Math or Mathematics is the abstract study of topics such as quantity (numbers), structure, space, and change.
4
votes
4answers
695 views
Performing FFT at low frequencies but high resolution?
To put this in context, I'm looking to achieve both high speed and high accuracy for measuring biosignals through the FFT. I'll describe a quick example to see if I understand this properly as well as ...
0
votes
3answers
53 views
PID Control: Controller of the type \$\dfrac{1}{s+k}\$
In PID control an integrator action is represented by \$\dfrac{1}{s}\$
Does anyone know what would be the effect of using \$\dfrac{1}{s+k}\$ instead of \$\dfrac{1}{s}\$, where \$k\$ is a constant? ...
0
votes
0answers
24 views
Accuracy calculation for SMD compass magnet-triangulation
I'm designing for an application where size is to be kept at a minimum (board space of a square inch or less; boards should be circular or square, not long in one axis, or they might break). I want to ...
5
votes
4answers
419 views
converting watt values over time to kWh
This is probably an elementary question, but I wanted to be sure.
I have a system that reads instantaneous watts values, and stores them as "events", with a power value and a time value.
According ...
1
vote
1answer
21 views
PV array project
I am working on a PV array on simulink and I just need help on a math question.
On the article I'm basing the model on, the model voltage equation is
Vm = VmT - (5- G/0.2) for the voltage to vary ...
0
votes
0answers
26 views
VLSI and Carry save adder (CSA) and multiple operand addition?
I read this PPT on page 146 we have this figure:
as Better to have the same sum and carry delays (both contribute to critical path) in Carry save adder (CSA) and multiple operand addition. ...
1
vote
0answers
18 views
SiC Schottky power diode MATLAB simulation issue
Hi Everyone (first time poster),
I am modelling a 4H-SiC Schottky power diode in MATLAB and I have come into some issues with MATLAB when trying to make an I-V curve. I was reading this paper and I ...
3
votes
3answers
124 views
SI derived units: Another name for the Volt [closed]
\$ V = \frac{Kg \cdot m^2}{s^2A} \$
I know it's basic but I was having a hard time understanding the relationship between volts, ohms, watts, amps and ohms until I broke everything down into base ...
2
votes
2answers
105 views
Under what conditions does jw equal the laplace variable s in an electrical circuit?
Imagine I've got an electromagnetic actuator and solved the underlying differential equations. I got an solution for sinusodially excitation, as follows (just an example, no physical backround):
$$G(\...
1
vote
2answers
40 views
Voltage Drop Across Wire With Fixed Load Wattage
I am looking for an equation to calculate DC voltage drop across wires that run a distance, with a switching regulator and fixed load at the end (a known wattage).
Here are the specifics:
The power ...
0
votes
1answer
59 views
Calculating amperage in a current source
How do I determine the amperage at "?" based on the selected resistors in this current source?
Falstad Simulation
I took a bunch of measurements from the simulation and plotted them. I know that ...
-1
votes
1answer
73 views
Digital Signal processing-Sampled period
Please can you help me with exam test preparation. I have take the below past year exam paper.
I want to know if I am on the correct track and my answers are correct.
x(t) = cos(50.pi.t + 30) ...
1
vote
0answers
39 views
What does K(k) mean in a transmission line equation
I'm reading through a book I have about transmission line structures. They frequently use the math:
$$\frac {K(k)} {K(k')}$$
For instance, characteristic impedance:
$$Z_0 = Constant \cdot \frac 1 {\...
0
votes
2answers
132 views
Fourier transform of \$x(t) =t^2e^{-|t|}\$
I have to find the Fourier transform of this function.
(- sign exists BEFORE modulus). I thought of using this standard result.
If I split this fourier transform into this will it be correct ...
-1
votes
1answer
181 views
How to properly describe a Math Equation in Verilog to be synthesizable?
I have not been able to find a book or information in internet, about the correct way to describe a Math Equation in Verilog.
With the correct way I mean for example, how to analyze the equation and ...
2
votes
1answer
75 views
Find dBm and watts of the attenuator?
The question says "A signal of 40 dBm is passed through the first attenuator. The first attenuator has a gain of 1. The second attenuator has 20 dB output. Find the dBm and watts
This is what I tried ...
0
votes
2answers
73 views
How is the solution for \$\alpha\$ and \$\beta\$ current gain of a BJT derived?
