All Questions
55 questions
1
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3
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162
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Feasibility of methods for nodal analysis of a complex RC circuit network
<Circuit 1>
simulate this circuit – Schematic created using CircuitLab
I need to perform nodal analysis on the <Circuit 1> and much larger lattice RC circuits. The resistance and ...
- 13
0
votes
2
answers
91
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Nodal analysis with inverse Laplace transform of a simple RC circuit with an AC voltage source gone wrong?
simulate this circuit – Schematic created using CircuitLab
This is a simple RC circuit with an AC voltage source, \$E = V_0 \cos(\omega t)\$. In the sinusoidal state, \$Y_{\text{resistor}} = G\$ ...
- 13
0
votes
1
answer
54
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Charge on a capacitor in a RC circuit [closed]
I have been given this problem in which one capacitor is initially charged to some voltage and then connected with another uncharged capacitor and resistor as shown in the figure. I am trying to find ...
- 45
1
vote
2
answers
513
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Energy in capacitor paradox
Recently I have been thinking about a circuits problem that caused me a lot of confusion.
First of all we know from thermodynamics that energy is conserved. I wanted to show a problem that seemed to ...
- 179
1
vote
3
answers
219
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Transient response of capacitor connected to current source with no resistor
I have this HW problem:
It has me completely stumped because the usual equation for the transient response of a capacitor assumes the circuit has a voltage source, not a current source, and requires ...
0
votes
1
answer
69
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What is the capacitor charging equation for this circuit [closed]
The capacitor is charged to 20 V at time=0. Now it is connected to a battery of 80 V. What will be the charging equation. If the terminal are reversed it will be the discharging of capacitor-charging ...
- 27
0
votes
1
answer
106
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When finding ESR/ESL of a ceramic capacitor, what frequency should I assume during a load step?
I want to determine the output droop in a transient load step for a buck converter I am designing.
The output capacitor will supply current during this load step, and there will be a drop associated ...
- 346
0
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1
answer
132
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Circuit analysis (transient state) of a circuit with inductors and capacitors
I am trying to perform transient state circuit analysis for the following circuit and find the voltages across the inductors:
I was using the superposition principle. I started by turning voltage ...
- 1
0
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2
answers
164
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How to guess the particular solution form from forcing function?
$$2\frac{dv(t)}{dt}+v(t)=5t\sin(t)$$
According to the general equation for first-order differential circuits, \$5t\sin(t)\$ is my forcing function. My task here is to find the particular solution.
I ...
- 153
3
votes
2
answers
1k
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Why doesn't the capacitor fill to the maximum?
I am comparing a simulation and a real experiment I did in which my capacitor didn't fill all the way.
The capacitor I used is 10 μF with a 1 kΩ resistor with a 12 V source. I have both graphs:
This ...
- 31
1
vote
1
answer
77
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Forcing current on capacitor tied to ground [closed]
I have a device with a capacitor tied to ground. If a negative current of 1 mA is being forced out of that pin, I am trying to better understand capacitor operation in this area. My questions are as ...
- 21
2
votes
4
answers
278
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Capacitor-charging parallel circuit and given current
Given is a parallel circuit in which one branch consists of a capacitor C with a resistor R1 and the other branch consists of a resistor R2. See the image:
If we apply a known voltage \$U_{tot}\$ ...
- 23
-1
votes
1
answer
121
views
Transient Behaviour of current source into capacitor + resistor
Can someone please explain this transient behaviour circled - particularly the capacitor current?
Capacitor has a relationship of I = C * dv/dt.
I know the AC current will split based on the impedance ...
0
votes
2
answers
729
views
Series capacitor not blocking DC voltage
In my understanding a series capacitor (with some resistance) works as a DC block, essentially forming a high-pass filter, blocking DC. Under this assumption, a unipolar square wave of amplitude V ...
- 587
1
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2
answers
112
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Output voltage of capacitor discharged in other capacitor?
Considering this circuit. How can I compute the maximum voltage across the resistor ?
In this example, the capacitor on the left is initialy charged with 10 V. The second capacitor (on the right) is ...
- 157
0
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3
answers
298
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Explanation of the transient in an integrator circuit
Using LTSpice I have simulated the following circuit. It is a circuit integrator using the op-amp model: LF356. The simulation has a saturation voltage of 12 and -12 V and a square wave input source. ...
