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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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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1answer
112 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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91 views

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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2answers
153 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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5answers
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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
281 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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177 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
92 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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731 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
110 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
102 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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1k views

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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2answers
247 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
332 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
326 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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2answers
174 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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2answers
158 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
444 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
240 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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3answers
58 views

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
820 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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2answers
980 views

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
154 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
301 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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2answers
713 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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845 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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173 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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1answer
249 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
335 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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422 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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2answers
293 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
972 views

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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1answer
279 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+...
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1answer
475 views

Can you increase the input impedance.?

Consider the common emitter amplifier in the schematic: simulate this circuit – Schematic created using CircuitLab The input impedance is \$Z_{in}=[(R3\left | \right |R4)\left | \right |\...
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4answers
170 views

Why is there current flow in the sub-circuits?

I'm struggling with the theory of this(unusual) circuit: simulate this circuit – Schematic created using CircuitLab The load receives no power at all, due to the voltages cancelling out, yet ...
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2answers
168 views

How Would a CPU Improve if its Logic Circuits were Reduced? [closed]

Is there an estimate as to how a common CPU (for example, Intel i7) would improve if all of its logic circuits were reduced to their theoretical minimum, in the sense explained here? By "improve" I ...
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BJTs drawing collector current from a limited current source

simulate this circuit – Schematic created using CircuitLab Let's make everything ideal by ignoring the voltage drops: Q1's allowed collector current is: 22.4 mA Q2's allowed collector current ...
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6answers
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Ceramic caps vs electrolytic. What are the tangible differences in use?

A quick google around and all I seem to be able to find are people talking about the physics & the chemistry of the capacitors but not how this affects choosing which to use. Avoiding talking ...
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2answers
374 views

Two batteries connected to a resistor

In the circuit shown here the conventional current direction is from V2 to V1 and is equal to 3 Amp. I understand the theory. But, if I make this circuit with two batteries, according to the schematic ...
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1answer
447 views

How does a cascode or beta-enhanced voltage amplification stage work?

I'm studying electrical engineering and we just finished a project where we had to build a power amplifier. But I think I can do better than what we did. I read Distortion In Power Amplifiers where ...
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1answer
684 views

Understanding microphone sensitivity

My goal is to figure out a relation between output voltage and input SPL: $$dB(SPL) = f(V_{out})$$ First, I get the sensitivity in volts from this formula: $$Sensitivity_{dB(V)} = 20 * log_{10} (...
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2answers
527 views

Is this measurement of a cricuit's output impedance valid?

The following circuit is a simple voltage regulator. The Vout is maintained at -1V, however the opamp in the circuit has a non-zero output impedance. This is represented by the resistor R1. simulate ...
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1answer
640 views

What is the explanation with shorting vcc and gnd to power up the whole circuit in a breadboard? [closed]

I was building a logic circuitry that performs 8 bit multiplier 16 bit divider using decoders as finite state machine in breadboards. the circuit is a bit large and i wonder why grounds or low voltage ...