Thanks for the change, .99. Any chance you'll do a replication of this circuit, and tests including Pout / Pin?
In my 2nd post above, I noted good results with Rr = 3.1 ohms.
...
I have added Rr and replaced the standard diode by a low power LED from the LTspice library. It doesn't change much. We see that the frequency is less than 100 Khz, which is compatible with the time constant 1/Rb*Cb.
See first trace in: FEosc-traces.png
Then I have considered the capacitance between Lb and L0 due to their proximity. In real life, there are always parasitic capacitors
. So I added Cp=20pF connecting the two coils.
The simulation seems much more realistic, see the second trace in: FEosc-traces.png.
The time constant 1/Rb*Cb still plays its role, but modulates a new signal due to Lb/Lo/Cp ringing (around 2 Mhz).
Then I replaced the ideal NPN by the LTspice model of 2N2222.
Now the time constant 1/Rb*Cb does no more appear except for the first burst.
See the third trace in: FEosc-traces.png
Finally I visualized the power and the energy (COP<1, no surprise). The output power is calculated from the product of the voltage available at the emitter by the current passing through the LED/R0/CSRout.
See the final circuit and the traces of the power in FEosc-Power-Energy-schematics.png
For those not familiar with LTspice, one can get the energy or rms values by a ctrl+click on the title of the trace in the simulation window.
LTpsice model is in FEosc-2N2222.asc.
May be I will duplicate the circuit if time permits.