# Questions tagged [equation]

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### Theoretical equation to describe capacity fade

https://www.researchgate.net/publication/357842717_How_do_Depth_of_Discharge_C-rate_and_Calendar_Age_Affect_Capacity_Retention_Impedance_Growth_the_Electrodes_and_the_Electrolyte_in_Li-Ion_Cells I am ...
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### RC circuit equation why have negative sign

I'm reading a book named The Art of Electronics. What are some of the features of circuits with capacitors? To answer this question, let’s begin with the simple RC circuit (Figure 1.31). Application ...
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### Noise added by an amplifier when deriving Friis's formula

I have been asked to derive the equivalent noise factor for a cascaded system of two amplifiers. Here is the figure of the system (assuming a general configuration where $G_1$ and $G_2$ are ...
31 views

### I have problem with finding the equation of AC to DC voltage for three phase five wire rectifier [duplicate]

I am writing a thesis about telecommunication tower. A problem came up when I examined the power supply. Most telecommunication equipment uses -48V DC and my supervisor wants me to add the equation ...
174 views

### Simple example of first order ODE and Operational Amplifier

Hayt's (8th edition) Engineering Curcuit Analysis (Chapter 9, p360) contains an illustration of Operational Amplifier solving $\frac{d^2v}{dt^2} = -9v$. It is hard for me to understand how it was ...
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### Shockley equation of an E-MOSFET with a B instead of a K

I have a question about the following homework exercise. I have no clue what B means in this equation. I could not find meaning of it in google nor in the books. Could someone link me a resource or ...
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691 views

### Why does this op-amp circuit show current flowing like that?

This image shows an op-amp being powered. Is there any reason why it shows current flowing from the negative side of the bottom battery into the op-amp or why it shows current flowing from the ...
102 views

### A circuit fulfilling equation

I am curious about establishing a circuit that satisfies the equation below: −Vout =3⋅Vsource + 2000 ⋅ Isource I tried to use an operational amplifier but could not ...
186 views

### How to find the voltage of the coil in this RLC Circuit?

I am looking for the voltage of L1. What I tried to do is this: Vsource = I(R1+R2+1/iwC1+iwL1+iwL2) Equation 1 Vsource = IR1+IR2+Q/C1+L1dI/dt+L2dI/dt Equation 2 Equating 1 and 2, I(R1+R2+1/iwC1+iwL1+...
146 views

### Linear line on loglog plot

I'm trying to plot a -20dB/dec line on MATLAB but can't seem to get it correct. I know that a linear line in a loglog plot is actually an exponential curve in the linear scale. So writing a y = mx + ...
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1k views

### Low Percentage PWM LED Brightness (Equation?)

I have a 5 V embedded circuit where a 10 kΩ pot controls the duty cycle of an LED. I noticed that when the duty cycle is only 0.39% (or 1/255 bits), the LED is still perceptibly bright. I'm looking at ...
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177 views

### Electric field of line charge and coaxial conductor

I'm currently having trouble understanding why the electric field inside a coaxial conductor (assuming that the charge is evenly distributed on the inner and outer conductor and opposite signed) is ...
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1 vote
154 views

### Crystal capacitor selection equation

So I've recently discovered that when a crystal oscillator says "20pF", it does not mean "use 20pF caps". (Despite that the design I made under that assumption appears to work.) ...
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1 vote
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### Nodal Analysis with constraint equation

We were asked to form the node-voltage equations of this circuit. But how can I form the equation that specifies the constraint imposed by the controlled voltage source on the nodes it is connected ...
1 vote
84 views

### Seeking clarification on equation used in MIPS assembly problem

I'm currently studying MIPS assembly code, and I'm having trouble understanding the solution for question (b) of a particular problem. I was hoping someone could help me clarify a specific part of the ...
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1 vote
331 views

### Sallen-Key LP design algorithm

I am facing this design from Analog Devices: Image source: Analog Devices - Mini Tutorial MT-222, Sallen-Key Filters I don't understand how they reach the value for the coefficient m. I did a sanity ...
• 1,431
487 views

### Deliyannis-Friend design: where is my mistake?

I am losing my mind over this. I am trying to design a Deliyannis-Friend section and I am stuck in a loop and don't know what to do. These is the circuit and its equations. Based on this I have ...
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1 vote
118 views

### Multiple feedback design methodology

I am having trouble finding a step by step approach to the MFB filter. I came across a tutorial from Analog Devices but I am struggling to find what is the reasoning behind their equations, and can't ...
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### How can I solve these two equations to determine resonant capacitors for a wireless charging coil?

My questions: What are S, D, and the apostrophe above Inductance? Is the equation looking for the inductance of the coil or the circuit? Once I know what S and D stand for how can I determine their ...
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1 vote
217 views

### EE applications for parametric equations

I am trying to learn electronics, specifically audio amplifiers. I paused my study after realizing that my math skills (or rather my lack of math skills) were holding me back. I undertook a study of ...
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### Solving for Normalised Frequency with LLC Gain Equation

I would like help solving the equation below for Fn within matlab or Octave (preferably). What I know is the following: MG = 1.3 QE = 0.52 LN = 3.5 Because I am following this reference(https://www....
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1 vote
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### Averaged first-order difference of Vout in QUCS

I am looking at a very simple LM317 voltage regulator circuit to drive a motor (represented by R3 in the diagram). I want to be able to sweep capacitor C2's capacitance and plot the mean 1st-order ...
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### I want to understand this circuit and these equations

