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.
Homework Statement
I'm having problems with PF's cut and paste images. They are not showing up on the actual webpage only on my editor.
See these:
http://i.imgur.com/mKfn27m.png
http://i.imgur.com/jCO2JRM.png
http://i.imgur.com/oUWFsuI.png
I created the above problem by modifying this...
Homework Statement
Determine the Thevenin equivalent with respect to the terminals a,b
Homework Equations
Rth=Voc/Isc
The Attempt at a Solution
I'm doing this practice problem and I calculated the the short circuit current below:
500uA*100ohm/(100ohm+1310ohm)= 35.460 uA
since 80*ib=current...
Homework Statement
http://oi57.tinypic.com/263tqvr.jpg
I decided to try using mesh currents for thisFirst mesh is IA, second IB, third, ICSo I have the equations
IA = 500 μA
1310 IB + 100(IA - IB) = - 4*10-5V2
IC = -80IBAre these equations correct so far? I get the feeling they're not
Homework Statement
I am to find the thevenin equivalent circuit without the load resistor (to the left of terminals a &b
Homework Equations
From class notes:
1- Remove the load resistor
2- find the open circuit voltage across a & b
3- Remove all voltage sources (replace with short circuit)...
Hi everyone. I need some help with regards to a question on Thevenin's equivalent. I attempted to solve it in 2 ways but I got different answers when I tried to do it another way. However, I am not sure of my answer as I do not have the answer key at the moment. The picture below shows one of my...
Homework Statement
Hi everyone! I'm trying to find the thevenin equivalent for part A of this circuit: http://imgur.com/4Jdg8w8
Homework EquationsThe Attempt at a Solution
I first remove part B, that is, open circuit it entirely. Then I try to find Voc across the two terminals that are open. I...
Homework Statement
I'm trying to understand where the (β+1) comes from.
[b]2. Homework Equations
vth=-βiR2
i+βi+is=0
vth=-β(-is/(β+1))R2
[b]3. The Attempt at a Solution
vth=-βiR2
i+βi+is=0
vth=-β(-βi-is)R2
1. Homework Statement
Find the Thevenin equivalent circuit with respect to terminals a, b by finding open-circuit voltage and the short-circuit current.
2. Homework Equations
i1+i2+i3..=0
v1+v2+v3..=0
i=v/R
The Attempt at a Solution
I was trying to shove this on my own for...
Homework Statement
Find the Thévenin equivalent of the circuit and the required value of the load for maximum power transfer for Z = 15 + j24 Ω .
Homework Equations
Voltage divider equation and Z_{in} = Z_{load} 'complex conjugate' for maximum power transfer.
The Attempt at a...
Homework Statement
Find thevenin equivalent of resistor circuit
Homework Equations
The Attempt at a Solution
This may be a dumb question, but does a thevenin equivalent NEED to have a voltage source? On my final exam there was a question that asked for the thevenin equivalent of...
Homework Statement
I have the network attached below. I need to find the open circuit voltage and short circuit current between A and B and then use these to find the Thevenin equivalent for the circuit.
The Thevenin equivalent voltage is of the form VTsinwt and the equivalent impedance is...
For this problem, I added in an external source, and found an expression for the external current in terms of ix. Then I divided Vex/iex to get the Rth. Then I did superposition to find the Vth. I had some troubles getting rid of the extra currents, particularly i3 and i2. I was wondering if...
Hello,
I had read in my textbook that when a dependent source is in a circuit, and you wish to find the thévenin resistance, then the method to solve for the thevenin resistance is to turn off the independent sources and add an external voltage, then find the external current.
The external...
Hello,
For thévenin equivalent circuits, I thought current sources are replaced with open circuits and voltage sources are replaced with short circuits.
In this video, the guy replaces both with open circuits, so I am not understanding how that works.
Because of all the different...
Homework Statement
Find the Thevenin equivalent circuit at terminals (a,b) of the circuit below:
Homework Equations
The Attempt at a Solution
my currents aren't adding up right. When I try to solve for Ix using my two equations that should find it, I get different answers.
Homework Statement
Find the Thevenin equivalent circuit at terminals (a,b) for the circuit below.
Homework Equations
The Attempt at a Solution
I am having a conceptual issue for this circuit. I can't combine any of the resistors, and my gut is telling me that something about the...
Homework Statement
Problem located in attachment.Homework Equations
Parallel, series and wheatstone bridge equations for resistorsThe Attempt at a Solution
Converted the circuit to look less confusing. Work shown in other attachment.
