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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295 views

Should Kirchhoff's Law be changed to account for information removal? [closed]

If I have a simple DC circuit consisting only of an LED output, how does Kirchhoff recognize the fact that information has left the loop? Since, in accordance with relativity(?), you can't have ...
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57 views

What is the main carrier in a semiconductor with n-type material being electrons and p-type materials being holes?

Not even gonna lie this is for a crossword. it is a 15 letter word. I have searched online, in my textbooks and I cannot figure out what it is. Closest I've found is Extrinsic Semiconductor but it's ...
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2answers
846 views

Does electricity always flow in a closed loop and why does current flow to ground?

I have been taught that current flows in a closed loop back to the source. And with electrical distribution, current flows to ground because the whole grid is effectively grounded back to the source. ...
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45 views

What are (if there are any) the major applications/implications of relativistic electrodynamics in engineering? [closed]

I was wondering about the relativistic and covariant formulation of classical E&M and Maxwell's Equations. Does they have any major implication in engineering (not exclusively talking about ...
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4answers
367 views

Why earth ground connection does not leak current?

This seems like a question which has been asked multiple times on forums. I researched the problem but I still was unable to figure out the answer which I can at least intuitively understand. So in ...
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Connecting capacitor to the ground and potentials question

I am a newbie trying to enter the world of electronics and currently struggling with getting a good grasp of basic concepts of electricity. I understand that electrons which usually produce the ...
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2answers
1k views

How to calculate value of R2 in this circuit?

I'm reading a Floyd electronics book and working through some problems. This one has me stumped however. I already know the answer as it's given in the book (110k). However, I don't know how to ...
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1answer
336 views

What is behavior of this virtual ground circuit when sourcing/sinking current?

simulate this circuit – Schematic created using CircuitLab This is the virtual ground circuit from a battery-powered headphone amplifier(direct link to schematic PDF). What is the behavior of ...
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Calculating Thevenin Resistance

I am having difficulty calculating the Thevenin resistance of this circuit I know I need to replace the batteries with links but then I am confused about how to approach R1,2 & 3 in terms of ...
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1answer
178 views

Simplifying capacitor input network

For a design I am working with a capacitive feedback network. I can't show you the actual network, but I intend this to be a more general question as it should be applicable to any input network. ...
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3answers
80 views

Theory: Creating “LPS” transmitter for GPS receivers

As I understand it, GPS works by having transmitters with known locations send a timestamp, and calculating the time it took to receive it, so that you can triangulate your own position, (essentially ...
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114 views

Flow of current, isn't make potential difference?

I've learn some electronic knowledge at school and so confused by some questions. Q1. IS it possible a flow of electricity without an electric field? Q2. I've learn that moving of particle with ...
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BJT Voltage Divider Bias Circuit Theoretical/Ideal Model Help ..LTSPICE?

simulate this circuit – Schematic created using CircuitLab I've been trying to study BJT Voltage Divider Bias Circuits. In particular, as they relate to their active region, amplification, and ...
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How can I calbrate my power meter?

I used to work for a company that made power meters but only worked on the desktop application (user interface) side of things and never really learned completely how some processes occur, like the ...
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158 views

“Current is pulled not pushed” they say. Doesn't the transistor working the other way around? [closed]

The emitter current is defined by hfe and the base current not the load. The load does not "define" Iemitter.
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1answer
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Flow of electricity. Need explanation [closed]

simulate this circuit – Schematic created using CircuitLab People are taught how to calculate this very simple thing, and the calculation goes from source plus to minus, and the diode is there ...
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Is there a formula to determine the size of decoupling capacitors? [duplicate]

I have used many decoupling capacitors in circuits and have seen them in many textbooks, but they never give an explanation about why they picked a certain size of capacitor. Everyone seems to have a ...
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1answer
286 views

Theoretical: Would it be possible to have a worldwide AC standard at 55hz

The question comes from a discussion I had years ago with a keyboard player who had perfect pitch. His problem came from the fact that he lived in a very small appartment in an old building and he ...
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3answers
2k views

Subthreshold regime advantages/disadvantages

Could someone explain the most important reasons for an analog designer to use MOSFET transistors in the subthreshold regime? What are the advantages and disadvantages? Generally, the circuits in mind ...
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215 views

Cgs,Cgd capacitor in Mosfet/ problem with measurement unit

I am a little confused with this problem. I would like to ask if I have a Mosfet(in saturation)and I have find that Cgs=16fF and Coverlap = 0.5fF/um(this is given in the description of the exercise), ...
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1answer
106 views

How to Convert between dB Voltage and Power

We read that the formula for expressing microvolts in decibels is different from that for milliwatts by a factor of 2: \$U = 20\log_{10}{\frac{u}{u_0}}\$ \$P = 10\log_{10}{\frac{p}{p_0}}\$ (Note ...
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813 views

Overdrive voltage and Early effect in MOSFET

Can anyone explain to me if there is the Early effect in MOS transistor then the Early effect affects the expression for VOV which is \$VOV=\sqrt{\frac{2ID}{kn'(W/L)}}\$?
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Why are dependent sources not disabled with the superposition principle?

I've been wondering this recently. My intuition says that a voltage drop across a dependent source is no different than any other circuit element whose response depends on the inputs of one of the ...
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1answer
111 views

How much energy could we harvest from a 0.1V source (gedankenexperiment) [closed]

For the sake of a thought experiment, suppose two 10-metre balls appear magically somewhere on land. In the middle of the Sahara desert for example. The balls are the terminals of a perfect voltage ...
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1answer
103 views

What hypothesis are needed to support the following argument on a three phase system?

Given the following three-phase system: simulate this circuit – Schematic created using CircuitLab Suppose to set 2 wattmeters as follows: \$P_{21}\$ which measures current \$I_2\$ and ...
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6answers
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Electricity through water can injure a person?

