As originally stated in terms of direct-current resistive circuits only, Thévenin's theorem states that, "For any linear electrical network containing only voltage sources, current sources and resistances can be replaced at terminals A-B by an equivalent combination of a voltage source Vth in a series connection with a resistance Rth."
The equivalent voltage Vth is the voltage obtained at terminals A-B of the network with terminals A-B open circuited.
The equivalent resistance Rth is the resistance that the circuit between terminals A and B would have if all ideal voltage sources in the circuit were replaced by a short circuit and all ideal current sources were replaced by an open circuit.
If terminals A and B are connected to one another, the current flowing from A to B will be Vth/Rth. This means that Rth could alternatively be calculated as Vth divided by the short-circuit current between A and B when they are connected together.In circuit theory terms, the theorem allows any one-port network to be reduced to a single voltage source and a single impedance.
The theorem also applies to frequency domain AC circuits consisting of reactive and resistive impedances. It means the theorem applies for AC in an exactly same way to DC except that resistances are generalized to impedances.
The theorem was independently derived in 1853 by the German scientist Hermann von Helmholtz and in 1883 by Léon Charles Thévenin (1857–1926), an electrical engineer with France's national Postes et Télégraphes telecommunications organization.Thévenin's theorem and its dual, Norton's theorem, are widely used to make circuit analysis simpler and to study a circuit's initial-condition and steady-state response. Thévenin's theorem can be used to convert any circuit's sources and impedances to a Thévenin equivalent; use of the theorem may in some cases be more convenient than use of Kirchhoff's circuit laws.
Hey,
I'm trying to find the thevenin equivalent of a particular circuit so that I can calculate the current across an inductor.
I've attached a pdf with the circuit and the working out I've done so far.
When I'm talking about i0 I'm talking about the Thevenin equivalent current and...
A strain-gauge bridge is made up of four resistive elements, each element having an unstrained
resistance equal to R, as shown in the diagram below. When a strain is applied to the bridge
elements R2 and R4 increase in resistance by an amount ΔR, whereas R1 and R3 decrease by ΔR,
where...
http://img855.imageshack.us/img855/5369/eehmwk.jpg [b]
I haven't done this before with 2 voltage sources so I'm not sure how I would go about doing it.
If someone could show me step by step how to understand this, I would appreciate it.
Equivalent resistance = 2.5ohms, right?
But...
Homework Statement
Hello, i was studying diodes for my exam on monday, but i had some struggle finding the Thevenin equivalent. Here is the circuit:
http://img411.imageshack.us/img411/5336/schakeling.png
Homework Equations
I have no clue what to put here?
The Attempt at a...
Here the attachment is the question.
I have some experience in solving Thevenin with Voltage source, but not with current source.
Any idea?
thanks and regards,
May
hi everybody,
please help me if you can the question in this link .
i try many many times but i don't know how i can solve thevenin equivalent with dependent sources.
tomorrow i have a home quiz on this question.
http://imageupload.org/?d=49E036571
Homework Statement
Find the Thevenin equivalent network of the lattice network (see attached), viewed from points As and Br (terminals Bs and Ar are not connected to anything).
Homework Equations
The Attempt at a Solution
Without the resistance f, the problem is quite simple. I...
For the circuit below, can someone please help me understand why Zeq = 0 (in words...not by solving):
I know Vth = 50<0° since this is the voltage drop across the parallel elements. I don't understand why the equivalent impedance would be 0. I know when you shut off a voltage source...
Homework Statement
[PLAIN]http://dl.dropbox.com/u/9699560/EE%20Problem.jpg
(I added the text V1, V2, and Voc to the image).
I'm only trying to find Voc because I got the wrong answer. I got Isc correct.
Homework Equations
Basic node voltage analysis techniques.
The Attempt at a Solution...
Homework Statement
Find the Thevening Equivalent Circuit for the following circuit:
Homework Equations
KVL, KCL.
The Attempt at a Solution
First of all, I calculate the current in the middle mesh, which I'll call i2:
- j25 = ({i_2} - {i_1})(3 + j4) + {i_2}(10)
where i1...
i am trying to find the short circuit current for the following circuit.
the RL is the thevenin equivalent resistance. i am trying to find the current when RL is a wire (short circuit).
by KVL, i have
IR1 + \mu1(v2-v1) + IR2 + \mu2(v3-v1) + IR3 = 0
(the above is not formatted...
I need help finding the thevenin equivalent voltage for the following network:
i did source transformations so that i could analyze it using the node voltage method.
my equations are:
I1 = v1
(a) vx + vx - vT = v1 + av1 - bv1
2vx - vT = v1 + av1 - bv1
(b) vT - vx + vT = bv1
2vT - vx = bv1...
