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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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What is “Hardware-in-a-loop”?

I have a revision question which is something like this "Describe the “hardware-in-a-loop” cycle for the example of a Lego Mindstorm robot which solves a maze; the robot implements a “hand-at-wall” ...
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1answer
372 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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4answers
110 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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1answer
70 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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73 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
414 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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60 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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70 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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3answers
661 views

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 ...
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1answer
48 views

What are the differences between Greinacher and Bridge voltage doublers?

I was reading a wiki article on Voltage doublers, and wondered - what are principal diffirences between two following schemes: They all share same amount of components, but when and why should be one ...
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Help me understand what happens with the circuit when an AC signal is applied

Consider this circuit. Transistor is 2N2222A. Ic is chosen to be 10 mA. Hfe is 225 for that current. Resistors are calculated to have Vbe = 0.7V and Vc = 4.5V. I am trying to understand what happens ...
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How do I really calculate these resistors?

I am learning about it. I would like to focus on this circuit I am trying to calculate R10 and R11. I want Ic = 10 mA. Transistor is 2N2222A. This is an amplifier. If I understood how amplifiers ...
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2answers
53 views

Does a current source have a difference in potential?

I am doing a nodal analysis of this circuit. I have found that \$ V_A = 10 V \$ and \$ V_B = -20 V \$ is it possible to have a situation like that? I mean a difference in potential between terminals ...
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2answers
66 views

How do I calculate I2 by nodal analysis only?

I am trying to do a nodal analysis of this circuit. and I need to do this by nodal analysis only. I need to find \$ i_1 \$, \$ i_2 \$ and \$ i_3 \$. I have found that \$ i_1 = \frac{V_B - V_A}{R_1}...
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66 views

How do I determine the unknowns for this equation?

Suppose a series RLC circuit in series with a 12 V battery and a switch initially opened. R = 100 Ω, L = 100mH and C = 10uF. L and C are initially discharged. A t=0 the switch is closed. I want to ...
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1answer
135 views

What is the meaning of current at infinite time for a series RLC circuit formula

I am reading this doc. At one point, the author says the current equation form a critically damped series RLC circuit when a step function is applied is: \$ I_L(t) = I_{\infty} + (B_1 + B_2t)e^{-\...
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1answer
185 views

Degenerate circuit concept and its theoretical and practical implications

I came across with the term "degenerate circuit" when I was studying solving linear differential equations with Laplace transform. I have learned that a system is called degenerate when the ...
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1answer
42 views

How do I calculate the unknowns of the current equation for a RLC series circuit?

Suppose I was dealing with the following voltage equation for the RLC series circuit: \$ v(t) = Ae^{m_1t} + Be^{m_2t} + V_s \$ To know the values of A and B I would do the two initial conditions: ...
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6answers
557 views

What's the rationale behind these warnings about extension cords?

(Disclaimer: I've read the help center and I do understand that this is bordering on off-topic since it's about consumer devices. However I hope that I've managed to make enough on-topic by asking ...
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1answer
56 views

Trying to understand the transient current equation on a RLC circuit

I am reading this doc I see this magic happening on the third line of equations... How in the name of Math, does this \$ Ae^{st} \$ appeared there? Magic?
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1answer
91 views

MCU sinking current from a higher voltage source

In previous designs, I have used an MCU digital output to drive the lower side of a resistor ladder to the supply voltage, to prevent power consumption when the ladder is not being sampled: Schematic ...
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1answer
50 views

Is this negative resistor model valid for any type of LC self oscillating circuit?

Is the following negative resistance model valid for any type of LC oscillator? If not, what are the exceptions? Image Source is from here
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85 views

When deriving the instantaneous power equation for an AC power system, I get different answers depending on how I model the V & I signals. Why?

When I define \$v(t)\$ & \$i(t)\$ like this: \$v(t)=V_m\cos(\omega t)\$ \$i(t)=I_m\cos(\omega t-b)\$ where \$V_m\$=Voltage Amplitude, \$I_m\$=Current Amplitude, \$\omega\$=rotational frequency,...
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1answer
347 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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35 views

Understanding generator wear and rotor electrical measurements

I have a generator that I am attempting to fix, and I am getting readings that are out of spec on the rotor brushes. Per some instructional videos I found, I should be measuring 5V AC on the rotor ...
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1answer
75 views

Deriving resonance frequency of RLCC circuit

I am trying to determine the resonance frequency of an RLC resonator with added capacitor, as shown below: simulate this circuit – Schematic created using CircuitLab Two cases are easy to ...
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2answers
175 views

Does an LED’s free electrons ever run out?

