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Questions tagged [calculus]

Anything related to (differential and integral) calculus, i.e. the branch of mathematics concerned with the manipulations of infinitesimally small quantities. Concepts from calculus are often used in engineering to build more complex and accurate models of physical systems than those which can be built using basic algebra alone.

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3answers
84 views

How to find mean value of square signal

I have a comparator circuit and I need to find the mean value of the output square wave. I have calculated it like this: \$Vmean=1/T*integral(U*dt)\$ from 0 to T and I got \$Vmean=-0.7896V\$ Can ...
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0answers
50 views

How to express a function in terms of singularity functions?

This is the question from the domain of the operational calculus related to circuit analysis. Here is the graph of the sawtooth function: It is asked to represent this function as a combination of ...
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43 views

Calculate U(t) when capacitor C1 charges C2 via a resistor R

simulate this circuit – Schematic created using CircuitLab The switch SW1 is activated at t=10s and charge from C1 is transferred to C2. The power supply charges continuously with 1kV 1mA. How ...
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2answers
310 views

Capacitor sizing for known current load

Apologies in advance for the long question, but I've hit a dead end trying to work through an interesting capacitor sizing problem. I'm hoping someone here can help. Problem Description I have a ...
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5answers
264 views

why does RC time constant happen to equal 1/e?

I understand that the time constant in AC RC circuits is defined the value of resistance (in ohms) x the value of capacitance (in farads). Indeed, ohms(R) x farads(C) yields time (seconds). $$\tau ...
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3answers
156 views

I have 3.1V LED 20mA and wire 20 or more [closed]

How you calculate how much Volt battery you need? Like: 20 x 3.1V = 62V ....or is it something else? I want to wire them in series manner.
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2answers
205 views

Cannot predict closed-loop gain of this amplifier

This is the circuit I am currently analyzing: (link to LTSpice file) I am trying to predict each stage closed loop gain and overall gain (with all loops closed). First thing I did is calculate DC ...
4
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5answers
202 views

Average of a periodic voltage

I know that this question is math related, but I still don't get why we can say the following formula holds: I've a voltage \$V:\left[0,\infty\right]\to\mathbb{R}\$ and \$V\$ is periodic with \$T\$....
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2answers
174 views

How to Find DC Step Response of Semi-Parallel RLC Circuit

Hi everyone, I find myself stumped on how to approach this problem since there is a resistor in series with the capacitor for what is otherwise a parallel RLC circuit. First off, I am attempting to ...
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1answer
216 views

Mesh Current Method Circuit Analysis For AC Transient and Steady State Solution of RL Circuit

Hi everyone, I'm trying to find the currents through each branch for the above circuit using mesh current method (as I don't really know how else to do it), and end up with two simultaneous ...
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2answers
103 views

RLC without Source, finding the value of Resistance given I(0)

A capacitor of 1.58mF was charged by a battery of 12V and lies on the ground of an abandoned radio station. During a storm, an old telephone cable fell from a rack and one of its tip got in touch with ...
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1answer
52 views

How to derive this formula from this schematic?

This is the voltage multiplier from the paper ,it said the rectified output voltage is given by \$ V_{out_i}\$= \$ V_{out_{i-1}}\$ +\$2(V_A-V_{ON})\$,\$V_A\$ is the AC voltage amplitude at the input;\$...
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1answer
283 views

Help in Thermal PAD and glue calculation (equivalence) in shared heatsink

Hello if I have 15 chips to dissipate 1W each (thus 15W in total), by math calculation, which of the next three possibilities is better: 1) using a unique shared heatsink @1.7K/W with 0.5mm thermal ...
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2answers
308 views

DC DC Boost Converter - Why that high Ampere?

