6.002
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Obsolete |
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| 6.002 | |
|---|---|
| Official Title | Circuits and Electronics |
| Prerequisite(s) | 18.03 |
| Credits | 15 (4 -- 2 -- 9) |
| Next Offering | Spring 2008 |
| Next Prof. | ? |
| Other Details | 4 Engineering Design Points |
There's a reason why 6.002 doesn't have "Introduction to..." in its title. It's a deceptively easy-sounding class (it's the first thing you do in Circuits! How hard can it be?) but it's easy to be caught off-guard by the pace of the class. Nevertheless, if you pay attention, don't skip a lot of lectures (or at least don't miss getting lecture notes), and keep on track, it's not insurmountable. It's fast and assumes you can keep up; it requires a thorough knowledge of 18.03, as the end of it involves Laplace transforms and first/second order homogeneous/inhomogeneous differential equations.
The course covers a large number of topics, but its main topics are basic circuit analysis (through node method, Norton/Thévenin conversion, and superposition), MOSFET transistors (everything you ever wanted to know about them and more), small- and large-signal analysis, transfer functions, and op-amps (operational amplifiers). It's essential for Course 6 as a major, unless you're on the new track, and then it's replaced by 6.01 and 6.02. Course 6-1 should know it well; for 6-3, it's not so necessary to know it clearly.
More than a few times, the TAs for this class aren't on the ball and are inconsistent. They will often give students different answers as to what is on the upcoming exam, so make sure you double-check all of that, possibly with the professor. If pset dates on the main syllabus clash with the ones on the pset, ask the prof.
Labs
Labs in 6.002 have now been cut out to make the class 12 units instead of 15. There is, however, one mandatory lab at the end that yields no credit but is still required to pass, and that is the op-amp speaker lab. Students use op-amps, a memory chip with a sound recording, and a piezoelectric speaker (pre-made part)to amplify and play sound. This is done in a modular fashion; you build first a clock, then test it, then the next piece, then test it, and so forth. Each module is, in theory, standalone and can be tested with external inputs.
Troubleshooting for the lab:
Always, always, always check all your equipment before you start the lab. It sucks to spend 2+ hours hunting a bug that turns out to be your scope's problem, not yours. The equipment in the 6.002 lab is ancient, flaky, and many times downright broken. Even if it works, check the power supply for oscillations and other weirdness.
- Why is nothing happening?
Step 1 -- standard sanity check of, is it plugged in, etc. and so forth. Step 2 -- check your power supply and oscilloscope. Are you using a protoboard? Many of them have broken power pegs. Some have only one broken power peg (so your 15V may be putting out 5V) Step 3 -- make sure none of your wires came loose. If they did, plug them back in. Step 4 -- check the clock. Step 5 -- see below specifics if they apply. Step 6 -- ask a TA/Student Who Knows Things.
Help for specifics:
- My scope is giving me really crazy oscillations. What?
This can be a number of things. Start by isolating all your modules and testing them one by one. It's likely that you plugged a wire into the wrong port in the protoboard. If it's still there, check your power supply. Some of the protoboards are sketchy and flaky and will give you weird oscillations straight out of the box. If this is the problem, go find another power supply.
- My sound is too noisy,
Shorten as many wires in your circuit as you can. Look at your power wires especially -- are they long? Cut them down as short as you can. Long power wires make a huge impact.
- I smell burning stuff!
Unplug the circuit _now._ Hover your hand until you find the burning thing. Whatever it is, you've just shunted too much power to it. Watch where you've put your 15V power. The only place those should be running is into the power supplies of the op-amps.
- The inverters are doing weird things. Sometimes they flake out.
You probably fried them. Go get another inverter chip. If you made the above mistake, this is a likely result.
- My sound is too squeaky/deep.
You have the wrong size capacitor in the clock. Tweak the cap until it works. (Incidentally, the clock is a major source of many bugs. If all else fails, it's quite possibly the clock.)
- How can I check my filter?
Run an AC signal in and twist the frequency from 0 to 100K or so. You should see the filter change the amplitude depending on the frequency (either it will leave it be or shrink it). If nothing happens, rework the filter.
- What should my sound waves look like?
They should look like lots of scribbly lines moving to the intonation of whatever you're playing. If they make any sort of immediate Fourier sense (as in, if you can see the sinusoids very clear and organized), then you should make sure the signal is getting through correctly.
- My speaker is screeching.
Turn the volume (pot) down and know you're getting there. Screeching means it's picking up some kind of signal. Trace the sound file from the chip through the wires and see where it decays. Alternatively, your clock could be very off, meaning you need to adjust the cap until the pitch lowers and the speed decreases to something intelligible.
Professors
According to alcor(cdhill), Prof. Lang was easier to understand in lecture than Prof. Perreault. He also hands out lecture notes on time, while Perreault prefers to hand them out 10+ minutes into lecture to prevent people from popping into the lecture hall and then leaving. (This doesn't work well.) Perreault also doesn't post the notes online, while Lang does. Lang does all his equations/derivations in the notes as well. Lang also wrote the textbook and thus Obviously Knows His Stuff.
Recitation instructor Prof. Jing Kong is a good instructor to get; though her recitations are early (11 AM and 12 PM), she explains concepts from the ground up and very slowly. She is often available outside of class and always makes room for students who email her asking for help in the afternoons; however, she does take 1+ full days to get back to emails, so last-minute mails don't work.
