Thermocouples are very sensitive, requiring a good amplifier with a cold-compensation reference. So far Adafruit have carried the very nice MAX31855 which is an SPI interface thermocouple amplifier. The '855 is great but if you have a lot of thermocouples to measure it isn't terribly easy to use. That's why Adafruit are also carrying the new '850 model from Maxim - it's a "1-Wire" thermocouple amp which can have any number of breakouts on a single shared I/O line.
The MAX31850K does everything for you, and can be easily interfaced with any microcontroller that has 1-Wire support. This breakout board has the chip itself, a 3.3V regulator with 10uF bypass capacitors all assembled and tested. This board can be used with 'parasitic power' - where the power is on the data line - or with 'local power' where the power for the converter comes in on the Vin Pin.
Please note: this board does not have level shifting on the 3V Data line - Adafruit did this on purpose so that it can be used in parasitic mode. The data line must be level shifted to 3V - Adafruit's 4-channel shifter works wonderfully for level shifting 1-Wire and you only need one at the '1-Wire host' for all thermocouples on the shared data line.
The MAX31850K data format is very similar to that of the well known 1-Wire DS18B20 temp sensor but it is not drop in compatible without code changes to check for the new '1 Wire family' type. Adafruit have adapted the classic Arduino OneWire and DallasTemp libraries to be MAX31850 compatible, so please click on those links to grab Adafruit's libraries.
Comes with a 2 pin terminal block (for connecting to the thermocouple), 4.7K data line pullup resistor, and pin header (to plug into any breadboard or perfboard). Goes great with Adafruit's 1m K-type thermocouple. Not for use with any other kind of thermocouple, K type only!
- Works with any K type thermocouple
- Will not work with any other kind of thermocouple other than K type
- -270°C to +1370°C output in 0.25 degree increments
- Internal temperature reading
- 3.3 to 5v power supply. Data line is 3V only
- 1-Wire interface allows any number of thermocouple amps on a single data line
Thermocouple Amplifier with 1-Wire Breakout Board - MAX31850K (12:30)
Dimensions (without headers):20mm x 20mm
Documentation and Resources:
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