Today’s class went fairly well—I started by returning the students’ drafts of their design reports and taking general questions. Most of the questions were about the format I was expecting for the final report (which is due 3 weeks from tomorrow).
We then broke into groups and and the group tutor and I circulated answering questions. I had some time with each group. With the incubator group, which had mentioned using transistors to control power to the heater, I discussed how to use nFETs and how to read some of the critical specifications.
With the centrifuge group, I talked with them about the need to keep the motor case from turning—the torque on the motor is the same as the torque on the rotor. We also talked about how to measure the rotor speed, and the difficulty of printing large objects with a filament-style 3D printer (I suggested they look into buying a used cooking pot at the thrift store to make the case, rather than trying to 3D print it).
I only talked for a short while with PCR group, mainly about relay-based control vs. FET-based control (relays are simpler to design with, but can only do on/off control, not PWM for proportional control).
The students seemed to pretty excited about their projects, and stayed on topic for the full 70 minutes (80 minutes, actually, since we ran over by 10 minutes before anyone noticed).