I’m aware that LEDs are doped with impurities on each p-type and n-type material to increase the charge carriers of each semiconductor. My curiosity now is, how does each side continue to have extra ...
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1answer
261 views

Basic Theory - finding voltage between two points

I'm a neophyte here trying to learn using "Practical Electronics for Inventors, 4th Edition" (which received almost a 5 star review with over 500 reviews on Amazon). The preface of the book states "...
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2answers
378 views

Should the error term of PID be normalized?

By "normalized", I mean +/-1 ~= the maximum error the system can reasonably be expected to experience, or divided by the setpoint. Background: I am working on a PID controller for an SSR heater ...
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6answers
328 views

What is the voltage potential of ground during a short

During a short, is it possible for the voltage potential of the ground to change? Say for example, we short a 9V battery, how does the ground stay at 0V and not become 9V?
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159 views

Step Response of Ideal Inductor with Current Source

I'm taking an electronics course to get a physics minor (I'm an applied math major) and today, the professor shows a diagram of an ideal current source connected to an ideal inductor. Crazy stuff I ...
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resistance and current [closed]

I struggle to understand how if I increase the resistance in a circuit, it requires less current, based of ohms law.
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1answer
537 views

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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4answers
469 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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3answers
664 views

Doubling the voltage to a capacitor doubles the stored charge but does not make it charge slower. Why not?

This is a slightly theoretical question. If you charge a capacitor from say a 3V battery you get Q charge in T seconds. If you double the voltage to 6V you get 2Q charge also in T seconds. My ...
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1answer
117 views

Output resistance with no lambda SPICE parameter

I have a simple current mirror and am trying to find the output resistance in OrCAD. Somewhere I saw: $$R_O=r_{ds}={1\over g_{ds}}$$ Using this formula and the SPICE bias file, I get a theoretical ...
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1k views

Moore vs mealy, why the output is delayed in the former?

I am not an engineer (software developer myself) but would like to understand why moore machine output is delayed. I know that in Moore's machine, output depends only on the state, while in Mealy's ...
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5answers
242 views

Can I treat two identical capacitors with capacitance \$C\$ in parallel as one capacitor with capacitance \$2C\$?

Consider a circuit as shown with a battery, $$ V_b $$ and two identical capacitors $$ C_1, C_2 $$ (with C_2 being the one that's off to the side). Both have the same capacitance C. The resistor ...
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2answers
292 views

Should Kirchhoff's Law be changed to account for information removal? [closed]

If I have a simple DC circuit consisting only of an LED output, how does Kirchhoff recognize the fact that information has left the loop? Since, in accordance with relativity(?), you can't have ...
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2answers
55 views

What is the main carrier in a semiconductor with n-type material being electrons and p-type materials being holes?

Not even gonna lie this is for a crossword. it is a 15 letter word. I have searched online, in my textbooks and I cannot figure out what it is. Closest I've found is Extrinsic Semiconductor but it's ...
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2answers
635 views

Does electricity always flow in a closed loop and why does current flow to ground?

I have been taught that current flows in a closed loop back to the source. And with electrical distribution, current flows to ground because the whole grid is effectively grounded back to the source. ...
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What are (if there are any) the major applications/implications of relativistic electrodynamics in engineering? [closed]

I was wondering about the relativistic and covariant formulation of classical E&M and Maxwell's Equations. Does they have any major implication in engineering (not exclusively talking about ...
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4answers
332 views

Why earth ground connection does not leak current?

This seems like a question which has been asked multiple times on forums. I researched the problem but I still was unable to figure out the answer which I can at least intuitively understand. So in ...
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0answers
69 views

Connecting capacitor to the ground and potentials question

I am a newbie trying to enter the world of electronics and currently struggling with getting a good grasp of basic concepts of electricity. I understand that electrons which usually produce the ...
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2answers
743 views

How to calculate value of R2 in this circuit?

I'm reading a Floyd electronics book and working through some problems. This one has me stumped however. I already know the answer as it's given in the book (110k). However, I don't know how to ...
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1answer
278 views

What is behavior of this virtual ground circuit when sourcing/sinking current?

simulate this circuit – Schematic created using CircuitLab This is the virtual ground circuit from a battery-powered headphone amplifier(direct link to schematic PDF). What is the behavior of ...
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2answers
91 views

Calculating Thevenin Resistance

I am having difficulty calculating the Thevenin resistance of this circuit I know I need to replace the batteries with links but then I am confused about how to approach R1,2 & 3 in terms of ...
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1answer
116 views

Simplifying capacitor input network

For a design I am working with a capacitive feedback network. I can't show you the actual network, but I intend this to be a more general question as it should be applicable to any input network. ...
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3answers
73 views

Theory: Creating “LPS” transmitter for GPS receivers

As I understand it, GPS works by having transmitters with known locations send a timestamp, and calculating the time it took to receive it, so that you can triangulate your own position, (essentially ...