Here are my thoughts on the seventh week's material, etc.

• This week we worked on the FFT
• We worked to be able to interpret FFT plots:
• Determine frequency from plot peaks knowing the record length for the data.
• Determine amplitude from plot peaks knowing details of the computational algorithm in Mathcad and Matlab.  I needed to take an excursion here into the help files on the FFT for those two programs.
• Lab this week consists of getting data for three systems/devices.
• A "twang" bar - a bar with two strain gages, top and bottom
• A speaker that hangs from the wires.  Hit it with a bar or a pen.
• A light sensor, with a light shining on the sensor through a rotating fan.  The rotating fan interrupts the light giving a signal where the students can calculate the fan speed by counting the blades, etc.
• In-Class exercises
• I really like this little set of labs.  The real clinker is the light sensor because the lights are fluorescent and you get a strong signal at 120 and at 240 Hz.  Let the students figure it out.  I love this one.  It really forces them to think after the first two (twang bar and the speaker) go really well.
• Class Notes - Good
• Some things to think about.
• Not much here
• Sensors encountered to this point in the course.
• Thermocouples
• LM35s - giving two examples of sensors with voltage outputs
• Thermistor - giving an example of a sensor with a resistance change.
• AC Tachometers
• Pressure Sensors
• Strain Gages
• Light Sensors (Photovoltaic cells)