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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.

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74 views

Can LM35 temperature sensor be used to measure temperatures in bone in an in vitro setting? are they comparable to K type thermocouples?

I belong to the medical field. I have zero knowledge about electronics. For my thesis, where I will be measuring temperature within the bone during drilling, I am required to use a temperature sensor ...
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58 views

infrared and K-Type temperature sensors badly disagree [closed]

They are both cheap. There is a piece of PCB balanced on top of the K-type thermocouple's probe; there is also a red laser light from the infrared thermometer right in the middle of the same PCB where ...
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47 views

Soldering iron thermocouple measurement HELP

I'm working on a relatively simple soldering iron circuit. I'm using a T12 tip, which consists of a resistor and thermocouple in series. I'm driving the gate of the N channel mosfet with 20V via a ...
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61 views

Current from thermocouple (T/C)

Studying thermocouples (T/C), I have a question regarding the output. Generally speaking, in the case of T/C, we measure the thermoelectric voltage in millivolts. Why do we calculate not current, but ...
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55 views

Why does a thermocouple have two outputs (V+ and V-)?

Does that mean that there is two different voltages? The potential is used to determine the temperature. (?) I understand it's the seebeck effect dictates how the thermocouple works. Apologies ...
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MAX 6675 module not working shows 0 degrees celsious 0 fahrenheit

This isn't a problem, rather a solution. I have a MAX 6675 module connected to an stm32 development board which at the beggining it worked perfectly and suddenly, it just showed 0C and 32F. Always ...
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58 views

Need help troubleshooting after short-circuit, with heaters and thermocouples

There was a short circuit in one of the furnace that I designed. Description of the furnace and its components: The furnace is a copper tube, with 1/2 inch thickness, and 10 equally spaced 1/4 inch ...
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28 views

Inconsisent SPI data transfer with MAX31856

I am using an Arduino to communicate with a MAX31856 on a custom-built PCB. The Arduino is loaded with this library, which seems to be working correctly. Unfortunately the data being read by the ...
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38 views

Error deriving temperature from thermocouple amplifier

I'm using a K-type thermocouple to read the temperature of a 3D printer hot-end. To amplify the thermocouple voltage I am using the Analog Devices AD8495 chip. This chip is mounted on a custom-made ...
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1answer
41 views

Thermocouple amplification configuration

I am relatively new to thermocouples. We are wanting to get the temperature of fire ball blast. We are using a Type-K thermocouple and a Phoenix Contact mini signal conditioner to amplify the signal. ...
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Thermocouple chip & CJC compensation under 0°C

We are currently designing a "conditioning" module that takes a couple of sensors (T°, Pressure but also via digital bus) and repeats over CAN / also outputs them in nice and clean analog signals (0-...
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295 views

K-Type Thermocouple, Instrumentation Op-Amp and Arduino

I am Trying to read in a K-Type Thermocouple to 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 ...
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45 views

Connecting K-Type Thermocouple wires to a data logger with a male and female plug

I'm trying to setup a temperature data logger using Graphtec GL240. I will be using K-type thermocouples for the logger. I want to run short length of k type cables from the logger to a female K type ...
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37 views

How to convert a temperature readout to a K-type thermocouple voltage? (reverse thermocouple converter)

I am working with a commercial heating controller device which takes in a thermocouple input in order to regulate the heating temperature. However, in some cases, the thermocouple junction just isn't ...
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41 views

Connect Thick thermocouple wire to Type K Connector

I have purchased a high-temperature K type thermocouple that has two 14 gauge solid leads. I wanted to know what the best way to go about connecting these leads to a type K connector would be.
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78 views

Can I connect Analog and Digital Voltage Source together?

Is it bad if I connect the A_VDD and D_VDD Pins together if I want to use the same voltage? Or maybe I should ask: Why can I hook up different voltages other than galvanic decoupling? This is the IC I ...
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98 views

pass thermocouple K type through d-sub and circuit box - what might be error?

