Jeti Dual HighTemp Sensor

Want to know temperatures beyond capabilities of Jetimodels MT125/MT300 or RC-Thoughts Jeti FourTemp? Cylinder temp’s? Exhaust temps? Turbine-exhaust? Values up to 1000°C is not a problem! 

Jeti Dual HighTemp Sensor

Time for the wonderful world of Ebay! Get some parts:

  • Arduino Pro Mini 3.3V 8Mhz (Or equivalent) Example link to Ebay here.
  • MAX6675 Breakout-boards with K-type thermocouple. Example link to Ebay here.
  • Little wire and shrink-wrap.

Note about K-type thermocouples: For really high temps I strongly suggest to invest in good quality. While the actual thermocouple might take the heat like 800 °C it is likely that in the cheapest thermocouples wiring does not cope. So as usual, testing is critical! The actual temperature-probe can be any K-Type thermocouple, there are many different sizes and formats of them available in Ebay for example.

About MAX6675 : You have a few options here, you can get the type in the example or you can also get it as connectors not soldered. We prefer the breakout board without connectors but they are easy to solder off.

The board in the example-link above can be easily taken into parts, this is the result:

After a little bit of assembly this is about what you can end up with. (Or perhaps a bit cleaner…)

Picture from other side reveals some wires too:


One would think that a temperature sensor does not really have any features, bit it actually does:

  • Possibility to select one or two temperature-probes
  • Possibility to select EU or US units (°C/°F)
  • Possibility to name the sensor from pre-defined list of names
  • Measurement range 0 to 1024°C (32 to 1832°F)

The naming is a first in Jeti-sensors to my knowledge. Names of Temp-1 and Temp-2 can be set to any of following:

  • Temp-1
  • Temp-2
  • Cylinder
  • Left Cyl
  • Right Cyl
  • Exhaust
  • Left Exh
  • Right Exh
  • Turbine

Now, let’s make one!


Connections are simple and if you have built any DIY-sensors before they are familiar to you:

All connections are drawn and explained for a sensor with two temperatures. If you need just one leave the Arduino pin 11 disconnected.

  • MAX6675 GND -> Arduino GND
  • MAX6675 VCC -> Arduino VCC
  • MAX6675 SCK -> Arduino 10
  • MAX6675 CS Sensor 1 -> Arduino 9
  • MAX6675 CS Sensor 2 -> Arduino 11
  • MAX6675 SO -> Arduino 8

You also need the connection to Jeti receiver:

  • Arduino 3 -> Receiver signal
  • Arduino RAW -> Receiver positive
  • Arduino GND -> Receiver negative

NOTE: Some boards have GRN where my boards have GND. Do NOT use GRN, use GND!


And this is the schematic as a picture:

Looks harder than it is, really. I put the two MAX6675-boards on top of each other with some two-sided tape and draw all the common wires (all but CS-wires) with one wire each.

Programming Jeti Fuel Sensor

Go and get the suitable .hex or .ino (Named RCT-DualHighTemp) file from my Github here. Easiest method is XLoader + .hex-file. With Arduino and .ino you need to use the libraries included in Github repository. For info on how to use these look in RFID-sensor how-to here.

Jeti Dual HighTemp in transmitter

As usual, go to Main Menu -> Timers/Sensors -> Sensors/Logging Setup and do a sensor search. You will find a new sensor with one or two values, temperatures are in celsius or fahrenheit and there is one or two sensors depending on your settings:

Setting up Jeti Dual HighTemp Sensor

There are a few settings available.  So after first connection first verify that transmitter can see the sensor, then open Jetibox, go to right to “MX” and then down, you should see the sensor’s start-screen:

Pressing right takes you to temperature-screen for those who use physical Jetibox. You can see the value for Temp-2 is zero since settings default to one sensor.

Press right for settings, first up is the setting for one or two sensors, toggle between 1 and 2 senors with down-button, when done press right.

Now it’s time to select EU/US units, again toggle setting with down-button and when done press right.

Next up is a cool thing. To my knowledge for the first time you can name the actual sensor. Why have a boring “Temp-1” on your main screen when we can have it as “Cylinder” or “Exhaust”, right? Press up or down to go through the available names (seen in gif below) for sensor 1 and when done press right for next screen.

Next screen is the same setting, this time for sensor 2. After you are done press right.

Next up is the reset or save-screen. Remember that every time you change one setting you have to come to this screen and save all settings. If you want to reset sensor to defaults (one sensor, EU-units and Temp-1/Temp-2 as names) press up and down at the same time or if you just need to save your settings press right.

After saving the settings the physical sensor is restarted. After changing settings you need to go and do a new sensor-search in your transmitter for sensor count-, unit- and name-changes to take effect.

Using sensor values in transmitter

Here’s screenshots of values on main screen with different names:


A lot better with the name than with the boring “Temp-1”, right? And if you want some new names those are easy to add to the code yourself or then send the wishes to me via contact-page here and I’ll add them.

Version history

  • 1.0 Initial release
  • 1.1 Small fix to serial speed


Always make sure everything works as it should. Do not use faulty devices. neither RC-Thoughts and/or me are in any way liable or responsible for anything you do with your equipment or to others with equipment used as described here. You should never use LUA-apps for operation-critical functions.

If you find something that is not working or is behaving strangely please let me know. I’m a car-mechanic by training, not a programmer-geek :)

Most important thing

Is to have fun building and using, this will not bankrupt you in any way :)