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  1. kostoglotov

    Diode Question: need to understand why my approach is wrong

    Homework Statement A screenshot of the problem: imgur link: https://i.imgur.com/ljtoclm.png Homework Equations The Attempt at a Solution My first attempt at the solution was this: imgur link: https://i.imgur.com/TJcvOzy.jpg However, I have access to the worked solution, and it is...
  2. kostoglotov

    Which data set should I trust more?

    Homework Statement Control systems subject. Have a DC motor setup on a difference op-amp, then with gain, and the axel moves a wiper on a pot used for feedback. I understand the concepts reasonably well enough to complete the assignment. I'm using MATLAB scripts to approximate parameters...
  3. kostoglotov

    Viscous drag parallel to the axis of rotation: Control Systems

    Homework Statement https://i.imgur.com/WPAKuf4.png seeking G(s) = \frac{\theta_2(s)}{\tau(s)} Homework Equations The Attempt at a Solution What does it mean when the viscous drag is parallel to the axis of rotation?[/B] It also turns out that this system needs two equations. I can...
  4. kostoglotov

    Nyquist and FM and Signal Mixing...

    In an assignment I have, we are told to implement a Frequency Modulating function without using any of MATLAB's in-built functions, and not to use it's integration function either (use cumsum instead). I've been getting a lot of problems trying to solve these assignment problems without telling...
  5. kostoglotov

    Holiday project goals for undergrads with an FPGA?

    No. The entire point of the project is to get experience with FPGAs and VHDL and Vivado.
  6. kostoglotov

    Holiday project goals for undergrads with an FPGA?

    It's a student project for vacation research, under-grad, not sure how many of us, there'll probably be 4-6, we're motivated. My original proposal was to get an FPGA (on an Artix-7 or Z-board) to run a CID camera sensor as a dumb peripheral, do some basic image processing stuff on it (perhaps...
  7. kostoglotov

    Can a basic envelope detector demodulate a DSB-SC signal?

    ie: http://m.eet.com/media/1072296/RFFig84.jpg I am 99% sure the answer is: no, it can't. I've read that DSB-SC demodulation requires the carrier frequency to be put back into the signal at the receiving end prior to demodulation (or as part of the demod process), and that if its too out of...
  8. kostoglotov

    Why is pipelining easier on a RISC vs a CISC?

    Reduced Instruction Set vs Complex Instruction Sets for the CPU control logic. In the first half of the nand2tetris course a series of projects lead me through describing a very basic CPU from the nand gates up in a basic custom HDL. The CPU I eventually described was actually a Harvard...
  9. kostoglotov

    Why is pipelining easier on a RISC vs a CISC?

    I know very basically what pipe-lining is. My understanding is that the output from one "computing element" (usually a small set of instructions solving a simple task, such as say, finding a geometric mean) should flow immediately into the input of the following "computing element" where it is...
  10. kostoglotov

    Finding the closed form of a recursive LTI system

    The x[n] is there as an impulse at time 0 and 1, at t = 0 the impulse is 1 and t = 1 the impulse is 7. if n <= 0: return 1.0 if n == 1: return 7.0
  11. kostoglotov

    Finding the closed form of a recursive LTI system

    Homework Statement Find the closed form of the impulse response of the system y[n] = 7y[n-1]-12y[n-2]+x[n] using the peel away and guess method. Ie, by using Python code to find the geometric ratios and amplitudes of the outputs as n grows large, then calculate residuals, and find the...
  12. kostoglotov

    How transfer functions become Bode plots

    Homework Statement I have a question related to taking the logs of transfer functions, getting the individual Bode plots of each subsequent factor, and adding those plots graphically. I'm working from Fundamentals of Electric Circuits, 5th edt. Let me start with the following screen capture...
  13. kostoglotov

    Infinite series question with z-transform addendum

    Homework Statement Hello, I am currently doing some holiday pre-study for signals analysis coming up next semester. I'm mainly using MIT OCW 6.003 from 2011 with some other web resources (youtube, etc). The initial stuff is heavy on the old infinite series stuff, that seems often skimmed...
  14. kostoglotov

    Calculating Vrms

    Homework Statement imgur link: https://i.imgur.com/9jozS67.png Homework Equations The Attempt at a Solution [/B] Shouldn't I use V_{rms} = \sqrt{\frac{1}{T}\int_T v^2 dt}? Which would be \sqrt{\frac{100}{2\pi}\int_0^{2\pi/100}(20+60cos(100t))^2dt} This equals \approx 79.88 V The...
  15. kostoglotov

    Help with a BMD and deflection of beam problem

    Homework Statement I am given this beam: imgur link: http://i.imgur.com/tw6EEJz.jpg and asked to express the slope at A and the max deflection in terms of a, E, I, and Mo. I am being told that my answer has the wrong multiplier...so I assume that my overall approach is ok (??) but I've...
  16. kostoglotov

    Which inverse Laplace form can I use?