Homework Statement
A variable resistor (RL) is connected to an unknown circuit. It is found that the
maximum power that can be dissipated in the resistor (RL) is 10W, and that this
occurs when the value of the resistor (RL) is 25ohms.
Derive the Thevenin equivalent circuit for the unknown...
In a thevenin equivalent circuit are you able to find the power used in the circuit by the variable load?
I have a circuit where the variable load is in parrallel I was thinking the power used in the original circuit by the variable load would be different than in the equivalent because it is...
hi :smile:
I'm having some trouble figuring out the Thevenin equivalent for this circuit.
As you can see, there are two dependent sources (current dependent current source & voltage dependent voltage source) and no independent source.
I have started trying to analyse the circuit by...
Homework Statement
The question asks to find the Thevenin equivalent circuit as shown in the attachment. (It's a BJT problem, but I'm having difficulty with the first part).
Homework Equations
Where are terminal points I need to worry about when making it an open circuit? That's the biggest...
May anyone please help with the method of getting Thevenin Equivalent resistance (RTH) for the attached circuit. I have already found VTH to be 8V.
Sim
http://img69.imageshack.us/i/circuitf.jpg/
Can someone explain what was done to go from Figure 4 to Fig 5? I tried source transformations but I cannot simplify it to that.
Homework Statement
https://www.physicsforums.com/attachment.php?attachmentid=32837&stc=1&d=1299373667
Determine the Thevenin equivalent circuit parameters, VTh and RTh, referred to terminals A and B of the circuit shown below?
Homework Equations
The Attempt at a Solution
My...
Homework Statement
I need to find the Thevenin equivalent of the circuit shown:
I found the open circuit voltage (VAB) by noting that VAB = V3 and used the voltage division
V_{AB} = V_s\left ( \frac{R_3}{R_1||R_2 + R_3}\right ) = 12\V
I am having a little trouble finding the short circuit...
Homework Statement
Homework Equations
The Attempt at a Solution
I am not getting this at all. I know that I need to calculate the open circuit voltage Voc and the short circuit current Isc. I really have no idea how to find Voc. There is some conceptual leap I need to make...
Homework Statement
Find the thevenin voltage and thevening resistance of the circuit.
[PLAIN]http://img573.imageshack.us/img573/2525/thevening.png
The Attempt at a Solution
The posted answers for the question are 5v and 1k ohm. But I can't see how the thevenin resistance is 1k...
Find the Thevenin Equivalent circuit between A and B
the circuit is in the attachments...
i don't know how to start and don't know what it meas "Between A and B"
and i never encountered a problem with a dependent source.
Thanks...
Homework Statement
The question is to find the Thevenin equivalent of the network across the terminals a,b.
The circuit is as follows:--
The solution is Zth = 12.166 angle(136.3*)ohm and Vth = 7.35 angle(72.9*)
I can find out the Vth, that's easy. But I can get the Zth right coz there...
Homework Statement
This is in norwegian but hopefully you can understand it.
Here is the assignment and circuit:
http://img835.imageshack.us/img835/3619/krets.jpg
Find the equivalent Thevenin circuit when when RL is the load
Homework Equations
The Attempt at a Solution
I really don't know...
Homework Statement
An automobile battery when connected to a car radio provides 12.5 V to the radio. When connected to the headlights, it provides 11.7 V. Assume the radio is modeled as 6.25 ohm resistor and the headlights are .65 ohms. Find the Thevenin Equivalent for the battery...
Homework Statement
I have this circuit (attached) and I am required to give the thevenin equivalent circuit...since its a current source, the first 300ohm resistor is ignored, right? but then is the 100 ohm and 25 ohm resistor afterwards taken to be in series of parallel, i took series...
Homework Statement
See Figure
Homework Equations
The Attempt at a Solution
See figure.
Did I do this right?
I just want to make sure I'm understanding things correctly.
Homework Statement
Compute the values of the Thévenin equivalent seen by the 20 kΩ resistor using circuit analysis techniques. Draw the equivalent circuit and list the values.
Homework Equations
V=IR
Nodal analysis
mesh analysis
The Attempt at a Solution
I know a Thévenin...
Homework Statement
I wish to obtain the Thevenin equivalent for the network show in the attachment between the terminals a and b.
2. The attempt at a solution
First I considered the voltage source alone (replaced current source by an open circuit).
I = \frac{V}{Z_T} =...
