Unknown thermal sensor

I have two thermal sensors from a wireless (433 mhz) thermometer system that I would like to an Arduino Uno. There are no external markings and it is sealed in a stainless steel tube. (Sealed is good, because I want to use it under water.)

I know that the sensors work on the old thermometer system, which has a battery operated base station and two remotes. I can hold the sensor and see the temperature rise on the wireless system as expected. When I connect the same sensor to my Arduino Uno (A1 or A2 or A3) I read a voltage, but no change when I hold it in my hand. I tried Pinmode(input) and pinmode( input_pullup. I have tried 5v and 3.3v drawn directly from the board.

1 - Any thoughts on how I can change the circuit to be able to see a change? Resister?
2- Any thoughts on how I can calibrate the value (that I hope to see) into a usable value for degrees?

Maybe a photo could help?

gremark:
I have two thermal sensors from a wireless (433 mhz) thermometer system that I would like to an Arduino Uno. There are no external markings and it is sealed in a stainless steel tube. (Sealed is good, because I want to use it under water.)

I know that the sensors work on the old thermometer system, which has a battery operated base station and two remotes. I can hold the sensor and see the temperature rise on the wireless system as expected. When I connect the same sensor to my Arduino Uno (A1 or A2 or A3) I read a voltage, but no change when I hold it in my hand. I tried Pinmode(input) and pinmode( input_pullup. I have tried 5v and 3.3v drawn directly from the board.

1 - Any thoughts on how I can change the circuit to be able to see a change? Resister?
2- Any thoughts on how I can calibrate the value (that I hope to see) into a usable value for degrees?

They are most likely thermistors. Use the search icon on the upper right of the forum page (lollypop) to search for the word "thermistor". Lots of posts and circuits.

Paul

Here is a pic

The image:

I don't have experience with those but a thermistor seems possible. Other option is DS18B20, they are in similar cans. Try to measure resistance vs temperature.

Use your multimeter to measure the resistance between the connections, and check whether that changes if you heat or cool the steel tube.

HA! ... Multimeter test worked very well ... I am new, but I'm getting there ...

Warming in my hand reduces resistance from about 50k ohm range down to the 40k ohm range ... It gives me a good working start. ... Thanks

Thermisters ... something new to learn about I will check into it now ...

Thanks so much

gremark:
HA! ... Multimeter test worked very well ... I am new, but I'm getting there ...

Warming in my hand reduces resistance from about 50k ohm range down to the 40k ohm range ... It gives me a good working start. ... Thanks

Thermisters ... something new to learn about I will check into it now ...

Thanks so much

Good for you! Now, don't assume that because your thermistor has a stainless steel case that the whole thing is water proof.

Paul

Thanks Paul ... It does seem that it is also filled with epoxy. Worst case, if it fails, well ... it was free ... LOL

Experimental results: (close will be good enough for this application)

Wiring: 5.0V -> thermister -> Analog pin 3 -> 10k ohms -> GND ... and ... pinMode(A3, INPUT);

Raw readings from sensor:
in ice (approx. 0C) : 59
in mouth (approx. 37C): 248

degreesC = map(rawreading, 59, 248, 0, 37); // works with 5.0V input

I will do same test with 3.3V, if I really get curious

Thanks again for all the help

I think you will really like this link:Calibration | Cloud Thermometer | Adafruit Learning System

It shows how to calibrate any thermistor and generate the Steinhart–Hart coefficients so you can accurately calculate the temperature.

Have fun!