What might be temp error if I'll pass my TC through simple d-sub (green & pink) and from my circuit box (blue) to destination device (yellow) I want to use copper wire, wire lenght between them ...
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50 views

k-type thermocouple with latency

Bought from here I have tried the magnet trick and it does not stick to either of the two wires of this TC. More so, screwing it inside an oven and turning the temperature up does produce some micro ...
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42 views

Can I amplify a thermocouple Signal with the GS8332-SR OP-Amp?

Theremocouples have a very small voltage of around 0.4mV/10C. K Type Thermocouple Voltage Table I want to amplify that signal so I can read it with an ADC on my Arduino Microcontroller. The Voltage ...
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108 views

Effect of wire gauge change on thermocouple measurement

I'm working on attaching to a thermocouple harness that had six 16AWG chromel wires and one 12AWG Alumel. The alumel would T off with each of the chromel wires to make a pairing and so the common was ...
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171 views

Negative voltage at the output of non-inverting opamp

I want to amplify the output voltage of a thermocouple by using a two-stage operational amplifier but the output that I get is a negative voltage at or below room temperature(<=30 degree Celsius). ...
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53 views

Reading T/C voltage when Heater is present in series

I am trying to read the thermocouple voltage of a Hakko T12 tip which has the heating element present in series with the thermocouple. The problem is that 24V DC will be present on T+/T- of the ...
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181 views

How to Amplify Thermocouples (and DC sensors between 1mV and 1µV DC)?

This is a bad idea, I know Here's what I know about amplifying really tiny DC voltages: it's impractical to build your own for production there's going to be noise the signal is relative to the cold ...
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46 views

Can a grounded thermocouple cause GFCI to trip?

I noticed the tip of my soldering iron is case grounded. I understand the GFCI compares voltages and trips if there is a difference (in the millivolt range). If the thermocouple generates a small ...
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159 views

How do I determine whether a sensor is a thermocouple or a thermistor?

Is there any nondestructive way to determine wether a soldering iron uses a thermocouple or a thermistor? The documentation on the iron claims it is a PTC ceramic heater. Some manufacturers mention ...
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123 views

Can resistors be used to bring a heating element within range?

I have a replacement 24V/60W desoldering gun I would like to modify for use on my Aoyue Int958A+ soldering station. My 968A+ has a smoke absorber which has enough suction to double as a solder vacuum. ...
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53 views

Why do heaters vary widely in resistance even though they have similar power requirements?

I have a soldering station equipped with a 24V/60W soldering iron. Its heating element (pins 1-2) resistance measures around 50 ohms. The resistance of the thermocouple (pins 4-5) measures around 2 ...
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72 views

Erratic behavior of thermocouple input

I am reading temperature from a K thermocouple on a PLC which is then forwarded to a trending software to see the data on a graph. The thermocouple is in a water trough/reservoir. In fact, there are 3 ...
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80 views

4-20mA current loop - transmit sensor reading

I am working on design loop current transmitter- to transmit reading value from thermocouple sensor using below design. I measured co-junction temperature using NTC instead of RTD. During applying ...
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28 views

Perdiodic thermocouple signal buffer for hot tub

I'm not exactly sure what to call this technically, which has hindered my ability to research solutions, so I think best just to describe the challenge and see what we can figure out. I have an older ...
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156 views

Differential amplifier with common voltage far above the rail?

I have a thermocouple with one end connected to +24V. I want to be able to read the voltage (-5mV - +20mV) on it using a 3.3V ADC. The most reasonable solution I see is lowering the voltages using ...
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770 views

High resolution ADC vs amplifiers

I have started a design for work where I want to interface some sensors, (strain gauge, bridge, thermocouple, low voltage stuff) to a national instruments sbRIO card. This card has analog inputs built ...
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44 views

Supplying two temp controllers with a single element thermocouple

I am installing a process temperature controller and an overtemp controller for a heater bundle. Normally I would just install two thermocouples, one for each controller. But space is limited and I ...
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1answer
81 views

Will thermocouples sharing a common wire create inaccuracies during measurement?

Specifically, I've been working with pre-existing temperature cables which are T-type thermocouples which share the same Constantan wire. My question is if one of the thermocouple junctions is heated ...
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52 views

Selecting temperature probe for home use with long cable / low power [closed]

I would like to monitor the temperature outside my home. The sensor has to be located at least 20m cable length from the display unit. Whole system should be powered by a battery (doesn't matter which)...
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82 views

Modelling a temperature measurement system

The accuracy of a measurement system can be significantly reduced by loading effects in the system. A thermocouple is used together with an indicator to measure temperatures. The thermocouple has a ...
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621 views

How to read a thermocouple chart

Studying for the PE exam, everything seems to be a breeze, but I cannot for the life of me read a TC chart. Specifically, I have a sample problem in a study guide where the measured voltage is 21....
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166 views

What options are available for measuring grounded thermocouples?

I'm using 4 MAX31855 ICs to measure 4 K-type thermocouples and realized that 2 of my thermocouples have grounded junctions; I simultaneously also realized the MAX31855 is stated to not support ...
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306 views

Instrumentation amplifier output stuck high

I tried to design an inamp for a K-type thermocouple. In theory the gain of this amp should be 250 (close enough to 10 mV/K), and if my understanding of instrumentation amplifiers is correct the ...
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191 views

What can you tell about our circuit diagram? Any suggestions?

This is our circuit for our research which is the conversion of heat to electricity. The TEG module will convert the heat to direct current. It will give energy to the voltage booster moduleto and the ...
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87 views

ads1232 SCLK pin timing

I'm working on reading analog voltage from type S thermocouple which is approx 10 microvolts per degree Celsius using ADS1232 TI converter. according to the device datasheet page 19, serial clock ...
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559 views

How to use LM35's temperature as cold junction for K type thermocouple?

I have been trying to built an thermocouple base temperature monitoring system which can measure negative temperatures (say about -150 C). I previously have used max6675 but later on I found out it ...
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891 views

Can I cut off a thermocouple's metal head?

I want to attach a thermocouple to my 40Watt soldering iron in order to make it temperature controlled. The thermocouple I'm going to buy is a K type MAX6675 thermocouple that looks like this: But ...
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1k views

Why does a thermocouple circuit need to have minimal current flowing through it?

I was reading on this website that it is imperative that current in a thermocouple circuit be kept as low as possible for good measurement accuracy Why is this the case? Also, if one makes it so ...
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Peltier Module constant time and thermal Load

Hi everyone I am new to this forum. I am doing a project where I need to control one of the sides temperature of a Peltier device against human skin. So one side is in contact with the skin, and the ...
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375 views

Thermocouple noise causing spurious reading with SSR

I have a thermocouple PID SSR heater as shown, based on the MAX31855 ( datasheet ). I get spurious readings when the arduino is plugged into my laptop, my laptop is plugged in to its charger, and the ...
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Accidentally misconfigured T type thermocouples as J. How do I convert my data?

I was running a test between -70C and 70C using T type thermocouples but misconfigured it on my DAQ(keysight) to J. Is there a way to convert the data I gathered to the correct settings?
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100 views

How can I tell from a datasheet if a thermocouple amplifier IC will work with a grounded thermocouple?

There are several different solution available for thermocouple amplification such as the MAX31856, AD8495, and LTC2983. Some of these support grounded thermocouples (AD8495) and some don't (MAX31856)....
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303 views

Where is the ground reference when using a thermocouple?

I am using a MAX31856 to read thermocouple voltages. I have an ADG707 differential multiplexer feeding the MAX31856 from various ungrounded thermocouple probes (see diagram below). I am using the ...
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302 views

Does the AD8495 thermocouple amplifier allow for grounded thermocouple probes?

I recently purchased a MAX31856 thermocouple-to-digital chip for a project. However, I discovered that the chip does not support grounded thermocouples. I am looking for an alternative and the AD8495 ...