MCP9808 Precision Thermometer

Read room temperature to ±0.25 °C accuracy over I²C — ten times better than the usual NTC voltage divider.

Difficulty: Breadboard. Estimated build time: about 25 minutes. Estimated parts cost: about US$3.50. 4-part bill of materials with live supplier pricing. A digital thermometer built around the Microchip MCP9808, an 8-pin MSOP I²C temperature sensor that ships factory-calibrated to ±0.25 °C from –40 °C to +125 °C.