I want to learn thermocouple type k,j etc,

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Joined Jan 30, 2021
Hello evryone,
I start studying Eletrical and computer engineering and I want to learn thermocouple type k,j etc, however I've been searching and I can find to measure temperatures is using water bath 0° in cold junction so voltage will be the same as thermocouple tables on google, however that's not practicall so can someone help me to understand how that "cold junction" is made electronically? Or am I understanding the cold junction concept wrong?
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You have the tables. Polynomials or a lookup table for t(v) is available at 0 deg C.

You have to independently measure the temperature of the terminals (isothermal) where the thermocouple connect with a )e.g. calibrated thermister, diode or silicon sensor), then reverse lookup the voltage at that temperature.

You then add or subtract, forget which, your measured value and then lookup the temperature for that voltage.
Cold junction compensation is generally valid over a smaller range.
To understand it, you can do the ice bath thing and a voltmeter.

Then, you want an isothermal connection. You can probaby make one. Get couple of to220 insulator kits and some copper or brass and make a fairly large thermal mas, but thermally conductive and read the temperature with some other sensor.

You can buy isothermal blocks for thermocouples.

One last thing: Th wire with the Red insulation is negative,