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

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How is current split with two parallel LED's?

I have two LED's in parallel with different forward voltages, and want to know how much current flows through each of them. They have one series resistor connected before being split. Like so: As ...
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1answer
29 views

Analyzing/designing positive feedback amplifier

I've been searching all around to find a tutorial on analyzing/designing a positive feedback amplifier, especially a single transistor in common collector mode, but with no luck... So, lets say I ...
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4answers
120 views

KVL loop current direction convention--should be same in all loops?

Do we have to take the same sense of direction for loop current, like clockwise, in each loop when applying KVL to a circuit or can we take different directions in different loops? If we must take ...
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3answers
56 views

RC filter on a clamping circuit

I have designed a clamping circuit to protect pins of my microcontroller and I have to add a low pass RC circuit at the microcontroller end to filter out the high frequency noise. My circuit analysis ...
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1answer
55 views

Help Running Xmas Lights On 6V AC Flying Saucer

first time here. First I will explain what I have then ask for a solution to my problem... I have a fiber optic UFO display that has a slow turning electric motor to revolve a color wheel to light ...
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3answers
34 views

RC high pass Circuit Step Input why C Initially acts as SS

In RC high pass circuit when you apply a step input the capacitor doesn't have any drop initially. My professor's justification for the question was that the capacitor doesn't change voltages ...
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1answer
71 views

Diodes and CMOS 4060 (14-stage counter)

Take a look at this popular circuit for a fridge alarm based around the 4060 binary counter (http://free-electroniccircuit.blogspot.co.uk/2012/02/refrigerator-alarm-schematic.html): One thing I ...
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1answer
243 views

Not sure if my calculation is correct, can anyone check this RC circuit for me?

Hello everyone, so in my book I decided to do this practice question but failed to notice that the answer was not given in the back of the book. If anyone can help me confirm my answer I would much ...
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0answers
56 views

Why does this State-Variable low pass filter overheat when turning up resonance?

I am trying to build an audio-frequency state-variable resonant filter. Power supply is ±15V. The circuit contains three TL072 op-amps and three LM13700 OTAs. It receives audio input from -2.5V to ...
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1answer
39 views

Norton Method Problem

$$ I = 1.43 \mu A \space \space R_p=1.8M\Omega \space\space R_s = 17k\Omega$$ I am trying to find the Norton current. This seems like a simple problem, but I keep getting it wrong. I tried using ...
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1answer
66 views

Component usage in this constant-current source circuit

In the April 2014 edition of Elektor magazine, they present a circuit for a high-precision current source device (page 42). It allows the user to select a constant-current between 10nA and 20mA. They ...
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2answers
144 views

A cubical LC circuit

I would like to solve for currents through inductors and the voltage across capacitances of the attached circuit. I am trying to figure out a correct method to solve such circuits which could have the ...
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3answers
39 views

Need help deriving cutoff frequency of output (collector) RC network

According to the book I'm studying, the cutoff frequency for this circuit is given by $$f_c=\frac{1}{2\pi(R_C+R_L)C_3}.$$ I tried to derive it by solving for the frequency at which \$V_{out}\$ is ...
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1answer
55 views

Simple RC Circuit, switch position

Most textbooks use this circuit as an example of the most basic RC circuit. The solution for V(t) for this circuit is (if capacitor is initially uncharged): I've had an exam recently where the ...
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1answer
143 views

How can I control a 120v, 1amp fan with a Nest thermostat?

I have a fan (hot, neutral, ground) that requires 120V and uses 1amp max. I'd like to be able to control this with a thermostat so that the fan turns on when the temperature is above a certain set ...
0
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1answer
151 views

Circuit diagram for uninterrupted usage of a 12V 1A device using 12V 7Ah battery with auto charging and full charge cut off

I have a modem which runs at 12V 1A, also I have an UPS battery of 12V 7Ah. I need to design a circuit so that during power outages my modem works from the battery. Also, a circuit to charge the ...
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2answers
67 views

Time domain and Frequency domain

what is the difference between time domain and frequency domain components? How do these domains differ from each other?
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0answers
29 views

Breaking down currents into mesh currents?

