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Simple RLC Circuit problem 
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#1
Oct1606, 11:08 PM

P: 19

Please help me to solve this RLC circuit problem. I am completely confused.If you give me the direct answer it would be much appreciated.
For the series RLC circuit in Figure, find the input/output difference equation for 1.[tex] y(t)=v_{R} [/tex] 2.[tex] Y(t)=i(t) [/tex] 3.[tex] y(t)=v_{L} [/tex] 4.[tex] y(t)=v_{C} [/tex] I have attached the Circuit diagram in a .jpg file. 


#2
Oct1706, 09:35 AM

Mentor
P: 40,961

You must show your own work in order for us to help you (PF homework forum rules). Would KCL or KVL be the best way to start?



#3
Oct1706, 08:07 PM

P: 19

Hey first I tried taking the KVL around the loop
something like [tex] x(t) + v_c(t) + v_L (t) + v_R (t) = 0 [/tex](1) replaced v_L(t) with first order Ldi_L(t)/dt and make an equation for [tex] v_C(t) [/tex] and then as its in series I tried to write a function for [tex] i_L(t) = \frac {v_R (t)} R [/tex](2) and for [ tex ] v_R(t)/R=C \frac {dv_c(t)} {dt} [/tex](3) Then tried sub (3) in (1) and got [tex] v_C(t) = x(t)  \frac {L} {R} dv_R(t)/dt  v + R(t)[/tex](4) and then tried sub it i eqn 3. and didnt come up with a satisfactory result. Please help. Thanks 


#4
Oct1806, 07:20 AM

P: n/a

Simple RLC Circuit problem
Since the current is the same for all elements, write [tex]v_L[/tex] and [tex]v_R[/tex] as functions of the current. Finally write the current as a function of [tex]v_C[/tex]. 


#5
Oct1806, 11:11 AM

P: 19

Thank you very much for your info SGT, would you please help little bit more.



#6
Oct1806, 03:03 PM

P: n/a




#7
Nov2306, 03:05 PM

P: 19

I tried And I am not going anywhere. please help



#8
Nov2306, 06:20 PM

P: n/a

Post what you have done and I will give you more hints.



#9
Nov2706, 11:48 PM

P: 19

heres what I got so far.. please help after this point..
thanks 


#10
Nov2806, 02:41 AM

P: n/a

In the second equation don't use the integral term. Keep it as [tex]V_C(t)[/tex].
In the two other terms replace i by [tex]C\frac{dV_C}{dt}[/tex]. You get a second order equation in [tex]V_C[/tex] 


#11
Nov2806, 12:56 PM

P: 19

Would you please not mind to show me please. I have tried this so far. please help after this.
thanks 


#12
Nov2806, 02:00 PM

P: n/a

The rules of the forum are that you must do your work. We only give hints. Rewrite the second equation with the suggestions I made and post it here.



#13
Dec606, 07:48 AM

P: 2

The easiest way to solve any RCL circuit with an input vs(t) is by a difference equation.
Let curr= (q1q0)/dt q2=2.*q1q0 + dt**2*( q1/(L*c) (R/L)*curr +vs(tdt) ). Then everything else follows , Vc(t) = q2/C , VL = L * ( q22*q1+q0)/dt^2 , VR = R*(q2q1)/dt SEE http://www.geocities.com/serienumerica/RCLfree.doc 


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