Archive of the former Yahoo!Groups mailing list: Homebrew PCBs

I have modified my PIC based temperature control to use a K thermocouple instead of a LM34. I used an AD595 chip to linearize K thermocouples to 10 mV/∗C. This is a simple circuit using a PIC12F683 for analog input and a PWM output to a digital panel meter for display of temperature and set point. Two switches are use to set the temperature. Normaly the temperature is displayed. When either the increment or decrement switch is pressed the unit displays the set point and allows it to be changed. A relay with on/off control keeps the overshoot to less than 8 degrees C.

I changed to thermocouple input when i needed temperatures in the 160 ∗C + range.

The AD595 and K thermocouple can be obtained from Spark Fun Electronics. Tho not cheap.

RD