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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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2answers
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How do I use superposition to solve a circuit?

Yes, this is a pedagogical question. While answering another recent question, I wanted to refer the OP to concise instructions for using superposition to solve circuits. I found that all the easily ...
13
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3answers
40k views

How does the tester screwdriver work?

How does the tester screwdriver work? If I put the tester screwdriver inside the "hot wire" of an electrical socket, it lits up if I press my finger against the metal cap on top of the screwdriver. ...
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4answers
43k views

Do electrons actually flow when a voltage is applied?

It's said in books that a circuit is a closed path and thus that electrons come back to the source. If that's the case, what would happen when there were an earth fault in a circuit? How would the ...
8
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2answers
1k views

Logic level converter using Transistors

I am trying to make a logic level converter using transistor BC547. This is to convert Voltage level of Rpi Gpio from 3.3 to 5V. I have wired the circuit according to this diagram: I have done this ...
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1answer
172 views

Operation of tuned collector feedback oscillator

I am trying to understand the following tuned collector feedback oscillator extracted from here using LTSpice. I understand that L1 and C1 creates the resonance at the oscillation frequency and L2 ...
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5answers
3k views

What is AC actually?

What is actually alternating current (AC)? And direct current (DC)? I've been reading several books about basic electric circuits analysis and they are contradictory. Some books say that AC is the ...
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2answers
759 views

How does early voltage affect collector current?

The transistor in the following circuit is said to feature \$I_{C} = 1.0mA\$ at \$V_{BE} = 0.7V\$ and \$V_{CE} = 10V\$. If \$V_{A} = 50V\$ and \$\beta = 50\$, find \$V_{B}\$ and \$V_{C}\$. simulate ...
3
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4answers
3k views

Does the resistor have to be before or after the component [duplicate]

I am an electronics beginner and I created a small little circuit, just a battery a resistor and a led, then to ground. This is the circuit: simulate this circuit – Schematic created using ...
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2answers
46k views

STM32 Understanding GPIO Settings

In STM32 Standard Peripheral library, we need to configure the GPIO. But there are 3 functions which I not sure how to configure them; GPIO_InitStructure.GPIO_Speed GPIO_InitStructure.GPIO_OType ...
24
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6answers
6k views

What is a flip flop?

There seem to be a number of different definitions of flip-flops and latches out there, some of which are contradictory. The Computer Science text book for the course I teach is probably the most ...
6
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3answers
23k views

Superposition principle: Dependent sources treated as independent sources

Since I began studying, I was taught that when analysing a circuit using multiple sources, independent sources could be turned off, meaning that I could transform a voltage source into a short, and a ...
5
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4answers
6k views

How does this timer circuit work?

I am stumped on how this circuit works. I am quite new to electronics but I know the basics of capacitors, transistors, ohm's law .etc, but I have no clue why when the switch(S1) is switched on the ...
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4answers
2k views

Why superposition theorem fails here?

I have a simple circuit consisting of 2 ideal voltages sources (each 5V) parallel to a resistor of 5 ohms. The current along the resistor is 1A, right? But by applying the superposition principle (i.e....
3
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1answer
643 views

Self Checking Circuit

I was reading the specs. of an electronic module used in process-safety applications & came across this note: Self-Checking (Circuitry): a circuit with the capability to electronically verify ...
3
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2answers
445 views

How does a Miller cap physically create a pole in circuits?

If we consider a single NMOS transistor (with its source terminal grounded) and a Miller cap (C) between its input (gate) and output (drain) nodes, circuit theory says that this Miller cap will be ...
5
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7answers
5k views

What is the most economical way to drive an array of single coil latching relays?

Please read the question to the end. The answer to this question may be non-trivial. Replacing a number of 2-coil latching relays with single coil latching relays ...
3
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2answers
707 views

Analysing a circuit to determine what is in series or in parallel

This is probably a very basic question but I have the following circuit, I am not sure what is in series and what is in parallel or if they are all in parallel, initially I thought R2 and R3 were in ...
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2answers
757 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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3answers
3k views

Why is the voltage across the inputs of an ideal OP Amp zero?

The property that the voltage across the inputs of an ideal OP Amp is zero cannot be taken as an axiom because it isn't a property you can directly "adjust" (as opposed to say the resistance across ...
2
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3answers
404 views

Help understanding how op amps work

I've just been introduced to op-amps and am having a little trouble understanding exactly how they work. Take this circuit, for example. Suppose that there's a 1V source here. Without the op amp ...
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2answers
7k views

How does a capacitor function in a 120v ac motor circuit?

I dont understand the direction of current flow when a capacitor is wired in series with the start windings in, say, a fridge or ac motor running on der 120v ac. Wiring diagrams seem to suggest ...
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3answers
2k views

Find total resistance of this circuit

I want to find the total resistance between A and B. This is a HOTS mcq, which has the following options: A: 45\$\Omega\$ B: 15\$\Omega\$ C: 5\$\Omega\$ D: 22.5\$\Omega\$ A book says that the answer ...
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1answer
327 views

Is this an astable multivibrator?

In this circuit the LED flashes on and off, however could it be classified as an astable multivibrator?
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2answers
242 views

Why is the voltage of a capacitor equal to the voltage of a battery connected it?

I am confused by this question. If we connect a resistor in series to capacitor then the voltage will drop across the resistor and now voltage across the capacitor is less than the source, then why ...
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5answers
765 views

Intuition behind why nodal and mesh analysis work?

I'm looking for an intuitive explanation (not a proof) of why the equations produced by nodal analysis and mesh analysis are always linearly independent and always have a unique solution, if the ...
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2answers
657 views

Calculation of Steady state power limit

I am confused with the above problem. I was thinking shouldn't we maximise \$\mid E\mid sin(\delta)\$ instead to get steady state power limit? \$\mid E\mid sin(\delta) = 1.8 sin(\theta)\$ maximum ...
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5answers
3k views

Counter with 4 flip flops jk synchronous from 3 to 13!

I have to create a counter with 4 flip flops jk synchronous. The counter shall count in this order: 3 to 13 and then to 3 to 13 and so on.. I have to use logisim simulator. Ok. So i think its ...
13
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2answers
1k views

How do you determine the effective resistance of a finite grid of resistors?

Disclaimer: I am a geophysicist with limited electrical engineering background. I am not sure if this problem is incredibly easy, incredibly complex, or completely nonsensical. My goal: Determine the ...
3
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1answer
2k views

Meaning of Sigma in Laplace transform

I found the question below in a forum and I also have same problem. Unfortunately, there is no answer at all so I will post it here hope someone could make it clear. A gain relation in a circuit of ...
15
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2answers
2k views

Under what conditions is the star-mesh transform invertible?

We all know and love the Δ-Y (delta-wye) and Y-Δ (wye-delta) transforms for simplifying three-resistor networks: Image from Creative Commons The Δ-Y and Y-Δ transforms have the nice property that a ...
5
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5answers
996 views

Electrons of the current in a circuit?

I have a traditional circuit (a conductor wire, and voltage source and a resistor). The voltage source may be a battery in this case. My questions(s) are: From where do the electrons that flow in ...
3
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2answers
7k views

Zener Noise Generator - NPN BJT Amplifier Analysis

I'm interested in creating a low voltage white noise generator by means of a zener diode, as detailed here: Zener & BJT Noise Generator. Specifically, I want to use the circuit here, in order to ...
1
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1answer
2k views

OP Amp with T network feedback

Hello i want to know how to calculate the equivalent T network resistors in the inverting amplifier below (the answer is 10M but i dont know how) ,i dont need formula but indepth circuit analysis ,...
14
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8answers
3k views

Why, in a passive circuit with a sinusoidal input, do all voltages and currents have the same sinusoidal behavior as the input?

I am familiar that in any circuit composed of linear passive elements and a sinusoidal input, all voltages and currents through and across any element will exhibit the same sinusoidal behavior and ...
5
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4answers
993 views

Application of Complex Numbers [closed]

I was just wondering how complex numbers can be applied in electrical engineering and why we use complex numbers over regular, real numbers for this application (e.g what capabilities does the complex ...
11
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3answers
2k views

A 1USD 11W led bulb circuit and parts analysis

I know this is not a huge deal, but still I want to do it because for Three reasons: 1, it only costs 1 usd. Yep, this is a very cheap led bulb, and I need to take it apart to see if it's trust worthy....
3
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1answer
1k views

Solving an Op-amp circuit

The image of the circuit is shown below and it required to find \$V_0\$, My first attempt at solving this problem is by changing the current source into a voltage source with 1-V and 2k\$\Omega\$ ...
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3answers
418 views

Why does DMM show AC and DC current when source is a battery? (How to calculate power in this case?)

The circuit is an altered Joule Thief of my design that is driven by an AA or AAA battery. I’m observing the current at the battery anode with my DMM in series. (Extech EX330) This circuit is ...
2
votes
2answers
291 views

Analyze a circuit with two diodes and two voltage rails

I want to find \$I\$, \$I_{D2}\$ and \$V\$ in this circuit. The diodes are made of Silicium. I'm a beginner and normally I would assume the Diode bias and then apply KVL to see if it is true. However, ...
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1answer
16k views

Choosing a correct diode

I am trying to find a suitable diode to place on the wire that connects c and e in the circuit, with the cathode on the right hand side. I need to justify why I chose the specific diode as well. ...
0
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1answer
83 views

can you explain me the working of this circuit in detail? [closed]

this circuit is a occupancy light circuit i want to know the working of the transistor regarding base,collector and emitter in the transitor
0
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2answers
521 views

Nodal analysis with Laplace of simple circuit

Using nodal analysis with Laplace transform find “v” for “t > 0” Founded initial conditions: i(0-)=i(0+)=0A v(0-)=v(0+)=0V i(infinite)=3A v(infinite)=4*3A=12V My nodal analysis with Laplace ...
6
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4answers
2k views

Short circuit = zero voltage?

Reading this question and its answers (as well as other questions), it seems that in an idealized short-circuit with zero resistance, one concludes the voltage is zero. This seems completely wrong. ...
3
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3answers
7k views

Why reverse polarity causes damage

Is it because it can exceed the reverse breakdown voltage of semiconductors? For instance in low voltage devices say 1-5v is the reverse voltage rated a lot lower than that for damage to occur? Also ...
3
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1answer
82 views

Norton equivalent with a single voltage source

I'm trying to find the Norton equivalent with respect to the load resistor RL for the DC circuit below. Each of the resistors have an equal resistance R. Removing the load resistor, I am having a ...
2
votes
2answers
964 views

Controlling Two Circuits with One Switch

I'm trying to build a circuit with multiple timers, each with an SPST output relay. I want to connect up my circuit so that if any of the timers reaches their set point, they turn on a beacon. It ...
2
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3answers
1k views

How to interpret Vgs(th) min/max in a MOSFET datasheet?

This is a screenshot of IRF9640 MOSFET datasheet. Will you please tell me, what is meant by max and min value of Vgs threshold voltage. Also what they mean by test condition. Whether the max and min ...
2
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1answer
221 views

AC analysis of a oscillator

This question relates to my previous question. I am interested in deriving an analytical relationship for the oscillation frequency of this oscillator. As the first step, I have initiated the ...
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6answers
5k views

Difficulty solving op amp problem

simulate this circuit – Schematic created using CircuitLab I am attempting to solve the above circuit for V0. Current and Voltage variables are from me. Thus far I've used KCL to say that $$i_3 ...
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3answers
377 views

Understanding this AC coupled circuit

I'm having a little trouble understanding this circuit and could use some help. So far I understand that this is an AC coupled circuit, and the capacitor is a blocking capacitor. I also know that ...