# 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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### Simulation results of MC34025 are different using same files for the LTspice

I made the converter circuit using MC34025 for the PWM signal. The computer, I used to design the circuit, works well. However, when I moved the file and ran it on another computer, the wrong waveform ...
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### What is the best technique to find out which diode is conducting and which diode is cut-off in the circuit?

What is the best technique to find out which diode is conducting and which diode is cut-off in circuits below?
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### Guitar amplifier emits a continuous beep, which pitch vary depending on "bass" and "gain" knobs. Finding what's wrong in the circuit

I have an old transistor (EDIT: not transistor, but OP, from comments) guitar amp, a Laney Session 45 Reverb. I couldn't find any schematics online unfortunately, it doesn't seem to be a very popular ...
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### How to figure out the direction of current and polarity of a circuit element?

How do I determine the direction of current in the boxed region? Also, how do I figure out the polarity of the resistor?
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### Phasor of transfer function

Say I have the following transfer function: $$\mathcal{H}(s) = \frac{Bs^2}{a^2 + \frac{a}{Q}s +s^2}$$ I want to prove it is a Low-Pass filter. In order to do it I'd like to change it to phasor form so ...
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### Response of diode circuit

I am a bit confused by the response of this circuit given the input. For the positive part of the circle, the diode is reverse biased. As such, the circuit becomes 3 kΩ in series, with a 7 kΩ sticking ...
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### Factorize generic transfer function

This is not homework. I'm just trying to understand concepts and methods, and for that I'm using a generic Transfer Function for an Active Filter like $\mathcal{H}(s) = \frac{1}{1+BAs + A^2s^2}$. ...
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### Input impedance of op-amp

How can I calculate the input impedance of this circuit?
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### Converting vehicle instrument cluster lights to LEDs: one light stays on

I have a 1998 K1500 (GMT-400) and I would like to convert the lighting in the instrument cluster to LEDs. There is a semi-known issue with this type of vehicle, where if an LED light is used for the ...
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207 views

### Why is this an example of actuator?

Hi, I know that an actuator is: a component of a machine that is responsible for moving or controlling a mechanism But how is a simple LED circuit as I’ve attached an actuator example please as there ...
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### 3 dB frequency of first-order active high-pass filter

Using the KCL law in the red dot in the circuit shown above, I got this equation: $$\frac{V_\text{in}}{R_1 + \frac{1}{j\omega C}} + \frac{V_\text{out}}{R_2} = 0$$ From this equation the transfer ...
1 vote
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### Nodal analysis with LEDs

How does nodal analysis work if I have not only resistors but also LEDs in my circuit? Do I then have to convert the LEDs to resistors somehow?
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### RC differentiator / RC integrator explanation (input waveform is square wave, triangular wave, sine wave)

The circuit below is an RC differentiator (RC high pass filter.) The input and output waveforms: I can understand this. Mainly due to capictor charging and discharging. How about an RC integrator (...
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1 vote
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### Charging equation of a capacitor in circuit with two capacitors

Following the answers received to my previous question, I obtained many ideas and I realized that what I was really looking for was something else and needed a new post: I would like to analyze the ...
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1 vote
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### RC differentiator / RC integrator explanation

I am watching a Youtube video about a very simple RC differentiator. Quote from: Dipayan Das I really cannot understand how the output waveforms looks, where there is a negative part. I know it is a ...
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1 vote
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### What is the importance of R1 connected in this circuit?

What is the importance of R1 in this circuit? What would happen if I removed R1 and kept VR1?
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### Does the L/C-shunt vs C-shunt/L order of an L-match matter?

Two different sites with L-match calculators show different LC schematics as shown below. Note that Schematic 1 shows C1 on the source-side and Schematic 2 shows C1 on the load side. Both sites ...
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### How to distinguish bus voltage (in the context of network models) from line-to-neutral or line-to-line voltage (in the context of transformers)

Figure 7.2 (from Power Systems Analysis by Grainger/Stevenson) shows bus voltages Vm and Vn. From what I understand, Vm represents the potential difference between bus m and the reference bus I came ...
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### I need a detailed explanation on how to solve it [closed]

Given the circuit below, find the value of V1 and VT and current IT in the circuit.
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### Help with circuit behavior

(All transistors are of the same size) (Both signal transitions occur at the same time) case 1: (initial stored value is 0) The PMOS transition didn't really matter, the X-coupled INVs were capable ...
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1 vote
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### 9 V to 12 V step-up converter to drive load between 10-100 mA, and no load

I'm working on stepping up the voltage from a 9 V, 150 mA power supply to 12 V, with a load of 10-100 mA and moments where there's no load. I have implemented something similar with this IC ...
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1 vote
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### TL494 with synchronized output rectifiers for push-pull converter

I want to build a push-pull converter with synchronized output MOSFETs using a TL494 IC which has two outputs that can directly drive only two transistors. The output of the push-pull converter is 12 ...
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### Final voltage at a node - calculation

Considering the following circuit: What would be the final voltage on Csn when its initial value is: 0+x (degraded 0) 1-x (degraded 1) I tried calculating this, and: I got a value of 0+x+2Vt ...
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1 vote
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### Can I use a 700V transistor with a 12V collector and base?

