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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Designing a common emitter audio pre-amplifier

I am trying to design and simulate a common emitter audio pre-amplifier using 2N2219 with characteristics based on industry standards (audio frequency response, etc. Corner frequency must be less than ...
73 views

AC voltage and frequency as complex number?

For some software I am writing, I coded classes of electrical systems that receive a voltage and return the current response. For the DC case that's easy: I pass a real number as argument, the voltage,...
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Why BJT thermal voltage can be not equal to kT/q in SPICE3

In SPICE, apart from effects such as basewidth modulation and base-collector leakage the collector current is given by the expression (according to the original SPICE2 PhD work) But actually, ...
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How to show that all power in an RC circuit is delivered to the resistor

I am new to electronics and I've been working my way through the Art of Electronics. I've have been able to complete all the exercises up to this point but I have been struggling on this one. Right ...
1 vote
128 views

Why is my best placement of a directional antenna so weird?

I moved to an offgrid house with a 3G/4G repeater, with a short, enclosed directional antenna. It was wobbling and poorly mounted on an unstable wood plank at the base of a window, so I decided to ...
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What would a theoretical Group II, Group IV Transistor's Properties be? [closed]

This question is for more than a theory. I would like to disprove that what I'm working on is not a Group II, Group IV transistor. I know they CAN exist. I don't know why they don't exist or what ...
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Transistor analysis with 2 voltage sources

I want to calculate the DC currents of this circuit, and based on the superpostion theorem, I thought of ignoring Vqdc9 first, in order to calulate I2, I21 and I22, as shown in figure 2. After that, I ...
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Parallel LC circuit Q factor inductance role

I'm wondering why Q factor in parallel LCR circuit is proportional of C and inversely proportional to L according to the formula $Q = R \sqrt{C/L}$ completely lost here
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What are the modern uses of SPI and I2C protocols [closed]

I have been using I2C and SPi for a few years now, but as I begin working with USB, I realize it is much faster. I still see devices with 2 MCUs that could potentially communicate faster with USB, but ...
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1 vote
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Meaning of the determinant of an ABCD transmission matrix

In a thesis, [1] I found the following statement: To determine [characteristic impedance and] dispersion relationships for an arbitrary reciprocal network having the transmission matrix  \begin{...
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Algebraic Data Type

I understand the concept of algebraic data types, but I don't see in what context they are useful or when they would be beneficial. When should I consider using them and how are they useful in ...
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Diodes and resistors theory

I came across a problem which I cannot calculate by theory. How does this circuit with diodes and resistors work? In the above diahram, I can calculate the current simply by subtracting the voltage ...
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Early Deadline First (EDF) scheduling in real-time systems feasibility test proof

I am trying to prove Theorem 6.2 on page 127 of the book Real-Time Systems by Jane W. S. Liu: http://www.cse.hcmut.edu.vn/~thai/books/2000%20_%20Liu-%20Real%20Time%20Systems.pdf It is based on Early ...
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1 vote
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How to deal with a negative resistor in Z parameters of a passive network?

This question is so basic but for some reason I am not seeing it: Assume an arbitrary passive 2-port network having only isotropic materials. This implies S21=S21 and Z12=Z21 (see https://www....
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Possible to control a transistor by BC terminals?

I'm thinking about a strange working mode: the CB part is forward biased and trying to control EC current by CB current. EB is reversed. May it work? Transistor is BJT.
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Why passive component has better drift characteristics than active components had?

I came across this paragraph in the classic reference Op Amps For Everyone by Ron Mancini where it says on the first page: Many attempts has been made to make a stable amplifier, but temperature ...
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Common emitter amplifier's $R_C$ breaks

What happens if the collector resistor breaks (its value goes to infinity) in a textbook example circuit? I assume that $I_C$ hits zero, $U_{CE}$ decreases until the transistor goes into ...
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Why is power of a signal equal to square of that signal?

Is there any logic as to why the power of a signal $\mathrm{x(t)}$ is taken as $\mathrm{x^2(t)}$? I searched everywhere and there's no clue. My professor told: "It's a standard result so shut ...
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Imagine a thermionic diode connected in series with a resistor $R$. The circuit is hooked up to a voltage source $V$. The diode conducts a certain current $I$ and \\$\Delta V_\text{diode}\ + \...