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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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simple circuit analysis kcl kvl

can i know what, why and how this Rth is parallel / how its calculated? answer by jonk: thevenin analysis i mean my solution would be: I1 = I2+ I . I1 = (9-V2)/10k I2 = V2/20k I = V2-...
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Finding \$L\$ value in simple circuit

Hello and first of all sorry for posting a screen, I don't know how to make my own schematics. This is one of the excersises from previous year's electrotechnics. The formula to calculate the result ...
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Automatic counting of the number of nodes, branches, contours in the electrical circuit

For scientific work, I need an automated counting of the number of nodes, branches, and contours, since need to work with large schemes with a large number of complex relationships. I use Microcap, ...
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47 views

Delay In circuit

I am working on a mini project using op amp.The circuit uses comparator so when a resistance is changed i.e the Vin is changed(cause I am using Resisters Voltage divider )comparator gives output and ...
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Equivalent Circuit of Howland current Pump

Why is at norton circuit for Howland current pump the current source is taken as vi/R1 instead of vi/R0? Because the formula for Norton current is IL=In*(Rn/(Rl+Rn))
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How is this equation valid?

I am trying to understand the Howland circuit.But how is the following equation formed .Isnt it should be(vi-vo)/R
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Function generator output

A function generator is hooked up to two resistors in series. The voltage across the function generator changes over time, shown by the different graphs The questions asks to find the output voltage ...
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PTT works not as excpected [on hold]

I bought the following headset with a push to talk (PTT) button and four pin headset jack. If I connect this to my windows notebook the microphone is always on / working. But the curious thing is ...
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Differential equation of an OP AMP circuit with RC elements

I have to find the differential equation which describes the relation between input and output voltage for the circuit below. Per how the RC components are arranged, I simply can not find a ...
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Circuit Analysis: Obtaining Close Loop OP - AMP Transfer function

Trying to figure out the Close Loop System transfer function of an op-amp, however the math isn't working out as it should. Circuit In question: simulate this circuit – Schematic created using ...
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Can some one explain me how this equation about op amp came? [on hold]

I dont understand how is the summing of current equation is derived .plz help me to understand it
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61 views

Thevenin equivalent of the following circuit

So...I have to find \$v0\$ using exclusively Thévenin/Norton equivalents. I am completely lost since in this case I have a dependent voltage source which relies on \$v0\$ itself. \$v1,a,R1,R2\$ and ...
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48 views

How do I calculate the voltage across a capacitor when the source is a square wave?

I have a series RC circuit with R= 2.2K Ohm and C=100 nF, and the voltage supply is a 2.5V peak square wave. And I'm not sure how to calculate the voltage across the capacitor.
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Why the opposite of the passive sign convention is not the active sign convention?

Studying the fundamentals of circuit theory, I was reading the Wikipedia article on the Passive Sign Convention and found out about the Active Sign Convention (ASC). After searching many introductory ...
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Reverse Engineer DIN 5-pin connector

Summary I have a digitial guitar amplifier that can be controlled via a footswitch. The footswitch is connected to the amplifier via a DIN 5-pin cable. I want to be able to control the amplifier with ...
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1answer
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Why is this component that looks like a capacitor with ground lines in this circuit diagram different from a polarized capacitor? [duplicate]

What is the component that is represented with two horizontal lines like a capacitor with three Ground Chassis lines connecting them and a + at the top and a 10μ label. See picture below (top right ...
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151 views

Impedance calculation from voltage and current (exponential) waveforms

If we want to find the impedance across two terminals (a port) at a frequency \$\omega_0\$ using the voltage waveform across \$v(t)\$) and current through (\$i(t)\$) the terminal, general intuition is ...
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Voltage law not correct [closed]

Is the voltage wrong? Across the resistor there cant be any voltage drop because the electric field of a battery that forces the electrons to move is constant for all points inside the conductor.Just ...
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2answers
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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 ...
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125 views

The Art of Electronics (Integrators)

Reading this topic from "The Art of Electronics" : Integrators How does RC keep V << Vin?
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Explanation of Source-Absorption Theorem Example

In the section on the Source-Absorption Theorem, my textbook has the following example: I was wondering: If the voltage $$v_\pi = - v_e,$$ then why do we get $$g_m v_\pi = g_m v_e$$ instead of $$g_m ...
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Changing impedance of load [closed]

For this representation, why is there a change in the variation of the impedance when Zload = R2?
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1answer
33 views

Finding Norton voltage and resistance and max power

My directions for this problem are to find the power delivered when RL=3 and then find the maximum power. simulate this circuit – Schematic created using CircuitLab I found Rth = R1//R2 = 1 ...
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2answers
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Thevenins Theorem

Can someone please help, I'm struggling with this circuit. I don't quite understand what I need to do, mainly with whats series and parallel. My tutor is not helpfull in the slightest! He' only given ...
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Feedback on a simple motion activated motor circuit

I have been working on a motion activated motor which uses a PIR sensor to detect the motion. The idea is when PIR detects user in front of it motor should start running and when the user moves away ...
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1answer
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Algorithm for getting currents and voltages from resistances in circuit as graph

For my CS project I have to write simple circuit simulator, where I get list of edges of circuit as (a,R,b), where a and b are nodes at the end of the edge and R is it's resistance (it has a resistor ...
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1answer
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What is this SMD part?

