It’s Saturday afternoon(*) and I’ve just completed the 6.002x midterm exam. In total, there were five multi-part questions, covering some basic circuit analysis (Q1), Thevenin and Norton circuits (Q2), a common gate MOSFET amplifier (Q3), a logic circuit consisting of a couple of inverters and a NOR gate (Q4) and a diode circuit (Q5).
Q1 – which involved finding a couple of node voltages and the power drops over resistors in the circuit, Q2 and Q5 were straightforward, although I confess it took me three attempts to get the Norton current right for Q2 (even though I managed to get the equivalent Thevenin voltage right first time – go figure!). Q5 was a repeat of an earlier homework question, but with slightly different values used, so it was pretty simple.
Q4 was a little trickier. I manged the first few parts of it easily, but then managed to over complicate the calculations for the falling and rising time constants so ended up taking a second attempt to get those values correct. I spent ages (and all three attempts) trying to work out the maximum power that could be used by the circuit, assuming it obeyed the static discipline. Eventually, I realised that only two of the MOSFETs could be on at the same time (rather than the three I’d assumed originally) and managed to get the answer right.
The question on the common gate MOSFET amplifier was, for me, the toughest of the lot. On the first attempt, I found that I’d only managed to get one part correct. Furious scouring through my notes, the textbook and a couple of other sets of notes from the internet saw me get three out of five parts correct on my second attempt. My final attempt saw me get four out of five parts correct. I’m kicking myself over the part I got wrong – as it was one of the large signal parts of the question and I’ve now figured out what I managed to mess up. D’oh, as a popular cartoon character might exclaim.
So my overall course progress now looks like this:
I’m part way through week 8 at the time of writing (and had got part way through the lab for week 8 by the time I remembered to take a screen capture of my progress), so unless I manage to mess the remainder of the course up spectacularly, the only question that remains is what level of pass I’ll obtain. I’ve set my sights on an “A” now of course, but I’d be happy enough with a “B” too. There was an ominous warning on the course information page a few days ago that the algebra and maths was about to get difficult again in week 9 …
(*) In compliance with the MITx honour code, the publication of this post was deliberately delayed and scheduled to appear well after the 30th April 1200 GMT midterm exam deadline.