I am simply using the equations relating to simplifying...
Homework Statement
http://postimg.org/image/5wtty6dvr/
I'm trying to find the Thevenin equivalent of the circuit on the left side and but having trouble in getting the open circuit voltage.
Does no current flow through R3 since that way leads to a dead end?
Homework Statement
http://imgur.com/w5AQ1A8
As shown in the image:
In the circuit below R1=100Ω, R2=1000Ω, R3=99Ω, R4=1000Ω, R5=10Ω, and V=10V.
(a) Relying on the Thevenin theorem, find the equivalent voltage and equivalent resistance for the circuit below when the resistor R5 is taken out...
I am trying to refresh my basic electricity knowledge so the questions might be a little stupid lol.
1) Am I correct in saying that the voltage, V1, across the 6 ohm resistor is equal to the VOC?
2) Why isn't the voltage across the voltage source, V2, equal to V1 and VOC? I thought that...
Homework Statement
Homework Equations
The Attempt at a Solution
I am trying to find the equivalent resistance for part b.
First, we turn off independent sources. We open circuit the 2A source and we close circuit the 30V source. We're left with two resistors. Are they in series or parallel...
Homework Statement
Homework Equations
The Attempt at a Solution
I got ##R_{ th }=4\quad Ω## easily but I am having trouble finding ##V_{th}##. Assume the negative terminal of the 32V voltage source is ground. Here is the nodal analysis at node 1:
$$\frac { 32-V_{ 1 } }{ 4 } +2=\frac { V_{...
i am confused at the 20v voltage since it becomes short circuit.i had started reading the circuit from the left side 1M ohm and 2k ohm are in parallel and in series with the 3k.knowing that current wants less resistant ways it will go to the killed voltage source...after that I am wasnt able to...
Homework Statement
Find resistance R so that maximum power is transferred to this resistor.
http://i.imgur.com/XsxTFCq.png
Homework Equations
Rth = Voc/Isc
The Attempt at a Solution
I tried to find the Thevenin equivalent circuit across the resistor R because the Thevenin resistance must...
Homework Statement
Above given is the circuit I am supposed to simplify where the 1/5Ω resistor is the load. I'm unsure how to convert this circuit into an equivalent Thevenin Circuit.
Homework Equations
V = I*R (Ohm's Law)
The Attempt at a Solution
Using Microcap and it's...
Homework Statement
Find the Thévenin equivalent of the circuit shown in FIGURE 1.
Homework Equations
Any two-terminal network can be replaced by an equivalent circuit consisting of a voltage source and a series resistance equal to the internal resistance seen looking into the two...
Homework Statement
Apply source transformation to find the Thevenin equivalent circuit
Homework Equations
voltage division, source transformationThe Attempt at a Solution
Simplify the far left current source to get
Then Vth of this = (50V + 20V)*(100/200)
= 35V
and Rth of it = 100||100 =...
Homework Statement
Use source transformation to find the Thevenin equivalent circuit with respect to terminals, a, b.
Homework Equations
Voltage Division: (V in)*(R1/R1+R2)
Thevenin / Norton / source transformation procedures
RTh = RNo
VTh = INo*RNo
Polar...
Homework Statement
Given the circuit (Attached in image) Find the thevenin equivalent circuit.
I know its a fairly simple thing, But I am not understanding where the lecturer is getting this answer from, unfortunately his solutions just state the voltage so I feel like I must be missing...
Homework Statement
determine thevenin equivalent of circuit at terminals (a,b):
Homework Equations
Z(L)=jwL
Z(C)=-j/wC
V(th)=V(oc)
R(th)=V(ex)/I(ex)
The Attempt at a Solution
actually 1st i need help with finding V(th). i do know that V(th) would be the voltage across the 2ohm resistor, so...
find the thevenin equivalent circuit (just need my values checked!)
Homework Statement
find the thevenin equivalent circuit (using open/short circuit method is how i did it):
Homework Equations
n/aThe Attempt at a Solution
I just need to verify that my V(th)=V(oc) value is right:
Vc/4 +...
Homework Statement
https://www.circuitlab.com/editor/#?id=wt59bd
Homework Equations
ohms law
The Attempt at a Solution
Ok, from what I understand about this circuit, I can:
eliminate R1 (resistors in parallel with a voltage source don't effect voltage), and eliminate R3...
