Topics for Midterm 2 1 Everything from Midterm 1 but I wouldn t bother going back and studying earlier stuff because you ve been constantly using all the most important stuff 2 Basic properties of capacitors and inductors everything on the cap inductor cheat sheet 3 Solving 1st order RL and RC circuits a Writing out and solving 1st order ODEs by whichever method you want e g separation of variables method of particular and homogeneous equations intuitive method for DC sources i Note the mistake I made on the board in class the first time we discussed RL circuits for the intuitive method not which is the root of the characteristic polynomial the equation you get when you replace by s b But aren t these all the same Can t you just combine all the resistors together and just have a simple RC or RL circuit i No you can have dependent sources ii No you can have op amps HW5 problem 3 iii Source may be some kind of strange thing like Volts c Understanding how to calculate when the source has reached 63 2 of its final value or some other amount So if you have long it takes to decay to 63 2 same as you should know how to find how of 2 it s easy just some algebra 4 Terminology Particular solution a k a forced response a k a steady state response Homogeneous solution a k a natural response a k a transient response 5 Finding initial and final conditions in arbitrary RLC circuits like problem 14 on HW4 or the question on the pop quiz I handed out this basically comes down to using a The fact that for DC sources capacitors eventually act as open circuits because eventually voltages will settle down and if dvC dt 0 then no current in capacitor b The fact that for DC sources inductors eventually act as closed circuits similar reason c That when a switch is flipped somewhere in a circuit at time whatever it was right before switch flipped for each capacitor i can be ANYTHING because current is allowed to instantly change ii Note d That when a switch is flipped somewhere in a circuit at time whatever it was right before switch flipped for each inductors i ii Note can be ANYTHING because voltage is allowed to instantly change e KVL and KCL 6 Setting up arbitrarily large ordinary differential equations for any number of Rs Ls Cs a No need to solve these 7 Understanding of how to solve 2nd order LC circuits see handwritten notes for lecture 10 http inst eecs berkeley edu ee40 su10 lectures lec10 or if you did it the long way on problem 2 of HW 5 8 Qualitative understanding of RLC circuits a If you have an RLC circuit with some non zero initial condition what can it do 9 10 11 12 13 14 15 16 b I d put the formula for a series RLC and a parallel RLC circuit on your cheat sheet I won t give you a problem which will just be an application of this formula but it might help with some intuition on a problem yet to be written maybe Phasors what they are Just a complex number which represents a sinusoid Using impedances to solve for the PARTICULAR solution a k a forced response a k a steady state of arbitrary RLC networks a You don t HAVE to use phasors I know that at least one of you guys prefers the method in the book where you replace sources by complex sources and then do impedances then find the real part I think this is more work but you re free to do this Understanding of what happens when two impedances sum to zero denote the steady state solutions a k a particular solutions a k a a If and forced responses of the two node voltages connected by the impedances in question then Understanding of what happens when two impedances sum to infinity for example and in parallel a Steady state current flowing in to the box containing those impedances like if you draw a circle around them is zero b Current may still flow within the box see HW6 problem 1 Deriving Transfer functions Conceptual understanding of what a transfer function is a Using transfer functions to calculate magnitude and phase response for a given input Understanding of how transfer functions are sensitive to loads just like the voltage divider from homework 1 was sensitive to the load resistor Also how op amps help avoid this problem just like they did when we talked heavily about op amps Making Bode Plots on a loglog scale for magnitude and a semilogx scale for phase a Sorry that these weren t taught well I assumed more knowledge of loglog plots so I started a little too far into the process during lecture and moved a little too quickly This probably made HW6 really frustrating in parts b If you re uncomfortable with these see my long filter case study http inst eecs berkeley edu ee40 su10 notes filter case study pdf c If you want remember you can always just plug in points into your equation directly instead of thinking of asymptotes d If you can do HW6 problem 6 and the case study example you will be more than fine e Understanding of the terminology low frequency asymptote and high frequency asymptote i Low frequency asymptote is basically just the behavior of a function as gets very small So for a lowpass filter the low frequency asymptote is a constant plateau where doesn t really do anything when it gets small enough ii High frequency asymptote is basically just the behavior of a function as gets very large So for a 1st order highpass filter the high frequency asymptote is that the system is inversely proportional to which on a loglog plot will be a downward sloping line However just understanding that it s inversely proportional to is the key concept 1 note the order of a filter isn t required terminology but basically for a 2nd order high pass it s inversely proportional to and so on 17 Definition of a low pass high pass band pass and band stop a k a notch filter Conceptual understanding of when these might be useful 18 Key concepts in lab that GSIs have noticed you guys not really getting for example a Schmitt Triggers conceptual understanding of how they work and the fact that they have hysteresis b Use of op amps with no feedback e g lab 4 c Using potentiometers for voltage division Using potentiometers as a variable resistor Specifically don t need to know 1 How to solve RLC circuits from scratch 2 How to use phasors to calculate power 3 Details of Thevenin and Norton equivalents for Impedance circuits though the concept might maybe make some problem easier but it s a low priority item 4 How to show summing point constraint works in RLC circuits though it is cool 5 How to pick an R so that a 3rd …
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