Questions tagged [math]
Math or Mathematics is the abstract study of topics such as quantity (numbers), structure, space, and change.
447
questions
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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 ...
2
votes
2
answers
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 ...
0
votes
1
answer
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Mathematical relation between \$I\$-\$V\$-curve nonlinearity and harmonic distortion spectral components
A nonlinear resistor has a bent/distorted \$I\$-\$V\$-curve. We can approximate its \$I\$-\$V\$-curve with a polynomial model such as:
$$I(V)=I_0 + \frac{1}{R_1}V + \frac{1}{R_2}V^2 + \frac{1}{R_3}V^3 ...
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0
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How to find the direction of phase difference of sine signals using multiplier phase detector?
I am using a multiplier phase detector like here 1to find the phase difference between two phase shifted sine signals, and I got the value of magnitude but how to find if the signal 2 is leading/...
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0
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19
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How do you calculate output voltage noise for reactive circuits?
For circuits without any reactive elements, like voltage dividers for example, it's a relatively straightforward process to find what the output noise will be due to any present resistors. First, I ...
0
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0
answers
38
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How do I calculate Io and n from the Shockley equation given two operation points?
In this exercise I'm given the Vd and Id in two operation points and I need to calculate Io and n from the Shockley equation. I've tried isolating Io and replacing it in the other equation but then I ...
0
votes
1
answer
42
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How we change equations in passive bandpass filters?
I tried it myself, but I couldn't understand how the equation ended up in the given form. After bringing it to that form, the cutoff frequency values can be determined, but since I couldn't do that, I'...
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1
answer
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I'm getting 11.547 kVA, but the answer is supposed to be 10 kVA. What am I doing wrong?
A 3-phase transformer bank consists of three identical 2300/230 V, 15 kVA single-phase transformers connected in delta/delta. The bank supplies a 20 kVA, unity p.f. 3-phase load. If one of the single-...
0
votes
2
answers
68
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How do we get the gain and cut off frequency values of the active low-pass filter?
I'm trying to find the gain and cut off frequency values myself. But I can't get the same result when fiddling with the formula. The last screenshot is from my own solution. Where am I doing wrong?
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3
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117
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Input impedance of a round straight copper antenna
I got some help from a discussion of yesterday about network impedance matching for transferring data between antennas (Basic RF signal amplifier). The discussion was about that the current and the ...
- 325
0
votes
0
answers
21
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Driving resistance in Arnoldi reduced order RC models
I am new to this community and I'm learning to write a model order reduction engine for a lumped RC network.
The network has a few nodes connected by a few resistances and capacitances. There can also ...
- 1
0
votes
1
answer
96
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How much time the load would take to drop 1 volt of source battery?
I am trying to figure out how much time a load takes to drop 1 V of the power source. I have a load (vehicle tracker) of 12 V 0.1 A (as per the datasheet) and a car ...
- 25
0
votes
2
answers
36
views
Correct way of referring to property of a component in an equation
What is the correct way of referring to voltage drop of a diode in an equation? For example I want to show the output voltage of the following circuit in an equation Imagine that the diode is labeled ...
- 755
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votes
0
answers
47
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Active clamp flyback current dip
There is a paper that discusses the ACF current dip. I have been attempting to derive the equation from the current dip equation following the method provided by the editor.
However, I have ...
- 555
1
vote
2
answers
63
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Analyzing the complexity of a number in the Arduino IDE
I'm working on a project where I'm linking a calculator (TI-84) to an Arduino (Nano) and I want some way of classifying or quantifying how complex a single number is (small whole numbers being very ...
- 313
2
votes
1
answer
36
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Mistake in calculation of RMS current flyback primary switch node
I'm trying to calculate the RMS current of a flyback converters primary switch node. The Waveform is shown below:
I'm okay with assuming it is a triangle wave with a duty cycle of 50%. The peak value ...