Homework Statement
http://imageshack.us/a/img14/2387/homeworktest2prob2.jpg
a. Find the Thevenin equivalent circuit with respect to terminals a, B for the circuit.
b. Find also the Norton equivalent circuit with respect to the terminals A, B, for the circuit
Homework Equations
V = IR...
Homework Statement
http://imageshack.us/a/img809/9307/homeworkprobsg210omgthi.jpg
Find the Thevenin equivalent circuit with respect to the terminals.
Homework Equations
V = IR,
KVL, KCL
voltage division, current division
Thevenin formula / procedure
The Attempt...
Homework Statement
Find Thevenin equivalent circuit as seen across terminals A and B for each circuit.
Homework Equations
V=IR
The Attempt at a Solution
Those resistors are in parallel because not all of the current going through the top one is going to go through the next one...
I'm given the circuit in the attached image (I just quickly re-created the circuit in LTSpice to save on drawing time).
In the first part of the question I managed to find the S domain transfer function without any issue. I found the transfer function as some function of the resistors...
Hi, can anyone help me on how to find Thevenin equivalent resistances for a Wheatstone bridge configuration? I've searched all over google and youtube, but I haven't been able to fully understand the procedures.
Hi guys,
I have a question that is nagging me quite a lot. Let us say that we have a circuit who has two independent sources (any combination of voltage and current sources). In the determination of Vth, can we choose whether or not to use superposition to find this Vth? Because my...
Homework Statement
This isn't for a class I'm actually taking. Just self study.
I'm reading a book on electronics. When I got to the part about Thevenin's theorem I got a little confused. Specifically, I'm confused about the equivalent voltage for the Thevenin equivalent circuit. It said...
Homework Statement
http://i.imgur.com/fSRqw.png
Homework Equations
V_{th} = V_{oc}
The Attempt at a Solution
I got the thevenin voltage by using node voltage
\frac{V2-40}{5} - \frac{80+2V2}{5} -8 + V2 = 0
(\frac{1}{5} + \frac{2}{5} + 1)V2 = 32
\frac{8}{5}V2 = 32
V2 =...
Homework Statement
Find the Thevenin resistance.
http://i.imgur.com/XoEfy.png
Homework Equations
Rth =Vex/IexThe Attempt at a Solution
I found that the thevenin voltage is 869.304mV. I read in my textbook that in order to find the thevenin resistance in a circuit that contains a dependent...
Homework Statement
http://img507.imageshack.us/img507/6493/f7868b61c6cb4d6084fa5ba.png
Homework Equations
The Attempt at a Solution
I've tried to deduct how my textbook has actually done this Thevenin Equivalent. No one in my class (that I've come into contact with anyway)...
Hi!
I'm having some difficulty understanding how to go about solving the following problem. I'm a beginner at this and am completely lost. I've seen a few similar problems that could be solved with node/current analysis, but I don't really understand if or how to apply that here.
Can someone...
Homework Statement
I am attempting to solve problem number 4 from the following picture:
http://img641.imageshack.us/img641/7950/imageisx.jpg
In the picture you can see the suggested line of "cut" for the first application of Thevenin's theorem.
The Attempt at a Solution
I...
Homework Statement
See attached image
Homework Equations
Thevenin's theorem
Node voltage method?
The Attempt at a Solution
So if I want the current Io, I believe I need to treat the 1K resistor as an open circuit in finding the Thevenin equivalent. I think setting ground to be the bottom...
Homework Statement
How would I go about determining the Thevenin equivalent of a simple circuit involving a battery and an LED? I suppose there could be a series resistor to prevent excess draw and burning out of the diode.
This question seems very odd since LEDs by definition don't...
Homework Statement
Find the thevenin equivalent circuit of the circuit to the left of the terminals AB.
Circuit diagram is attacted below.
Homework Equations
The Attempt at a Solution
I know that the thevenin resistance is 1kohm.
I also know that the thevenin voltage is the voltage across...
Homework Statement
(a) For the circuit above find the physical parameters of the Thevenin equivalent source with respect to terminals “a” and “b”. Assume that the resistances and reactances of the circuit are given at signal frequency 1 MHz.
(b) Find the impedance of the matched load for that...
Homework Statement
Work out the Thevenin Equivalent of this circuit:
https://www.physicsforums.com/attachment.php?attachmentid=46120&stc=1&d=1334164751
The Attempt at a Solution
I worked out the Rth to be 300Ω, not sure if this is correct, and then I have no idea how to work out Vth
Any...