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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32 views

Type 1 surge protection: parallel or series?

Type 1 surge protection devices (SPDs) are installed at the outside edge of electric service, usually between the power meter and the meter base/socket, and protect the entire house. But how do they ...
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2k views

Is Gaussian noise equal to white noise?

If noise on a signal is randomly fluctuating in time domain around its mean following a Gaussian normal distribution (Gaussian noise), would this be equivalent to an constant intensity in the ...
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3answers
74 views

Energy Transformation in Flyback Transformers

I am trying to understand how is energy transferred as a current to secondary of flyback transformer. First due to the dot convention and secondary side diode, current will not flow in secondary and ...
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1k views

Is a hole in a conductor the same thing as a positive ion?

The flow of current in a (semi-)conductor is often described as holes and/or electrons moving between atoms. In this context: Is an atom with a hole the same thing as a positive ion (cation), and Is ...
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Noise and what does V/√Hz actually mean?

Noise figures in (op amp) datasheets are expressed in V/√Hz, but Where does this unit come from? Why the square root? How should I pronounce it? How should I interpret it? I know lower is better, ...
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Why do I get such high values when calculating the power dissipation of MOSFET in boost-converter circuit?

I'm a hobbist interested in electronics so I don't have any "professional" training on that. Currently I'm trying to design a boost converter and now I'm stuck at some calculations. I wonder ...
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607 views

Is there any relationship between frequency of signal and distance it travels?

I'm currently researching 5G technology. Many videos/articles on this topic claim that 5G is designed for communicating on lower distances (than 4G), because of higher (than 4G) frequency. So to build ...
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23 views

BJT Hre simulation problem

im having problems understanding the behavour of the hybrid parameter hre in the bjt AC model. im using the pi equivalent circuit to simulate the relation between hre and Ic (Dc value). i am not ...
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40 views

relation between transmission line & circuit impedance

What is the relation between the impedance of lumped components and the characteristic impedance of transmission lines? I have noticed that in some cases transmission lines are loaded with lumped ...
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1answer
46 views

Digital regulator for DCM Boost - How does it relate to duty cycle?

I really hope someone can help me here, I'm tearing my hair out trying to bridge the gap between control theory and electronics. My aim is to control a discontinuous conduction mode boost converter ...
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6answers
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How do computers output a signal without an input? [closed]

I'm curious about how an output pin gets turned on at a low level when there is no input like pressing a button to complete a circuit. If you program a raspberry pi to turn on and off an LED how does ...
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4answers
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How to calculate the input and output capacitors of a common emitter amplifier using BJT?

Sorry if the question is stupid, but my head is still hard as a coconut and I am learning... I am dealing with this circuit that I have calculated from scratch. This circuit was designed to have Vc =...
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Are E and B fields in phase in electromagnetic radiation?

I recently wrote this answer, in which I said: Radio waves are electromagnetic radiation. Electromagnetic radiation contains of two components, one electrical and one magnetic. These components ...
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1answer
542 views

Parallel RLC Resonance bandwidth

Good day ,I need help in understanding a practice problem that my professor gave us. A parallel resonant circuit has Q = 20 and is resonant at ωO = 10,000 rad/s. If Zin = 5kΩ at ω = ωO what is ...
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Discharging a capacitor through a resistor and an LED in series

Suppose you have a capacitor of capacity \$C\$ and initial voltage \$U_0\$, a resistor \$R\$ and a LED with threshold voltage \$U_S\$ (\$U_0 > U_S\$) in series. Now I want to calculate duration \...
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5answers
405 views

Generalized Power Equation, Ohm's Law and Ohm's Power Loss?

I'll try to state my questions precisely as I can. I'm a beginner in Electronics and since I have a background in Physical Chemistry and basic Calculus, the book Practical Electronis for Inventors, ...
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3answers
145 views

What exactly does a resistor's tolerance rating mean?

I thought that I had this pretty much figured out over 30 years ago during my initial schooling, but various answers posted to a support forum of a major semiconductor manufacturer(name withheld to ...
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Which books should I read to gather practical and useful electronic design skills?

I need some guideance from the experienced users here, I need to know where to focus my studies: Ive been reading several electronic books, and they are quite different, I decided I want to re-learn ...
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74 views

Why are 22pF capacitors so common? [duplicate]

I've noticed that many circuits use 22pF capacitors. For instance, the Arduino uses them to ground the oscillator pins of its AtMega328. Many tutorials call for exactly this value for simple circuits. ...
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1answer
90 views

Why don't commercial metal detectors clearly distinguish between iron and other metals?

I've read about how metal detectors work, and what I learnt here on EE.SE and other articles, the main principle is that ferrous metal will increase the inductance of the search coil, while non ...
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2answers
63 views

Why does lumped discipline not hold as dimension approaches operating signal wavelength?

I'm studying some basic introduction to the lumped matter discipline on my own. I completely understand where the first two constraints come from (i.e. lumped matter can only interact through their ...
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2answers
108 views

How can I tell if this boost converter is in continuous or dis-cont. mode?

I'm trying to intuitively understand a boost converter, so I've built a variable duty-cycle oscillator circuit that can go from 1kHz to 50kHz and allows me to adjust the duty cycle from 5-95% without ...
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2answers
85 views

Why do NPN/PNP transistors need to use doped semiconductors for the 'N' region?

By my understanding, as long as the P layers are properly doped (to have fewer free electrons), the electrons could not flow between collector and emitter until the P is given a satisfactory level of ...
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1answer
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Intuitive and iterative approach to understanding of blinking LED circuit

I've used following schematics to build blinking LED circuit and it worked. I tried to understand how it works qualitatively without solving differential equations. By this I mean understanding ...
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1answer
68 views

Can the 1D wave equation be recreated in a conductive wire?