I have maybe a simple question.I would like to know if current can travel through water and can injure a person. For example as shown below(A little funny picture!!!) a man watering his grass and his ...
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The History of conventional current

I would like to ask why the first scientists choose the current flow from high voltage(High potential) to low voltage(Low potential) which we know that it's wrong.I had heard and read that they take a ...
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277 views

Explaining capacitance formula of electrolytic capacitor

As stated in this article at page 5, capacitance of a capacitor is generally expressed with the following formula: My question is about surface area S, where it is ...
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0answers
382 views

Conduction angle in three-phase rectifier

In a standard three-phase bridge rectifier, which consists of 6 diodes, each diode (or thyristor) conducts 120º of the full 360º period. I have built a synchronous rectifier (for research purposes), ...
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1answer
340 views

Must the characteristic impedance of a transmission line be non-real for it to be lossy?

In Does conductance in the transmission line model represent a physical quantity? it came up that a non-real characteristic impedance just means the line has some loss. With real transmission lines ...
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1answer
36 views

What determines current through a VS in parallel with a resistor?

This is more of a conceptual question with ideal voltage sources, I am fully aware of its impracticality, but bear with me for the sake of a theoretical discussion. Consider a simple circuit shown ...
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209 views

Find a stabilizing controller for a transfer function

I need to find a controller C(s) that can stabilize a system G(s) with the following transfer function: G(s) = \$s^2/(s^2-1)\$ Any tips?
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170 views

Electric networks with an open-loop

This is a generic concept question that I encountered during the first day of an EE course. Our lecturer told us that electric circuits are essentially electric networks with closed loops. I would ...
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1answer
511 views

What is “formal verification” of hardware?

I read that testing and verification are different but in what way? I read that somebody writes theory to prove that the hardware is "correct" but how is that done? I tried reading Wikipedia and ...
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1answer
274 views

How is an inductor a lumped element?

While learning the Lumped Circuit Abstraction (and the Lumped elements discipline), an inductor was considered a lumped element. But I fail to see how it fits the requirements of LCA: For it, the \$\...
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Where does the formula for Voltage in AC with inductance come from?

This is what the textbook says: I don't understand why does ωLIm equal Vm so if someone knows please explain it to me Thanks
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1answer
906 views

Calculation and measurement of input and output impedances of a Class-D amplifier

How would I calculate, from datasheet information or elsewhere, the input and output impedances of a Class D power amplifier, in general or for say a chip like the LM4670 or the TPA2000D1? {Note that ...
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Proving RC and RL circuits as integrator and differentiator using differential equations [closed]

I need to use first degree ordinary differantial equations to prove (solve) the Differentiator and Integrator Circuits of RL and RC (for example if RL is differeantiator or integaror or both i need to ...
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3answers
162 views

neutralize charge in series capacitors

I have a simple circuit as in the picture below. My question is why the negative charge -Q at the bottom plate of C1 moves and neutralizes with the positive charge +Q at the top plate of C2?
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Is the Nyquist plot a plot of Re(G(s)) v.s. Im(G(s) or Re(G(jω)) v.s. Im(G(jω))

It seems that people in control theory are divided over whether the Nyquist Plot/Diagram (that is the plot, not the contour!) is a plot of $$\text{Re}(G(s)) \text { v.s. } \text{Im}(G(s))$$ or $$\text{...
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1answer
333 views

If I have an obtuse trace, will the complementary acute angle cause issues?

I was wondering if the complement of an obtuse trace would cause issues when routing, would it be better to have a 90 degree trace or one that comes in like this? or 90 degrees EDIT: Added a third ...
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734 views

Why do we use a common collector on a linear regulator?

In my electronics class, we just saw the principles of a linear regulator (like the LM140L or uA78LXX). But I didn't understand why we are controlling a common collector with the differential ...
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1answer
910 views

Relationship between voltage/current & LED strips?

I recently bought a WS2812 LED strip (5 meters, 300 LEDs) When the LEDs are driven at full brightness and each color lit, they draw 60mA each--or 18 amps for all 300! This led to a problem, which ...
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186 views

Nonlinear circuit v(i) function for I-V plot

I'm trying to understand how to theoretically derive the equation that could be used for plotting the I-V graph. The points of interest are Out + and ...
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2answers
311 views

Why is the gradient of Energy vs. wavenumber(k) zero at the edge of Brillouin zones?

My question relates to semiconductor physics. The relationship between energy E and wavenumber k for the Kronig-Penny model looks like this, where a is the period of the potential function: I am ...
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1answer
351 views

What are the required parts for an 8-bit computer?

I've decided that I want to build my own 8-bit computer with the WDC 65C02 CPU. The only problem I have, is that I don't know what the requirements to build one is in terms of other chips and ...
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461 views

Physically lightest topology for SMPS?

I'm being vague about part of my project, but please ask me to fill in critical details I'm missing. I need to power a 24V @ 20A device for 5 hours (one time), within a weight budget of 700 grams, at ...
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313 views

Modelling transistor V_be and bulk resistance

I'd like to calculate algebraically the DC behaviour of various bipolar transistor circuits that used matched pairs or quads (exponential converters, current mirrors etc.), taking into account the ...
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1answer
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Why does my UART connection still work without connecting ground?

On my prototype PCB, I have a microcontroller with reserved pins for UART communication with a debug terminal. I'm curious from a theory perspective about why my terminal works fine whether or not I ...
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283 views

Help with AC circuit theory problem

I need help with the following AC circuit problem: Given the circuit (attachment 1) with known data: $$\underline{Z_3}=200(3-j4)\Omega$$ $$\underline{Z_4}=100(3+j20)\Omega$$ $$\underline{Z_5}=100(3+...