For the above circuit, I calculate that the equivalent resistance of the charging circuit is 2.668 kΩ, and the equivalent capacitance is 2.055 µF. Therefore, the time constant would be
2.668*2.055 = 5.48 ms as the amount of time required to charge.
I simulated the circuit and got the following time constant:
It is almost twice as doubled, while it should be approximately the same. Can anyone explain to me the difference? Thank you.