Electric circuit analysis

[electronicsLearner77]

I am trying to analyze the below circuit


The circuit is basically for reading the DC Bus voltage from the battery voltage, as of now i have given 12V only for testing purpose. My question is when i simulated the voltage across R2 it is 0.75V, what is the impact of having the capacitor C1, because without C1 also i get the same voltage. Please advise.

 

[danadak]

C1 would slow rise of power when V1 is turned on, but once charged
effectively out of the circuit as R1 R2 would set the V.

Varying C1 from 1 nF to 100 nF.




Regards, Dana.
Regards, Dana.

 

[electronicsLearner77]

Thank you for the reply, i simulated the same circuit in LTSPICE i don't get the same waveform, please advise.

 

[danadak]

Post your LTC File.


Regards, Dana.

 

[Harald Kapp]

(LT)Spice calculates an operating point before starting the transient simulation. This ensures that the components are correctly biased.
The operating point of your circuit includes a charged capacitor because you use a fixed DC voltage source.
To overcome this you can add a statement to your simulation:

.ic V(n001) = 0

This assumes that the node connecting R1, R2 and C1 in n001. Make life easier for you by adding a label to this node and use the label's name like so:


Alternatively use a pulsed voltage source that is at 0V initially and then steps up to 12 V shortly after the simulation has begun like so:

 

[electronicsLearner77]

Thank you it works now.

The LT spice file is