Have you ever wanted to upgrade your hotend or extruder system only to find that new unit uses a K-Type Thermocouple or another Thermocouple; if you have ever tried to just plug that into your RAMPS 1.4 or other board you'll find out fast that it just won't work. You need a break-out board to get the job done... well, the crack MakerGeeks research team found this little gem and started making it up so you can, "plug 'n play" your K-Type Thermocouple with your RAMPS board. Very nice to have around and easy to use to, here's what you do to hook it up: For two-pin connector, "+""-" to thermal-coupler; For three-pin wire: "+""-" to power, "S" to main-board. Then here is what you need to do in the Config file in Marlin (it's the same for Sprinter Firmware): a. modify Configuration.h on firmware Marlin: #define TEMP_SENSOR_0 -1 (the value is set to be -1) b. modify pins.h on firmware Marlin: Find configuration for Pins on Ramps1.4: If the original value is #define TEMP_0_PIN 2 We'd revise to #define TEMP_0_PIN 3 (p.s We can not use the original pin for thermistor. The recommended is A3, as it is located next to 5V and GND, so quite easy for connection). c. connect thermal-coupler to this board (need to check if polarity is correct), and connect signal to this breakout board. d. connect signal wire to Aux-1 on Ramps, red wire to 5V, black wire to GND, green or blue wire to D57.