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

240 questions
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Norton's and Thevenin's theorems importance

Are Norton's and Thevenin's theorems used in real life? And in which situations? I'm reading a circuit analysis book and I asked myself: do electrical engineers use these theorems to get current and ...
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Physical changes caused by charge pump

Charge pumps are very cool circuits because they challenge my ideas about how voltage works. I'm very comfortable with the math behind line integrals, so to define "voltage" as the work done to move ...
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Why is the Ampere the only SI fundamental unit for electricity?

According to wikipedia the only SI fundamental unit for Matters Electrickal is the ampere. Don't you at least need the ohm to derive anything? How would you make volts from only amps? Perhaps I ...
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Channel Coding with Higher modulation

Just had a theoretical question. I'm reading a book on LTE, and I came across an introductory section that talks about using higher modulation with channel coding. I understand that usually using ...
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Inductance of toroidal-cylindrical inductor?

If the inductance of a solenoid is $L_{\text{sol}}=\frac{\mu N^2 A}{l}$ and the inductance of a toroid is $L_{\text{tor}}=\frac{\mu N^2 r^2}{D}$, is it correct to assume that the inductance of a "...
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How does cascoding helps

In order to improve the output impedance of a current mirror emitter resistance are added to them..but on the other way these emitter resistances have certain drawbacks which involve restricting ...
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Why does output impedance behaves this way

Why does the output impedance(Ro) of a common emitter amplifier is considered in parallel with the collector resistance(Rc)...as according to the KVL--->Vcc=IcRc+Vce+IeRe they seems to be in series......
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Why would Z/P cancellation with real part > 0 between the plant and the controller make the system unstable?

Can someone help me verify the claim if there is a zero pole cancellation with real part > 0 between controller Gc and plant Gp, then the system is not stable? I can't find any literature that ...
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Working of a current mirror as an active load

Ordinary resistor as load in a transistor amplifier has a certain short coming…we cant have voltage and current gain simultaneously ….. In this circuit a current mirror is actings as an active load ...
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Why does Nyquist plot only need loop gain but not the entire closed loop transfer function?

I was trying to compare a Bode plot and a Nyquist plot of the same system and realized that I was probably comparing apples to oranges Bode plot is plotting the entire closed loop transfer function, ...
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Why pulsed DC passes through a capacitor?

OK, the current flowing through a capacitor equals C*dV/dt, I'm aware of that. What I don't understand is the physics of the process: why does a capacitor pass pulsed DC (0-10V for example) when ...
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current flow to vcc

Hi, i want to build an encoder schematic using zener diode, so the input voltage from encoder can more than 5V (using zener 5.1V), if the input voltage from encoder 0V, voltage to uC is 0V, if the ...
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no distortion amp circuit, max. (d(Vout)/dt )max< slew rate, why not (d(Vin)/dt)max?

I think slew rate is how fast a circuit can react to a given input. I was asked to find the frequency limit where the output would show no distortion and tried to find it by (d(Vin)/dt)max < slew ...
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high side vs low side load control

Background Fairly standard scenario - I have an inductive load (servo or something similar) that I turn on and off as needed (several times per hour, nothing high frequency). In a scenario where the ...
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What are some of the real life example of the so called “tracking and regulation” problem in control theory?

Given a plant, we need to design a controller that takes in an input r and then ensure that steady state error between the output and input goes to zero while the system remains stable. What is a ...
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Control theory: What is the physical interpretation of asymptotic stability

For Bounded Input, Bounded Output stability (BIBO), there is a very nice interpretation. All it means is that if for any finite signal the system produces a finite output signal, then the system (...
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Can an electric circuit do recursion?

Can an electric circuit do recursion? By recursion I mean any kind of recursion, tail, binary, nested, etc: http://www.sparknotes.com/cs/recursion/whatisrecursion/section2.rhtml By electric circuit ...
681 views

How to solve first-order RC circuit?

I've got a question, and I just keep getting myself confused when I try to solve it. The problem asks to find voltage and current and resistor currents transients (the switch is opened at t=0). Before ...
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Relaxation oscillator period

For an electronics project I am using a Schmitt Trigger relaxation oscillator. The equation for voltage across a capacitor in time t is $$V_c = V_s(1-e^{\frac{-t}{RC}})$$ My Schmitt Trigger uses a ...
634 views

8 bit computer graphics [closed]

I'm working on learning how 8 bit computers work and operate. I know you can make a (tedious) microprocessor with a larg amount of logic gates and such, but how does it read graphics? I know this uses ...
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Caculating baud rate of Ethernet per wire

I'm trying to find the answer to what should be a simple question. How do I calculate the physical rate bits are transmitted on an individual Ethernet wire? I am interested specifically in 100 Mbps ...
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why ohmic losses increase with resistance?

Electrical newbie here. I'm trying to get understanding how is resistance involved with power dissipation (ohmic losses, eg. heating). Primarily I'm looking at Electromagnet coil, it says the losses ...
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How to convert noise to noise density in mic pre amps

I am trying to compare two low noise mic pres for the lowest noise, and I am looking at the TI1012 and MAX9814 MAX9814: ♦ Low Input-Referred Noise Density of 30nV/√Hz TI1012: Output Voltage Noise (...
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Early Effect, Ebers-Moll, Common Emitter Resistance, reverse alpha/beta and saturation current

Ive been reading Sedra/Smith's Micro Electronic Circuits book, and it has a lot of info which I like, however I dont know how much of it is actually practial and useful, for instance it talks about ...
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In adaptive signal processing, what does it mean for an arrow to go through a block?