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1
vote
3
answers
154
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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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0
votes
1
answer
35
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Get a motor to move my camera based on a point in an image [closed]
Let's say that I have this image:
Obviously, the camera is pointing to the center of the image, but I need it to point to the center of the bbox. I need to calculate how to get my motor to move so ...
- 1
0
votes
1
answer
85
views
Power absorbed by placing 50 Hz appliance on 60 Hz source
We know that we can calculate AC power using
$$
S=VI^{*}=|S| \angle \varphi .
$$
Given that a grid works as constant voltage source, we can calculate the absorbed power in
$$
S = |I|^{2}Z = \frac {|V|^...
1
vote
0
answers
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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 ...
- 313
0
votes
1
answer
146
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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 ...
- 49
1
vote
1
answer
116
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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 ...
- 11
0
votes
0
answers
69
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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
2
answers
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 ...
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8
votes
3
answers
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 ...
0
votes
1
answer
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.
0
votes
0
answers
63
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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 ...
- 1,133
0
votes
1
answer
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 ...
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votes
1
answer
94
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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 ...
- 1
0
votes
0
answers
51
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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
1
answer
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 ...
2
votes
3
answers
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 ...
- 169
3
votes
2
answers
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 ...
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0
votes
1
answer
57
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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 ...
- 135
0
votes
1
answer
57
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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, ...
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1
vote
0
answers
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.
0
votes
0
answers
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
0
answers
29
views
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 ...
- 47
3
votes
1
answer
128
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Power system question: How do you derive the reactive power transfer equation?
I'm reading the EPRI Power System Dynamics Tutorial textbook.
On page 3-12, it defines the reactive power as
$$
Q_{S}=\frac{V_{S}^2}{Z}(V_{S}X_{L}-X_{L}V_{R}\cos\delta+RV_{R}\sin\delta-\frac{V_{S}}{X_{...
- 41
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votes
1
answer
550
views
RFID Conversion hexadecimal to decimal
How do I convert this hexadecimal code to decimal: 5A 95 62 80?
And also this one: 67 64 07 68?
I need this to use in an ...
0
votes
1
answer
101
views
Is it possible to ignore Nyquist-Shannon theorem?
I have a case in which I have to find a frequency of wavering object with camera (some kind of visual odometry). There is a limitation: frequency of a filming camera (fps) should be at least twice ...
4
votes
1
answer
187
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Combine uncertainty of multiple measurement instruments
I'm currently working on a project where I'm trying to figure out if there exists a significant difference between measurement instruments for RF power measurements. I will measure multiple Bluetooth ...
- 133
0
votes
1
answer
285
views
Triangle RMS calculate
About BCM PFC current, why I_L RMS value is
this is from ST document
I try to use rms formula to calculate it, and I also do the research I find the result should be like the below.
- 555
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votes
1
answer
241
views
How to calculate the scale factor of non-linear ADC output value?
I am not good in maths. I am trying to find a scale factor (or closest) of the output of an ADC without success.
I prefer to don't use a table to calculate the value.
My ADC gives a value that is not ...
-1
votes
1
answer
208
views
Magnitude and phase of parallel RLC with series resistor
I have been looking for a while for this issue, but unfortunately I am bit stuck on getting the magnitude as well as the phase of a RLC circuit with a series resistor, seen from V1 (see picture).
...
- 69
0
votes
1
answer
78
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Active inductor
I am designing active inductor using OTAs (Transconductance amplifiers) and have a problem writing an equations.
I wrote two equations for nodes V2+ and V2- and input current Iin.
$$ 0=sCV^+_{2}+g_1(...
0
votes
1
answer
122
views
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 ...
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votes
1
answer
80
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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?...
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votes
2
answers
92
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Understanding the Formula for Amperage with Copper
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)$...
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2
votes
0
answers
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Small signal analysis of MOSFET circuit
The other day I got the following exercise on one of my exams:
For those who don't speak German, for transistor 1 lambda is 0, but not for the others. The backgate-effekt should be neglected ...
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