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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41 views

Voltage drop from a logic gate?

In the following schematic with a logic-AND gate: I would expect that since the inputs are logic-high of 5V for both input A and input B, that the output would also be logic high at 5V, yet it looks ...
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24 views

Undesired noise on isolated zero-cross

I have a prototype board which I'm currently testing the signals of its zero-cross circuit. This is the schematic of the PSU, the power supplies of the low voltage part of my circuit (12V, 5V, 3V3) ...
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38 views

DAC Signal Clipped By DC Voltage Source

I'm using a TI F28379D to generate a sinusoidal waveform from a DAC channel. The output of the DAC is shown in Figure 1 with a Vpp of 688mV. This signal is then connected to a resistive network of 1k ...
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Circuit design - please explain to me the usage of these capacitor and inductor

I am studying this circuit, but unable to understand why they put capacitor C30, C33, EC4, inductor L3 on their current place, and their value, i keep searching on google for decoupling capacitor, ...
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17 views

how do we find the Norton equivalent circuit current of the both node ,a-b

Determine the Norton equivalent circuit current of the both node ,a-b, of 9 ohms resistors simulate this circuit – Schematic created using CircuitLab Solution: simulate this circuit \$V=RI=(...
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61 views

Why should we modify the voltage source value if the resistor is connected with it directly?

Why should we modify the voltage source value if the resistor is connected with it directly?i mean,there are two different circuit below ,and their corresponding equivalent circuit. As we can see,...
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4answers
88 views

Why can we see the current source as a open circuit and voltage source as a close circuit?

What is the \$R_L\$ value can maximize the power of \$R_L\$? simulate this circuit – Schematic created using CircuitLab The solution: simulate this circuit \$R_{th}=1+2+1=4\$,so when \$R_{L}=...
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2answers
68 views

Relaxation Oscillator circuit analysis

I'm trying to find the output expression of a relaxation oscillator in the Laplace domain, to then convert it to the time domain to be able to trace its output. However, my circuit analysis isn't ...
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39 views

AVR: How to share SPI and ISP over level shifter?

I am currently facing the following problem: An AVR, specifically the ATmega2560, communicates with some SPI-Slaves. The AVR runs at 5V (16 MHz), the SPI slaves run at 5V or 3.3V. Due to the ...
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33 views

Capacitors bridging over transformer in insulated power supply

I need an isolated power supply for powering a device that’s very sensitive to current leak (see below). I bought one such isolated power supply from Aliexpress. What surprised me is that there seem ...
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First principles modeling of op amp CMRR

Introduction I'm trying to analyze an op amp circuit from first principles (i.e. without using the two rules of ideal op amp analysis -- virtual short circuit and infinite input impedance). The ...
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1answer
20 views

Dependent vs. independent current paths

Taking the following circuit: The path on the left will be on and the same, whereas the path on the right is dependent on what is connected to the base of the transistor (not shown in the above ...
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1answer
49 views

Requirements for closed, open, and short circuits

In terms of understanding paths in a circuit, let's take a few example circuits: (1) Would the following circuit be considered closed or open (or something else) since it doesn't have a voltage ...
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1answer
79 views

Converting a schematic to a graph [part 3]

This is part 3 in my journeys to try and graph a basic resistor circuit programmatically (part 1 and part 2. I think I have finally figured out how to treat components -- which if I looked at any ...
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1answer
56 views

Determining gain, KCL/KWL (Basics)

Below is a pi model schematic of a cascaded amplifier. The goal is to find the gain with Rp as load. So the gain would be: \$ A = \frac{V_{out}}{V_{in}}\$. So i set out to find \$V_{out}\$ in terms ...
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47 views

what's the voltage across F

Given: Va= 10V, Vc= 15V Ve= 20V find Vb and Vf so I calculated the voltages using KVL and I got Vb= 10V and Vf= 25V but when I checked my answers it showed that Vf was 5V is Vf = 5V if so then why?
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27 views

Op - Amp and Unbalanced Input Differential Signal

Let's consider for instance an Open Loop Op-Amp (for instance with double power supply: VDD and -VDD), which is a good comparator circuit. The sign of its input differential signal (Va - Vb) ...
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1answer
57 views

How the electric water heater and stove works? [closed]

I notice that some appliances have heating elements such as electric stove and water heater. I know that both of them using heating elements maybe some type of a resistor or something. I want to know ...
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1answer
34 views

Saturation of Constant Temperature Anemometer

Continuation of this question, apologies for the schematic. Rwire and Roh are depicted in balanced state. This is a common Constant Temperature Anemometer circuit, however the diff amp output (...
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3answers
98 views

How is this load able to perform any useful work other than heating?

Consider a voltage source with some internal resistance, in series with a load. It turns out that the voltage source produces a power equal to \$I^2R_\text{total}\$ (this can be seen by using P=IV and ...
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1answer
32 views

Equivalent circuits in case of equipotential nodes

I have the following basic questions about circuit theory. 1) Consider a generic circuit. Suppose that, because of symmetry or other reasons, we conclude that two nodes A and B of it have the same ...
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2answers
166 views

What is this circuit's purpose

The input is a current source (photomultiplier), and the output is connected to a charge amplifier (I belive). I tried to draw the schematics from the circuit board, but I don't know what the three-...
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52 views

Voltage potential of an open circuit [closed]

Can an open circuit have negative voltage potential? Note: it is connected to a ground terminal and not a battery. Thanks!
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75 views

If a silicon cyrstal is connected to a battery does current flow through the wire?

In a circuit consisting of a pure silicon crystal with each end attached to a different terminal of a battery via conducting wire, is there a current flowing through the wire? It seems that there is ...
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3answers
50 views

Netlist for symmetrical component

Is there any difference between the following two netlists for a resistor connected between node5 and node0 with resistance 20K ohms? • R1 5 0 20k • R1 0 5 20k If not, is a resistor the only type ...
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104 views

How to find voltage across a capacitor?

I was given this problem in a basic engineering circuit analysis class. I really don't know where to start.
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Series circuits and serial circuits

I have seen quite a few times now where someone creates a simple circuit and when describing the configuration of the components they say that it is either in parallel or serial. I have only ever ...
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25 views

Circuit Automata with D Flip Flop (replacing with JK FlipFlop)

Hello I have this circuit with this I want to learn about Mealey and Moore. Is this a Mealy Automata? I would say yes because of the upper LED depends on the variables I got. Otherwise isn't the ...
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1answer
75 views

Converting a schematic to a graph

This is a follow up to the question about I posted last night, Converting a schematic into a graph. From some of the answer, I was able to re-work how the graph is done -- with components as edges and ...
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35 views

Single phase neutral current & three-phase neutral current with respect to kirchhoff's law

In the below schematic, would be the sum of all current in the single phase neutral wires equal to the current in neutral wire going to the 3 phase main disconnect? In theory, we know that if the 3 ...
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2answers
61 views

Converting a schematic into a graph

I've been working for some time trying to figure out how it might be possible to translate a schematic into something like a node graph, where each node is a component. I've taken some liberties in ...
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1answer
41 views

Node analysis: estimating variable current branches

Is there a way to get the number of potential currents that could be in a circuit? (Note: in the following circuits ignore the Resistor value, I've just added a resistor with the default schematic ...
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1answer
83 views

OpAmp comparator circuit having unexpected behavior

I'm working with the following circuit. It integrates a constant current, and when the output reachs a threshold, another circuit activates the switch, discharging the capacitor. The switch is ...
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1answer
28 views

Verification of power law

Here is the solution that I have so far. How are the values of Vx different if we solve it using KVL and different if we use Ohms Law? And to verify the power law, do i need to calculate the ...
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1answer
44 views

I need to verify the power law in this question

Question. I suppose the value of Vx must be positive. So how do I manipulate the equation such that Vx becomes positive? Can this be the solution to this question?
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2answers
74 views

What exactly is this question asking us to do?

Based on the model and circuit shown in Fig. 2, draw a circuit model of the path of current through the human body for a person touching a voltage source with both hands who has both feet at the same ...
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2answers
34 views

Calculate the potential and current in the transistor circuit

I'm stuck on a question where I need to calculate the potential Vx and the current Ix in the circuit below. I have managed to get some equations, but the question does not mention what the ...
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1answer
39 views

How do I calculate i, i1, i2 and v2?

I'm unable to figure out how to use the current dependant voltage source in KVL The following are the equations I've found, up till now: 20i+V2=10, V2=50i1, 20i+50i1=10, i=i1+i2
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3answers
62 views

Nodal analysis for resistive circuit

Given the following circuit: I know that I1 = I2 + I3, but what would be the relationship between I2,I3,I4, and I5? I would assume if there are 5 unknowns, we'd ...
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4answers
44 views

Estimating current when voltage drops > voltage input

Let's say I have a circuit with a 5V battery and a 2V LED and a 100 ohm resistor. Ignoring certain properties of an LED, I can estimate the current by doing: ...
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2answers
47 views

Solving for current with voltage drops

Given the following circuit: Why is the current through the circuit 34.7mA instead of 35 mA? My thinking was that: The LED draws two volts, so it effectively makes the battery 7V instead of 9V. ...
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1answer
23 views

Passive Convention for current flow direction

I understand that passive convention in circuit analysis is when current flows in through the positive terminal of a resistor, thus indicating that the element is absorbing energy as shown in the ...
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1answer
61 views

Equivalent drawing of a parallel basic circuit

I have the following circuit in Everycircuit: Ignoring the component values, when I try plotting this in a network graph, I get something like this: Are these two circuits identical? I suppose the ...
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1answer
54 views

How do we do source transformation in complex circuits to get one source

I have a problem in analysing complex circuits by source transformation like this circuit: For the previous circuit, if the independent source of the simplified circuit is a voltage source, what is ...
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2answers
64 views

Finding value of resistor between two diodes

I'm using an Arduino and I have the following circuit: I couldn't find the symbol for analog signal, so the voltmeter represents a connection to the Arduino's analog input pin. How can I work out ...
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960 views

We can ignore the wire resistance if the current delivered by the wire is low?

In this question asking about the Resistance of wire, the answer by user 比尔盖子 provided the following explanation for When Resistance Can be Ignored: Most of the time, resistance of a wire is too ...
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1answer
31 views

MOS working point in a differential analog mixer

let's consider this simple configuration of a balanced differential mixer (analog multiplier): I have understood that the local oscillator is generally a high signal, while the radio-frequency signal ...
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1answer
50 views

Small Signal Voltage Gain - Analog Multiplier Analysis

I'm having trouble with calculating the following: Small Signal voltage gain from input to output at 400kHz (no LO) Small Signal voltage gain from LO to output at 400kHz (no signal at input) The ...
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45 views

How the capacitor charges in this circuit?

I have been working on a kind of edge detector, and I would like to be guided about how the capacitor will charge in this circuit. when I don't have any transistor I could easily calculate the ...
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1answer
62 views

Intermediate Op Amp Practice and Material [closed]

I have an interview coming up where I will likely be tested on the basics of ideal op amps. I am confident in my fundamentals, such as solving the typical basic configs (inverting, non inv, summer, ...

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