MAX6675 K-Type Thermocouple Thermometer

Read temperatures from a glowing soldering iron to a sub-freezing freezer with one chip and a few wires — the MAX6675 turns a fragile K-type thermocouple into a clean 12-bit SPI reading.

Difficulty: Breadboard. Estimated build time: about 30 minutes. Estimated parts cost: about US$9.50. 5-part bill of materials with live supplier pricing. A digital thermometer that reads from a K-type thermocouple over a range of 0 to about 1024 degC, accurate to roughly +/-2 degC across most of that span.