2
votes
1
answer
822
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confusion in RC circuit regarding initial conditions and capacitor voltage
Actually i was practicing circuit analysis with Differential Equations. This question has some confusing parts like-
In Steady State, t<0 switch is still open the 10mF capacitor is Charged to 5V ...
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-1
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2
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818
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0
votes
1
answer
505
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How to analyze first-order transient circuits using Simulink?
I have been trying to design a first-order circuit with a capacitor but, I could't achieve to initaliaze the steady-state condition. I mean I was not able to close the switch at t = 0. Since, I am ...
- 5
0
votes
1
answer
523
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Calculating capacitor voltage with initial conditions in an RC circuit
If the initial voltage of the capacitor at 0s is 20V, would the equation for the voltage of the capacitor at a specific time be; 60 + (20-60)e^(-t/RC)
or would it be 80 - 60e^(-t/RC)
- 55
2
votes
1
answer
368
views
What is the time constant for this circuit?
In this practice problem, the book apparently got the value for the time constant to be 0.1ms. This means that it only considered the 100k resistor to be the Rth. Why is the 10k resistor ignored? ...
- 95
0
votes
4
answers
1k
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Short-circuit current through disconnected capacitor
I have a large capacitor made of two smaller 200V rated 560uF capacitors. If I charge this capacitor to 30V with 4.5A from a bench power supply and disconnect it after around 7 seconds, how do I ...
- 9
0
votes
1
answer
85
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About series RLC circuit
Here I am trying to solve the circuit and from my calculation, I got, I(t)=3e^(-2t) - 3e^(-3t) and Vc(t)=12-18e^(-2t)+12e^(-3t)
When Initial conditions are;
I(0-)=0A and Vc(0-)=6V
From my assumption, ...
0
votes
0
answers
350
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Transient analysis of parallel RLC circuit
Here, I am solving this circuit where Capacitor acts as a voltage source of 10 V. Switch is closed at t=0,and Vc(0-)=10V,I2(0-)=0. When t≥0, what will be the time constant and frequency of the circuit?...
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3
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1k
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Capacitive dropper power supply for LED - zener/decoupling capacitor?
Let's say you have a standard capacitive dropper power supply like the following (from Wikipedia):
I understand that these work well for driving LEDs since they act like a constant current source. I ...
- 79
0
votes
1
answer
2k
views
Resistor in parallel with a short circuit. Will current flow through it?
I'm trying to find the Isc of this circuit seen by the capacitor at t > 0 so I could find the Rth and get the circuit's time constant. If I make the capacitor a short circuit, it will be in ...
user263783
3
votes
2
answers
817
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Transient analysis of a marx generator
I wanted to mathematically find the voltage on all capacitors in a Marx generator circuit. I thought that each capacitor would be charged like its own RC charging circuit. I came up with these ...
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0
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1
answer
89
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What happens to the steady state of the series RC circuit if changes happen to any circuit element?
The question that I'm trying to understand is the following:
In any series RC circuit that is in steady state, WHEN any of the
elements changes (R, C, or applied voltage), the following will happen ...
- 317
1
vote
0
answers
145
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How can I make LTSpice calculate the transient response starting from a time different than t=zero?
I'm creating a schematic and I'm trying to simulate it using LTSpice.
However, my RC time constant is quite large, and I'd like Spice to simulate only from around 10ms onward. I know that if i set ....
2
votes
1
answer
223
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RC Circuit Transient Response
I was going through some questions on Transient Response of circuits. Then I encountered this question! Though, I was a bit confused at first, I initially approached in an intuitive way. My first ...
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2
answers
106
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Why is the current for \$i(t)\$ \$5mA\$, not \$5e^{-\frac{t}{0.8m}}\$ mA?
Close the switch of the circuit, and it is in the steady state. We open the switch at \$t=t_1\$ suddenly. What is the value of \$i(t_1)\$?
simulate this circuit – Schematic created using ...
- 551
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1
answer
696
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How do I measure the duration of transient from a transient analysis graph?
I've assembled the following circuit:
And the following graph is the output: (Green: Voltage across C) (Red: Supply Voltage)
How do I measure the transient duration from the graph? Is it the same as ...
- 1
1
vote
1
answer
42
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This clamping circuit output is -ve compared to what is expected?
Clock Pulse of Vpeak =10. Providing that the first cycle is -ve why does the output in first is -20 then 0 then -20 and so on? I expected it to be 0 and 20.
- 19
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3
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799
views
Two charged capacitors connected in series
simulate this circuit – Schematic created using CircuitLab
The circuit has the initial condition as shown in figure. What will Vfinal be when SW3 and SW2 are open but SW1 is closed.
