Electrical Engineering Stack Exchange
Electrical Engineering Stack Exchange

Questions tagged [thermocouple]

A thermocouple is formed by a contact of two (2) dissimilar conductors. The voltage across thermocouple is governed by Seebeck effect. Thermocouples are widely used as temperature sensors.

Further reading

Linear Technology AN28. Thermocouple measurement.
classical 1988 application note by late Jim Williams

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Differences between thermistors and thermocouples

As I understand it, both thermistors and thermocouples are temperature sensors. So what are the advantages/disadvantages of using one over the other to measure the temperature? What are the specific applications for either of the sensors?
m.Alin
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Why do temperature-voltage curves of all thermocouple types pass through the origin?

Notice that the temperature in the graph is in °C, not even in °K. 0°C is the border between temperatures of water and ice under 1 atm pressure. Why do thermocouples give 0V voltage at a temperature of 0°C? Is there any relationship between water…
hkBattousai
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Can an infrared thermometer (IR gun) be used to measure the ambient room temperature?

I know the principle of an IR thermometer, but have one question regarding that are as below. As an IR thermometer senses the radiated IR waves from external bodies coming in their field of view and gives surface temperature reading, can we point…
Viral Embedded
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Current produced by thermocouples

I can't seem to find an answer to this on Google. Take a K-type thermocouple for example. The voltage produced is around 41uV/K. I'm wondering how this changes when a load is put across it. What equation determines the current? Can I assume that the…
Jodes
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Are special terminals required for connecting thermocouple wires to a PCB?

I'm currently trying to integrate a type K thermocouple into an electronics project. I intend on interfacing this thermocouple with the MAX31855 cold-junction compensated thermocouple-to-digital converter IC. I am not an expert on thermocouples and…
Izzo
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Where is the cold junction on the commercial thermocouples?

According to all textbooks and articles, a thermocouple must have a cold junction somewhere on the middle of it. But none of the commercial products have a middle point or a marked spot for indicating the position of the cold junction. They are…
hkBattousai
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What is this component in series with my water heater's thermocouple?

The other day we had our water heater go out and the issue was diagnosed to a faulty thermocouple. When the repair man removed the faulty thermocouple he noticed the following disk-like component in series about mid-way down the copper tubing. This…
SiegeX
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Grounded thermocouple vs "grounded" thermocouple

I'm having problems with documentation and what appears to be conflicting use of the word grounded. The way I understand it, a thermocouple can be [grounded, ungrounded, or unsheathed] (http://www.omega.com/techref/themointro.html). But neither of…
Bob Baddeley
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Effect of length on a thermocouple's accuracy

I'm a mechanical engineer working on acquiring some temperature data using thermocouples. Q. I wanted to know the effect of wire length on a thermocouple's accuracy. I don't have much of electrical engineering knowledge. I did some amount of search…
Bharath
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Temperature sensors for an Arduino sous-vide project

I'm creating a PID controller for sous-vide, like this one, and am trying to decide which temperature sensor to get. Priorities: Cost: < £25 delivered in the UK Accuracy: +/- 0.5C Range: 0 - 100C Output: something that can be read by an Arduino…
Richard Russell
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How do I protect analog circuit from relay switching noise?

I'm making a thermocouple based temperature controller. The thermocouple voltage is measured by using cold junction compensation IC LT1025 and precision opamp LT1050. The measurements are read by ADC and the relay is switched on by a MOSFET…
miceuz
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cheap thermocouples. Homemade?

I need to make a bunch of thermocouples but I don't want to spend a ton buying them pre-made. I only need short thermocouples (like 6-8" long) so if i were to buy them it would be wasting a lot of wire too. I know thermocouple wire is pretty cheap…
PICyourBrain
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Can an op-amp reduce its own gain after a failure?

I have a pellet stove that after few minutes from startup turns off. I discovered that the cause is the smoke temperature that is too low (~ 30 °C, read on the remote) even when it's burning. Of course it thinks there is no flame and turns it off as…
Mark
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K-type thermocouple, instrumentation op-amp and Arduino

I am trying to read a K-type thermocouple with a 0-5V Arduino Uno. I can read my thermocouple directly using a Fluke meter on temperature setting giving me the correct value of 21°C, but when I switch to mV setting I read 0 mV on my Fluke. …
posop
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PCB-mount connectors for thermocouples

Has anyone had good/bad experiences with particular PCB-mount thermocouples? I need to design a circuit board with a connector I can plug a standard thermocouple connector into. (and yes, I am aware that when you connect thermocouple wires to copper…
Jason S
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