Please forgive any misunderstandings, as I am not an expert on electrical components. I am trying to build the following circuit: I need to be able to run 1.5A through the transistor. Can I use a ...
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### I need help on identifying the value of a schematic symbol

I came across the schematic of RAK3272-Sip development board, but I couldn't identify the value of this inductor. Here's a link that contains the full schematic.
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### About MOSFET circuit behavior

When I look at the waveforms of simulated circuits, how do I know when their behavior (for example flipping value stored on a node, or an unexpected drop in strong level value...) is due to MOSFET ...
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### Multiplexer voltage reference

There is a potentiometer on a circuit board that I want to simulate with a DAC. I want to be able to either use the original voltage from the potentiometer or simulate the voltage from the DAC, hence ...
61 views

### Problem finding voltage in a circuit with mutual inductance

I'm trying to solve an example from Hayt's Engineering Circuit Analysis: let $i_1=4i_2= 20\cos(500t-20°) \mathrm{\ mA}$. Determine $v_1(0)$. Using $k=\frac{M}{\sqrt{L_1L_2}}$, I got \\$M=0.6\ \...
1 vote
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### Determining combination of resistors for an equivalent time constant in an integrator circuit

I have a varying source voltage for maximum of 15 V and am using an error amplifier to maintain it using an integrator. Reference voltage is of 5V. I want a time constant of 100 msec with a capacitor ...
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### Triangular wave response of RC circuit

I am trying to intuitively understand the response of the RC circuit for a triangular input. My understanding is as follows: Let the ramp be mt.u(t) Initially, the voltage drops mainly across the ...
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### How do you calculate Vout/Vin in this circuit? [closed]

I don't quite understand how you are supposed to get the voltage going to the first op-amp. I do understand how I would get the answer from that point forward.
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### Does each load in a three-phase balanced load consume the same average power which they get from three-phase voltage sources?

Assume three-phase balanced loads in Δ or Y configuration connected to three-phase AC voltage sources in a Y configuration. Does each load in three-phase loads consume equal average power? Assume ...
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### How to choose the right type of capacitor?

I built an AC power supply (we called it a TENG) based on the tribo-electric principle. It can light up about a hundred 3 mm LEDs. Now I want to try supplying the power from my TENG to an LCD ...
1 vote
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### Is there any method to identify if a loop is an "independent loop" or not? [duplicate]

I know a loop to be independent if it contains at least one branch that is not a part of any other independent loop. But it is kind of recursion. I think it is not giving me the actual definition of ...
1 vote
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### Not sure about input impedance of this PNP transistor circuit

I have to find the input impedance Zi of the following circuit: Using the small signal equivalent for the transistor, I get the following schematic: It is easy to see, that we need to write the ...
348 views

### Circuit analysis: connecting positive terminal of battery to reference node

In the circuit given below, how can I apply KVL to the loop on the right side? The reference node being connected to the positive terminal seems wrong.
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### Short circuit delta

Assuming I have the following system: and a single-phase fault is on the 2.4 kV side. How do I calculate the voltage between the neutral resistor and ground? How do I calculate the zero sequence ...
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### Why does capacitance affect the charging time of a capacitor?

I'm trying to understand the relationship between the capacitance with the voltage output of this circuit. If the capacitance is greater, why does it take more time to charge the plates of the ...
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### Time constant of a high-order RC circuit

I have an unknown system that can be modelled as a high-order RC circuit: I performed the impedance spectroscopy measurement of it and fitted the equivalent components. Now I should calculate the ...
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### Op-amp output as gate voltage to MOSFET

As I understand it, the MOSFET here provides negative feedback to the closed-loop op-amp configuration. Hence, Vout2 = 1 V. Thus, the current through NMOS = Id = 1 mA. So Vout1 = 5 - (RD·Id). Then ...
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### Sensitivity characteristics of MQ-7 [closed]

When we look at the sensitivity characteristic graph of MQ sensors, Let's take MQ-7, which is a log_log graph, we find the definition of R0 at 100ppm, this resistance is defined to be The sensor ...
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### How to calculate voltages in op-amp circuits?

I don't know how to solve the following problems; I don't even know what the best way to start solving them is. Can someone help me with the calculation steps so I can then try to solve them on my own?...
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### Problem where you are supposed to use Kirchhoffs laws

Apologies for the non-descriptive title, didn't really know how to word it. I'm familiar with Kirchhoffs Laws, studied them in high school physics like many others. Got pretty good at problems ...
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### Workings of single constant-current source with four MOSFET-switched LEDs

Background I have several hundred RGB+White LED lights which are controlled by a driver circuit which is no longer manufactured, and trying to plan some maintenance and possible replacement of the ...
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### Current through the capacitor at t=0

DO NOT edit or rollback this question There have been multiple rollbacks and misunderstandings and some vandalism. Please keave as is for now and we'll to sort things out. Major obstruction of this ...
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### How to solve this problem using transient time-domain analysis?

Find V0(t) in this circuit assuming zero initial conditions. I solved it (refer image above) using frequency-domain analysis using Laplace and found the answer, but I am not able to get the same ...
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### First-order differential equation without using a Thevenin (or Norton) equivalent circuit

$$\frac{V_c-V_2} {R_2} + C \cdot \frac{dV_c}{dt} + \frac{V_c} {R_3} = \frac{V_1-V_c}{R_1}$$ $$V_c(0) = V_2$$ I have tried to solve this with the help of MATLAB, but the answer from the book is ...
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### LTspice how show FFT of n004-n008? Expression? How? Example?

In LTspice, how can one show the FFT of the difference v(n004-v(n008) i.e v(n004,n008)? Expression? How? Example? What are the steps for bringing up such an expression so it can be FFT'd? The computer ...