This circuit is a high frequency oscillator, and I think it produces high voltage. It is something like Tesla coil.
How this circuit oscillates? I can not find any resonance or something like that ?
What is the frequency of the oscillation?
Thank you very much,

 

The 3 turn coil creates positive feedback ='s oscillation.
Max.

 

This circuit is a high frequency oscillator, and I think it produces high voltage. It is something like Tesla coil.
How this circuit oscillates? I can not find any resonance or something like that ?
What is the frequency of the oscillation?
Thank you very much,
View attachment 96748

The feedback is the tail of the secondary - there has to be some load current for the oscillator to work.

It has some similarities to the photoflash inverter in a disposable camera. That arrangement boosts the oscillator to charge the capacitor rapidly, as the cap comes up to full charge; the feedback current tails of until the oscillator is just idling - so it can be left in a state of readiness without undue battery drain.

The camera inverter usually has a base drive winding in addition to the secondary side feedback boost. Its pretty much the blocking oscillator of Joule thief fame.

 

This appears to be the Slayer circuit from Hackaday's Micro Tesla Coil demo:
http://hackaday.com/2014/12/22/micro-tesla-coil-makes-a-perfect-stocking-stuffer/
It's pretty cool!

Here's a SystemVision simulation for the circuit:
https://www.systemvision.com/design/slayer-circuit-tesla-coil
Note that the capacitance in the circuit (c_load) models the effect of placing objects near the Tesla coil (such as fluorescent tubes) -- It's not part of the circuit that you build.