Questions tagged [circuit-analysis]

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

Filter by
Sorted by
Tagged with
1 vote
1 answer
82 views

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 ...
  • 11
1 vote
1 answer
70 views

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.
2 votes
0 answers
47 views

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 ...
0 votes
0 answers
49 views

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 ...
2 votes
1 answer
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
1 answer
30 views

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 ...
  • 11
2 votes
1 answer
53 views

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 ...
-1 votes
3 answers
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.
  • 11
0 votes
1 answer
41 views

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 ...
  • 63
-1 votes
0 answers
23 views

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 ...
  • 63
-1 votes
1 answer
62 views

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 ...
-2 votes
2 answers
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
1 answer
105 views

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
0 answers
35 views

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 ...
2 votes
3 answers
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.
  • 33
0 votes
0 answers
30 views

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 ...
  • 119
2 votes
4 answers
379 views

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 ...
  • 525
2 votes
4 answers
139 views

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 ...
  • 21
0 votes
3 answers
74 views

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 ...
-1 votes
1 answer
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 ...
0 votes
1 answer
82 views

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?...
0 votes
3 answers
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 ...
2 votes
1 answer
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 ...
  • 3,440
-2 votes
2 answers
220 views

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 ...
3 votes
2 answers
80 views

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 ...
0 votes
2 answers
66 views

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 ...
0 votes
0 answers
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 ...
  • 11
0 votes
0 answers
36 views

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. ...
  • 1
4 votes
4 answers
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, ...
  • 41
5 votes
2 answers
141 views

Compute voltages and equivalent resistance in the presence of a bridge

Problem. Given the circuit in the figure, I wish to compute the equivalent resistance between node A and D, voltage \$V_{\mathrm{BC}}\$, both under closed and open bridge K. \$R_1=50\,\Omega\$, \$R_2=...
  • 153
0 votes
2 answers
131 views

Power consumption in a Wheatstone bridge

Q1) Explain how the power consumption of each resistor will change as the resistance of Rs increases. A) It is a circuit in which parallel connections of R1 and Rx and parallel connections of R2 and ...
5 votes
7 answers
488 views

How can same points have different current?

Aren't B and D the same point and shouldn't it actually be (B and B)? If they aren't the same point what should be the current from B to D? Why is it 2 amperes (from the answers) and not 10 amperes as ...
0 votes
1 answer
37 views

How do I simplify the circuit using source transformations to get the Thevenin equivalent?

I don't know what to do with the 17 Ω and 9 Ω. Can someone help me?
  • 1
0 votes
3 answers
118 views

Can a battery's open circuit voltage be measured without actually disconnecting the load?

Is there: a specific tool for it or a method for its calculation which includes the terminal voltage I'm actually in need of a method which would not require disrupting the circuit by removing the ...
  • 43
1 vote
2 answers
141 views

How can I analyse this circuit (analog PD controller)?

We had op-amps at school but I do not know how I can go about analysing this circuit because it has an additional node in the backwards branch. For me, I can not see why the capacitor is inside a ...
  • 123
1 vote
2 answers
75 views

Current expression after closing the switch

In the picture below the switch \$S_1\$ is open for a long time, and I need to find the expression of \$i(t)\$ for \$t>0\$ (when \$S_1\$ closes): Since this is an RLC circuit, I need to solve a ...
  • 115
5 votes
1 answer
253 views

Why does the ground in LTspice affect the simulation result?

I am simulating a 220 V to 5 V circuit using LTspice. Somehow the position of the ground will affect the simulation result. Picture 1: when the ground is put at the 220 VAC voltage source's '-' side, ...
  • 65
1 vote
1 answer
35 views

Will the saturation current through one of these NMOS circuits always be greater than the other?

Is there a definitive way to know for all cases if an NMOS would have a greater saturation current if a resistor R is connected to 1) the drain side or 2) the source side? The assumption is that the ...
2 votes
2 answers
200 views

Need help solving a differential amplifier circuit

I've been trying to solve the circuit below for hours now but to no avail. I can't figure out what to do. I've been given a single input, unbalanced output differential amplifier circuit to solve for ...
0 votes
1 answer
56 views

Question regarding state-space modeling of a simple electrical circuit

Consider the circuit in the picture, where we have a voltage source (input) \$V(t)\$ and a capacitor \$C\$. The goal is to derive a state-space model of this circuit. The circuit satisfies the ...
  • 101
2 votes
1 answer
86 views

Is there a typo in this question because I don't think the emitter node of Q2 should be grounded?

In this problem, it's asking us to draw the small signal equivalent of an amplifier but I think the answer they gave is wrong. In the second picture (b) I don't think the emitter of Q2 should be ...
1 vote
1 answer
136 views

Triggering 120 MP3 players with an Arduino Nano and a 4066 chip

I have a circuit that sends a 300 ms signal (a short button press) from pin D13 on an Arduino Nano to a 4066 chip, which then sends it to 4 boards (A, B, C, and D). Each board connects to 30 MP3 ...
-2 votes
0 answers
69 views

Simplify and redraw a given circuit and add parameters

Updated - pls see my given answer to let me know if correct or wrong I'm only new to electrical engineering and circuits, but I wondered how I would answer this question. So, How would I redraw the ...
2 votes
2 answers
308 views

Resistor equivalent for RC circuit

Hi there! I stumbled upon this circuit, and I have a hard time trying to understand if the Req for the following circuit is in series or parallel. I have tried with parallel but does not look too good....
  • 37
0 votes
4 answers
62 views

Load resistor in Thévenin-Norton equivalence for impedance

Lets say I have this circuit in the picture and I want to calculate Thévenin/Norton equivalent impedance from the terminal a-a' standpoint. Would the resistor \$R_2\$ be accounted for the Tévenin ...
  • 525
-1 votes
1 answer
81 views

Order of RC circuit

In the given RC circuit, there are 3 capacitors, out of which the voltages of 2 capacitors can be uniquely determined. This implies that it is a second-order circuit. But when I found the expression, ...
1 vote
1 answer
74 views

Help with supercapacitor charging circuit

I need to design a circuit to charge a capacitor from 0 to 2V. The circuit should not be that complicated and no matter the type of capacitor, it should never exceed 2.7 V when charging. The capacitor ...
2 votes
2 answers
57 views

Transistor in saturation mode conditions

I have this circuit where the voltage \$V_A = -4.6V\$ is imposed. I made the hypothesis that the transistor is saturated. Then I calculated \$i_B\$ through KVL: $$-2 + R_Ci_E + V_{EBon} + R_Bi_B + V_A ...
  • 525
6 votes
5 answers
758 views

Transistor working region hypothesis

In the following circuit of a transistor I know that \$V_A = 2.5V\$. How do I know in which zone the transistor is operating? As I understand it, I should make an hypothesis into one of the working ...
  • 525
2 votes
2 answers
165 views

Supply-independent current source

In the given circuit, the resistor defines the current and it is connected at the source of M2 in this circuit. What will happen if it is connected to the source of M1? I don't see any problem, but I ...

1
2 3 4 5
115