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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1answer
58 views

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 ...
3
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1answer
56 views

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 ...
0
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2answers
88 views

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 ...
0
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3answers
61 views

Is it possible to have a continuous quantized signal or a discrete infinite precision signal?

When converting an analog signal to the digital domain I understand that one does two things. An analog signal is continuous and must be sampled in to discrete time segments (Discretization) The ...
7
votes
3answers
363 views

Where does U for voltage come from?

I believe in Europe the letter U is commonly used for voltage in (eg.) Ohm's law \$U = I × R \$. I think I understand where the letter V came from, commonly used in North America. But what's the story ...
1
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3answers
98 views

Biological 'Black Box' - how to test for underlying logic?

Firstly, I am a neuroscientist - so bear with me! I have a collection of connected brain cells (network) and a means of recording the electrical output, as well as manipulating the input to the ...
5
votes
1answer
179 views

What are the technical challenges to store electricity from lightning strikes? [duplicate]

I ask myself that question every time I watch a Tesla documentary. So, let's get some answers down so the smart ones can think about it and we can clean-up our environment. There is free electricity ...
9
votes
7answers
1k views

When people talk about a device “drawing” current, what do they mean? Why do devices under load “draw” more current?

In my (extremely rudimentary) understanding, the amount of current flowing in a circuit is determined by a) its resistance, and b) the voltage of the power source (voltage from beginning to end), ...
1
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1answer
64 views

Radios and Power [closed]

RF newbie here. Lately I've been experimenting with RF. I built some simple oscillators, managing to get a tank circuit working as well as buffering the 1 megahertz output of a tin can oscillator. ...
2
votes
4answers
115 views

Series/Parallel DC circuit analysis training issue

I'm blocked in this exercise. I don't get how I can compute R1/R2/R3 voltage. Here's the schema : simulate this circuit – Schematic created using CircuitLab So I was able to calculate ...
2
votes
2answers
73 views

Current divider rule calculation issue

I'm doing the exercises from Wisc-Online. This one I think they are really great to learn and practice and have already done a bunch of their practical trainings. But here I'm starting to be crazy. I ...
0
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2answers
158 views

What does common mode voltage stand for in an instrumentation amplifier?

I was reading a text about instrumentation amplifiers. I couldn't find any easy explanation what really common mode voltage means and its importance.
1
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3answers
197 views

How does a domestic appliance “know” how much current to draw?

I have a small wall plug which takes 240V 50Hz AC from the mains, and can give me 500mA 5V DC. I suspect there is a transformer stepping the voltage down and a bridge rectifier converting the AC to ...
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1answer
57 views

How would i go about finding Rl when rl is r3

How would i go about finding Rl :/ I'm so lost iv looked for examples and all they have done is confuse me
6
votes
4answers
184 views

Another question concerning transistors

I know it's been asked 1,000,000 times how/what/why transistors work and I feel like I've read every answer but I still struggle with the basics. The struggle for me is the difference between ...
2
votes
4answers
207 views

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. ...
15
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6answers
988 views

Do electrical devices “take what they need”

One concept of electronics I have a hard time understanding is if things like motors, actuators, solenoids etc. use as much power as they need or what you give them. If a motor needs 12 volts and ...
0
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0answers
123 views

unity opamp - what it did for my digital volume control circuit

simulate this circuit – Schematic created using CircuitLab So I took apart the control pod for my 5.1 surround sound logitech speakers. Inside I found a 50k pot for the volume. At first I ...
3
votes
2answers
126 views

Differential equation into circuit and back - good book

I have had some electronics, but we only built our circuits and then measured the input / output signals with oscilloscopes... Today I found an interesting question on physics stackexchange where ...
8
votes
3answers
389 views

How does control theory apply to my real-world processor-controlled boost converter?

I have a limited understanding of control theory. I dealt with poles and zeroes and transfer functions in school. I've implemented several microprocessor-based control schemes for DC/DC converters. ...
7
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2answers
328 views

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 ...
1
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2answers
133 views

How and why is “floating input” a valid state for RF/IR encoder IC's?

RF/IF encoder/decoder IC's such as this one, will accept the address-pin in one of 3 states: Floating High Low As per this excellent answer, I believe "Floating" input can assume either High or ...
1
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1answer
153 views

Calculate current in branch using Thévenin's theorem

E1 = 20 V E2 = 5 V R1 = 10 Ω R2 = 20 Ω R3 = 10 Ω R4 = 10 Ω R5 = 5 Ω Calculate Ix. It's obvious that the Thévenin's theorem should have been used, but the implementation is a bit ...
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1answer
162 views

How correct is electric theory taught in school? [closed]

http://skeptics.stackexchange.com/questions/15779/is-the-electric-theory-commonly-taught-completely-off I made a question on skeptics about homepage, that made some pretty big claims about electric ...
5
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5answers
548 views

