Being cheap, I decided to build my own automatic temperature controller for my UDS smoker. I built using a PID controller and thermocouple from Auber Instruments. I installed the PID controller in a small aluminum housing with connectors on the rear for 12Vdc power supply, thermocouple, and power output to blower fan. I have the PID controller configured to turn on the fan at 95 degrees and turn off the fan at 115 degrees for demonstration purposes.
I used a computer cooling fan, rated at 12 CFM, I had lying around for the blower fan assembly. I installed the fan in a hobby box with a 1/8″ mono headphone connector (power from PID) and 3/4″ pipe fitting that will screw into the ball valve on the UDS. That way, I can close the ball valve when I complete the cook and need to shut down the smoker. Cost was about $80 total to build this setup. For more detailed information about this project, go here: http://www.bbq-brethren.com/forum/showthread.php?t=182961
To see wiring diagram I used, go here: http://www.maliburacing.com/BBQ/ATC/ATC%20wiring.jpg
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