# Questions tagged [laplace-transform]

Questions regarding or involving Laplace Transforms with respect to Electrical Engineering.

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### Is it possible to sketch a bode plot for a discrete-time transfer function?

For a regular s-domain transfer function, there are simple rules you can use to draw an asymptotic bode graph, basically by taking a slope of +/-20dB per decade and a phase shift of +/-90 degree for ...
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### Learning process automation starting from general engineering background [closed]

I'd like to study process automation by myself, could you suggest a good entry-level book to start with? I have engineering college math level and I remember a bit of Laplace transforms to model ...
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### Solving for the current/charge across the elements of this RLC circuit?

I have a circuit which is composed of an inductor (L), capacitor (C), and two identical resistors (R1=R2): This represents an equivalent electrical circuit to a guitar pick or piano hammer as an "...
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### Laplace transform in a block system

I'm trying to understand the resolution of the problem 5.11, but I can't understand how she gets the expression in the rectangle: $$\dot{x}_1=-x_1+2u$$ How can I get the expression in the rectangle?
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### Getting different impulse responses by solving with Laplace transform and plugging delta-dirac

If I know that the output of a system $$y(t) = 2e^{-3t} \cdot u(t)$$ and it's specified that the input is $$x(t) = u(t)$$ I was trying to find the impulse response h(t). So I solved it using ...
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### Laplace Transform

can anyone help in finding the expression for the voltage at the output of the circuit if the input is a step function with 1V amplitude. simulate this circuit – Schematic created using ...
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### Closed Loop System

Why is RC circuit considered closed loop system with negative feedback? Is it because it has a differential equation due to which current 'I' through capacitor 'C' will be C*(dVo/dt) = C*{Vo(t)-Vo(t-h)...
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### How does Laplace transform include the transient response?

When we provide a sinsusoidal input, the evaluation of the solution of the differential equation head-on becomes horrendous. So we give an imaginary, complex exponential input and solve the ...
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### Laplace Transform Question

looking at laplace transform for electrical applications, I don't understand how the provided answer works? Like how did they get the e^(-sT), through using the laplace conversion table? And also, ...
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### Analysing an s-domain circuit with multiple sources

So I am working on the following circuit: I have already worked my initial conditions and the next step is to perform analysis of the charged up circuit. My charged circuit is shown below: The ...
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### Final Value Theorem yielding the wrong result?

C1 has an impedance of 1/0.1s Ohm in S-domain. Its impedance together with R1's is 100/(10s+10) Ohm The transfer function is: $$\frac{V_2}{V_1}=\frac{5}{\frac{100}{10s+10}+5}=\frac{50s+50}{50s+150}$$ ...
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### Calculating steady state output using Laplace transform

I've tried to obtain the the steady state output with the help of final value theorem and multiplication properties of Laplace transform.But I'm not sure whether I've solved the problem correctly or ...
170 views

### Inconsistency in Values of Laplace Transformed Current when Changing Units

I was trying to convert the units of the following current in Time Domain and Complex Frequency domain (s-domain): $$i(t)=20\cdot e^{-t}H(t)\,\,\,\,\,\text{[mA,ms]}$$ Where $\text{[mA, ms]}$ ...
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### Transfer Function Derivation

Where did the following transfer function come from? $H(s) = -H_o\frac{\frac{\omega_o}{Q}s}{s^2 +\frac{\omega_o}{Q}s + \omega_o^2}$ $H_o$ is the gain at resonant frequency. I'm told it ...
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### How to determine the transient response of a circuit to causal periodic inputs?

As you know, analyzing a circuit with phasors provides only the steady-state response, and is only useful for sinusoidal signals and DC signals. Fourier series allow us to analyse a circuit with ...
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### If I look at a signal in its frequency domain, are there some guidelines by which I can tell how that signal looks in the time domain?

I was studying the Laplace transform and the Fourier transform, and I can't figure out if there is some intuitive way of finding out how a signal looks in the time domain if we know its frequency ...
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### Laplace Transforms and the imaginary input

When we get an exponential on the RHS of our differential equation (or if we give an exponential input) it's quite easy to solve the equation, but if we provide a sinsusoidal or cosinusoidal input, ...
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### How to do Transient analysis?

Consider the above example earlier I used to form a differential equation and then do its solution using Laplace,but for this example the differential equation comes out to be non-ordinary. Please ...
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### How to calculate damping ratio and natural frequency of a high order system?

To calculate the rate of damping and the natural frequency of second-order systems is easy, third order as well. How do I calculate the damping rate, natural frequency, overshoot for systems of order ...
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### Phase, Frequency and Laplace transform

I have a doubt on the relationship between phase and frequency. We know that the definition of angular frequency is: ω(t) = d($phi$(t) / dt, where $phi$(t) is the istantaneous phase of our ...
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### How do I refer the transfer function of a system from its Laplace equivalent?

I have a problem, I know how to analyze circuits in Laplace domain to get the transfer Laplace function. However, I don't know how to translate the answer to "real life" Suppose that I have a ...
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### Phasors and Fourier Transform

I have always been told that for a sinusoidal variable (for instance a voltage signal), the fourier transform coincides with the phasor definition, and this is the reason why the analysis of ...
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### Is the following op-amp-circuit-in-the-Laplace-domain analysis correct?

I am relatively new to analyze circuits in the Laplace domain. So I decided to solve some problems as an exercise. Below presented a problem and my solution to it and I have two questions: ...
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### AC signal analysis: Voltage dip (amplitude dip) at time = 0

I'm working on a series RLC problem where the input voltage is a sinusoidal function for all time. The catch is, for t < 0, the sinusoidal function is of greater magnitude than t >= 0. There is no ...
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### Solving capacitor voltage with Laplace

I saw this example and I got confused. The example shows: $V_{C}(s)=\dfrac{R\parallel\frac{1}{sC}}{sL+R\parallel\frac{1}{sC}}V_{in}(s)$ . Isn't it enough to express $V_{C}(s)$ with the voltage ...
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### What is difference between natural response and zero-input response of a system and how to find natural response?

In most books it is said that natural response is another name to zero-input response while in some resources is is mentioned that the classification is based on poles of transfer function and input....
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### How to tackle circuit containing time variable resistor?

simulate this circuit – Schematic created using CircuitLab For instance above schematic find current as function of time in circuit above I studied it about months before and am not able to ...
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### Why inverse of time delay is non causal

Please explain the following statement "If $P(s)$ contains a time delay term, $P^{-1}(s)$ is non-causal". Here '$s$' is Laplace variable. Can someone please explain the reason of non causality?
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### Combining two ideal voltage sources with an impedance between them

Solving a problem, I came across the following source transformation:        My question is: I know that I can do the following:       &...
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### Degenerate circuit concept and its theoretical and practical implications

I came across with the term "degenerate circuit" when I was studying solving linear differential equations with Laplace transform. I have learned that a system is called degenerate when the ...
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### Laplace transforms for transient analysis

simulate this circuit – Schematic created using CircuitLab For t<0 the switch is opened. Att=0 the switch is closed. ...
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### How to get the transfer function of electrical network using nodal method

We have the following circuit: I am trying to get the transfer function using the Mesh Method. The first equation I've got is: (s+1) I1(s) - sI2(s) = Vi(s) The ...