This was shown in the “Inductor-based astable 555 timer circuit”. In Figure 1, ... This led us to the Equation 1 for calculating the pulse widths: The symbols are defined in Table 1 where the columns ...

It is worth mentioning that the idea of getting PWM from a 555 timer was published by EDN back in 2007, see https: ... all the timing equations remain exactly the same, making R2 look completely ...

Simply adding a diode and potentiometer to a 555 timer operating in the asynchronous mode yields a pulsewidth modulator (PWM) with a duty factor adjustable from 1% to 99% (Fig. 1).