Mstechca,
Your "0.69" calculation for the amount of time a capacitor would take to charge to a certain voltage is not correct at any point on the curve. It is not as simple as you think. :lol:
Looking at my graph of the percentage of charge vs RC time is simple and accurate too.
Experimenting with an oscillator having a repetitive RC charge will let you see my graph right on the screen of a oscilloscope. A simulation program would do the same thing.