I have drawn a circuit above, but instead of components, I've just drawn squares to act as black boxes for components. In this hypothetical circuit, say the currents are as indicated in the ...
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2answers
53 views

Proff of that in RLC circuit in series where AC source works in resonant frequency the sum energy of the inductor and capacitor is zero at all time

can anyone help me please prove the statement that: In RLC circuit in series where AC voltage source works in resonant frequency the sum energy of the inductor and capacitor is zero at all time. I ...
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1answer
29 views

what is the dependence of Current through inductor in parallel RLC CIRCUIT with a AC source at resonance frequency

Consider the parallel RLC circuit simulate this circuit – Schematic created using CircuitLab Assuming $$ C,L> 0$$ $$ I(t) = U(t)*cos(t/(LC)^(0.5)) $$ So, we have a source that starts ...
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2answers
67 views

Where does the term “lumped” come from anyway?

I think I understand the idea of dealing with lumped circuit elements in electrical engineering, but how did they come up with the name "lumped"?
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2answers
74 views

Why am I not able to simulate a circuit as it is given in a problem?

I'm currently in the process of working through some circuit analysis books on my own. Though it's easy enough to compare my answers to those given in the appendices, I figured that it would be ...
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1answer
51 views

Need help finding my mistake using Thenevin's Theorem for this circuit (not homework!)

So I have the following circuit (an example from my textbook). The answer for V_o is 3.88V. I got the wrong answer and I'm not sure where I went wrong. I know I could solve for V_o using other ...
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4answers
61 views

Number of independent KCL equations?

When using nodal analysis, my book says you will always end up with \$n-1\$ linearly independent equations, where \$n\$ is the number of nodes. Can someone intuitively explain why this is true? If ...
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2answers
126 views

What actually happens in a RC circuit?

I'm currently working my way through a beginner's electronics book(electronics for dummies) where i am introduced to RC circuits as shown in the schematic below. simulate this circuit – ...
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1answer
67 views

Measuring voltage output in a voltage divider

I'm currently working my way through Electronics for Dummies, where I am shown a simple voltage divider circuit consisting of a 9V battery and two resistors, R1 (12,000 ohm) and R2 (15,000 ohm). ...
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2answers
179 views

Ohm's Law for voltage divider

I'm currently working my way through electronics for dummies, where I am shown a simple voltage divider circuit comprising of a 6V battery and 2 resistors, R1 (220 ohm) and R2 (1000 ohm) in series. ...
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1answer
54 views

Resistors in parallel?

From what I understand, the proof is suggesting that $$i(t) = (\frac{1}{R_1}+\frac{1}{R_2})v(t)$$ implies that replacing the two resistors with 1 resistor of value \$\frac{1}{R_1}+\frac{1}{R_2}\$ ...
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1answer
78 views

Equivalent resistance problem

I'm trying to find the equivalent resistance to this problem. The 6 ohm and 3 ohm resistor are in parallel since they connect at both ends. What would be the next step?
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0answers
61 views

State Variable Filter analysis

I'm in the process of making my own adaptation of the classic State Variable Filter (SVF) in the analog domain. Reading up on this article. I discovered that they use superposition to get the ...
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2answers
64 views

Get transfer function from electrical scheme [closed]

Is there any software/SPICE tool in which I can draw electrical circuit and after that, software prints the transfer function in Laplace domain? I will find this kind of tool very helpful and ...
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1answer
82 views

Using Pspice to analyze BJT transistor

As always I have a rookie question. In a project, I need to analyze the circuit below in a way that the transistor would be in forward active mode. I need to calculate resistors and voltage sources, ...
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1answer
184 views

Voltage drop in RC filter

There is something I'm struggling to understand about passive RC filters: When considering a simple low pass RC loop, what exactly is the gain/output at DC and low frequencies? I've been assuming two ...
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1answer
115 views

Cascade BJT [ Exercise solve ]

