Questions tagged [thevenin]

Thévenin's theorem for linear electrical networks to simplify the analysis of complex electrical circuits.

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12
votes
3answers
675 views

Help me solve this DC circuit problem

The circuit looks like this: All the elements are known, except for \$I_{g2}\$. \$E_1=3V,E_4=10V,E_6=2V,E_8=1V,E_9=4V,I_{g7}=1mA,\$ \$R_1=1k\Omega,R_2=1k\Omega,R_3=1k\Omega,R_4=2k\Omega,R_5=4k\Omega,...
8
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3answers
2k views

Why is the voltage drop across this 1 ohm resistor being neglected in this practice problem? (Thevenin's Theorem)

We are given the following circuit and told to calculate the equivalent voltage of everything to the left of the a and b terminals: It omits the load resistor and lays the circuit out as such for ...
6
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4answers
1k views

Trouble finding Thévenin equivalent for this circuit

I'm having trouble finding the thevenin equivalent for this circuit To solve this problem, I changed the voltages from 20V and 5V to 25V and 0V as shown below My resulting output voltage is 10V ...
6
votes
2answers
51k views

How to find the Thévenin voltage?

How do I find the Thévenin voltage in this diagram? In parallel the voltage remains the same, so should it be 10 volts across AB? I am given that since \$R_3\$ and \$R_4\$ are not connected on one ...
6
votes
1answer
103 views

Why is the verification of Thevenin's theorem more accurate than that of Superposition theorem?

In my first course on Electrical Engineering, we have an experiment in the Electrical lab that asks us to verify the Thevenin theorem and the Superposition theorem and cross-check our results with our ...
5
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3answers
2k views

Thevenin Equivalent Voltage: why ignore the 3-kΩ resistor?

In order to find the Thevenin voltage here, why is it that the 3k Οhm resistor is ignored and no current goes through it? (hence \$V_{TH}=8mA \cdot 7kΩ = 56V\$)
5
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3answers
672 views

Contradiction:Maximum Power Transfer and High resistance of load

Whenever we load a circuit, there's a drop from the open circuit voltage \$v_{oc}\$ due to the internal source resistance or Thevenin's resistance\$R_{th}\$. So we need to have an \$R_{load}\$ that ...
5
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4answers
2k views

Thevenin equivalent of nmos

I was reading my textbook(razavi) and came across this circuit where to calculate vout2/vin1 he drew a thevenin equivalent of nmos. I dont understand how thevenin voltage(Vt) and Rt in the equivalent ...
5
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1answer
1k views

Thevenin equivalent with dependent source

Well, I'm trying to find the Thevenin equivalent of this circuit: As you can see, the only current source is a dependent source. However, the control variable is in a wire where, if nothing is ...
5
votes
1answer
2k views

What is the Thévenin equivalent of the mains power supply?

Thévenin's theorem says that any voltage source can be modeled as an ideal source in series with some complex impedance. How does one quantify this model for AC mains supplies? What parameters are ...
4
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2answers
907 views

Maximum power transfer

I have problems to solve the next exercise about maximum power transfer. I know that potentiometer has two internal resistors. In this exercise, I must find the \$R\$ value to transfer maximum power ...
4
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2answers
63k views

How to find Thevenin resistance of circuit with voltage source and three resistors?

The question is: Replace the circuit with a Thevenin Equivalent Circuit and find the Thevenin Resistance (Rt) in ohms. I've used Thevenin before and solved quite a few equivalent circuits as well. ...
4
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2answers
11k views

How to Calculate Appropriate R-2R D/A Converter Resistor Values?

I am trying to make a 4-bit R-2R D/A Converter where a +5V signal on D3 would output -5V, a +5V on D2 would output -2.5V, etc. How would the resistor values for R/2R be calculated?
4
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5answers
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Stiff Voltage Divider Bias for an Emitter Follower

Below is an ac-coupled emitter follower with base bias provided by a voltage divider. I'm having a slight issue with how the resistor values are chosen for the biasing in the design example provided ...
4
votes
2answers
20k views

Thevenin equivalent and op amp

I have some problems obtaining the thevenin equivalent with op amp. The next example is in Fundamentals of electric circuits of Sadiku. Can you help me get thevenin equivalent from the example?
4
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1answer
2k views

