV conversion of a 1931 Pierce-Arrow weighing in at over four thousand pounds. That's what my simulation suggests to me.
The remainder of the circuit merely supplies current dominating over voltage as the byproduct of a surge which can escalate towards infinite gain and at a rate which could become explosive if it were not for the six volt batteries acting as anchor weights on a 85% clocked duty cycle. Any voltage source is also a voltage regulator. Especially A/C voltage sources since they're already regulated as a sinewave. D/C voltage sources have no waveform. So, they tend to create surges (parasitic transients) more readily than do A/C voltage sources.
I wish I knew why simulators can exhibit parametric oscillations despite our lack of formal education on this topic for this is where 'overunity' and 'free energy' occur from. I have yet to see any instance that suggests otherwise.
It is this lack of information that leaves people to speculate, sometimes wildly, why free energy can exist at all. Certainly, the reactive nature of capacitors (in particular) suggest a reason for the birth of new terminology, such as the word: "radiant" energy.
Except for the stress which reactance imposes on a circuit's components, energy is truly free in that its ultimate source and goal is itself. In other words, energy comes from itself whenever it is synthesized and returns to itself whenever it decomposes. This would explain why energy can seemingly appear from out of nowhere or disappear into nowhere when in reality it doesn't have to go anywhere. It's already here and stays here, omnipresent, throughout all of Creation.
Decomposition must not be confused with thermodynamic losses for the latter is merely the transfer of energy from one location to another. Decomposition is not a transfer; it is a convergence of energy into a singularity reducing the quantity of energy available. Likewise, synthesis is a divergence out of singularities spawning multiplicities of energy.
So, energy is never created nor is it destroyed. It is always with us. But we must recognize a game of charade ensues whenever we consider the flexible nature to energy's quantity. This is mathematically modeled by the cardinal sets of infinite series designated by the first letter of the Hebrew alphabet: Aleph. Aleph allows for singular infinities becoming multiple entities each infinity unique with its own identity.