Adjustable duty/frequency OpAmp Oscillator

1-ce you get customized with these things (OpAmp-s) - they're nifty to use for all sort of tricks -- the below design was chosen due it's adjustability × lesser number of components compared to it´s TTL or CMOS variant

 the interesting point to note here is that the КР140УД1408 : LM308 specify their lowermost supply range at ±5V(+10V) : ±2V(+4V) respectivly -- while the voltage buffer/-follower configuration still works with +5V for КР140УД1408 without any fq. compensation ??? here´s the component level model of neither* УД14 nor LM308 OpAmp-s exactly (*also coz "we" don´t know the exact transistors used in the actual thing -- nor does the circuit exactly match neither -- about What? = it's close enough to simulate both (only some 10% of Spice simulations hit the real life - the small alterations to OpAmp model won´t significantly change that figure))

[EoP]