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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

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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 ...
hana's user avatar
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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 ...
risa's user avatar
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1 answer
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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 ...
hana's user avatar
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-1 votes
1 answer
80 views

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 ...
user3553471's user avatar
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3 answers
130 views

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 @...
Joshua Walker's user avatar
22 votes
3 answers
2k views

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 ...
Joshua Walker's user avatar
0 votes
3 answers
69 views

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)\...
Sam's user avatar
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3 answers
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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 ...
Wilhelm's user avatar
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1 answer
45 views

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?
ATJ's user avatar
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6 votes
5 answers
674 views

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-...
Brutal's user avatar
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3 votes
1 answer
459 views

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 ...
Mr. Blue's user avatar
2 votes
1 answer
550 views

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) ...
steve d.'s user avatar
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1 vote
5 answers
141 views

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 ...
MiNiMe's user avatar
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0 answers
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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?
Trisha Das Mou's user avatar
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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 ...
verarox's user avatar
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1 answer
126 views

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 ...
jonathanjo's user avatar
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2 answers
72 views

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 ...
Antel's user avatar
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1 answer
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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 ...
JBHOLIO's user avatar
0 votes
1 answer
113 views

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 ...
Computengineering's user avatar
0 votes
1 answer
191 views

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 ...
Computengineering's user avatar
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1 answer
56 views

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?
lub2354's user avatar
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3 answers
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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 ...
nuggethead's user avatar
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3 votes
3 answers
568 views

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?
Vambyte's user avatar
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12 votes
8 answers
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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?
static_rtti's user avatar
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164 views

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, ...
NNN123's user avatar
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0 votes
1 answer
62 views

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 ...
Emmanuel Lopez's user avatar
0 votes
2 answers
139 views

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 ...
Magezilla's user avatar
2 votes
3 answers
200 views

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 ...
Cory's user avatar
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4 votes
2 answers
659 views

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 ...
Sabretooth 2438's user avatar
0 votes
2 answers
619 views

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,...
flxh's user avatar
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2 votes
0 answers
169 views

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, ...
sx107's user avatar
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0 votes
1 answer
167 views

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 ...
Twar2600's user avatar
1 vote
3 answers
237 views

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 ...
MoonCactus's user avatar
2 votes
0 answers
64 views

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 ...
RobMcN's user avatar
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0 answers
182 views

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 ...
Gabriel Santos's user avatar
5 votes
1 answer
647 views

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: \$ \...
Geno C's user avatar
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0 votes
3 answers
119 views

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 ...
Criggie's user avatar
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0 votes
1 answer
249 views

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 ...
Freddie R's user avatar
  • 101
0 votes
1 answer
274 views

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
yohans hailu's user avatar
2 votes
1 answer
1k views

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° ...
Rintala's user avatar
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-1 votes
4 answers
2k views

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?
A2020's user avatar
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1 vote
0 answers
79 views

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.
xrosaber's user avatar
  • 135
3 votes
1 answer
813 views

Matching via sizes to trace widths

Let's say I've determined a trace width (\$t_w\$) for a trace, and now I want to determine the size of a via on that trace. My intuition is that to maintain the same amount of copper as the trace ...
Jason C's user avatar
  • 663
7 votes
1 answer
679 views

Why is BMC/k-induction used in RTL formal verification?

One popular approach for proving safety properties in formal verification of RTL designs is a combination of BMC and \$k\$-induction, which appears to stem from "Checking safety properties using ...
ferris's user avatar
  • 123
0 votes
0 answers
115 views

Is there a method to convert a Butterworth response into Chebyshev and Bessel responses?

I wonder if once there is a completed/aproximated a design model of any of the responses mentionated, it can be operated mathematically (or there is a method/recipe) to generate the other responses? ...
avelardo's user avatar
  • 495
5 votes
2 answers
1k views

How is the slope of the frequency response of an analog active filter defined?

I have seen different types of filters, and different slope values at -20 db, -40, etc. The literature says that the order define the slope, but how? How can it be mathematically justified? For ...
avelardo's user avatar
  • 495
0 votes
1 answer
695 views

How/where does a generator + motor dissipate heat?

I've got a mystery that I can't wrap my head around. A generator is generating 1 kW of electric power. The current goes through copper cables to a motor, which is consuming say 950 W of electric power....
DrZ214's user avatar
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1 vote
1 answer
573 views

ESP32 Input Voltage Divider, Concept

Thank you for reading. I have read many other voltage divider explanations and calculators on this site as well as the web. My application is using a voltage divider to lower a possible 5 V signal (...
Sparky's user avatar
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4 votes
4 answers
2k views

Will the net current drawn by a microcontroller equal the current supplied by it

Purely a theoretical question. Consider a microcontroller whose only job is to turn 1 pin high and in the process the microcontroller supplies I1 current throught the pin. But suppose we have to turn ...
jomon's user avatar
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1 vote
2 answers
308 views

How to explain the strange results from this circuit (op-amp : differential amplifier?)

I have a differential amplifier. Problem of "gain" of the op-amp or "how it is wired." I have simulated this as a voltage source controlled voltage (VofV.) As a generic amplifer. ...
Antonio51's user avatar
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