Thermocouple to NTC Sensor Controller

Thread Starter

draw2build

Joined Nov 25, 2022
12
I'm making a temperature controller for a water kettle that has no temperature controls. I'd like to use a thermocouple since it's solid and can be attached to the removable lid. I've connected a thermocouple to an XH-W1219, but all I get is HHH. It looks like the NTC sensor isn't understanding the thermocouple. Since I prefer Fahrenheit I've ordered, and still waiting for, the W1209WK. What can I add, or do, to get the NTC sensor to recognize a thermocouple? When connecting the thermocouple to the NTC sensor plug I tried connecting it one way, then tried swapping the wires, so if there's a negative and positive I wouldn't have gotten it backward. Nothing, still HHH. I've come to the assumption that it's possible because searching Amazon for "thermocouple temperature controller" I saw an Inkbird kit with a thermocouple.
Both the XH-W1219 and W1209WK run from 12VDC, so I'm using a 12 5A power supply.
Can anyone give me an idea of what to research to make NTC sensor to thermocouple possible?
Thanks in advance.
 

MrChips

Joined Oct 2, 2009
27,715
A thermocouple and an NTC thermistor are two totally different animals. You cannot replace one with the other.
You either use an NTC thermistor with the XH-W1219 or you get a thermocouple readout that accepts your thermocouple.
 

schmitt trigger

Joined Jul 12, 2010
510
For starters, what type of thermocouple are you using? Most likely it is a K type, they seem to be ubiquitous.
Like Mr Chips described a thermocouple is SIGNIFICANTLY different from a NTC thermistor. For starters, you require cold junction
compensation. Then you need to amplify a signal in the sub-mV range. Finally you have to apply the correct gain and linearization coefficients for the thermocouple type.
It simply can’t be done with a controller designed for a NTC thermistor. It is like asking whether one can teach a horse to fly.
 

Thread Starter

draw2build

Joined Nov 25, 2022
12
I have type K thermocouples since I use them on my coffee roaster. I'll have to do research to see if I can find a better NTC thermistor. I'd like to thank both of you for your insights.
 

du00000001

Joined Nov 10, 2020
113
Could you provide a schematic?
This one is from the XH-W1209 - equal or at least quite similar to the W1219:
1670611233491.png

It's by no way perfect (would you believe that "RT" shown in the lower middle is the sensing NTC with a pluggable connection ? :-(
What's required is an NTC with a nominal resistance of 10 k and e.g. 0.5 % tolerance.
(There is quite a number of NTCs with similar nominal data, differing in the details, but the "standard NTC 10k/0.5 %" will most likely fit if the sensor that came with the controller has been destroyed or lost.)
 
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