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Questions tagged [circuit-analysis]

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

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138 views

How to analyze RL circuit with sequential switching?

I am trying to solve this question: However, I am having difficulties solving as I only have come across circuits which are initially closed then opened, not vice versa as is the case here. ...
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75 views

GFCI red LED fault indicator circuit

Just kindly share what kind of input in the violet dot at center to inject so the red fault led would turn on? When the GFCI no longer function, the red led lights up. I'd like to understand how the ...
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2answers
157 views

Tri-state inverting buffer analog signal analysis

I'm using a tri-state inverting buffer with a self-biasing resistor (represented in the second image) as an amplifier. I'm trying to do a theoretical analysis, but I'm not sure how to get the gain ...
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33 views

How to figure out the pinout of this embedded netbook (Asus EEE X101h) webcam?

Sometime ago my old Asus X101H netbook died with a molten cooler fan. I've extracted it's webcam, which I want to use for another project. Now I'm trying to map the pinout of the connector. The ...
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1answer
36 views

How to calculate the phase difference between current and voltage?

Using the next circuit and the components of simulate this circuit – Schematic created using CircuitLab \$R=20\Omega\$ \$L=25mH\$ \$V_{DC}=36\$ \$v_{s}(t)=50+\underset{n=1}{\overset{\infty}{\...
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2answers
144 views

Current through cross coupled pairs

I recently came across this question in a series of articles about cross coupled pairs by Razavi: In Figure 6, M1 and M2 are biased and balanced by I1 and I2 ^ h I I 1 2 = . At t = 0, Iin jumps from ...
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2answers
57 views

A contradiction regarding flux conservation

Consider a simple circuit Initially switch S was opened till steady state is reached and then it was closed. My understanding regarding inductors is that you can't have a SUDDEN change in current ...
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367 views

Cannot get joule thief to work

For a few weeks now I've been trying to construct a joule thief using a schematic commonly found on the web as seen in this url: It consists of an npn transistor, a 1k resistor, two coils wound ...
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41 views

Boost converter output voltage error

I'm using LT3494a to generate 37v from 6v input. This is my circuit. According to the datasheet, this chip can provide up to 40v output, so it should be able to generate 37v. Also, the simulation ...
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1answer
32 views

Consistent Current Output From Batteries To DC Motors

I'm new to ECE and as a beginner project I've taken apart an RC car and attached an Arduino to the DC motors with an L298N module for control. The goal is for the car to drive a certain path with pre-...
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1answer
159 views

Superposition and average power dissipation

Unfortunately, I am having trouble getting started on the question above. How can one model the affect of a voltage source on a circuit without the knowledge of the resistor configuration inside the ...
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35 views

PNP darlington pair calculations

I have a 20ohms discharge resistor connected to my PNP darlington pair. I have simulated the circuit in my mobile (every circuit app).please find the attachment for circuit. But here I'm unable to ...
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40 views

Resistance and voltage [on hold]

Will this circuit need the resistance? Similarly what will be the prescribed voltage, resistance for these 3 leds of 3 watts.
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Measuring transistor beta (hFE) - Ib anomalies explanation needed

I've been struggling with details of building accurate (\$\pm1\%\$ tolerance maximum) beta meter. The simplest idea I came with went to a diagram as shown below, with R set to a value providing a \$0....
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1answer
28 views

What makes the SCR burnt up?

I removed Pin 1 to trace nuisance tripping of this GFCI circuit, and the SCR blows up: From this circuit: Removing pin 1 will make the pin 7 trigger the SCR continuously. But why would the SCR blow ...
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0answers
36 views

Switched circuit analysis - getting rid of “glue” equations

I have the following circuit: simulate this circuit – Schematic created using CircuitLab I would like to derive 3 differential equations, describing it, since it has 3 dynamic components [Csh, ...
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1answer
146 views

Two Op-Amp Instrumentation Amplifier - Gain derivation

I came across the following appnote(slyt647) which analyses the two op-amp instrumentation amplifier topology. The gain was found by finding individual gains for each op-amp and adding them in ...
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3answers
112 views

Power amplifier, does this circuit work?

I found that circuit for a power amplifier. Does it work? I want to build one for myself.
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1answer
160 views

Building a VCCS with AD8220 Instrumentation Amplifier

This question is to help me with my work in building a VCCS for the excitation signal of an Electrical Impedance Tomography measurement set-up to use with EIDORS. I have only basic knowledge in ...
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1answer
43 views

Finding resistance and how many appliances can be connected

A household electricity system can be modelled as a fuse in series with appliances, all of which are in parallel across the 240V mains supply. In one household there is a 16A fuse in series with the ...
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2answers
182 views

RLC Circuit with a resistance combined with the inductor. Is my solution correct?

I am tasked with finding the current I through the following circuit at an array of frequencies. I have a solution however I am fairly new to AC systems and just want to make sure I am on the right ...
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47 views

How to go about finding the transfer function of a non-linear circuit?

Note: The concept of Transfer Function is only defined for linear time invariant systems. Nonlinear system models rather stick to time domain descriptions as nonlinear differential equations rather ...
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0answers
20 views

Question about LKC LKV

I was answering probably a simple questions and I dont match the same result using the different method to solve that circuit below: My 2 resolutions: KVL: \$\frac{30-V}{4}+2\cdot I_x-\frac{V}{6} = ...
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30 views

Ideas for electronics related c++ projects [closed]

I am engineering student ,I have learnt c++ to advance level covering OOPS, polymorphism, inheritance, template. I want to apply my knowledge learnt in my electronics engineering of various subjects ...
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0answers
25 views

Calculating Load Power in a transformer circuit

I've been learning about AC circuits and they seem pretty straight forward, except when it comes to transformers. I have this circuit and I want to figure out the Voltage and Power at R2, and also the ...
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0answers
17 views

How to apply Thevenin's theorem in multivoltage(3) sources?

Here is a question I am not able to tackle as the requirement is to solve it by Thevenin's theorem. The question is to find the value of current passing through 20 ohm. I can perform Mesh analysis ...
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2answers
66 views

How is voltage divided between two reverse-biased ideal diodes?

Suppose we have two identical ideal diodes (without any resistance or voltage drop). We connect these two diodes in series, in the same direction, and reverse-bias them with voltage V. Now we have two ...
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2answers
66 views

Two-port circuit with input/output duality

Suppose I have a circuit with two ports. One port is considered the input, and the second port is considered the output. Assume it's described via $$V_{out} = \frac{V_{in}}{2}$$ Now assume there's ...
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2answers
54 views

How to construct the DC equivalent circuit of a BJT amplifier

How would the DC equivalent circuit be constructed? I have a vague idea knowing that AC voltage sources are connected to the ground and capacitors are open circuited but what happens to the resistance ...
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1answer
91 views

Finding current through an LED in an amplifier using a BJT

Suppose you have the schematic: My job is to find \$I_{LED} \$ knowing that the impedance of the capacitor in negligible against \$V_s\$. Here's my attempt: I intend to do an AC analysis followed by ...
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1answer
53 views

Apparent contradiction in AC analysis of BJT amplifier

Suppose you have the circuit: For an AC analysis we can draw the following circuit: Now my job is to find \$v_{out}\$, which can be easily found by: $$ i_E=\frac{v_{in}}{R_E} \\ i_C=-\frac{v_{out}}{...
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1answer
167 views

Finding asymptotic stability of RLC circuits

Given the state model for an RLC circuit, how can I show that it is asymptotically stable? So my state assignment is as follows: x1 = Vc x2 = iL And using the KVL and KCL equations I can get a ...
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1answer
39 views

Determine the value of Vx if the power dissipated by resistor Rx is 450W and Rx=50 Ohms

I keep getting figures that are out of these ranges. Maybe I am doing it wrong. So far I've been adding the possible voltages with 200V to get a total voltage, then using Ohms's Law to see if any of ...
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1answer
30 views

Find admittance( G ) matrix of a resistive circuit

I am taking Signals And Systems class where I have to calculate the admittance parameter of a given circuit. A given circuit for example: This is tedious and calculating the parameters takes so long....
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2answers
162 views

How to determine diode will conduct or not

Here we had to find the voltage for which the diode will act as a forward bias. I am a little confused about how do we find whether or not a diode will conduct or not in a network having more than ...
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1answer
23 views

NAND Simplified with xy + !x z

I've been trying to work on a few problems, though I'm not sure how to rewrite this a few circuits using only NAND/NOR --> an example is shown below; How am I able to rewrite only using NAND + NOR ...
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1answer
49 views

Can a system have constant phase response other than +/- 90 deg (and multiples)?