Thevenin equivalent circuit with current and voltage source

I have the circuit below and I have to calculate complex current i1using thevenin equivalent circuit method: I tried to follow the rules and open the terminal <...
4
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1answer
4k views

LM324 op-amp wheatstone bridge amplifier formula

I'm planning to use an LM324 opamp as a signal amplifier for a cell load (strain gauge in a Wheatstone bridge). This particular application is shown in the datasheet (see image). It shows the ...
4
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1answer
6k views

Questions about Thevenin's Theorem

I am reading up on Thevenin's Theorem and this has prompted a few questions that I hope somebody will be able to answer. This is the tutorial I am reading. The circuit below is then given as an ...
3
votes
4answers
1k views

Impedance matching confusion

A long time ago I understood this, but right now it totally escapes me. Taking an audio amplifier for example. Say it drives a speaker which is 8 ohms at all frequencies. Taking the amplifier as a ...
3
votes
3answers
3k views

Thevenin equivalent in a nonlinear circuit

Is it possible to use the Thevenin equivalent of a voltage divider driving an emitter follower? simulate this circuit – Schematic created using CircuitLab In general, when is it safe to use ...
3
votes
2answers
4k views

Thevenin equivalent resistance of circuit with diagonal resistors

I'm trying to find the Thevenin equivalent for part A of this circuit: I begin by opening the circuit at the dotted line of part A. Then I try to find \$V_{oc}\$ across the two terminals that are ...
3
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2answers
3k views

Are I/O pin internal resistances equal to the Thevenin resistance?

I'm trying to find the Thevenin resistance of an I/O pin for the ATmega644. I see on the datasheet that there is a 20-50 kohm range of internal pull-up resistance. So with that, I can create a ...
3
votes
1answer
1k views

Where does the power dissipation go in this Thévenin equivalent?

The circuit below contains an AC current source and an ideal transformer along with some passive elements. I marked the points A and B, because I'm trying to find the power dissipated in the terminal ...
3
votes
2answers
6k views

Thevenin's theorem in transistor circuit

When analyzing this transistor circuit it was suggested that I simplify the left side by using Thevenin's theorem with the points A and B as follow. Before I jump in let me apologize the lenght of the ...
3
votes
2answers
4k views

Calculating max power from an RMS Voltage Source

I have a question that asks me to calculate the maximum power output from a power supply that can be delivered to a load. I know what the answer is (0.5W) but I am struggling to get too it. I tried ...
3
votes
3answers
357 views

Thevenin analysis

I have a hard time understanding why Thevenin analysis works. I can see the math, and I can find the equivalent resistor, but I am not sure why it is a valid analysis from a practical point of view. ...
3
votes
2answers
8k views

Finding a diode's operation point (Q-point)

I'm struggling with what should be a fairly simple excercise, I have to determine the diode's Q-point using the load line method given the diode's characteristic curve, however if you look at the ...
3
votes
1answer
55 views

Can we apply maximum power transfer theorem to SMPS rectifiers?

Thevinin and Norton equation simplifies BJT and MOSFET analysis leading to the hybrid pi models. Can we apply the same concept while analysing an AC-DC Converter with PFC and PSFB full bridge topology?...
3
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1answer
15k views

How do I decide which method to use in circuit analysis?

I'm an Electrical Engineering student, and circuit analysis can be really confusing to me. I sort of understand the concepts of solving circuits, but I don't really know when to use which method. Are ...
3
votes
1answer
2k views

Diode-connected transistor, small-signal, Norton, Thevenin

How do I calculate the equivalent Thevenin resistance of the small-signal model of a diode-connected transistor (base tied to collector)? Early-effect is neglected. The port of interest is between C ...
3
votes
3answers
370 views

Finding current when short-circuiting the terminals

I am working with the circuit shown below. I am having trouble with the situation where: if a short circuit is connected between Terminals A and B. what current would flow through the short circuit ...
3
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3answers
2k views

Confusion about Thevenin's theorem for linear circuits with non-linear elements

My question is about **linear circuits** which has non-linear elements. When I read about Thevenin's theorem, all explanations say that it is basically about ...
3
votes
1answer
229 views

Confused with mesh analysis

something about mesh analysis confuses me and I can't find an explainaton anywhere, as you can see on this picture (it's in French, but the schema and formulas should be enough to understand) They ...
3
votes
2answers
131 views

Why do we not include the current source when finding the Thévenin equivalent impedance?

