# Questions tagged [transient]

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151 questions
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### voltage transient protection for MV Motors

What types of transient voltage protection is applied on medium voltage motors and are these types of protection that are applied depended on the type of motor it is e.g Synchronous vs Induction motor?...
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### How does this isolation transformer protect user from transients/mains?

I'm looking at a pretty simple overvoltage/transient protection circuit designed to protect users but I don't understand what the transformer is doing. The circuit is designed to protect the output ...
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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: ...
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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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### LTSpice: How to offset the start time in a transient simulation?

I see how to set the total run time for a transient simulation, but what if I didn't want the simulation to start at 0s? For example, if I have two voltages sources that are stepping at offset times ...
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### 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 ...
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### Choosing an Automotive Fuse with ISO 7637-2 (Pulse #1 24v system) in mind … -600v Transient

In designing a input power protection circuit in an automotive application with a 24V power bus, how does one deal with the -600V transient described in ISO 7637-2 Pulse #1: In particular, I'm ...
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### What is causing this long tail in the transient reponse?

I have a fifth order transfer function for which I designed a controller using pole-zero cancellation technique on a root locus. I am after <5% overshoot and <2s settling time. Currently, ...
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### Significant low frequency content from digital oscilloscope measurement

I have been using a digital oscilloscope to measure a fast transient signal and have then processed the data in MATLAB. Performing an FFT on the data I consistently see a significantly large low ...
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### Multisim Transient time point did not converge (peak detector circuit)

I'm building a peak detector circuit with mcp6002 op amp. The signal is 8k Hz 20%dc square wave filtered through a low pass filter whose capacitor varies between about 10pf to 1000pf. The schematic is ...
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### Howto debug ngspice error PPerror: syntax error during transient analysis

In an effort to better understand software and how my computer actually works I have been experimenting with simple electronic circuits. I am working up to having three two bit registers (A, B, C) ...
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### 1st order circuit analysis

I'm having trouble with this exercise which I don't have a solution for, I'm used to dealing with simpler 1st order RL or RC circuits. Mostly I'm a little confused with the sinusoidal generator and ...
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### LTSpice transient analysis and current amplification problem

Im simulating LC circuit in LTSpice: It's tuned at resonance at 1 MHz in the transient response simulation plotting the source and R1 current. Both of which are equal in amplitude 600mA but with a ...
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### Superposition theorem for transient analysis

Can we apply superposition theorem in transient analysis of circuits? I don't think it can be used since during transient state the input and output relation is not linear and is rather explained by ...
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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.
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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 *...
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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 ...
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### Pulsed DC, kA range inductive transient protection method

I would like to design a transient protection solution for HVDC_pulse_unit. HVDC voltage = 3500V , current > 40kA. Events: D1 flyback diode survives(50kA surge forward current). MOVs section did ...
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### Simulation result of bjt cascode amplifier

I use square wave as the input source to my BJT cascode amplifier. However, I got my output voltage as I used transient analysis in PSPICE to obtain the simulation result. Can someone tell me whether ...
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### Transient analysis of square wave using PSPICE

I need to do a transient analysis of my BJT cascode amplifier. I was asked to use VPULSE as the source. I need to set VPULSE for +-10mV, 50% duty cycle square wave at 128 kHz with rise time and fall ...
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### LTspice parametric sweep: how to force the simulator to continue with the next step?

I'm running transient simulations as I am sweeping a couple of parameter values (resistances, capacitances) to give a first hint about what range of values make a certain circuit stable. In addition, ...
131 views

### Is this optocoupler front-end safe?

This is a follow-up to Is this line detector safe? I'm re-designing the front-end based on some great feedback from the community. I've decided to move to the following topology: The phase of 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 protect LEDs from high voltage during NPN transitor transitions?

