These probes have T+ and T- which are connected to the tip and sleeve of a 2 or 3 terminal jack
okay, thanks
Grey
The device I am trying to make has to be made from off the shelf products to make it repeatable for other people. But also to make it easy to replace parts. Making the probe yourself is adding a failure point that would require time to fix, compared to ordering a new probe from AliExpress / Amazon.
I do not want to have 2 devices for reading the temperature and prefer wifi over bluetooth.
I also want to be able to change the software with ESPHome, and enable other people to do so.
Both to keep it simple and customizable.
That is improving for laziness or just having limited time like many people have.
This project is some time and money investment from my part now, but hopefully other people can have exactly the ESPHome meat temp probe that I was also looking for and safe time.
Like what Zuidwijks SlimmeLezer+ did for me.
so for multiple probes, you just wire the SO and SCK to the same pins on the 8266 and use a diff pin for cs?
# Example configuration entry
spi:
miso_pin: GPIO12
clk_pin: GPIO14
sensor:
- platform: max6675
name: "Meat probe 2"
cs_pin: GPIO15
update_interval: 10s
sensor:
- platform: max6675
name: "Meat probe 1"
cs_pin: GPIO13
update_interval: 10s
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I was just trying to explain why a DS18B20 is unsuitable for a meat thermometer, not intending to thread crap in any way.
I think you have cool project, it motivated me to work on a meat thermometer project.
Randy
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Yes, that is correct
Hi,
I ordered those probes from above and they do not seem to work?
I have 2 max boards with some meat probes I had. They were 3.5mm and they work great
There are many discussed products listed earlier in the thread, which ones didnāt work?
Having the right probes might be problematic for this project.
I have seen some discussions with the IKEA meat probes being different, but I do not think that in general the K-Type probes are any different.
Please note that the 2.5mm probes I used for my test setup are from some cheap bluetooth meat probe, I think they are quite generic.
Can you share the exact links of the purchased hardware, also from the 3.5mm probes?
Do you have any datasheet of the 3.5mm probes?
How did you connect everything for testing?
Can you share a picture of your test setup or schematic?
Probes I had came from here BBQ Guru Food and Pit Temperature Probes
I used these to connect the probes Amazon.com
How did you connect the 2.5mm probes from aliexpress? Picture?
same way. I used these 2.5m sockets to wire into the max board
I think these probes I got from aliexprese are ntc
Is your Bluetooth therm an InkBird?
It might be that your aliexpress things are broken. Others have positive reviews.
I highly doubt they are NTC, although easy to check if that would be the case.
My bluetooth therm has no brand on it. Very cheap thing.
I tried two of the six I ordered. They may work for the thermometer it is a replacement for.
I wonder if the inkbird replacement probes would work. They cost twice as much 
Cool little project! One I have also been thinking about for quite some time.
One thing I was wondering when reading through this thread was that when I was looking at it before, I was under the impression that most probes āwith a pointy end and 2.5mm jackā are actually thermistor types, not thermocouples. Sadly most ali-specs do not list this, so its still a bit difficult to know what is whatā¦
But as the MAX6675 is only for thermocouples, that might be where things go wrong, so as you identified already, getting the right probes might be the most problematic part as you would need a completely different setup for a thermistorā¦anyway, definately keeping my eye on this
Thanks. Going to be following. Iād like to make a PID controlled fan for my charcoal smoker/grill.
Question: The meat probe you mention is a thermistor rather than a thermocouple, right? As far as I know the MAX6675 is only for thermocouples. An interesting thing about thermocouples is that they self-calibrate at their ācold junctionā point. This is where the 2 different alloy wires enter the MAX6675. Connecting plain copper wires between the Thermocouple and the MAX6675 (like the mini plug and jack) will change the calibration. Not sure how much difference that makes n the range of temperatures weāre dealing with.
@ronkmd @Aza The probes should be thermocouples or it will not work. The AliExpress description is indeed minimal and unreliable, however the temperature range gives the suggestion the meat probes are all thermocouples.
For this project I only want to use thermocouple probes, as I need up to 400 degrees for the BBQ.
The MAX6675 has cold junction compensation.
Thanks for clearing that up. And also explaining what ācold junction compensationā means!
Iāve put this aside for a while but Iāll probably start up again soon. I was kind of frustrated with noisy and inaccurate thermocouple readings thru ESPHome.
I do have a couple of Yummly wireless meat thermometers that Iād like to integrate. However, their Bluetooth protocol isnāt public and they donāt have plans to release it. I donāt have any experience with BT sniffing and reverse engineering so it might be over my head, especially if any proprietary encoding is involved. The cool thing about the Yummly is that it reads Ambient temperature as well as meat temperature. This would eliminate the need for any external probes to be connected to the ESP32.
FWIW, I got an inkbird IBT -2x and it works fine with openMQTTgateway He may be able to get your yummy things integrated?
for giggles I tried the 2.5mm jacks with the max6675 and they do not work.
I am not sure I follow the cold joint thing as it is just copper wire going through the shielded cable to the probe. From what I can tell with all my diff things now taking temps they all seem to be the same
So I have yet to find a cheaper probe that works with the max6675 other than these from BBQGuru but for 26 bucks a probe I would just get inkirds and an esp32
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