When i was designing my DIY soldering station, i faced one big problem: how to read and use the thermocouple output. If you read the thermocouple theory, you will see that the voltage output of a thermocouple pair is in the scale of uV (micro-volts), which makes the reading-part a hell. I chose the easy way and i used the cool MAX6675 which does all the dirty job. But Kenneth did it the hard way with this super cool circuit. He used the LT1025 thermocouple compensator to compensate the TC-to-copper junction temperature, and the LTC1051 low offset op-amp to amplify the signal. These two chips are quite expensive (more expensive than the MAX6675), but i liked this circuit for 2 reasons: first the output is analog and second, there is not "Magician of the tribe" (referring to the MAX6675) to do all the cooking and just deliver the temperature. Instead, you have 100% control of what you are doing. Very good job Kenneth.
Also, he shared with us a nice trick for those who make PCBs:
|Nice little trick I picked up recently; if you use open frame sockets, you can actually fit a small ceramic cap inside the DIP socket, making it much easier to fit a filter cap near the power pins of the op-amp.|