DIY temperature controller

joseph.odoherty · 2006-03-19T19:45:42+00:00

I'm trying to figure out how to make a simple feedback (on-off)temperature controller.The basic problem that I want to solve is that I have an electriccooker ("crockpot") that unfortunately only has two temperaturesettings: on and off. I would like to have it hold a specifictemperature, a temperature that is lower than the temperature itnormally when in the "on" setting, and keep it there within atollerence of a few degrees. My initial thought is to use a temperatureprobe to do simple on-off control on the device.What I do not know is some of the circuit details:I've never worked with thermocouples or thermisters before. Do I needto worry about amplifiying them?My thought is to use an op-amp in inverting mode to compare themeasured temperature against a setpoint. How do this in practice? I'mnot completely clear on how to "tune" the assembly.What would be a good way to switch the power on and off? I'm nervousabout interfacing with the AC coming out of the wall.many thanks!