Look here for a stepper motor controller using a PIC16C73B driving some Allegro 3955 H bridge chips. The circuit controls two bipolar stepper motors. I use it to drive the RA and Dec on a German Equatorial Mount I built.
Look here for a platinum thermometer inspired by a series of articles in Scientific American. A note giving more details about the tin cell is here. A companion project is a circuit used to measure the resistance of the thermometer and send it to a computer over a serial line.
Here's an Excel spreadsheet that can be used to calculate the dewpoint given the current relative humidity and temperature.
You can reach me at email@example.com.