I'm just an enthusiast, and not too good at maths; I'm exploring constant current source circuits, in doing so I came across two equations for BJT current gain:
Could someone help me understand how \$...
0
votes
1answer
59 views
Quick question about a closed loop control system
Using above loop, we see that
\$
\dfrac{y(s)}{r(s)} = \dfrac{p(s)c(s)}{1+p(s)c(s)}
\$
and
\$
\dfrac{e(s)}{r(s)} = \dfrac{1}{1+p(s)c(s)}
\$
(well known results)
Why is that:
If the close loop ...
-5
votes
1answer
65 views
Good book references for physics and math for electronics [closed]
Next year I'll join an engineer school in Dijon, France in the field of Electronics (Embedded Systems). I am currently taking a 2 years general IT education and my main problem is that I am very bad ...
0
votes
1answer
35 views
Simple problem with phasors
I'm trying to solve the following question (a):
According to the solutions manual and wolfram the answer is:
http://wolframalpha.com/input/?i=%28%285-6i%29-%282%2B8i%29%29%2F%28%28-3%2B4i%29%285-i%...
2
votes
2answers
101 views
Why is this second order system difficult to control?
Why is system of the type
$$T = 1/(s^2 - 1)$$
Difficult to control using standard control methods?
When I look at frequency plots, it doesn't seem to give me any important information as to why ...
1
vote
1answer
65 views
Function to Simulate Realistic Waveform
I need to simulate a realistic signal voltage triangle waveform in Mathematica. I know that a real waveform won't have sharp corners, but I don't remember exactly what a real triangle wave looks like....
5
votes
2answers
115 views
Control theory: is there any actual application for D in ABCD matrix?
Recall that a LTI state space of a dynamical system is given as:
Is there any actual purpose for D in the output equation?
If D was not zero, it would mean that the output is "directly" ...
0
votes
1answer
134 views
How to calculate capacitance and resistance for this simple A.M. radio?
\$v_i\$ is the A.M. signal, \$v_o\$ is the modulation wave. How do I calculate the optimal capacitance and resistance, for a given carrier wave frequency? If there isn't necessarily an "optimal" ...
0
votes
2answers
225 views
Designing voltage summer without op-amp
The above circuit is from Operational Amplifier Adder.
Now remove feedback resistor and op-amp, and get the output. From the answer of the question, I know how the end result for Vout would be, ...
0
votes
1answer
157 views
How calculate standard deviation of ADC histogram for rms noise analysis?
Some papers from Analog Devices (like this one - page 2) and other sources indicates that the rms noise of a histogram plot of an ADC output can be found by calculating the standard deviation of the ...
1
vote
3answers
235 views
Collector current vs. temperature
In The Art of Electronics 2nd Ed. it is said that:
The Ebers-Moll equation is $$I \approx I_s(T) e^{\frac{V}{25 \, mV}}$$ and the change of voltage with temperature at constant current is
$$\left. \...
1
vote
1answer
444 views
Is there a way to Divide two 8 bit number in PIC 18fXXX assembly language not C?
I Can easily do the division in C of PIC micro controller.
But is there a way to divide two number stored in two 8 bit registers.
For example look at this code.
I have to do it in PIC assembly for 8 ...
-1
votes
2answers
72 views
Control: what is the proper justification that you can't just make the output equal to the input if the system produces unstable output
Suppose we have a signal, it goes into the plant and generates an unstable response, a common question then arise at that point is why can't we just set our output to a "hard-coded" input. Think of ...
1
vote
3answers
87 views
How can the FFT analyze a wave in which the components are changing?
Based on what I've read about Fourier Transforms, it seems that they are designed to work on waves whose components are constant. For example, a simple square wave is
\$\sin(\theta) + 1/3sin(3\theta)...
1
vote
1answer
100 views
Distinguishing between FIR and IIR filters from transform function
I was good at this but unfortunately I have forgot almost everything... So the question is what are the steps to tell if a transform function is for IIR or FIR filter:
$$H(z) = \frac{z^3+5z^2+3z+1}{...
0
votes
2answers
958 views
Positive feedback and virtual short in Operational Amplifiers
Can anyone please explain, with sufficient mathematics, why the virtual short concept is not applicable to an operational amplifier in positive feedback.
0
votes
1answer
96 views
Return Loss \$ (S_{11}) \$ Equation for a nth-order Butterworth Filter
I need a closed form equation for the return loss \$ ~S_{11}~\$ of an n-th order Butterworth low-pass prototype filter.
