Temperature-measuring device made from two wires

Thermocouple is a simple device to measure temperature by using Seebeck effect where a current is created in a heated conductor. The amount of current depends on temperature and the material from which the conductor was made. It's a common tool when measurement of relatively high temperatures is needed, also a lot of altimeters can measure temperature by using a thermocouple that usually is part of the multimeter set.

The thermocouple consist of two different conductors placed in the same temperature, because each one is made from a different material, the voltage that they produce differs. A thermocouple measure difference between those voltages.

In this post, I will present a simple version of a thermocouple, that I made by myself. If you like the idea of building your own sensors (even just for fun), you might be also interested in articles about home-made photo-element and DYI pressure sensor

I've tried built this sensor as simple as possible, so I used iron nail and a copper wire as parts of the thermocouple. I used a multimeter to measure voltage created by the thermocouple.

Without a source of a heat, the multimeter shows 0mV, when the thermocouple is heated, it shows 0,7mV. This is demonstrated on below images.

A small candle was used as a heater, that's why there's a black coating (soot) on the thermocouple.

Since I was only interested in building a working prove of concept, I didn't perform any calibration.

For me it's amazing that such a simple thing can produce quite a lot of energy - it can be directly measured with a multimeter, without any amplification.

12 comments:

  1. Very nice demonstration! There is no expencive material, nor complex making process ;)

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  2. Would it be possible to measure room temperature with this device? Would it create sufficient voltage?

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    1. TBH I don't know, but I think that it's not possible (at least directly) - a thermocouple measure difference in temperatures between its ends, if the ends have the same temperature, then no current is created. It's possible to measure temperature of things that are hotter or colder that environment, but it's impossible to measure the temperature of the environment.

      ..but as I said, I'm not sure.

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    2. For room temperature it would be impractical, better results could be achieved with a regular terminator (you can obtain one from a broken laptop power supplier) or diode/transistor.

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  3. You really should solder those cables :)

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    1. Yeah, it looks awfull now

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    2. Yes, but it's just a prove of concept, also it's hard to solder iron objects and I didn't have soldering acid.

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  4. Very nice demonstration! Thanks Robert for sharing it! This was well put together. I doubt I would of done any better creating something like this. lol.

    Thanks again!


    For those interested in purchasing a thermocouple, a great place to go to is Thermo/Probes Inc. For more information, feel free to check out their website!

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  5. Very interesting.

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