The problem is from Basic Engineering Circuit Analysis, by J. David Irwin, Robert M. Nelms, chapter 9.3. When I tried to solve this problem, I tried to find the Thévenin equivalent circuit by ...
3
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1answer
79 views

Thevenin Method

I need help solving the following circuit using the Thevenin method: simulate this circuit – Schematic created using CircuitLab The unknown in this problem is current i5, the correct answer ...
3
votes
2answers
147 views

Thévenin's Theorem Example

I just started learning Thévenin's Theorem. My textbook gives the following example: I'm referring to online sources such as this to complete this problem. However, all of the circuit diagram ...
3
votes
1answer
185 views

Termination for backplane

I'm developing on a small modular computer system using the Z80 just for fun. The backplane is a prototype PCB with five DIN41612 connectors wired in parallel, running about six inches from the first ...
3
votes
1answer
315 views

Thevenin's equivalent exercise

I have this exercise of a Thevenin's equivalent that really got me confused with it's usage of a transistor and was wondering if I could get some help with understanding how to solve this particular ...
3
votes
1answer
115 views

How to go on from here (Thevenin circuit)?

Basically, I've discovered the "total" resistance, being 6/11 Ohms. Same resistance would be found in Norton's circuit. Now, I know that the sum of all voltages should be zero. I was thinking to go ...
3
votes
2answers
951 views

Simple NMOS transistor circuit output impedance

I am having trouble figuring out the best way to determine the output impedance of this simple NMOS transistor circuit: Both transistors are equal, and the body effect is ignored. What method ...
3
votes
2answers
223 views

Result with Thevenin method doesn't equal node method

I'm following the MIT lectures on circuits and electronics. They introduce the Thevanin method for solving linear systems in lecture 3 (https://youtu.be/RsJ1eg7XNVs?t=46m49s). I can't seem to get same ...
3
votes
1answer
395 views

Intuition on Thevenin's Theorem

In the following lecture by Prof. Anant Agarwal at 36:00, he intuitively proves Thevenin's Theorem using the following circuit simulate this circuit – Schematic created using CircuitLab If ...
3
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1answer
203 views

Transmission lines and superposition

Below is the circuit in question. Good evening, I'm working on a problem that requires me to graph voltage at point A between -10 ns and 120 ns. I know that we must factor in wave reflections that ...
2
votes
1answer
3k views

Norton's and Thevenin's theorems importance

Are Norton's and Thevenin's theorems used in real life? And in which situations? I'm reading a circuit analysis book and I asked myself: do electrical engineers use these theorems to get current and ...
2
votes
1answer
1k views

Why does a Thévenin equivalent exist but not a Norton Equivalent, and vice versa?

In the following diagram, the Thévenin equivalent of the circuit on the left is shown on the right: simulate this circuit – Schematic created using CircuitLab However, it appears that there is ...
2
votes
7answers
358 views

Thevenin voltage for a simple circuit

Trying to find the Thevenin equivalent voltage for the circuit on the picture below. This voltage is supposed to be found at the round dots to the very right in the circuit. According to the answer ...
2
votes
3answers
3k views

Norton's theorem application problem

The first image shows the circuit we start with. The second image shows the circuit in which I had the load removed (as I know from Thevenin's theorem). After that I'm getting confused because of the ...
2
votes
1answer
94 views

Thevenin's Resistance

I can't understand why the answer is like in the picture and not R = [ ( 4 + 6 ) // 8 ] + 2. Isn't 4 in series with 6 and parallel to 8 ?
2
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2answers
687 views

Solving a Thevenin equivalent circuit

Suppose \$R_{1}\$ and \$R_{2}\$ are replaced by resistors of unknown values which are different from those assumed in part (a). Using a variable external voltage source, a student applies \$+1.5V\$ ...
2
votes
1answer
427 views

Total resistance of circuit

Hi I'm struggling a bit with obtaining the total resistance of this circuit, I know it's an easy one I'm just a bit confused on how the resistors are merged using parallel and series operations, here'...

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