I’m trying to repair a powered recliner touch sensor, and I’ve isolated the part that I think is the problem. The issue is, I don’t know what it is! In the first image, you can see that it has three ...
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1answer
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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 ...
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What is the Thevenin Norton equivalent of the folloing circuit

I am trying to find the Thevenin Norton equivalent of the folloing circuit. I am familiar with the procedure. However, when I am taking off the voltages to calculate the equivalent resistance, I am ...
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1answer
47 views

LTSpice current dependent current source timestep too small error

I solved this circuit by hand.Which asks to calculate vo and Io in the circuit. And I tried to verify results with LTSpice. If I change dependent current source B2's equation to I = I(R1)* 50 it ...
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2answers
71 views

Does connecting LEDs in parallel use more current then connecting them in series in my circuit?

Sorry if this is a dumb question, I need a sanity check on this stuff. Is it possible to give LEDs varying current, without sacrificing efficiency? Basically I have 4 LEDs which could all use ...
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2answers
105 views

How would I go about converting a change in capacitance into frequency? [closed]

I have to make a model for a pressure sensor. The sensor measures the pressure by changing the capacitance. I only have the datasheet for that. Summary: pressure>> diaphragm deflection >> change in ...
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3answers
137 views

Why does a capacitor charge faster when there is a diode connected?

In an series RC circuit why does a capacitor charge faster when there is a diode connected in parallel with the resistor? I tested on an oscilloscope, using a square signal and this is what I got. ...
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65 views

Solving a circuit with Nodal Analysis [closed]

I've been trying to start solving the circuit for a long time now, but I've no idea where to begin, what node should be grounded. Someone please solve this circuit ina detailed manner
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About dynamic equations and the transfer function for the circuit

/ Attempt Follow my setup $$v_1=u_2$$ $$i_1=C\frac{du_2}{dt},v_2=L\frac{di_2}{dt},i_2=\frac{u_2-v2}{R_2},i=\frac{u1-u_2}{R_1}$$ According to KCL: \$i=i_1+i_2\$ Let \$s=\frac{d}{dt}\$ Get \$R_2(...
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1answer
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I cannot find information about some chips in 3 stage LNA circuit

Hi, here you can see 3-stage LNA circuit. I want to know information about two chips(6 pins) with R8 mark at the top. Also, 4 chips with D4 mark with 3 pins at right side. Is there anyone who has a ...
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1answer
43 views

This SR latch built with 180nm CMOS does not work in ltspice. How do I fix its behavior and parameters?

EDIT: I copied over the latch from another larger model that had Vdd defined, but missed it when copying over the design. However, after adding in Vdd, I still run into this confusing issue where the ...
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1answer
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altium input/output pin error

I have a problem (stm32f407vgt6) with altium input output pin error. I will use 3.3 volt in my mcu that's why I added 5-3.3 voltage regulator in the circuit but I ve taken this error. Details VCC0 ...
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1answer
43 views

LED switching: Circuit reacts unexpected

I have my current circuit in LTspice and am trying to simulate it. The idea is the following: I have a UV LED (360 nm) which I want to switch off in at most 6ns. For this I have my LED in parallel ...
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2answers
91 views

Question on the Power efficiency of a circuit

I wanted to find the effect of load resistance on the power efficiency of a circuit. When I apply the max power transfer theorem, the internal resistance of a cell = the load resistance right? So when ...
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1answer
57 views

Why superposition theorem has not been executed here?

Here is the given circuit In this problem while finding V1 we didn’t took the voltage contribution at that point by Vo(Superposition theorem)Only current source Is has been used to find the voltage ...
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What is the purpose of a capacitor in an ideal op amp schematics?

I'm trying to understand the purpose of the capacitor C which is in parallel with the resistor R3. Current sources IB are indicative of the current offset which was the part of the lecture we had ...
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1answer
99 views

Driving IRF9530 MOSFET with 5V

I want to drive the IRF9530 P-Channel FET with 5V PIC microcontroller. My load is 3.2A. schemtic shows one row in my LED matrix. Scanning @ 1/16th rate, so peak current per LED will be 64mA and the ...
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1answer
48 views

Current through a diode changes for the same forward voltage in two circuits

In LTspice IV, I am simulating a 1N914 diode behavior in response to a variable current source in two circuits. One circuit has just the current source and the diode, and the other has the current ...
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1answer
55 views

Trying to have NMOSs in parallel while passing current through only one at a time

If I wanted to have a bias current I1 going through M1 or M2 and I want M1 to alternate between on off (M1 on/M2 off, M1 off/M2 on) would this work? I simulated this with spice and for the first ...
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47 views

Sizing capacitor in capacitor-diode charge-pump circuit

How I should calculate the capacitor for a frequency of 200k and my output have to be 5 times my input. I know the voltage doubler circuit but in this case i dont know how to do this.
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Do photodiodes break KVL?

I know what you are thinking, but hear me out. Let's do KVL in this loop: simulate this circuit – Schematic created using CircuitLab We get: $$ -V_{PD}+I(R_s+R_L)-V_1 = 0 $$ Now we solve for ...
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How to tackle circuit containing time variable resistor?

simulate this circuit – Schematic created using CircuitLab For instance above schematic find current as function of time in circuit above I studied it about months before and am not able to ...
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1answer
34 views

Doing KVL on PNP BJT

I'm trying to find the voltage at the emitter and i use the property they give me of the absolute value VBE where in the book its equal to the small AC signal plus the DC VBE ( in this case that small ...
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What is the voltage across a photodiode bellow the Saturation Limit?

This is the equivalent circuit for a real photodiode: simulate this circuit – Schematic created using CircuitLab Source. I added a Bias Voltage based on Figure 1-9 (a) of the Opto-...