I think many of you are making something very simple, difficult, because you don't understand the basic principle and are trying to copy circuits without grasping what you want to accomplish. All the Kapanadze circuit does is cause resonance in multiple stages, initiated by spark gaps. The nature of spark gaps is they contain ALL frequencies, hence a tank can find it's favored frequency without any skill at tuning on the part of the operator. Resonant tanks demonstrate gains of 10x to 1,000x depending upon the Q (Quality) of the circuit, which hinges on Resistance. One resonant tank feeding another will increase gains by orders of magnitude and the capacity of components to handle those values. The weakness of resonant tanks is they need to be tuned to fixed loads, as varying loads knock them out of tune thereby losing the gains (but we really only need to worry about loads at the final output.) Another point: ideally we would want to tap power from a resonant tank without loading the tank or spoiling the resonant conditions. Don Smith shared ways to do this, but there are others. Note just because these methods are simple doesn't mean they're not dangerous or that you don't need to be extremely careful around high voltages, frequencies and/or currents.