Recent content by mathg33k

  1. M

    Understanding RC Capacitor Discharge Theory

    Thanks for your post Simon. I didn't consider that the sign simply changed and the diagram was pointing in a reference direction. I managed to reason through it myself, here's how. Say that the capacitor was charged up to 6V and the resistor has a value of 2 ohms. At t(0-), the current...
  2. M

    Understanding RC Capacitor Discharge Theory

    Homework Statement This is not a true homework problem but rather my interpretation of RC Capacitor theory. What is the action of a capacitor in RC first-order circuits?Homework Equations The Attempt at a Solution From what i understand, when a capacitor is being charged, charges move from...
  3. M

    Engineering Constructing an op amp circuit of variable gain neg to pos

    This was actually an exam problem on last year's final at University of Texas worth ~15 pts. The teacher I have is notorious for his classes' difficulty. The averages on these tests are in the 40s.. but they are curved. Attached is a diagram of my solution. (Vn - Vs)/(R/2) + (Vn - Vo)/R =...
  4. M

    Engineering Constructing an op amp circuit of variable gain neg to pos

    Hello aralbrec, thanks for your hint! I was able to solve the problem by connecting Vs to the negative input in series with two parallel resistors R, and connecting Vs to the positive input with variable resistor aR and one resistor R leading to ground. Then the other two R were used for the...
  5. M

    Engineering Constructing an op amp circuit of variable gain neg to pos

    Homework Statement Suppose you are given an ideal op amp, an ideal voltage source with voltage Vs, 5 resistors with resistance R, and one variable resistor whose resistance can be adjusts continuously between .2R and R. Use these components to design a circuit, assuming ideal op-amp behavior...
  6. M

    Solve Infinite Summations w/o Pi: Tips & Tricks

    Looking for ways to solve infinite summations, I found an ancient topic here talking about solving infinite summations that come out to answers with pi. How would I solve an infinite summation that does not come out to an answer with pi? Such as: \sum_{n=1}^{\infty}\frac{n+1}{6^n} The...
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