Gas station without pumps

2014 June 12

Starting on book for circuits lab—scheduling labs

Filed under: Circuits course — gasstationwithoutpumps @ 23:59
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In Revised plan for circuits labs I provided a tentative schedule for the applied circuits course and lab, which I ended up not really following (dropping the FET measurements, moving the sampling lab after the loudspeaker lab, and swapping the order of the pressure sensor and the class-D amplifier).

I’m now trying to turn the course lab handouts into a book (which means adding everything that was previously just in lectures), and I’m trying to rearrange the lab schedule to fit better into the 10-week quarter and to flow a little better pedagogically.

In this post, I’ll ignore the lecture component, but just look at a possible reordering of the labs.  Squeezing the KL25Z soldering and both halves of the thermistor lab was too much, and the sampling and aliasing lab did not work well late in the quarter, so I’ll strip the filter design out of the sampling lab and simplify it a bit to get it in the first week, and move the thermistor lab fully to the second week.  I’ll have to squeeze somewhere else, and I think that the best bet is the hysteresis lab, which took far longer than it should have.  I still want to have data-analysis Wednesdays, and reports due on Fridays.

Tuesday week 1 Unpacking parts, labeling capacitor bags, using wire strippers, making clip leads, Soldering headers onto KL25Z boards, downloading data logger to KL25Z.See soldering instructions at Soldering headers on a Freedom board and Jameco soldering tips
Thursday week 1 Sampling and aliasing lab (no filter design)
Tuesday week 2 Measuring input resistance of multimeter, and of oscilloscope.
measuring thermistor resistance at many temperatures.
Thursday week 2 Measuring voltage of thermistor voltage divider, recording voltage vs. time.
Tuesday week 3 Measure I-vs-V DC characteristic of resistor and of electret mic, both with multimeter and with KL25Z board.
Thursday week 3 Look at mic with resistor load on oscilloscope (AC & DC coupling).  Filter design for AC coupling. Loudspeaker on function generator?
Tuesday week 4 Characterizing impedance of loudspeaker vs. frequency
Thursday week 4 Characterize hysteresis in Schmitt trigger chip using data logger. Breadboard hysteresis oscillator with various R and C values, measuring frequency or period (oscilloscope or frequency meter?).
Make and test touch sensor with breadboard oscillator. Solder hysteresis oscillator. Estimate capacitance of touch from change in period of hysteresis oscillator.
Tuesday week 5 Impedance of stainless steel (polarizing) electrodes in different NaCl concentrations (at several frequencies).
Thursday week 5 Impedance of Ag/AgCl (non-polarizing) electrodes in different NaCl concentrations (at several frequencies)
Tuesday week 6 Low-power single-stage audio amplifier with op amp
Thursday week 6 catchup day? characterizing photodiode or phototransistor?
Tuesday week 7 Pressure sensor day 1: design and soldering instrumentation amp prototype board
Thursday week 7 Pressure sensor day 2: further debugging.
Recording pressure pulses from blood-pressure cuff.
Tuesday week 8 Photodiode or phototransistor with single-stage simple transimpedance amplifier.
Freeform soldering to attach leads for fingertip transmission sensor.
Cut-and-try design for transimpedance gain needed to see reasonable signal without saturating amplifier. (Determine AC and DC components of current)
Thursday week 8 Fingertip pulse sensor with 2-stage amplifier and bandpass filtering.
Tuesday week 9 class D audio amplifier day 1(preamp and comparators) (problem with Memorial Day on Monday?)
Thursday week 9 class D audio amplifier day 2 (output stage)
Tuesday week 10 EKG day 1:  breadboard and debugging (confident students could go directly to soldering)
Thursday week 10 EKG day 2: soldering, debugging, and demo.  Last day for any catchup labs.

I’m not really comfortable with the class-D amplifier in the week with Memorial Day. I’ll have to double check when Memorial Day comes next year.

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