Questions tagged [rtd]

Resistance Temperature Detector (RTD). An RTD sensing element usually consists of a metal filament, which is coiled on a mandrel or etched on a substrate. The RTD element is made from a pure material, typically platinum, nickel or copper. The material has a predictable change in resistance as the temperature changes; it is this predictable change that is used to determine temperature.

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What is the correct configuration for 3-wire RTDs connected to an ADAM 6015 module?

I have connected four RTDs by wire (via a 12 pin cable). The common wires of all four RTDs go through only two of the wires in the cable. After soldering those wires together and connecting them to ...
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3answers
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Why is there a negative value on the scada when the analog input wire is disconnected from a field instrument?

I'm an apprentice electrician at an fmcg company. I've been seeing a trend recently, at the plant, where the scada actually reads a negative value instead of zero when a field device such as a ...
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50 views

What causes long-term RTD reading drifts?

I am working with a controller that was designed to read multiple types of inputs including 3 wire RTD signals. In some cases, we have observed the controller suddenly spike up +15 degrees and ...
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63 views

How are and what are the sources coupled to a 3-wire RTD leads? [duplicate]

I can understand two or four wire connection for RTDs. But I don't get where they apply voltage or current and how they measure the resistor values for 3-wire connection: Here is a page about these ...
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1answer
47 views

ITS-90 Tempature coefficents for a standard PT100 385 RTD

I'm currently using the ITS-90 formula to convert a resistance of an RTD to a temperature. I got the coefficients from the manufacturers calibration sheet. The problem is I have another probe that I ...
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PT100 - 39250 Cubic fit formula

I'm currently using a cubic fit formula I found online to derive the temperature of a PT100/385 RTD using resistance. The formula is -247.29 + 2.3992*R + 0.00063962 *R^2 + 0.0000010241 *R^3 where R is ...
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47 views

RTD circuit in industerial application

I'm trying to design RTD measuring for industrial use which has EMI/EMC/ESD. I have 3 wires input to the board. obviously 3 wires out of the board are going to 3-wire configuration PT1000 1- 3V3 (...
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RTD wheatstone resistance question

I have a question im currently working through, its as follows 'A platinum resistance thermometer has a resistance of 100 Ω and a temperature coefficient of resistance of 4x10-3 °C-1. Given that a 10 ...
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2answers
51 views

RTD temperature measurement system resistance question

I am trying to produce a bridge circuit for the following temperature measurement system: Designed to measure temperatures between 0 C and 100 C with a high accuracy. When supplied with a 10 V ...
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1answer
50 views

Which temperature transducer has these characteristics?

The resistance temperature characteristics of a temperature transducer is show in the figure below, The transducer in question is which of the following? A) Nickel RTD B) NTC thermistor C) Platinum ...
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49 views

2-Wire RTD techniques

I'm trying to understand the difference and caveats of those two different ways of measured the resistance of RTDs: the voltage divider and the unbalanced bridge: simulate this circuit – ...
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1answer
145 views

PT100 sensor for measuring liquid resin, fully submerged

Edited Link to Pt100 sensor (That's the best i could do) https://www.intech.co.nz/products/temperature/mrh.html Link to ESP8266 datasheet http://www.handsontec.com/pdf_learn/esp8266-V10.pdf ...
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1answer
55 views

Removing/Subtracting Lead Resistance Using Op Amp Circuit

I'm working with RTD sensor, and need to use Op Amp circuitry. Can someone explain to me how this Op Amp circuit work to remove the lead resistance? So that Rw1, Rw2, and Rw3 vanish, hence the ...
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MAX31865 RTD converter will it acccept only floating inputs?

We intend to use MAX31865 for measuring resistance values. Since MAX31865 is RTD to digital converter, kindly clarify whether the MAX31865 will accept only floating inputs or it can be used with ...
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1answer
190 views

Sallen-Key filter for PT100 RTD measurement

I am going to build temperature sensing system using PT100 sensor (and later Raspberry PI 3). I refer my work to Microchip note AN687 Precision Temperature-Sensing With RTD Circuits. On the page 4 is ...
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3answers
264 views

What does this resistor do in this RTD wheatstone bridge?