    Homework Statement I have the second order diff eq: Solving by Laplace transform gets me to: I could use the inverse laplace transform that takes me back to e^{at}cos(bt) with b=0, but that only solves for the homogeneous (complementary) part of the equation, it won't reproduce the dirac...
  17. kostoglotov

    Is there a mistake in the assignment?

    Homework Statement I'm actually a tutor, and a student of mine at uni has the following differential equation with initial conditions to solve imgur link: http://i.imgur.com/ptuymQv.gif From y(t) = c_1sin(3t) + c_2cos(3t), it is not possible to solve for the constants using the given...
  18. kostoglotov

    How can I solve this indeterminate truss bay?

    I found a way that will get the members to within about 5-7% of what the computer simulates. Basically I assume that there's only three equal stresses, horizontal, vertical, and diagonal, then through some logic, by knowing which members are in tension and which compression, it becomes a simple...
  19. kostoglotov

    How can I solve this indeterminate truss bay?

    Homework Statement For a larger project we had to redesign a truss to prevent certain members going beyond yield stress. I've found that due to the nature of the reaction forces and the supports used, the only way to do this is to introduce an X-brace in the bay nearest the supports (as well...
  20. kostoglotov

    Will an infinite impedance cause no phase shift?

    Homework Statement imgur link: http://i.imgur.com/0Zc8nQe.png Homework Equations Y-Delta transformations The Attempt at a Solution Since it's a proof, I can't check the answer in the back. What I did: I transformed the three impedances in their delta config to a Y config, and my TI89...
  21. kostoglotov

    Engineering RL circuit Q. I must be missed something simple

    So the voltage across the inductor is just the square root of the source voltage squared minus the resistor voltage squared. That gets the right answer. But I don't fully understand why. For a long time I was thinking that the 85 V drop on the R was measured at some particular time in the AC...
  22. kostoglotov

    Engineering RL circuit Q. I must be missed something simple

    Homework Statement Homework Equations The Attempt at a Solution I would show my working, but honestly, I'd really just like a hint as to how to begin, because I've tried multiple different things and just gotten tangled up in multiple equations that are way more complicated looking than...
  23. kostoglotov

    Difference between phase angles

    Homework Statement [/B] imgur: http://i.imgur.com/9ktFGSs.png Homework Equations The Attempt at a Solution [/B] I came up with both 150 and 210 as the difference between the phase angles. I chose 150. If you draw the vectors and compare their angles, the angular difference between them...
  24. kostoglotov

    Good beginner's resources for power factors and grids

    I am doing a BSEE and going power side. I am also applying for scholarships and bursaries, and would like to be able to talk specifically about power factors. More than this though, I want to understand it. Most of what I've found so far is very specialized and technical. What good resources...
  25. kostoglotov

    Buck regulator design, which parts can be slightly different?

    I want to build http://www.hobby-hour.com/electronics/lm2576hv-adj-buck-regulator-schematic.png From http://www.hobby-hour.com/electronics/lm2576-step-down-switching-regulator.php I might not be able to source exactly the same parts. I assume I have to use the same IC, but could I use a, say...
  26. kostoglotov

    Shouldn't f(t) = V have inverse f^{-1} (V) not f^{-1} (t)?

    Homework Statement I'm actually a tutor, and a student has shown me one of their assignments. I think there's a notation error, I'm quite confident there is actually, but I don't want to assert this, or have my student go asserting it, without some more certainty. This is the question...
  27. kostoglotov

    Why are these capacitor voltages opposite polarity?

    Exactly, eqn 4 needs to have that missing - sign if we are to accept the previous equations. So, I need to take this back to the tutor or professor.
  28. kostoglotov

    Why are these capacitor voltages opposite polarity?

    No worries. I don't notice what you're seeing, perhaps because I'm using a large monitor?...I'll keep it in mind.
  29. kostoglotov

    Why are these capacitor voltages opposite polarity?

    No, this is not from a textbook, this is from an assignment. I1 and I3 are going in the same direction around the loop that we use in KVL though, no matter how you set it up. I've only followed the current directions indicated. I haven't chosen my own directions independent of the problem.
  30. kostoglotov

    Why are these capacitor voltages opposite polarity?

    Homework Statement imgur link: http://i.imgur.com/JETj0Cq.png Homework Equations V_L = L\frac{dI_1}{dt} V_L + V_1 + V_2 + V_{R1} = 0 The Attempt at a Solution [/B] Just using basic KVL, shouldn't V_L = -V_2 - V_1 - V_{R1} and so therefore we should get \frac{dI_1}{dt} = \frac{-V_2 -...
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