Raspberry Pi BBQ temperature tracker

Hi, I am looking at doing my first hardware project and would like to some guidance on setting up a simple BBQ temperature tracker using a Raspberry Pi Zero WH. I am looking at Thermocouple Type-K Glass Braid Insulated

  1. Do I need an amplifier or will something like the cheaper SparkFun Thermocouple Breakout be ok? If i need an amplifier which one do you suggest?

  2. Do I need any additional parts to connect the amplifier/thermocouple breakout to the to the pi zero wh?

  3. If I wanted to programmatically control a 12v fan from the pi would this relay be suitable?

Thank you very much!


Hi Anthony.
You will certainly need something. The direct output from a K thermocouple is only 40 microvolts per Deg C with 0 Deg = 0 V.
This will need to be a dedicated K thermocouple device as a thing called “Cold junction compensation” needs to be taken into consideration. Without doing this the error could be equal to ambient temperature at that time. A quick experiment you can do to demonstrate this. Put a short circuit across the thermocouple input of a multimeter (usually “K”). The meter will compensate for a non existent thermocouple and the reading will be the internal temperature of the meter.
That Sparkfun device or something similar would do the job. All the above is taken care of for you and appears to output a digital signal directly readable by Raspberry, Arduino etc.
Whatever device you use must output something useful. With the very low level and the cold junction thing some processing is required to provide anything like a useable result.
Cheers Bob


Thanks for the background info, Bob. Very helpful!


Don’t forget as per Core text yellow wire is positive and red wire negative.
Cheers Bob


What do I need to connect my RP Zero WH to this breakout board? https://core-electronics.com.au/thermocouple-type-k-stainless-steel.html

And also to connect the breakout board to this thermocouple? https://core-electronics.com.au/thermocouple-amplifier-max31855-breakout-board-max6675-upgrade-v2-0.html


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Hi Anthony.
Firstly I think you have the above links reversed with respect to your text.

Some wire and a trip to the tutorial associated with that link.

A socket to suit the thermocouple connector or cut this off and use the screw terminals catered for on this breakout board. I note the PCB is marked Red (neg) and Yellow (pos).
This would appear to be a useful little board. Apparently the IC used does all the cold junction compensation for you. (Cold junction??? Refer my original reply above)
Don’t know why the probe you linked has limited range. The actual K thermocouple (inside) has far greater range than this. This probe may have a slow response time, stainless is pretty terrible regarding heat transfer. That is why there is a big slug of copper in the bottom of saucepans. If you need a fast response use a bare thermocouple.
Cheers Bob


Really appreciate your help, Bob!