akg
New Member
a voltage across a capacitor ,which charges through a resistor, is exponential (It has nothing to do with 555) . Vc=Vo(1-exp(-t/RC)) if i remember correct , Vc voltage across the cap and Vo the voltage applied , t time and RC -> time constant. the comparators just monitor the voltage across the cap with its internal ref and switches on and off the discharge transistor.