For example, in this case the FIR digital filter has an arrow going through it. This is common in the signal processing comunity but very unintuitive from a control perspective i.e. where is the arrow ...
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AC Analysis Mindset [closed]

I'm just trying to solidify my foundational knowledge of ac analysis. So when approached with a basic circuit, lets say a RLC circuit, should my first instinct be to convert each group of components ...
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Help understanding the function of my circuit. (Bug swatter)

The important thing is the image below. I want to know how it works. Here's what I understand so far. First I'll identify the pieces: -The blue "packet" is a capacitor. Its a $0.030 \mu F$ with ...
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Op amp has a biased output

I'm designing an op amp circuit to amplify 20mV, 18kHz square wave up to measurable levels (~2-3V). Why is the output signal: Biased at ~400mV Triangular (high output capacitance? is that a thing?) ? ...
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Why is the Nyquist data rate lower than the Shannon data rate?

In the book Computer Networks, the author talks about the maximum data rate of a channel. He presents the Nyquist formula : C = 2H log$_2$ V (bits/sec) And gives an example for a telephone line : ...
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How to calculate a current being drawn by a full wave rectifier diode bridge?

I've been studying power supplies and diodes, all books I've read discuss a great deal of things, but there's something I haven't found, and that is how to calculate how much current a bridge ...
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What would happen if an ideal voltage source was connected to an ideal wire?

I've seen it mentioned in discussion that an ideal wire doesn't exist (all wires have resistance), but even if it did, an ideal voltage source doesn't exist (all batteries have internal resistance); ...
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What is the difference between the substitution principle and Thevenin theorem?

The substitution principle (as seen in this book; in italian, sorry) Let A and B be any two part of an electrical network with voltage and current sources and only resistances, connected by ...
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Why don't infinitely many sinusoidals exist in an oscillator circuit?

A sinusoidal oscillator, takes the ambient thermal noise or any imbalance in the circuit as input and gives out an oscillation. This kind of oscillators are called to be linear. By the nature of a ...
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When is it theoretically possible to fit PCB circuit on x Layers (emphasis: x =1)

When is it theoretically possible to fit a given circuit on a certain number of layers? (Presumably PCB layers.) What is/are the name of the mathematics/algorithms that might determine this, or ...
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Why do op-amps keep amplifying?

I was reading an old copy of Horowitz and Hill's The Art of Electronics and I am trying to wrap my head around operational amplifiers in negative feedback circuits. As the book explains, as the op-...
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Would it be practical to build a chip that can do this math?

I was theorizing a new kind of 64-bit number for use in data storage, but then started wondering if it could become practical if created in hardware. (I believe it would be too slow if only software ...
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Why doesn't linear resistance scale proportionally with the square of length?

I have an in depth question about basic proportionality of resistance. Why doesn't it scale with the square of length? I ask this because what is causing the potential difference on two leads is ...
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Induced dipole moment and 'electronic polarization'

Principles of Electronic Materials and Devices - Hasap, pg: 586, he says: The induced dipole moment depends on the electric field causing it. We define a quantity called the polarizability a to ...
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How to light a fluorescent lamp?

There are a lot of circuits on the internet for lighting fluorescent lamps. But they don't reveal the working mechanism of the lamp itself. I'm more concerned about the theory rather than the ...
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Absolute and relative permitivitty

Principles of Electronic Materials and Devices - Hasap, pg: 585, he says: $$\epsilon_r = \frac{Q}{Q_0} = \frac{C}{C_0} = \text{relative permittivitty}$$ Then he says: It is important to remember ...
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Is there a maximum possible voltage?

This question got me to wondering if there is a maximum theoretical voltage. It seems to me there's a limit to how much positive or negative charge you could have--say, a container full of electrons ...
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Design vs reality and what to do when they differ

I've been trying to focus a bit more on Analog circuits lately and found that my design and actual results often don't match up exactly. An example is a Pierce oscillator I built a while back, the ...
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How can the SI unit of resistivity [Ωm] be interpreted?

The way I interpret the resistance $R$ of a resistor, which has dimensions $[\frac{\mathrm{V}}{\mathrm{A}}]$ is: how many volts must be applied across the resistor to achieve 1 ampere of current?...
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Am I doing this right? (LED's to music)

simulate this circuit – Schematic created using CircuitLab I have been charged with designing and making a circuit that makes LEDs brighten or dim to an audio source. At the time I thought I ...
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Resistivity and resistance. Permittivity and?

We know that resistance is dependent on both the materials resistivity and the geometry of the material. For a cylindrical or rectangular material the resistance is: $$R=\rho*\frac{l}{A}$$ where l ...
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What if you put a capacitor betwen the plates of another capacitor?

Based on: Is there a dual of the transformer? The picture of the capacitor inside another capacitor seems viable to me. If a transformer is two inductors with a common magnetic field, its dual would ...
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At what resistance do I not see a voltage drop across a resistor?

If I have a circuit like this and measure the voltage drop across the resistor I get a value, regardless of what resistor I use: However, if I stick a piece of wood in there instead of the resistor I ...
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Resistors and the water analogy

The the most prevalent analogy for understanding electricity is the water hose one. I personally like this because it's very understandable but I have a question about how this works with resistors. ...