Homework Statement
Find the open circuit voltage across A & B:
Homework Equations
V = IR
The Attempt at a Solution
If I0 is the current leaving the voltage source and passing through the first resistor, I1 is the current through the left resistor in parallel, and I2 through...
Hey I can't figure out how to convert the below circuit into its thevenin equivalent. I am used to having two points to work with, but in this circuit there is only one and a ground.
http://img715.yfrog.com/i/13332492.jpg/
for some reason the image doesn't show up on my screen; if that's the...
Homework Statement
^We're asked to find the "Thevenin's equivalent circuit for the source"
The Attempt at a Solution
I'm a bit unsure how to start this problem. What i initially thought was that i'd combine all my impedances in parallel to the point where it's them combined plus the...
Homework Statement
Find thevenin equivelent of this circuit with respect to a and b
Homework Equations
Mesh Currents
The Attempt at a Solution
Here I will try to find V(open circuit) = Vth = Vab ((I think this anyways))
I apply mesh currents (any faster methods are welcome if...
Homework Statement
I am being asked to draw the Thevenin equivalent for
and to calculate the voltage that would appear across RL if it were connected across the 2 output terminals.
Using Kirchoff's law I found that the voltage across RL is -12.5 V. However I am really suppose to do it using...
Homework Statement
The circuit is attached as a jpg image. How can i find the norton equivalent when both current sources and voltage sources are present?
please help
Homework Equations
The Attempt at a Solution
Homework Statement
Find the Thevenin equivalent at terminals A-B of the circuit below.
http://img5.imageshack.us/img5/1723/thevenin.jpg
Homework Equations
The Attempt at a Solution
On the first image i have to find the thevenin equivalent viewed from terminals x, x' & y, y'
i get the Req as 7.32ohms but now i am having trouble calculating the vth, i have no I to calculate
thanks in advance
Homework Statement
Show that if a battery of fixed emf E and internal resistance R1 is connected to a variable external resistance R, the maximum power is delivered to the external resistor when R=R1
Homework Equations
Power = R * I^2
The Attempt at a Solution
We can think of...
Homework Statement
Find the Thevenin Equivalent resistance for the network below:
http://img27.imageshack.us/img27/8508/circuit.png
Homework Equations
R=(1/R1+1/R2)^-1
The Attempt at a Solution
Hi all,
to find the resistance i short circuited the volage sources and...
Homework Statement
I am trying to find the theoretical Thevenin equivalent resistance for a black box that I used in an experiment. The measured Thevenin equivalent resistance was roughly 4786\Omega. However, I have tried several times to solve the problem, but keep arriving at a theoretical...
Homework Statement
I am trying to find the theoretical Thevenin equivalent resistance for a black box that I used in a circuits experiment. The measured Thevenin equivalent resistance was roughly 4786\Omega, so the theoretical should be somewhere around that. However, I have tried several...
Homework Statement
Find the Thev Eq circuit for a DC power supply that has a 30-volt terminal voltage when delivering 400mA and a 27-volt terminal voltage when delivering 600mA.
Homework Equations
KVL: Vs=IsR1+IsR2
Vth=Isc*Rth
The Attempt at a Solution
Assuming that each 3volt...
Homework Statement
A car battery has an open-circuit terminal voltage of 12.6 volts. The voltage drops to 10.8 volts when the battery supplies 240 amps to the car's starter motor. What is the Thevenin eq for this battery?
Homework Equations
I think the root of my problem is the setup of...
Hi!
Good day! I was studying Circuit Theorems when I stumbled upon this circuit that has a dependent current source asking for a Thevenin equivalent. Up until now, I was only familiar with solving circuits with independent sources so this has me having a hard time. I tried using...
I have to find the thevenin equivalent of the following circuit in order to find the current and potential difference across the 6 ohm resistor. I can not get to know that where should I start. Should I divide the circuit into 2 parts or what?
http://img141.imageshack.us/img141/2690/416qr1.th.jpg
I start with the Thevenin equivalent.
\hat{R} = R_2 + R_4 || R_1 = 6 \Omega
R_{Th} = R_3 + \hat{R} || R_5 = 8 \Omega
The correct answer here should be 2 \Omega
Finding the thevenin equivalent of the above circuit
This is what I did, I set the current source to zero, no current passes through
so the Rth is the resistor on farthest right // with another 2 in series with 4.
so it is 5ohms?
Finding the open circuit voltage, I use a current...
Hi All,
My name is Joaquim and I'm new in this forums. I am a Electronic Engineer student (1st Year).
I have a question about a Thevenin equivalent circuit in AC.
I need someone to tell me if I'm doing the right math in finding the thevenin equivalent (AB point):
Please see the...