I am designing a high power RF (lumped element) n-th order Butterworth bandpass ...
0
votes
1answer
137 views
So how do control engineers control nonlinear plant with exponential output?
Say that a system (circuit, pump, population model, etc.) has a exponential output of the type $$y = ae^{bx}$$
What do control engineers do in order to achieve control objectives such as tracking and ...
2
votes
2answers
930 views
Low Voltage AC Smoothing Capacitor Calculation
I have a 9V AC source which will have a max load of 100mA. I'm trying to figure the value of a smoothing capacitor with less than a 10% ripple. I don't have a scope or else I'd just try a bunch out.
...
0
votes
1answer
40 views
Complex multiplication identity
From my EM theory book:
I have the solution for this problem, but I don't even understand the first step. How does V = r+jx => v(t) = rcos(wt) - xsin(wt)??
0
votes
1answer
84 views
Control Engineering: Model parameter estimation for a motor which will be under various loads
I am creating a closed loop controller for a motor which is part of a robotic arm. I give it a required angle, the controller calculates a control input, the motor moves, a pot feedbacks the angle, ...
1
vote
1answer
173 views
Control Engineering: Why are the Equation Error and Output Error different?
When modelling a system you must first estimate the form of the transfer function (order, time delay etc.), and then estimate the parameters (coefficients for the transfer function).
A common way to ...
5
votes
2answers
120 views
How come you cannot determine the capacitance of a MOSFET gate based on the other supplied values on the datasheet?
Conjecture
If it's the case that
$$
Cg = {Qg \over Vg}
$$
It must be the case that
$$
(Ciss + Coss + Crss)Vg = Qgon
$$
But it turns out that it is not. I don't understand what I'm missing.
I ...
3
votes
1answer
176 views
Half Adder and Two Function, A Contest Questions?
I ran into a 2013 contest question on computer-science filed.
What is the following True about F and G function. (The output ...
1
vote
2answers
102 views
Required math for setting up a laser diode
I'm new to electronics and come from a software background. Recently I got a laser diode that I would like to use with my arduino. The manufacturer says it is 5mW and draws 2.8-5.2V.
I'd like to ...
3
votes
1answer
299 views
adding two 64-bits number with m-bit carry ripple adder and multiplexer, a questions?
I ran into a question from computer architecture class. The professor says that for adding two 64-bit numbers A and B we use m-bit carry ripple adders and multiplexers such as following:
and that ...
0
votes
2answers
515 views
Understanding use of accelerometers to measure angular (rotational?) accelerataion
Imagine this: A rod is attached at one end to a rotating shaft. So, as the shaft rotates from 0 to 90 degrees back-and-forth (in the xy plane), so does the rod. My goal is to measure the instantaneous ...
2
votes
2answers
847 views
How do electrical engineers actually apply control theory in real life?
I am currently taking a course in control theory.
In control theory the system or impulse response is usually an algebraic expression in Laplace domain. Much of the work done in school is to find ...
0
votes
1answer
263 views
Calculating the gauge of wire required for the secondary in a Tesla Coil
I am looking to build a small Tesla Coil at home with limited supplies. I am reasonably confident (well.. as confident as a biologist can be!) with my calculations so far, however I have hit a mental ...
-1
votes
1answer
55 views
Just need to check if this equation correspond to this block diagram
$$y(n)=y(n-1)-ax(n-1)$$
Is this correct? Thanks in advance.
0
votes
1answer
59 views
Uncertainity Calculation
>
How can i calculate the absolute uncertainty dt in the following case T=(P/A)^1/4
if ...
1
vote
2answers
924 views
Question about the derivation of RC Filters frequency cutoff
We've learned that the operation in RC filters depends on how the capacitor reacts to different frequencies, in other words, the capacitative reactance.
The input is applied in series with a ...
1
vote
1answer
374 views
Why does the complex representation of a voltage \$V\cdot\cos(\omega t + \phi)\$ use the cosine function?
A voltage across a circuit component at time \$t\$ can be calculated by \$V\cdot\sin(\omega t + \phi)\$.
However, in the section of my book that introduces complex numbers to represent voltages, it ...
1
vote
1answer
1k views
Calculating single phase load from 3 phase power measurements
I need to record kW & kWh for individual phases on a circuit that has a 3 phase power meter that outputs the following data:
Total for all three phases:
kW
kWh
kVA
kVAr
power factor
...