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3
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133
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How to analyze a capacitor in series to a capacitor and resistor in parallel?
I would like to do a transient analysis on this circuit but I don't know how to use those formulas
$$V(t)=V_0*(1-e^{\frac{-t}{R*C}})$$
$$I(t)=\frac{V_0}{R}*e^{\frac{-t}{R*C}}$$
in this case.
There ...
- 178
-3
votes
1
answer
811
views
surge voltage characteristics of ceramic capacitors
I am reading a datasheet from Murata for a ceramic capacitor. According to the datasheet:
When AC voltage or pulse voltage is applied, the
peak-to-peak voltage shall not exceed the rated
DC ...
- 113
0
votes
2
answers
2k
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What is the voltage across the capacitor 3ms after the switch is closed
I have this circuit:
This circuit is working for a long time like this, with the switch open. So, the circuit is stabilized and the voltage across the capacitor is 40V.
At t=0, the switch is closed.
...
- 847
3
votes
2
answers
2k
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How to determine the steady state voltage across two capacitors in parallel
Say we have two capacitors C1 and C2, initially isolated from each other and each having an initial voltage Vc1 and Vc2 respectively, where Vc1>Vc2. When suddenly connected to each other in parallel, ...
- 69
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0
answers
256
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KVL in the capacitor during transient analysis
I can see that this topic has been discussed many times in this site. But I still can't figure out why I am still not getting my correct equation applying the KVL.
Consider a circuit as shown:
...
- 1,089
0
votes
2
answers
180
views
Capacitor Voltage during Transients
I am starting to learn transient analysis series RC which requires our own equations to be derived, but I don't understand how the voltage across the capacitor is given in the equation below from a ...
- 1,583
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votes
1
answer
3k
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how do i know if Vc(0+) or Vc(0-) is zero?
i mean like in this picture, why is Vc(0-) = 10 v? why isnt it =0? when do i decide that there exists a voltage there even though it was in steady state? im not completely getting it.
- 55
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2
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551
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Derivation of time constant for single source, single capacitor RC circuit
Take a circuit comprised of resistors, a single capacitor, and a single step response voltage source. Then:
Every single voltage and current in the circuit, except at the voltage source, will have a *...
- 113
1
vote
2
answers
808
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RC circuit with sinusoidal voltage - initial behavior?
For a simple RC circuit with a sinusoidal voltage source, the differential equation is: $$\frac{dq}{dt}=\frac{sin(t)}{R}-\frac{q}{RC}$$ When I plot the solution to this differential equation using ...
- 23
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votes
2
answers
949
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Simulating all transient solutions for RLC series circuits
I am reading this page that contains the transient solutions for RLC series circuits: over-damped, critically damped and under-dumped.
This site presents these graphics for the 3 cases:
Then I have ...
- 847
1
vote
5
answers
8k
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Source-free RC circuit current directions
I have the next circuit:
The textbook says that the capacitor is initially charged, but the current directions was selected as in schematic, why? If capacitor is charged and "+" is on upper node then ...
- 385
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votes
0
answers
324
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Assign signs with passive sign convention in transient analysis
It's known that most books prefer the usage of passive sign convention and recommends to set polarities to all schematic elements before writing KVL equations. But how to proper set signs in schematic ...
- 385
-2
votes
1
answer
197
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Help for general transient analysis
I need help with the circuit below.
I can't understant how to write:
$$v(\infty)=?$$
$$i(\infty)=?$$ (my suggestion is 0 for "i" because of capacitors will represent an open-circuit at infinity time)...
- 385
0
votes
1
answer
222
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Model of capacitor at breakdown
I have looked through the web and couldn't find a model of a capacitor at the moment of breakdown.
After a circuit that I built failed, I took a few capacitors to test and found out that some of them ...
- 7
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votes
0
answers
220
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Calculating the time constant for an RC circuit
I have this circuit where \$C1 = 2~\mu F, C2 = 4~\mu F, R1 = R2 = 1~\Omega \$. Here, I want to calculate the time constant of the following circuit.
I calculated the equivalence resistance and ...
- 101
4
votes
3
answers
22k
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Transient Current in an LC circuit with a DC supply
Here is a LC circuit with a DC supply.
When the switch is closed at t=0 capacitor behaves as a short circuit while the inductor behaves as an open circuit as the voltage across the inductor ...
- 1,586