# 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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### 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 $I=I_0e^{\frac{-t}{RC}}$?...
0answers
91 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 ...
3answers
2k 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 ...
4answers
1k 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 ...
2answers
1k 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.
4answers
14k 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 ...
1answer
795 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 new ...
2answers
222 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 ...
2answers
3k 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 ...
2answers
333 views

### Voltage divider ambiguity

considering the following circuit : ...
3answers
4k 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 ...
2answers
3k 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 \...
1answer
438 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 ...
5answers
25k 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 ...
3answers
570 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 ...
2answers
1k 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 ...
2answers
670 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 <...
2answers
126 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 ...
2answers
1k 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 ...
3answers
44k views

### 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, ...
2answers
655 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?
2answers
4k 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 ...
2answers
14k 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 ...
4answers
2k 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 ...
2answers
2k views

### RC/RL circuits and frequency selection

We have a lab that wants us to simulate an RC and RL circuit, and then a CR and LR circuit (series). From reading it is my understanding that reversing order of components results in reversing the ...
2answers
420 views

### Computing rlc circuit in parallel

So, if a resistor, inductor and capacitor in series sum algebraically, how do they work in parallel? Is it $\dfrac{1}{\dfrac{1}{R}+\dfrac{1}{\dfrac{1}{L}+\dfrac{1}{C}}}$ ? Many thanks in advance ...
1answer
334 views

### How can I describe the behavior of an inductor without reference to a magnet?

In class we have been given an exercise to simulate capacitance, inductance, and resistance without reference to - well, without refernece to much of anything. The resistor is straightforward, ...
4answers
1k views

### How Does FM Get Around the Gabor Limit?

The Gabor Limit states that it's impossible to simultaneously localize a signal in both frequency and time. FM communication modulates the instantaneous frequency of the carrier in step with changes ...
3answers
17k views

### What does E mean in this instance?

On all about circuits I keep seeing E in tables like this: In the table I and R make sense with the units. But the E doesn't. So where does it come from? I was looking at this article on ...
3answers
219 views

### A few questions regarding B/E-fields in practical circuitry

I have been trying a few learning resources to help unlearn some of the notions that electrons flow through as energy. Chiefly this resource is what I have used: Amasci - IN A SIMPLE CIRCUIT, WHERE ...
4answers
10k views

### 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 ...
2answers
18k views

### Capacitor Discharge through Constant Current Source

I was just thnking of how to model the voltage decay from a fully charged capacitor through a constant current source (CCS). A good approximation to this would be to model the constant current source ...
3answers
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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 : ...
2answers
818 views

### A little clarification regarding voltages, and “real” current movement

To my understanding, the voltage supplies the potential, and free electrons are taken from ground? This makes somewhat sense to me, for example if something has a "positive" charge then it will ...
1answer
284 views

### What is the software used in this image(semiconductor simulation)?

If I interpret this correctly, this means there is some nice software to simulate various properties of semiconductors. Does anyone know what it is or alternatively what packages do the same thing?
3answers
765 views

### what is a thyristor

As part of my 2330 lv3 am required to know about thyristors. I just want to confirm my understanding is correct. A thyristor is basically similar to a transistor, only it stays switched on when it's ...
2answers
2k views

### Average Fanout of Non-Clock Nets

Xilinx ISE Design Suite gives information about the resources that a particular design uses. One of the parameters that is given to measure the estimated resources is "Average Fanout of Non-Clock Nets"...
3answers
3k views

### Are TRIACs symmetrical?

When debugging a circuit using a micro-controller and triac to control AC current I ran into an issue (the triac wouldn't switch off) that was only resolved by flipping the polarity of the triac. The ...
11answers
3k views

### Is there a dual of the transformer?

Capacitors and inductors are duals of each other. A transformer is made of two inductors, and transfers power through mutual inductance, through the magnetic near-field (right?) Also, you can vary ...
3answers
14k views

### How do I decide whether to use Kirchhoff's Voltage Law or Kirchhoff's Current Law?

When I solve questions, I usually get confused between when to use the Kirchhoff's Voltage Law (KVL) and when Kirchhoff's Current Law (KCL). Please help.
3answers
314 views

### Grokking oscillators

Can someone explain to me / point me to a good explanation of the theory behind an electronic oscillator? The Wikipedia entry explains what, but not how, which is what I need to know. TIA.
8answers
763 views

### Does a radio station main amplifier work at the speed of light?

I'm having an argument with a classmate and we can't agree. He tells me that it's not possible for the amplifier of a radio station to amplify the input signal "instantaneously" (at the speed of ...
5answers
2k views

### In theory, is it possible to make a logic gate that uses zero current?

CMOS greatly reduces the current draw of ICs because one of the complementary FETs is always in the non-conducting mode, so there is only a flow of current during the transition between states, which ...