$$RC \approx \frac1.21,000,000 = 1.2\mu s$$
f≈1R⋅C⋅ln(VT+⋅(VCC−VT−)VT−⋅(VCC−VT+))f is approximately equal to the fraction with numerator 1 and denominator cap R center dot cap C center dot l n open paren the fraction with numerator cap V sub cap T plus end-sub center dot open paren cap V sub cap C cap C end-sub minus cap V sub cap T minus end-sub close paren and denominator cap V sub cap T minus end-sub center dot open paren cap V sub cap C cap C end-sub minus cap V sub cap T plus end-sub close paren end-fraction close paren end-fraction For quick estimations at , an empirical formula often used is: 74hc14 oscillator calculator full
(using one inverter):
Once these values are entered, the calculator will provide the required component values, including: $$RC \approx \frac1