Control electronics of a plasma ball

I've given the inner workings of a plasma ball and wanted to use it as a small AC-Hochspannungstrafo.
So far so good, the little transformer and corresponding control FET were quickly found. It is driven with 10 kHz.
However I wonder high voltage testing this 10 kHz are generated. A HEF4069UBP and a little stuff for control via microphone is only on the Board.
Google spat out that the HEF4069 of a CMOS inverter is, would in fact 6 be nice if somebody could tell me about how since now get out of the 10 kHz.
Took apart today even the circuit. Behold, the part to the frequency generation is really only 4 inverters, 4 resistors and a capacitor.
Individually built running the whole also still beautiful and the frequency changes by varying the capacitor - who would have thought it: hihi:
Schematic:
9864
Will try now to offline PD a controllable squarewave voltage generator.
The results come in here.
the page was interesting, thanks for the links.
I have a bad news however, it ran 50% cycle earlier perfectly with 10 kHz
Have nice full and equal to FET with transformer ran. Ran also, has unfortunately struck in the IC
Tjoa now he goes nichmehr: cry:
If I ran again in a try me again, but must also not, I stand 2 frequency generators here.
so, generator have built today with nem 555 a beautiful 10 kHz,
then with Mosfet(+Kühler) and transformer on a Board and finished it.
The 555 circuit comes from this page and run cycle with 50%.
The part runs with 1amp draws about 9 volts. Could see so theoretically as small handheld HV used time source
Today evening made then just a few photos with arcs, looks very nice
Again the girlfriend shows which was also enthusiastic. The tubes got out then...