I am using a 555 timer and an NPN transistor to drive an array of 12 LEDs from a 9v battery, and a potentiometer to control the duty cycle. I am concerned about the voltages the LEDs will be subjected ...
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### Protection of DIY car camera circuit

DESCRIPTION I have no background in electronics. As my primary reference I'm using "Practical Electronics for Inventors" (PEFI) 4th Ed., by Scherz and Monk (2016). I plan to get my basic electronic ...
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### Trying to understand the transient current equation on a RLC circuit

I am reading this doc I see this magic happening on the third line of equations... How in the name of Math, does this $Ae^{st}$ appeared there? Magic?
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### Transient Response Suppression

In my project i am using an ultrasonic transducer. The transducer has a high Q-factor so that it's zero input transient responses decay rate is quite low and i am suffering from that because the ...
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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 ...
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### Inserting an unused voltage source in LTspice messes up transient results

This took me three days to figure out. Consider this simple circuit in LTspice: Looks pretty innocent. The output is a 1V sine wave, as expected. Going to View->FFT, setting number of data points to ...
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### Transient Current Effects from Independent Charging Circuit

I've been working to automate a household appliance. The device is normally controlled by a switch that must constantly be depressed in order for the device to operate. Instead, I replaced this ...
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### Why do we use Laplace transforms to analyse transient circuits?

I just learned transient circuits and we solved them both in the time domain and the Laplace domain and I can't understand why we would use the Laplace domain as it seems it is a lot more simple to ...
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### transient noise plot in virtuoso

I was simulating a transient test on an SRAM cell, added a transient noise of 1-30MHZ frequency with 100 multiple simulations and calculated a VQ-QB graph(dots). I want to be able to only plot the ...
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### Transient of a circuit when a generic audio signal is applied

I know the importance of the behaviour of a circuit when a sinusoidal signal is applied: by using Fourier Transform, I can see a generic signal as a (continuous) sum of sinusoidal signals with ...
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### Mesh Current Method Circuit Analysis For AC Transient and Steady State Solution of RL Circuit

Hi everyone, I'm trying to find the currents through each branch for the above circuit using mesh current method (as I don't really know how else to do it), and end up with two simultaneous ...
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### What is the time constant L/R of this circuit?

I've solved this circuit but i got some issues about the alternatives. English question at this picture: Switch $S_1$ had been closed for long time and after that $S_2$ was opened. Therefore, ...
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### AC analysis on transient model of Buck converter

I'm unable to understand why can't we run AC analysis on a transient model of Buck converter.
356 views

### Transient analysis of op-amp circuit

What is the expression of V if V(0) = 4V? simulate this circuit – Schematic created using CircuitLab I am unable to proceed further after forming the following equation: -v/R1=(v-V)/R2+C1dv/dt
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### Analysis of simple RC circuit

For the above circuit, Natural response will be A×exp (-t/RC) where A is any constant. For forced response, capacitor is open circuited consequently, 10K resistor is also removed and thus, forced ...
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### How to solve a boost circuit (or any switched RLC circuit) in time domain?

I need to model a boost circuit with the following topology: simulate this circuit – Schematic created using CircuitLab I am interested in the resistor voltage, so I found the differential ...
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### Transient analysis with Laplace and nodal analysis error

Have the schematic: Solving using MathCAD: There is an error in my equations with nodal analysis but I can't find where? May anyone help me? I also add the solution using approach of series RLC ...
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### Circuit with sinusoidal voltage source - transient analysis

I've got this circuit(where u(t) should be calculated in t=3ms): Where:e(t)=260*cos(wt+25), w=2400 s^-1, Ro=15 ohm, R1=40 ohm, L=12 mH, C=20uF, t1=3ms. I've got huge problem to form equations (...
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### Preventing power supply startup transients

I am trying to build a huge array of WS2812b's and the wiring is all done. Now, I am in the process of installing it into it's final destination. However, I have read that these WS2812b LEDs are very ...
138 views

### RC Circuit Simulation gives unexpected transient response

I am currently trying to find the correct measure of current through the 4KOhm Resistor in a transient response after the switch is closed. I tried to replicate the switch using AC Voltage Source ...
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### Inductor suddently conected to current source [closed]

simulate this circuit – Schematic created using CircuitLab Assuming SW1 is closed for along time, and current in L2 to be zero initially. What sort of current waveform can I expect in L2 when ...
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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 ...
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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 ...
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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)...
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### Find inductor current with Laplace

I need to find the inductor current for t > 0 and initial conditions as in example below. I think it's enough to divide V1 by 5*s and take the inverse Laplace Transform but my answer 3*e^-2*t - 7*e^-t ...
There is an example in Book: Why is $V_R = 5i_R$? I can't see that. more info: