Questions tagged [theory]
Theory is a contemplative and rational type of abstract or generalizing thinking, or the results of such thinking. Depending on the context
350 questions
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What determines the resistance with which MOSFETs fail short?
In the case of electrical or thermal overload, MOSFETs usually fail short with a relatively low resistance in the range of ohms or tens of ohms. This answer on "Do MOSFETs usually burn open or ...
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Input impedance of an op amp when sharing bias resistor across multiple op amps
This is a theoretical question more than it is a practical one, and perhaps a bit simple, but I cannot find a reliable answer. Let's say you have a simple op amp buffer like the one below:
Source: ...
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Karnaugh Maps and "Impossible" Bit Combinations
I'm new to learning about how to use Karnaugh maps to optimise truth tables into efficient logic circuits, and have been following Dave Jones' excellent tutorial.
As an example to work on, I have ...
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Complex Power Conservation or "Boucherot's Theorem" - a proof without Nodal Analysis
Brief Question
I'm trying to figure out a proof for the Complex Power Conservation Theorem, which does not use Nodal Analysis.
Theory I know
In my university this theorem has ben taught with the name &...
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Capacitive proximity sensor - Working principle
I'm looking at the working principle for capacitive proximity sensors, when I read online I seem to get conflicting info.
I know that an oscillator is used to generate an AC current, and this is fed ...
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3
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Capacitor problem
I am studying for my circuit theory exam and I came across a problem which is shown in the picture. What will be the voltage here?
I simulated a similar situation by connecting the negative terminal ...
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5
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Is it true that a sine wave is the only signal that does not change shape in a linear circuit?
This is from Microelectronic Circuits by Adel Sedra and Kenneth Smith.
The book says,
In fact, the sine wave is the only signal that does not change shape
as it passes through a linear circuit.
Is ...
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How can one voltage value have multiple SOC? (Jackery Blog Graph)
https://www.jackery.com/blogs/knowledge/lithium-ion-battery-voltage-chart
This is a typical voltage discharge curve for a li-ion battery. I am wondering how one voltage value can translate to multiple ...
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Can we solve all linear circuits using only KVL and constitutive relations?
Can We Solve for Node Voltages and Branch Currents in Any Linear Circuit Using Only KVL and Constitutive Relations?
In circuits with a single loop, it's trivial to solve using only Kirchhoff's Voltage ...
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Theoretical equation to describe capacity fade
https://www.researchgate.net/publication/357842717_How_do_Depth_of_Discharge_C-rate_and_Calendar_Age_Affect_Capacity_Retention_Impedance_Growth_the_Electrodes_and_the_Electrolyte_in_Li-Ion_Cells
I am ...
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Does KVL guarantee identical voltages/currents in similar circuits?
I have a question that is a bit abstract. Assuming I have two proper linear circuits, A and B, which have:
The same ideal components (for example, voltage source, inductor, capacitor, resistor)
The ...
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Getting different answers for number of electrons in 1 amp? [duplicate]
I was looking up the number of electrons in a current with 1a and I keep on getting different answers. Some websites put the number at 6.24, some at 6.25 and others at 6.28 (all * 10^18)
Is there some ...
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Could QAM using a grid-like distribution be a quantization limitation?
This is a follow up from this previous question discussing why QAM encoding is spaced in a grid like pattern like this one:
versus another with more efficient packing:
After looking at @Attie and @...
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Why does QAM use a grid-like distribution versus a more efficient spacing?
"Stand-Up Maths" recently did a video about QAM/data encoding. He presented a diagram of the encoding spacing for QAM:
I'm from a software engineering background and I couldn't help but ...
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Am I correctly interpreting these two fundamental equations about capacitors?
Capacitors follow the fundamental equation \$I(t)=CV'(t)\$, from which we can derive
$$Q'(t) = CV'(t).$$
Recently, I read about the equation that describes the charging of a capacitor:
$$Q(t) = CV(t)\...
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What flows in a general circuit?
I've been learning electronics and have noticed there are pretty much only 2 ways people refer to what flows through the wires; electrons or charge.
I get that electrons are a type of charge but not ...
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Unit of integral windup reset parameter?
What is the unit of integral windup reset parameter? Is it the same as the unit of time, seconds?
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Behavior of BJT collector current in saturation [closed]
Let's assume that we have NPN BJT with absolute maximum rating of collector current = 1A.
Let's assume that we have separate power supplies for base-emitter and collector-emitter.
The collector-...
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1
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Diode Power Dissipation
I am having trouble solving this PD question. I feel like it’s straight forward but I can’t seem to get the correct answer. I was curious if I could get help from the community.
Question: A p-n diode ...
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Better to use low ESR or high ESR caps?
I'm replacing the old filter capacitors on Marshall guitar amp and I was wondering if I should use low/non-low ESR caps for this.
As my understanding is (which is neither deep nor correct probably) ...
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Definition of a short [duplicate]
I know what a short is, or I think I know. Well maybe I don't.
If two wires from a power source are crossed - it's a short. If a component is working normally - not a short. If the component however ...
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Antennas Far field radiation pattern
I want to understand this Far field graph of an antenna generated in CST, from the picture:
Is this a good radiation pattern?
If yes, then how?
How to explain the graph?
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Higher Resistance Measurement on Wet Tongue than Dry Tongue?
I'm trying to start learning about electrical engineering as a hobby. I'm reading from a book right now, and it suggests using my multimeter to measure the resistance of my tongue while it's wet and ...
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Estimating self-discharge rate of ceramic capacitors from datasheet values DF and ESR
I'm trying to make an estimate for self-discharge rate of a typical small capacitor, such as 0.1 uF ceramic capacitor. Horowitz and Hill says "A better measure of loss at low frequencies is ...
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Define the expression by the waveform [closed]
Could you explain how to define the expression for the dead time \$\theta\$?
$$f_{1}=\frac{2}{2\pi }\int_{\theta }^{\pi -\theta }{V}_{in}\sin(\omega t)d\omega t
$$
$$f_{1}=-\frac{2{V}_\text{in}}{2\pi ...
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Solar Array Theory Misunderstanding
I am new to solar panels and I understand their is a lot more physics involved but I am trying to understand this basic concept. Wherever I look it is told that PV panels add Their voltage in series ...
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Need help to find the natural response of an RC circuit
Here is the question I am trying to solve:
I am stuck with the point that I am not sure Vo is found as -50v or +50v. Another issue is that Ic(t) is calculated by derivative formulas or another simple ...
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Need help to find Thevenin resistance and Thevenin voltage
Here is the question I am trying to solve(there are 2 things I need to find. These are Vth and Rth):
Here is my attempt: ( please check Vth if it is true )
I couldn't find Thevenin resistance at all
...
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Phase velocity expression
We have a \$\beta l\$ expression which is represented as phase velocity.
I know \$\omega_o=2\pi f\$.
What is the exact expression for phase velocity used in here?
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EE applications for parametric equations
I am trying to learn electronics, specifically audio amplifiers. I paused my study after realizing that my math skills (or rather my lack of math skills) were holding me back. I undertook a study of ...
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Why is base current needed after transistor is switched on?
If there already is a current flowing from the collector to the emitter, can’t the electrons just keep jumping over the PN junction?
Why does killing the base current make that impossible?
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How many transistors at minimum do you need to build a general-purpose computer?
I'm wondering what the simplest design for a general-purpose (Turing complete) computer is. To my surprise, I haven't found much on the web. Surely this is a known problem?
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Get voltage and current noise P-P values for 0.1 to 10 Hz from integrating the curve in the datasheet and comparing the results to the datasheets valu
Usually from OpAmps datasheets, you can get the RTI noise values for both current, and voltage noises exact RMS values for 0.1 Hz to 10 Hz. For a wider frequency range the noise density curve is flat, ...
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How to calculate break down amperage of wire based on length, resistivity, and cross sectional area?
For this question, I'm assuming the current is continuous, the shape of the wire is cylindrical, and the air is STP air.
(I bridged a fuse with a piece of soldering wire, and I'd like to be stupid in ...
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Preventing power LED runaway with voltage and PWM [closed]
Using near-minimum voltage for the LEDs to light up, and PWM to control brightness by not allowing the frequency/brightness to go above a certain point.
Comments are telling me its not okay to not to ...
2
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3
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Electrical theory regarding load sharing
I am having issues understanding why raising frequency of one AC generator while in parallel with another causes it to pick up more load. Any help would be appreciated.
I operate with turbine powered ...
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Designing a common emitter audio pre-amplifier
I am trying to design and simulate a common emitter audio pre-amplifier using 2N2219 with characteristics based on industry standards (audio frequency response, etc. Corner frequency must be less than ...
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AC voltage and frequency as complex number?
For some software I am writing, I coded classes of electrical systems that receive a voltage and return the current response.
For the DC case that's easy: I pass a real number as argument, the voltage,...
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Why BJT thermal voltage can be not equal to kT/q in SPICE3
In SPICE, apart from effects such as basewidth modulation and base-collector leakage the collector current is given by the expression (according to the original SPICE2 PhD work)
But actually, ...
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How to show that all power in an RC circuit is delivered to the resistor
I am new to electronics and I've been working my way through the Art of Electronics. I've have been able to complete all the exercises up to this point but I have been struggling on this one. Right ...
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Why is my best placement of a directional antenna so weird?
I moved to an offgrid house with a 3G/4G repeater, with a short, enclosed directional antenna. It was wobbling and poorly mounted on an unstable wood plank at the base of a window, so I decided to ...
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What would a theoretical Group II, Group IV Transistor's Properties be? [closed]
This question is for more than a theory.
I would like to disprove that what I'm working on is not a Group II, Group IV transistor.
I know they CAN exist. I don't know why they don't exist or what ...
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Transistor analysis with 2 voltage sources
I want to calculate the DC currents of this circuit, and based on the superpostion theorem, I thought of ignoring Vqdc9 first, in order to calulate I2, I21 and I22, as shown in figure 2. After that, I ...
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What is the correct carrier concentration equation to use?
In this book I am reading, it gives the intrinsic carrier concentration as:
\$ n_i = \sqrt{N_c\cdot N_v} \cdot e^{({\frac{-E_g}{2*K*T}})} \$
While another book says the carrier concentration is:
\$ \...
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Why do we not see multiple or parallel DC PSUs?
A friend mentioned that his home router had blown its 12V PSU recently and had to be replaced.
That got me wondering - Servers and routers can have isolated dual PSUs for exactly this condition, but ...
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Is the amplitude of the sum of 2 transmitters of white noise at a given frequency greater than each individual transmission?
If you have two antennas \$T_1\$ and \$T_2\$ each broadcasting 10GHz Gaussian White Noise at the same receiver, each with an EIRP of say 20 dBW with a random phase offset between them, then is there ...
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Why is Line coding called "Line coding"?
Why is line coding also called digital base band modulation named "line coding" where does it come? and how is the name it to modulation
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About power dissipation of capacitors and inductors & I-V phase difference
For instance, The Art of Electronics (by Horowitz & Hill) states that
ideal capacitors cannot dissipate power, even though current can flow through them, because the voltage and current are 90° ...
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Difference between Message and Signal in Communication Theory [closed]
What is the difference between a message and a signal in Communication Theory?
It seems to me that often they coincide, is this always?
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Can someone confirm my derivation of the generalized power law from Practical Electronics, 4th edition?
I dont know how to use LaTeX, so I used Mathcha and took a snip from there.
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