I am ignorant of EE, but not the wave equation, so bear with me. The (scalar) wave equation \$d_{tt} - c^2d_{xx} = 0\$ describes the displacement (and velocity) of some medium through space and time....
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99 views

How to classify power electronics components in 2 main groups?

I'm working on preparing a course about power electronics, and with my basic search conclusions. I thought that if it's possible or acceptable to classify the power electronics components in 2 main ...
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2answers
325 views

Can an induction motor be used to generate power?

Induction motors do not have magnets in them, instead the magnetic field the outer coils generate creates electricity, and subsequently magnetic field, in the inner coil. This means those motors need ...
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1answer
1k views

Why are circuit results different from theorised?

From the following circuit: I got the following results in comparison to my theorized calculations: Why were my result different to my calculations? Here is my calculations: Equipment used: ...
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120 views

Why is RMS used for P=VI (where there are no squares)?

I understand why RMS values are used for $$P = {\bar{v^2} \over R}$$ because \$\bar{v^2}\$ would be the "MS" so to speak, and then by square rooting we get the "RMS" (\$\sqrt{\bar{v^2}}\$), which ...
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3answers
100 views

Transistor Analysis

Here is a problem I saw as an example of transistor analysis: (hFE is 50) simulate this circuit – Schematic created using CircuitLab The process is simple, the guy assumed that the transistor ...
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1answer
194 views

Average Power for “Infinite period of time” of a periodic signal

Last night in class we talked about the average power for any periodic function. I'm just confused of why the one halves are in the bounds for this equation. Since we are letting tau approach ...
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1answer
47 views

Isolated circuits: can their reference voltages (GNDs) be at the same potential?

Suppose there are two independent circuits isolated from each other. If they are isolated, the impedance is very high between them (ideally infinite) and there is no current flowing from one to the ...
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3answers
148 views

Why doesn't electricty flow to earth ground when I connect my oscilloscope ground clip to a floating circuit?

There are two concepts I keep reading about that seem to be conflicting each other. Firstly, whenever there's a potential difference between two points, and those points are connected, electric ...
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1answer
88 views

How can a resistor be given a positive and negative characteristic?

This question is not pertaining to a circuit, but to individual parts itself. If for any reason, i want to make a resistor have a positive and negative charge on its either ends, what would be the ...
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3answers
107 views

What happens to a computer as it is cooled towards absolute zero?

What happens to the behavior of a conventional circuit using conventional components as it is cooled towards absolute zero? To make this question more relatable: What would happen as we cool a modern ...
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2answers
394 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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2answers
177 views

Bipolar Transistor Inverter Circuit Analysis

I have been trying to understand this question and I'm just not sure what equation to use for the collector current. I'm not sure if I need to be using an output voltage function of time? All I have ...
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6k views

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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5answers
180 views

How can I describe and explain SMPS on a very basic level without diving down in heavy maths / EE lingo?

I'm writing a book about repairing electronics. The audience level for the book is "very little knowledge about electronics" and it's mostly about the mindset and mindtools for finding problem sources ...
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3answers
244 views

Is space division multiplexing really multiplexing?

I don't know much about electronics, but happened upon the Wikipedia article for Multiplexing, which defined it as: a method by which multiple analog or digital signals are combined into one signal ...
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4answers
434 views

No potential difference between the negative terminal of battery A and positive terminal of battery B?

I know that if you have two batteries, battery A and battery B, and connect the negative terminal of battery A to the positive terminal of battery B, there is no potential difference. If you consider ...
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4answers
147 views

How can Ohms law be used to calculate the resistor value for an LED when multiple voltage/current pairings give the same resistance?

Say I have a 9V supply, and I want to power an LED that requires 3V and 0.02A. From what I understand, I need to add a resistor that will drop 6V, and reduce the current to 0.02A, and I can calculate ...
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1k views

Estimate capacitor parameters

I am thinking of making a capacitor, just for fun/for studying purposes. And I thought of the following exercise. In my local store, there exists rolls of polyethylene food film and aluminium foil. ...
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3answers
11k views

Magnet that needs power to turn off? Inverse coil?

I have never heard of such thing. But it would really suit my needs. I'm inventing a device and during it's operation, it should be able to catch an iron object any time (with a permanent magnet). ...
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3answers
12k views

Why isn't a transformer a short circuit?

I'm a newbie with electronic components and I never fully understood why transformers, while essentially being a short-circuit from a wire perspective, don't act like short circuits (i.e. they don't ...
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2answers
75 views

current speed/flow [closed]

Note my questions are in form of explaining. its because I've scattered information (or assumptions) and it want to link them. that's probably why you can see me explaining to much? Question part: ...
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2answers
447 views

A question about electrons, charges and current

Let's talk about DC, a very simple circuit: a light bulb and a battery. Some authors say that electrons move from negative to positive and current from positive from negative. I always thought ...
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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
100 views

What are the initial conditions used to find the coefficients in the current equations?

Suppose a RLC series circuit. R, L and C are in series with a battery and a switch. The switch is open. L and C are discharged. At t=0, the switch is closed and the battery (V1) feeds the circuit. I ...
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1answer
191 views

How do I find the current equations for the RLC Series Circuit?

Let's talk about a RLC series circuit. R, L and C are in series with a battery and a switch. The switch is open. L and C are discharged. At t=0, the switch is closed and the battery (V1) feeds the ...

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