Today I wanted to make some temperature measurements in my lab because I recently moved to a new house and I have a feeling that some times the heating is on more often than it should. Some spare parts were laying around and a very simple but accurate enough k-type thermometer was born. The circuit is very easy to build and you can find a good guide in adafruit website. Basically I am measuring the temperature with the help of ic MAX31855. It is a Thermocouple-to-Digital Converter from Maxim in a very competitive price.

So here is the list with the parts i used:

• Arduino Nano (clone)
• Thermocouple Amplifier MAX31855
• 2×16 LCD
• 10k pot
• K-type temp sensor
• Wires

The schematic follows:

And the Arduino code which is making use of library Adafruit-MAX31855-library

#include "Adafruit_MAX31855.h"
#include <LiquidCrystal.h>

int thermoCLK = 3;
int thermoCS = 4;
int thermoDO = 5;

// Initialize the Thermocouple
Adafruit_MAX31855 thermocouple(thermoCLK, thermoCS, thermoDO);
// initialize the library with the numbers of the interface pins
LiquidCrystal lcd(7, 8, 9, 10, 11, 12);

void setup() {
  Serial.begin(9600);
  lcd.begin(16, 2);  
  lcd.print("MAX31855 Init");
  delay(500);
}

void loop() {
  // basic readout test, just print the current temp
   lcd.setCursor(0, 0);
   lcd.print("www.devacron.com");
   lcd.print("  "); 

   double c = thermocouple.readCelsius();
   lcd.setCursor(0, 1);
   if (isnan(c)) 
   {
     lcd.print("T/C Problem");
   } 
   else 
   {
     lcd.print("Temp = "); 
     lcd.print(c);
     lcd.print("c"); 
   }

   delay(1000);
}

And here is some photos of the finished thermometer:

And last but not least a small video footage: