variants RC low pass filter

[bsrivastava]

All,
I am not clear in solving such types of questions which are usually asked in the interview-
1) unit step input given to RC circuit
2) what if another R is added in parallel to R
3) what if R is added in parallel to C
4) instead of unit step if a pulse is given when the swing is -V to V volts

I don't want any Laplace type of solution.

Please help.

 

[narccizzo]

Are you asking for simple answer for that questions or how to solve them without laplace transform?

 

[bsrivastava]

No, am not asking the answer. I want the analysis in time domain.
Like in simple low pass filter, R is charging the C and time const is RC.
If one more R is in parallel to C, taking the Thevinin eqv. the Rth will be R/2 and Vth will be V/2. Now, R/2 will charge same C by V/2 voltage so time const is RC/2 now. Some intuitive explaination
When R and C are parallel and output is taken across another C, how will the LP will look like?

 

[hn1]

use KVL and KCL equation which are valid in the frequency and time domain.