# Questions tagged [circuit-analysis]

Circuit (Network) analysis is the process of finding the voltages across, and the currents through, every component in the network.

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### Can I use a 700V transistor with a 12V collector and base?

Please forgive any misunderstandings, as I am not an expert on electrical components. I am trying to build the following circuit: I need to be able to run 1A through the transistor. Can I use a 700V ...
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1 vote
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### I need help on identifying the value of a schematic symbol

I came across the schematic of RAK3272-Sip development board, but I couldn't identify the value of this inductor. Here's a link that contains the full schematic.
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### About MOSFET circuit behavior

When I look at the waveforms of simulated circuits, how do I know when their behavior (for example flipping value stored on a node, or an unexpected drop in strong level value...) is due to MOSFET ...
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### Multiplexer voltage reference

There is a potentiometer on a circuit board that I want to simulate with a DAC. I want to be able to either use the original voltage from the potentiometer or simulate the voltage from the DAC, hence ...
38 views

### Problem finding voltage in a circuit with mutual inductance

I'm trying to solve an example from Hayt's Engineering Circuit Analysis: let $i_1=4i_2= 20\cos{(500t-20°)}$ mA. Determine $v_1(0)$. Using $k=\frac{M}{\sqrt{L_1L_2}}$, I got $M=0.6$H. Which ...
1 vote
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### Determining combination of resistors for an equivalent time constant in an integrator circuit

I have a varying source voltage for maximum of 15 V and am using an error amplifier to maintain it using an integrator. Reference voltage is of 5V. I want a time constant of 100 msec with a capacitor ...
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### Triangular wave response of RC circuit

I am trying to intuitively understand the response of the RC circuit for a triangular input. My understanding is as follows: Let the ramp be mt.u(t) Initially, the voltage drops mainly across the ...
126 views

### How do you calculate Vout/Vin in this circuit? [closed]

I don't quite understand how you are supposed to get the voltage going to the first op-amp. I do understand how I would get the answer from that point forward.
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### Does each load in a three-phase balanced load consume the same average power which they get from three-phase voltage sources?

Assume three-phase balanced loads in Δ or Y configuration connected to three-phase AC voltage sources in a Y configuration. Does each load in three-phase loads consume equal average power? Assume ...
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### How to calculate combined power factor of Y-connected three phase balanced loads connected to three phase AC sources with a positive phase sequence? [closed]

This is a problem from a book on electric circuit analysis. A three phase Y-connected loads are installed on a balanced three phase four-wire system. Load 1 draws a total power of 6 kW at unity power ...
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### How to choose the right type of capacitor?

I built an AC power supply (we called it a TENG) based on the tribo-electric principle. It can light up about a hundred 3 mm LEDs. Now I want to try supplying the power from my TENG to an LCD ...
79 views

### Can resonance be present in DC power input? [closed]

I think there is no resonance in DC power input circuit because for resonance to occur, voltage and current must be in phase but in DC power input circuit voltage and current can't be in phase. Is ...
1 vote
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### Is there any method to identify if a loop is an "independent loop" or not? [duplicate]

I know a loop to be independent if it contains at least one branch that is not a part of any other independent loop. But it is kind of recursion. I think it is not giving me the actual definition of ...
1 vote
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### Not sure about input impedance of this PNP transistor circuit

I have to find the input impedance Zi of the following circuit: Using the small signal equivalent for the transistor, I get the following schematic: It is easy to see, that we need to write the ...
343 views

### Circuit analysis: connecting positive terminal of battery to reference node

In the circuit given below, how can I apply KVL to the loop on the right side? The reference node being connected to the positive terminal seems wrong.
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### Short circuit delta

Assuming I have the following system: and a single-phase fault is on the 2.4 kV side. How do I calculate the voltage between the neutral resistor and ground? How do I calculate the zero sequence ...
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### Why does capacitance affect the charging time of a capacitor?

I'm trying to understand the relationship between the capacitance with the voltage output of this circuit. If the capacitance is greater, why does it take more time to charge the plates of the ...
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### Time constant of a high-order RC circuit

I have an unknown system that can be modelled as a high-order RC circuit: I performed the impedance spectroscopy measurement of it and fitted the equivalent components. Now I should calculate the ...
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### Op-amp output as gate voltage to MOSFET

As I understand it, the MOSFET here provides negative feedback to the closed-loop op-amp configuration. Hence, Vout2 = 1 V. Thus, the current through NMOS = Id = 1 mA. So Vout1 = 5 - (RD·Id). Then ...
27 views

### Sensitivity characteristics of MQ-7

When we look at the sensitivity characteristic graph of MQ sensors, Let's take MQ-7, which is a log_log graph, we find the definition of R0 at 100ppm, this resistance is defined to be The sensor ...
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### How to calculate voltages in op-amp circuits?

I don't know how to solve the following problems; I don't even know what the best way to start solving them is. Can someone help me with the calculation steps so I can then try to solve them on my own?...
101 views

### Problem where you are supposed to use Kirchhoffs laws

Apologies for the non-descriptive title, didn't really know how to word it. I'm familiar with Kirchhoffs Laws, studied them in high school physics like many others. Got pretty good at problems ...
65 views

### Workings of single constant-current source with four MOSFET-switched LEDs

Background I have several hundred RGB+White LED lights which are controlled by a driver circuit which is no longer manufactured, and trying to plan some maintenance and possible replacement of the ...
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### Current through the capacitor at t=0

DO NOT edit or rollback this question There have been multiple rollbacks and misunderstandings and some vandalism. Please keave as is for now and we'll to sort things out. Major obstruction of this ...
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### How to solve this problem using transient time-domain analysis?

Find V0(t) in this circuit assuming zero initial conditions. I solved it (refer image above) using frequency-domain analysis using Laplace and found the answer, but I am not able to get the same ...
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### LTspice how show FFT of n004-n008? Expression? How? Example?

In LTspice, how can one show the FFT of the difference v(n004-v(n008) i.e v(n004,n008)? Expression? How? Example? What are the steps for bringing up such an expression so it can be FFT'd? The computer ...
39 views

### Laplace transformations of dependent sources

The following example is from the book Fundamentals of electric circuits by Charles K. Alexander. I don't understand how the dependent current source of 2δ(t) in the question becomes a 2 A current ...
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### Direction relay polar characteristic

I need help on how to draw polar characteristics for a directional relay. The circuit I have is: For this we have that zone 1 is 80% of the closest line and zone 2 is 120% of the closest line length. ...
252 views

### When performing KVL can currents NOT flow in an arbitrary direction relative to voltage sources?

simulate this circuit – Schematic created using CircuitLab The problem asks for finding the voltage across resistor R7 using KVL analysis. When I did the work, I identified 3 mesh currents. Ix, ...
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