The question is in bold at the bottom, the following is background. I am going to measure air flow with a hot wire anemometer using the FS7 sensor from Innovative Sensor Technology (IST). They ...
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3answers
109 views

self-heating effect of dual PT100 temperature probe in a moving mass of water

I'm trying to know how much self-heating should I expect in these conditions: Temperature range: 0-45 C Using a 1050Ohm pullup resistor to feed each PT100 (2-wire configuration) with 5 volt ...
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1answer
111 views

MAX31865 - can I use a 150 ohm Rref?

I'm building a circuit for a home brewing application which will use the MAX31865 chip to read in temperatures of liquids from a RTD100 sensor. The chip does this by reading the current that flows ...
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4answers
549 views

RTD sensor circuit design

Design Criteria For a project I'm making I want to measure temperature using a 10 bit ADC on a MCU. I don't care for absolute accuracy but I would like precision down to around 1/10th of a degree C. ...
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4answers
1k views

How does 3-wire RTD or resistance measurement works in bridge of wheatstone?

I cannot understand how 3-wire measurement will improve the resistance measurement. They say that IF lead resistance \$ R_L \$ is the same, it will compensate. How can this happen? If bridge is ...
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2answers
68 views

Amplifier Circuit for Thermopile

I would like to build a circuit for reading temperature from a thermopile temperature sensor. I found this application reference for the circuit (page 6, Single power supply type with thermistor). ...
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2answers
419 views

How to calculate temperature resistance for Ni-RTD

I would like to build a circuit to read the signal from a thermopile temperature sensor which has build-in RTD temperature sensor for cold-junction compensation. The datasheet of the sensor is here. I ...
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1answer
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Help on understanding how a strange RTD reading circuit works

I'm trying to figure out how this universal micro-plc works: https://www.maximintegrated.com/en/design/reference-design-center/system-board/6185.html It is supposed to read current, voltage, ...
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1answer
510 views

How do Resistance temperature detectors (RTD) work?

What is the difference between RTD and Thermocouples ?
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2answers
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ADC variable reference voltage

I'm working on a design which must read temperature using RTD pt100 with at least 0.5 degree Celsius accuracy in the range -10 to 50 degrees . I want to use AD7705 ADC. my design looks like this. I ...
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860 views

Can long cables induce that much noise?

[UPDATE The problem is fixed and the results are in my answer below] I have designed a board with, among other things, six max31865 on it. From those six I use five of them. The device reads out ...
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6answers
547 views

Alternate way to read Resistance temperature detectors (RTDs) with Microcontroller

After reading many posts with difficulties reading a Resistive Temperature Detector (RTD) such as a PT-1000, NTC with e.g. an Arduino, I am wondering if a time based approach could be used: If I take ...
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2answers
724 views

Accurate yet relatively simple way to use RTD probes

I would like to build a reference thermometer for checking and maybe calibrating other sensors and I was planning to use 1/10 DIN RTD probe in order to do that. You can get such probes for ~$100 and ...
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3answers
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How to choose the right amplifier for 100 Ohm RTD in 3 wire configuration?

I have been doing research for the past week on setting up a 100 Ohm Platinum RTD to work with labjack U3 LV (I have to use labjack). I know I have to start off with a wheatstone bridge, and use a ...
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1answer
520 views

Mapping a voltage range to whole ADC range using opamps

I want to use a micro for measuring temperature using PT-1000 sensor for range -40C to 150C. I have come up with these draft information, I appreciate it if a pro person can confirm my thoughts are OK ...
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7k views

What is the best sensor to use in a wearable device to monitor body temperature on a continuous basis: Thermistor, RTD or a semiconductor device? [closed]

Most wrist-worn wearables on the market today don’t seem to feature body temperature sensing which makes me wonder if all these sensors are inadequate in some ways.
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Precision voltage reference divider vs. constant current source to drive an RTD sensor

I need to measure temperature with an RTD between 0-300 C. I believe I have two options to make this work: A constant current source feeding the RTD A precision voltage reference and a resistor ...
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4answers
263 views

Tap into 4 wire RTD

Is there any way to tap into an existing 4 wire RTD without changing the resistance, and therefore changing the temp that the existing device will read? Here's the scenario. The device is a medical ...
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8answers
3k views

How to make a voltage controlled adjustable resistor?