I have a question for the electronic experts of you! I want to create an DC-DC boost converter circuit for a project to get from 5V to 12V. Calculated with help of this site: https://learn.adafruit....
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1answer
821 views

Using Fourier transform to solve current in a circuit with initial condition

I am trying to solve the inductor current for the circuit below by using Fourier transform instead of Laplace. The purpose is to see if Fourier transform also works for problems with initial ...
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1answer
3k views

Meaning of Sigma in Laplace transform

I found the question below in a forum and I also have same problem. Unfortunately, there is no answer at all so I will post it here hope someone could make it clear. A gain relation in a circuit of ...
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1answer
64 views

Find error in mathematical proof of electromagnetic fields

This is wrong but I can't figure out what is wrong, could someone help me find the errors.
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1answer
242 views

Confused about MOSFET math

So after the channel is pinched off in a MOSFET the equation that relates current and voltage through the MOSFET changes. What I am confused about though, is why in the derivation of this new formula ...
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3answers
125 views

About calculus and resistors [closed]

how can you know the voltage of a circuit, after passing through a resistor? for example there is a 5 volt supply and a resistor of 120 ohms, what will be the voltage after passing through this ...
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1answer
288 views

Ferromagnetic core with air gap

N=200 I=N*8A l=20cm=2*10^-1 d(delta)=1mm=10^-3 M=? M=(B/μ)-H How can I get the vector of magnetization? The relative permeability is not known. Everything I ...
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2answers
160 views

How does the definition of electrical power follow from the chain rule?

Just a small question for clarification. Here's what I know: current I is defined by \$I = \frac{dq}{dt}\$ where q is charge and t is time voltage V is defined by \$V = \frac{dw}{dq}\$ where w is ...
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0answers
2k views

Why do simulated results differ to calculated results?

Why, when using a program such as multisim, do the simulated results within the program differ slightly to those calculated analytically. Would there be any reasons other than rounding errors in ...
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3answers
5k views

Choose the better values (in terms of range) for resistors in this non-inverting op-amp circuit

These days I'm looking at operational amplifiers; from what I've seen, implementing them in a circuit is quite simple, at least when they are connected as "non-inverting". Determining the gain/...
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1answer
131 views

Trouble calculating time to drain a capacitor

Introduction I'm having trouble producing an equation that involving my MAX756 boost chip, a load and my 1.5F capacitor. Basically I'm trying to find out how long it would take for a 1.5F capacitor ...
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1answer
113 views

Explain this line of working when solving for the maximum power of a load resistor

Please, can you explain this line of working from the maximum power transfer theorem: For maximum power dissipation in the load, the condition given below must be satisfied $$\left. \frac{d^2P(...
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3answers
6k views

Inverse Laplace Transform of RLC Circuit

The voltage across the power source equals the summed voltage across the resistor, capacitor, and inductor at any time (t). This is shown in the equation below: $$Ri(t)+\frac{1}{C}\int_0^ti(t)+L\frac{...
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1answer
3k views

What is the general form of a first and second order dynamic system, in laplace and time space?

I have some of the information, but a lot of it is missing and I cant find a clear answer on the web. The general form of a second order dynamic system is: $$\frac{d^2x(t)}{dt^2}+2\zeta\omega_n\frac{...
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1answer
380 views

Voltage calculation for the schematic [closed]

I would like to know how to calculate the output voltage for the following schematic. I would also like to see the calculations step by step. Right now I am not able to do this, I'm kind of new in ...
5
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7answers
48k views

How to Calculate the average of a Square Wave?

I could not figure how to calculate the average of a square wave. Consider a square wave of +5V from time 0 to 6 sec and -3V from 6 to 10 sec. On integrating from time 0 to 6 the average: 3.0V On ...
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2answers
1k views

Heating time of an aluminum plate

I'm designing a circuit for my 3D printer's aluminium heating plate (200x200 mm) and I wanted to be sure before buying resistors. Also, I'm using a Sanguinololu 1.3a. I want it to heat at 120° fast. ...
2
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1answer
2k views

Derivation of I_d of a self-biased JFET

I find that derivations of formulas are a lot more useful to me than just recitations of formulas. I'm looking at a self-biased JFET circuit, and I'm interested in deriving the quiescent state of the ...
5
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1answer
1k views

Need help interpreting a basic circuit question

In my Nilsson "Electric Circuits, 5th ed" book, there's this drill exercise near the beginning of the book. Here it is: Current at the terminals of the element is t<0: $$ i=0 $$ t>=0: ...