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Electronics => Beginners => Topic started by: renzoms on October 19, 2019, 10:57:35 pm

Title: Id appreciate input about this RC circuit. Thank you so much :D ! !
Post by: renzoms on October 19, 2019, 10:57:35 pm

So I got some results that are both correct at some time t and incorrect at other time t. What can you say about the results. The topic is in the bottom right in red.

Title: Re: Id appreciate input about this RC circuit. Thank you so much :D ! !
Post by: renzoms on October 19, 2019, 11:34:43 pm

So I got some results that are both correct at some time t and incorrect at other time t. What can you say about the results.

I calculate the Voltage across C1 (V_C1) using a Thevenin EC. Then with that,

I got V_R1, I_C1, I_R1, I_Rs, V_Rs (everything on the left half.)

So then to calculate V_C2 and V_R2, I used 10 - V_Rs - V_C1 (method 1 "m1.")

With V_R2,  I got I_R2, henceforth I got I_C2.

So using m1 I got some weird results. 10V for V_C2 at t = 0 and -0.1 A I_C2 at t = 0.

I'd like to know if there is another way to get V_C2, without using another Thevenin EC.

And what do you think I should take away from this experience (the fact that there are correct and incorrect results for V_C2 and I_C2.)

Thanks like a lot.

Title: Re: Id appreciate input about this RC circuit. Thank you so much :D ! !
Post by: renzoms on October 19, 2019, 11:40:49 pm

It's affecting my graphs of I and V of C1 and C2

Title: Re: Id appreciate input about this RC circuit. Thank you so much :D ! !
Post by: rstofer on October 20, 2019, 01:30:29 am

I just plotted the voltage of the second capacitor over a short time (to see the fast rise near t=0) and a long time to see the steady state.
Really, this is a 5 minute thing with LTspice

I added names to the traces and added a trace at the output of the 2 Ohm resistor.  The voltage across C1 is not plotted but it is simply the difference between the traces.

Title: Re: Id appreciate input about this RC circuit. Thank you so much :D ! !
Post by: renzoms on October 20, 2019, 01:45:59 am

Thanks dude!

I did a Thevenin equivalent circuit, solved it, and then was off by a factor of 10 somehow. I'm happy with the experience though. I appreciate the effort use LTSPICE and offer those graphs!

Title: Re: Id appreciate input about this RC circuit. Thank you so much :D ! !
Post by: rstofer on October 20, 2019, 01:48:58 am

Quote from: renzoms on October 20, 2019, 01:45:59 am

Thanks dude!

I did a Thevenin equivalent circuit, solved it, and then was off by a factor of 10 somehow. I'm happy with the experience though. I appreciate the effort use LTSPICE and offer those graphs!

I changed them a bit.  I was going to add a trace of the voltage ACROSS C1 but it's pretty easy to see what it will be.

I attached a graph with the voltage across C1 specifically plotted.  Note that it charges quickly to some high voltage then drops over time.  This is a consequence of the 1mF capacitor looking like a low impedance for a relatively long time.

Title: Re: Id appreciate input about this RC circuit. Thank you so much :D ! !
Post by: renzoms on October 20, 2019, 05:02:57 am

Interesting! I'm very tired so I'm off for tonight. I found where that factor of 10 came from, so the circuit is solved :). Thanks again for sharing your graphs. I'll look at it tomorrow, again.