values for R4 if someone will be interested in building this circuit:
measured right from pot and rechecked with resistors after that.
1ms 4K9
1.5ms 10K1
2.0ms 13k
tolerances of my resistors are 20% so I assume you can round values if using silver or gold stripe(band) resistors.
value for R2 16K2.
Thanks everybody for participating in this discussion.