# Questions tagged [math]

Math or Mathematics is the abstract study of topics such as quantity (numbers), structure, space, and change.

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### Overdrive voltage of NMOS vs PMOS

I'm confused whether the overdrive voltage for an NMOS/PMOS transistor is supposed to be $$V_{ov} = V_{gs}-V_t,$$ $$V_{ov} = V_{sg} - V_t,$$ or $$V_{ov} = V_{gs}-|V_t|$$ and whether it matters ...
73 views

### System of First Order ODEs for a Parallel RLC Circuit

I understand the behaviour of an RLC Circuit in Series can be modelled by the equation: $$L \frac{d^2Q}{dt^2}+R\frac{dQ}{dt}+\frac{Q}{C}=0$$ Which can be represented by the system of First Order ...
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1 vote
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### Finding an analytical expression for a current distribution for conductors in parallel

Recently, I tried to set up an experiment at home to study what path the current takes at different frequencies for the circuit below. I think this will be a fun project, but I'll need your help. I ...
146 views

### Calculating inverse fourier transform and graphing it

Recently I stumbled upon Fourier transforms which means I am very new to it. I've been given a question from my professor to find the inverse Fourier transform of a frequency spectrum which is given ...
1 vote
116 views

### Construction of a Lagrangian function for a circuit

I was reading the paper "Introduction to quantum electromagnetic circuits", by U. Vool and M. Devoret and I am stuck in the construction of a Lagrangian function for the example LC circuit ...
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### Self-capacitance formula for planar inductors

I'm designing a Rectangular Planar Spiral inductor with a rectangular conductor cross-section (it's not made from cylindrical wire) for use in an RLC circuit (an NFC tag), and I can not optimise the ...
1 vote
161 views

### How to calculate the resistor values for the zener diode and the BJT base?

I try to convert ~12V signal from a car button (the input voltage can be from 10V to 14V) to a logic level signal for MCU, but the signal should to be inverted (1 = 0, 0 = 1). Below is my schema, but ...
747 views

### What do the poles and zeros of a system physically represent?

I've been working with transfer functions and control models for a while, but I never really have gotten an intuitive understanding of what the poles and zeros of a system really represent. I was ...
52 views

### How did he calculate the error in this example?

He found an error of about 18%. What is the error formula used in this example? From section 1.5.1 of the book Design of PLLs by Behzad Razav.
63 views

### Where to start theremin project

I am studying electronics and would like to design a theremin that uses discrete components. I have read that RF oscillators such as those needed for a theremin are not likely to work if built on a ...
31 views

### Am I solving this capacitance equation correctly?

The following is a datasheet excerpt about satisfying the clock-signal requirements for a low pass filter When using the internal oscillator, the capacitance (COSC) from CLK to ground determines the ...
94 views

### Do not understand how to multiply exponential values

Show how the current i_3=7e^(jπ/4) can be multiplied by Z_3 (in exponential form) to give the voltage through the branch. Calculate using exponential values, then convert to polar so show value and ...
51 views

### Digital value calculation clarification

I've done some math and I'd like someone to clarify if my math is right. I have a audio test chamber which the speaker is connected to and can tell me the dBSPL value that the speaker outputs. So i ...
1 vote
196 views

### Calculating PID gains analytically on a first order plant (RL Load) - is this possible?

Edit: Just for a bit of context. I have another higher order plant model that has a derivative branch in its control. I thought I'd just implement PID control on the current in an RL load I have just ...
557 views

### Valid or invalid logarithm operation?

Is the following operation valid or invalid? The question is to calculate receiver gain and this is one of the steps I got confused. The receiver sensitivity is given -45dBm and transmitted power is ...
1k 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 ...
57 views

### How to calculate break down amperage of wire based on length, resistivity, and cross sectional area?

For this question, I'm assuming the current is continuous, the shape of the wire is cylindrical, and the air is STP air. (I bridged a fuse with a piece of soldering wire, and I'd like to be stupid in ...
57 views

### Nodal Analysis wrong result

I'm trying to solve this problem, where I have to find the voltages v1 and v2. This is the circuit: This is what I came up with: Then I calculated the inverse matrix using WolframAlpha. Finally, ...
1 vote
83 views

### How to convolve these two signals?

I tried to convolve these two signals (top image). I’m not sure if I have done it properly. My partial answer (further below) is wrong.
41 views

### 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 ...
1 vote
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### LLC initial current and voltage estimate from the equation

There is a paper called Real Time Hardware-in-Loop Implementation of LLC Resonant Converter at Worst Operating Point Based on Time Domain Analysis I am trying to derive equations 25 and 26 from this ...
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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 ...
80 views

### How do I mathematically model a magnetic levitation system?

I am working on a magnetic levitation system project using PID control, and I am getting confused as to how I am supposed to mathematically model this system for my paper. Where am I supposed to start?...
From the beginning of Practical Electronics for Inventors: This makes sense to me up until the term 1A = \left( \frac{1C}{1s} \right) \left( \frac{\text{electron}}{-1.602 \times 10^{-19} C} \right)\$...