I would like to replace original NTC sensor for: https://www.aliexpress.com/item/TGT70-EP-Thermoregulator-Touch-Screen-Heating-Thermostat-for-Warm-Floor-Water-Electric-Heating-System-Thermostat/32669215824.html?spm=2114.13010308.0.64.mHnkr7 with self-made NTC probe. The problem is that manufacturer doesn't want to share any information on it. All I got is the picture and short description of it (not type or chart/table). Can anybody help to identify it?

Thanks enter image description here

  • \$\begingroup\$ Do you have a close-up photo of the sensor with the cap removed? \$\endgroup\$ – Dmitry Grigoryev Sep 7 '16 at 12:34
  • \$\begingroup\$ You'll have to match the sensors Temperature-resistance curve, If I was the manufacturer I wouldn't let you do that either because if you don't do it correctly you might break their system. \$\endgroup\$ – Voltage Spike Sep 7 '16 at 16:24
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    \$\begingroup\$ Assuming the yellow text is correct, you have all you need. It is 10k at 25C, and the beta value is 3950. You can read about NTC beta on wikipedia or some other website. en.wikipedia.org/wiki/Thermistor \$\endgroup\$ – mkeith Sep 7 '16 at 16:51

It's possible the manufacturer has no idea. The beta, as mkeith comments, is given, however the two temperatures at which beta is specified is not. It should be something like 25/50, 25/85 or 25/100.

I suggest you take a good sample of the instrument and adjust the input resistance with a pot until it reads 25, 50, 75, and 100°C. Read the pot with a digital ohmmeter (the first number should be 10K). Then you will be able to match a proper thermistor datasheet.

Or you could just buy some other no-spec sheet piece of 'stuff' that has the string '3950' in the description and hope it works well enough for long enough.

A reasonable and moderately educated guess would be that it's \$\beta_{25/50} = 3950K\$ but definitely confirm it.

That would imply it would read exactly 50.0°C at 3.5882 K, ideally.

  • \$\begingroup\$ This is a good point. There is more than one temp pair for measuring beta. \$\endgroup\$ – mkeith Sep 8 '16 at 7:40

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