I need it for simulating PT100, PT500, PT1000 RTDs, and thermistors in a temperature range of 0-200 °C. What I want to do is for example: enter 50 °C using a microcontroller, and through the DAC ...
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3answers
392 views

RC filter on ADC voltage reference pins: overkill or necessary?

I've been scouring the web for circuits suitable for reading RTDs using ADCs. In one document from TI it is suggested that the following filter be placed on the inputs of the voltage reference pins (...
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2answers
697 views

PT1000 2 wire probe. Can I add third wire?

I'v got 2 wire (81 cm) PT1000 probe which I want to utilize in a project. I would like to use current source and couple of opamps to make the measurement through ADC (uC) just like described here: ...
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507 views

RTD Sensor Datasheet Details

I need to read one type of rtd sensor using linked datasheet(page5) but as far as i know there must be a temperature vs resistance table. Am i missing something or given datas are enough to read ...
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1answer
1k views

Rtd Signal Output to 0-5v? [closed]

I have a constant current source and analog input channel but it seems I can not directly read rtd as resolution needs mv levels. I cannot use circuit so is there any product or solution help me to ...
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2answers
153 views

Fast detection of transient temperature change.. RTD? Thermistors? Thermocouples? or something else?

If I want to detect temperature changes on the order of 10ms, what is the best technology to use (besides IR)? I know Thermocouples and RTDs are pretty slow.. not sure about Thermistors.
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267 views

Rtd pullup Connection?

I have 10v output and analog input, i dont have constant current source 1ma or dont want to use whetsonebridge circuit, my question is can i read rtd sensor output with pull up resistor Xk, if yes ...
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1answer
2k views

How to use an instrumentation amp?

I have a two-wire Pt100 element and a 5V ADC and want to measure the temperature. I have made a wheatstone bridge like below and connected it to an instrumentation amp. No matter the resistance of the ...
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1answer
3k views

How to control the temperature of heating element

I am developing a heating application where temperature need to be constant. I am planning to set the temperature @ 200 degree C. when my sensor find the temperature exceeding the set temperature how ...
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1answer
1k views

Does self heating matter in a PT100 calibrated in a constant environment?

Higher current through a PT100 results in a bigger signal and better S/N ratio. OTOH, it also creates self heating which results in lack of accuracy. However, if the PT100 is in a fixed environment, ...
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1answer
240 views

Special terminal blocks for PT100?

I'm about to lay out a board that will connect to a 4 wire PT100 sensor. Are regular screw terminal block connectors OK or do I need something more specialist? I am mainly thinking about possible ...
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1answer
9k views

PT100 v PT1000 - which to use [closed]

Under what circumstances is one better than the other? I can't seem to find much data on their use, as opposed to their resistances.
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4k views

RTD sensors and the mystery of Voltage Vs Current sources

Alright folks, I know there are a decent number of threads about RTD sensors (resistance thermometers. most associated with platinum type ones) Let me first assure you then hopefully show you that I'...
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2answers
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Improving RTD Sensor filtering and readout

For an application a temperature sensor is required. an accuracy of around +-3 degrees is acceptable. For cost reasons I have chosen for this RTD. The sensor is sampled by a 12 bit ADC of an ...
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1answer
601 views

Automotive Sensor - Excessive Ripple Noise

I'm designing an automotive oil temperature sensor based around a 3-wire RTD. This is my analog circuitry: U1 and U2 provide a 1mA bias on the RTD which is measured by U3 and gained up by U4. R5, R10,...
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2answers
591 views

RTD readout using wheatstone bridge and MCP6N11

For a project I require simple temperature sensing. The specifications are as follows: temperature range: 50-250 Celsius costs resonably low (< 10 US) accuracy +/- 2 degrees for cost and ...
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1answer
509 views

Are 4-wire resistance temperature detectors sensitive to ambient temperature?

We're using a TI LMP90080 as an ADC to read a 4-wire resistance thermal detector (RTD) in the following circuit: The problem we are having is that when the ambient temperature changes, especially ...