I have seen frequency responses where amplitude response is constant( pure delay) and where phase response is constant(pure integrator). In an integrator the constant phase is -90 deg. In a pure ...
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1answer
57 views

Bypassing refrigerator door alarm piezoelectric buzzer

My appliances keep beeping at me. How can I deactivate or bypass this refrigerator door alarm buzzer without affecting the rest of the circuit? I thought I could just cut/connect the wires at the ...
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2answers
697 views

Calculation of output impedance of CE emitter bias configuration( unbypassed) with r_0

Can anyone please help me with finding the output impedance of the circuit.? I tried but can't find the answer
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1answer
421 views

Circuit analysis - laplace transform

So i have a circuit where R1 = 5 W, R2 = 2 Ω, L = 1 H, C = 1/6 F ja E = 2 V. And i need to figure out what is iL when t=0.5s with laplace transform. Switch opens when t=0 When t<0 i got ...
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2answers
65 views

Find Voltage of inductor in LC series circuit with resistor in parallel

I have a LC resonance circuit with a resistor between the capacitor and inductor: simulate this circuit – Schematic created using CircuitLab I want to find the Voltage at L1, more specifically ...
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1answer
228 views

Proof of type for Current mirror and Early effect (Mosfet transistors)

Can anyone explain me how I can prove this equation below (4.19).I know that \$V_{GS1}=V_{GS2}\$ and assuming that M1,M2 is in saturation then \$ID=0.5kn(vov)^2(1+\frac{V_{DS}}{V_{A}})\$
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3answers
88 views

Voltage in RC circuit with unknown frequency

We were given the task of finding the voltage drop across R1 of the circuit below with the following alternatives: 5.8V 4.8V 4.0V 10.0V All given information is contained within the image, i.e. no ...
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1answer
242 views

MCP 4725 with raspberry pi

I have an MCP4725 12 bit DAC from Sparkfun and i am trying to interface it with raspberry pi 3 Connections : Vcc -> 3.3V/5V of Rpi Gnd ->Gnd of Rpi scl and sda -> to scl and sda of rpi ...
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2answers
417 views

Thevenin equivalent for a transistor circuit

I'm having trouble with this circuit and was wondering if someone could help me. So far I know that the 20V source can be basically ignored since it is a NPN transistor here. The second circuit here ...
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2answers
859 views

KVL and KCL in MOSFET small-signal model, how?

I want to find the gain in this MOSFET small-signal model. KVL in loop 1: \$+V_{in}-V_{gs}-g_mV_{gs}R_s=0 \iff V_{in}=V_{gs}(1+g_mR_s)\$ KVL in loop 2: \$+V_{out}-g_mV_{gs}R_s=0 \iff V_{out}=g_mV_{...
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2answers
45 views

Bosch Glue Pen: Bypassing automatic timeout [closed]

I have this Bosch hot glue pen. It has an annoying habit of turning itself off. I guess it's probably intended to be a safety feature or a battery saver, but really it's just a nuisance. Can I modify ...
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1answer
272 views

How was the transformer reduced in this Thevenin equivalent circuit?

Below is an example of a one-port network and how to find its output impedance by using Thevenin model: I can understand that Vi is set to zero since it is an independent source. But how was the ...
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4answers
141 views

Op-Amp gain calculation

I'm trying to find R4 that will make: $$\frac{V_{out}}{V_{in}}=-120$$ The operational amplifier is ideal. My attempt: In the '-' input there is a virtual ground, so the equivalent resistor above is ...