I have a hard time understanding this circuit that I’ve been given because of the way it looks. I don’t know why, but electrical circuits seem very confusing to me even after reading the chapters to ...
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1 vote
539 views

### Equation for diode saturation current in photovoltaic cell model

I've been looking for mathematical models for photovoltaic cells. Most of the references I've found use the following circuit to the model the behavior: Particularly, the diode current is modeled ...
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### Help understanding equation

I'm trying to understand the following equation: 1/(2π·R·f) --> 10 μF, f ~ 0 Hz It is in this schematic in the bottom left. I can't seem to find a 10 μF ceramic/film capacitor. I did use ten 104 ...
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### Writing differential equation for second order RC circuit

I am trying to write an RC circuit's response in the form of a differential equation, but I can't find a solution and I haven't found a similar example on the internet. The circuit is as follows: I ...
4k views

### Length of wires after they are twisted?

I have looked all over and haven't seen any questions about this topic. This may be more of a mechanical question, but none the less, the dilemma on hand is how does twisting a set of equal length ...
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### Transformation of an equation

I'm not unterstanding what I'm doing wrong with this (simple) transformation (solve for Rv): I subtracted both sides by IL*RV, then I divided both side by -IL. This is my solution: But why is this ...
129 views

### What does V xtor (max) mean in this equation?

This equation is from an application note for the UC3825B. Title asks the question.
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### What would be the loop equation for circuit including resistor, diode, light emitting diode?

I am new to electronics. What would be the loop equation for the following circuit? How would I find the current through the LED and the silicon diode in the circuit? Any help would be appreciated.
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### Error with creating a equation in ADS with the variable already defined on the schematic as Var

I am trying to create a equation to plot the eye diagram from the voltage node Vout As I define the equation, it tells me that the "Tbit" is not defined!? I wonder why because I have already ...
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50 views

### Magnitute and phase, operational amplifier

I was solving exercises related to operational amplifiers and I got to a part where I am not sure how I am getting the arg part of the result. Can someone please explain this to me. Thank you very ...
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4k views

### The probability that an electron occupies the fermi level at 0K

I was trying to find the probability that an electron occupies the Fermi level at 0K. Fermi function: {exp[(E-Ef)/kT] + 1}-1; (k = 8.314 J/mol/K) According to my calculations, the answer would be 0.5. ...
215 views

### Any short formula for PCB trace capacitance when w/h <<1 [closed]

I have this formula/equation e(w/d) for capacitance of PCB traces (parallel plate). But as it appears, this equation is valid for the assumption w/d>>1 (much greater). And multiplying 11.3 with ...
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436 views

### Finding the current through an inductor in a second order circuit?

Assume that the circuit has reached a steady state. I'm trying to find the current through the inductor at some time, t, which should be a function of t. I'm having trouble creating a system of ...
1 vote
906 views

### Calculating time constant of a less than 50 % duty cycle 555 timer circuit

I am building a 555 timer circuit that generates a pulse for my servo motor. The circuit in mind looks like this: I got this circuit from this site, and it uses a (1N4148) diode, -the same one I ...
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171 views

### ohm's law and power equation

I have a question about electricity. I know that transmitting power over long distances is better in AC. I also heard that the voltage needs to be high to reduce losses. I want to calculate this for ...
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### Switching DC battery on ideal choke?

(Google translation). A switch is activated at the instant t = 0 in a series circuit containing a battery of voltage U (ideal) and an inductor L (ideal). I am in doubt with the answers I have found on ...
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398 views

### Inverter Fourier analysis

I have an inverter circuit like below: I will use bipolar control method to produce sine wave. Our teacher said us prove basic harmonic of inverter is equal to multiplying of modulation index and Vd, ...
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189 views

### In parallel current sources with capacitors

I have to get the correct equation of multiple parallel non-dependent current source in parallel with capacitors, as i seem to find the correct solution, the resulted simulation in LTSpice shows ...
132 views

### (Almost) Wheatstone bridge

I have this wheatstone bridge: Rmeasure is the impedance of my voltmeter between A and B. My goal is to have the equation of R1/R2. Because Umeasure changes if $R_2$ or $R_1$ changes. the values ...
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### Is there software with CAS to solve drawn electrical circuit in form of differential equations which describes that electrical circuit?

Is there any software with Computer Algebra System to solve drawn electrical circuit in the form of differential equations which describe that electrical circuit? Or to write symbolic solution (...
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### I think I found an error in an electronics book. Are my equations correct here?

I'm reading Practical Electronics for Inventors, 4th edition, to freshen up my long forgotten knowledge of electronics. I love the book so far, but I just came across an equation there which seems ...
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### Confused on the notation from a TI datasheet

So I'm trying to implement this IC onto a controller that I'm designing: https://www.ti.com/product/UCC5350 I understand for the most part how to apply it, I am just lost on one key part The specific ...
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1 vote
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### What equation should I use to calculate inductance of wire coil?

I've been working on a project recently which requires me to build an inductor, however in my research I found many different equations (with a range of variables used and giving very different ...
149 views

### BLDC motor equations

I've read this article about driving gimbal motors. I have some questions about these equations: I don't understand what "ψ" and "Lω" means and generally i don't understand how to ...
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### RC Circuit Equation

I am a beginner electronics hobbyist. I found this book called Basic Electronics for Scientists and Engineers and I am currently reading on RC circuits but got stuck trying to understand the equation. ...
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161 views

### Differential equation of the NPN transistor configured as a voltage divider

The mathematical model in AC of the NPN transistor is represented by the pi model which is only one resistance in parallel to the resistors of the divider and the DC source in parallel to the ...
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1 vote