How can I solve this circuit for \$\beta = 100 \$ , \$V_D = 0.7V \$ and \$V_{BE}= 0.7V\$ and arrows go to power \$V_{DD}=9V\$ simulate this circuit – Schematic created using CircuitLab ...
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3answers
94 views

Question about thevenin circuit analysis with voltage across voltage source

I have a certain circuit in mind and I want to find its Thevenin equivalent resistor: I see that there is an dependent voltage source so I add a voltage source of 1V between a and b and make the ...
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62 views

Thevenin & Maximum Power [closed]

Please guide me in the correct direction to solve this question. What I have tried is shown in the image.
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1answer
35 views

Determining the voltage labeled Vx by Nodal Analysis [Voltage Controlled Current Source]

How to find the voltage labeled v(x) by Nodal Analysis? The sum of currents from node 2 to node 0 is equal to 0. However, I do not know the the current of 0.1Vx. How to solve the question? Thank ...
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1answer
60 views

Calculating the current of an AC circuit

My goal is to calculate the current i(t) up in the right corner. Using the formula $$ Z_{total} = \left( U\over I\right), I = \left( U\over Z_{total}\right) $$ Given values are $$ R_{1} = 1k ...
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2answers
101 views

Tried connecting 2 things two 1 battery, smoke ensured

I'm assembling a quadcopter and have run into a problem So, I have one two cell LiPo battery if I've understood things right, it outputs about 7.4V and has one ampere hour. Now, I have one radio ...
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2answers
60 views

Link between zero state response and the particular solution for an everlasting exponential input

In an LTI system, when the input is the characteristic function (i.e. an everlasting exponential function say \$e^{st}\$ ), the ZSR which is obtained by the convolution integral with \$h(t)\$ is ...
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89 views

Node Voltage Analysis with independent and dependent voltage sources

simulate this circuit – Schematic created using CircuitLab I'm having trouble solving for the voltage drop across the 80 ohm resistor using the node voltage analysis method. I can get the ...
2
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3answers
231 views

How to deal with a complex circuit of resistors and capacitors?

simulate this circuit – Schematic created using CircuitLab Assuming i have the circuit from above and i need to find the current through every resistor and capacitor. the switch opens at ...
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2answers
319 views

Why use only oversimplified/ideal equivalent circuits?

Most circuit analysis books use ideal resistor, inductor, capacitor and don't even bother to show practical circuits of these components, let alone any solved examples with practical circuits. For ...
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1answer
55 views

Vorperian - Fast analytical techniques problem 2.1d [closed]

I am working my way through Vorperian's book Fast analytical techniques for electrical and electronic circuits, and I've run into some trouble on problem 2.1d... There is a sub-sub question that ...
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3answers
139 views

Calculate voltage, current and resistance in a complex mixed circuit

How can I calculate voltage and current on each resistor (especially R5) in this circuit? What is its overall resistance? I have no idea how to do this.
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2answers
285 views

Finding equivalent resistance for time constant in R-C circuit

Given the first order circuit above. The switch has been closed for a long time and is opened at \$t=0\$. Find the equation for the voltage \$vc(t)\$ across the capacitor after the switch has been ...
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2answers
151 views

AC analysis of a circuit including variable resistors

I have a problem concerning the AC analysis of a simple circuit, containing variable resistors (each variable resistor is a pressure sensor). I am sure this is quite simple, but I have never worked on ...
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2answers
339 views

BJT: What exactly is an AC Load line?

The DC Load Line is simple to explain, for a given circuit the relation between VCE and IC must comply to the KVL relationship for that circuit. In the graph we can choose a Q point, and then see if ...
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1answer
38 views

Nodal analysis with dependent voltage source

I need help figuring this problem. I'm reviewing for my final and I can't figure out how to write the nodal equations. What I have so far is: $$6I_x = V_2- V_1 $$ KCL @ V_1: $$7A + \frac{V_1}{10} = ...
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1answer
189 views

Help understanding how to use Thévenin's theorem in order to solve a first order circuit

simulate this circuit – Schematic created using CircuitLab Assuming the above circuit is given, and I need to find the voltage V on the capacitor for all t (v(t)). The controled current ...