Arduino compatible PID based temperature controller.
This controller has been used to control both hot plates and toaster ovens for reflow soldering. It has also been used for a few other tasks involving temperature control.
The sensor most often used is a modified Harbor Freight IR thermometer which works well for sensing the temperature of a hot plate surface. The design includes an optional K type thermocouple interface which is more suitable for temperature sensing in a toaster oven (and liquids, etc).
The original design used a MAX6675 thermocouple interface chip. The code for that design is checked in under tag v1_2. However, this chip is now end-of-life and has been replaced by the MAX31855. The latest software and hardware files support the MAX31855. The MAX31855 is a 3.3V chip so the V1.5 design incorporates 5V to 3.3V level shifting using the pull-ups and diodes design from the Adafruit breakout board.
For more information on the earlier design and some additional construction details, see my blog and the additional information linked there.
The firmware is derived from the Bare Bones Coffee Controller, some standard Arduino libraries and a couple of non-standard libraries (which are included in the libs subdirectory).
Pete Skeggs has modified the firmware to more carefully control the PID timing loop and has gotten good results with a toaster oven. Note that his code is for the V1.2 board (MAX6675). It shouldn't be hard to update to the V1.5 design based on the MAX31855.
Non-standard Arduino libraries used (snapshots in libs subdirectory):
RotaryEncoder, written by SunboX: http://www.arduino.cc/cgi-bin/yabb2/YaBB.pl?num=1205879808. The version in libs is updated for Arduino 1.0.
max6675 by Ryan McLaughlin: http://code.google.com/p/max6675-arduino-library)
max31855, by Ryan McLuahghlin: http://ryanjmclaughlin.com/wiki/MAX31855_Arduino_Library