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 ...
0
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2answers
117 views

What idea/field in electronics is revolutionary nowadays [closed]

i realize that back then in the 30's-40's Von Neumann architecture was revolutionary, parallel at MIT, information and communication theory, and vacuum tubes were revolutionary fields, in the 70's ...
1
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2answers
190 views

Basic circuit analysis - diferential equation

This is the circuit I got from an example in a book "Practical Electronics for Inventors", on page 48: How can one understand that \$0=R\frac{dI}{dt}+\frac{1}{C}I\$ implies ...
4
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0answers
70 views

What course of study is important for someone wanting to make analog audio equipment? [closed]

I do not have a background in electrical engineering. I do have experience building audio equipment from kits and I can build circuits from schematics diagrams. What I would like to do is to be able ...
1
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2answers
304 views

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 ...
3
votes
4answers
421 views

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 ...
0
votes
2answers
284 views

What sort of applications does the normal distribution have in electrical engineering? [closed]

Need to know just two. Sorry for posting this here (arduino). Seems there isn't a soft-questions tag. Thank you for your help.
4
votes
3answers
2k views

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 ...
-1
votes
1answer
223 views

Z-parameters. Is Z12*Z21 always greater or equal zero if a circuit has only resistors? [duplicate]

Possible Duplicate: Is equivalent resistance always lower if we add a resistor to a passive electronic circuit? Since my last question was probably badly formed and misunderstood this is a ...
0
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2answers
154 views

LC circuit poor man theory

Ok, let's suppose we want to explain the resonant frequency of an LC circuit. By kirchoff laws is not so difficult ending to the equation: By using the Wolfram alpha engine I end up with the ...
0
votes
2answers
508 views

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 ...
5
votes
2answers
181 views

Voltage divider ambiguity

considering the following circuit : ...
2
votes
2answers
980 views

AC Voltage source terminal polarity and grounding

Ill try to make it as clear as possible. This may seem like a simple question, but it is something that I havent quite figured out. It has to do with polarity on the leads of an AC source. Every book ...
2
votes
2answers
779 views

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 ...
3
votes
1answer
290 views

Why does a transformer's ratio change?

I've connected various transformers to a circuit (one at a time) in reverse (power supplied to secondary) and I measured the voltages at both windings and found ratios very different from the ones ...
7
votes
4answers
4k views

RC differentiator circuit explaination

This is the circuit of a basic RC differentiator, with the input/output voltage waveforms. First of all, I don't understand why there is decrease in the output voltage (discharging of charge from ...
10
votes
3answers
451 views

Is electronics driven by scientific papers?

Is electronics driven by scientific publication, similar to other academic fields? Two famous publications I came across, Gordon Moore's seminal paper, and Leon Chua's discussion of the memristor, did ...
6
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2answers
491 views

What is a mutator?

I'm reading this paper by Chua on the memristor. He claims that Using a mutator, a memristor with any prescribed phi-q curve ...
4
votes
2answers
312 views

Why is flux-linkage a fundamental circuit variable?

In his paper Memristor - The Missing Circuit Element, Chua theoritizes the memristor based on observations relating to what he calls the four fundamental circuit variables, namely, the current ...
1
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2answers
113 views

Amplifier theoretical analysis problem

I have this problem in a book and I've did good through the entire problem until I had to calculate current gain. I've been stuck for the past 30 minutes. The formula I get is different from the one ...
1
vote
2answers
354 views

I/Q (quadrature) carrier recovery

I was looking into I/Q demodulation, and when looking into the equations, I realized that the phase/frequency difference between the carrier and the LO in the receiver had an unwanted effect. The ...
14
votes
2answers
2k views

Noise and what does V/√Hz actually mean?

Noise figures in (opamp) datasheets are in expressed in V/√Hz, but Where does this unit come from, why the square root? and how should I pronounce it? How should I interpret it? I know lower is ...
1
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2answers
206 views

Is it possible to specify an equivalent RLC network for a loudspeaker?

Can an RLC network be defined that would behave in the same way as a theoretical loudspeaker? Since their behavior is frequency-dependent, would the values of R, L, and C also be frequency-dependent?
1
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2answers
967 views

How is phase angle calculated in an RLC circuit?

If I have a source with a phase angle, like this how may I count the phase angle of the voltages and currents across all the components, as well as the returning current? What is the angle between ...
3
votes
2answers
2k views

How is quasi peak calculated

As said in the headline, how is quasi-peak calculated? I was not lucky on google this time, so I will ask here. I'm just looking for the formulas behind the calculation, since I want to make some ...
6
votes
4answers
480 views

Physical properties of transformers

In class, we were given equations for the transformer in terms of number of turns primary/secondary and coupling coefficient K, however effect of distance between coils, presence/absence of core, and ...