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Thermocoupler Circuits

Thermocouplers:  #'s - N      M - Z

Last Updated: October 24, 2017 02:55 PM

Circuits Designed by Dave Johnson, P.E. :
Thermocouple Temperature Activates Relay -  Voltage from a high temperature thermocouple activates a relay when the sensor detects a temperature above 1000 degrees F. . . Circuit by Dave Johnson P.E.-July, 2006

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Micropower Thermocouple Signal Conditioner with Cold Junction Compensation -  A thermistor, shown as R3, is used to monitor the cold junction temperature.  its resistance becomes smaller as the cold junction temperature increases.  An increase in cold junction temperature will reduce the output voltage of the Type J thermocouple by 52uV/C.  The voltage reference and scaling of resistor values creates an __ Linear Technology/Analog Devices App Notes, Jun 21st 2011

Minimizing thermocouples maintains 20-bit DAC precision -  05/03/01  EDN Technical Article: Undesirable and unintended thermocouples are the primary sources of error in low-drift circuits.  Attention to layout and other construction details is the only way to tackle the problem.   __ Circuit Design by Jim Williams, EDN's most revered contributor, passed away in June 2011 after a stroke.  He was 63.

mV Source for Thermocouple simulation -  I realized early that for prototyping and troubleshooting, I would require a millivolt source which can simulate a type K TC.  For now, this circuit is what I devised.  When the ECU is complete, I will do final calibration with a lab-grade TC simulator, and develop software interpolation of the non-linear curve.  But to simply create the Op-amp interface to amplify the signal, this little circuit seems to work quite well.  it is mounted on a 2" square PC board with a 9V battery.  I used a 10-turn 1K pot (expensive).  A normal pot will work fine.  Vary the 120K resistance to increase or decrease the mV signal range.  in this configuration, it will output a fairly stable 0 to 40 mV.  __ 

Network imitates thermocouples -  11/08/01  EDN Design Ideas:  Thermocouples find wideaspread use for temperature measurement in systems.  During system design or testing, you must observe the system's response at different temperatures.  However, it's inconvenient to heat a thermocouple every tim __ Circuit Design by Abel Raynus, Armatron International, Melrose, MA

Peltier Devices or Thermoelectric Modules -  Also known as TE Modules or Solid State Heat Pumps.   __ Designed by G.L. Chemelec

Precision T/C Amplifier with cold junction compensation for the BS2 -  A thermocouple signal is quite small, and the long thermocouple leads often induce quite a bit of noise into the system.  This new circuit is far more accurate, stable, and less immune to noise.  it makes use of a Linear Technologies LT1025 chip to provide CJC (Cold Junction Compensation) , an LTC1098 8-bit 2-channel Analogue to Digital Converter, and an LTC1050 chopper amp.  The feedback resistors are designed to deliver 5V (full scale signal) to the ADC with a 1000 degree C.  Type K signal.  The 1050 is a great amplifier, delivering "rail to rail" output which makes powering the circuit simple.  __ 

Provide Cold-Junction Compensation -  11/28/02  EDN Design Ideas:  The accuracy of any circuit or system that uses a thermocouple to determine the temperature of a process is limited by the accuracy of the method used to perform cold-junction compensation.  in a thermocouple measurement, two wires  __ Circuit Design by Mark Maddox, Analog Devices, Wilmington, MA, and John Wynne, Analog Devices, Limerick, Ireland

Pseudodifferential Multichannel Bridge Digitizer & Digital Cold Junction Compensation -  This circuit enables pseudodifferential measurements of several bridge transducers and absolute temperature measurement.  Consecutive readings are performed on each side of the bridge by selecting the appropriate channel on the LTC2428.  Each output is digitized and the results digitally subtracted to obtain the pseudodifferential __ Linear Technology/Analog Devices App Notes, Apr 29th 2010

RTD & Thermocouple Remote Temperature Digitizer -  The LTC2449 is commonly used with thermocouples and RTDs as shown in this circuit.  Thermocouple outputs produce very small changes (tens of microvolts per degree C) and the output will be negative if the thermocouple is colder than the cold junction connection from the thermocouple to the copper traces on the PCB.  The __ Linear Technology/Analog Devices App Notes, Mar 30th 2010

Simple Circuit Diode Serves as a Sensor for a Thermal Probe -  02/16/12  EDN Design Ideas:  A two-transistor thermal probe can be used to diagnose circuit problems, such as hot components and thermal runaway.   __ Circuit Design by Raju Baddi, Tata Institute of Fundamental Research, Pune, India

Simple Circuit Thermocouple Amplifier -  Continuing with the thermocouple interface concept, the next step is to amplify the TC's millivolt signal into a more readable analog voltage, on the order of 0 to 5VDC.  This simple circuit fits the bill.  The LM358N is a dual op-amp IC .  i'm quite sure any op-amp IC would do fine, just be sure it can accept a Vcc which is compatible with your battery pack.  The IC draws ~ 1.0 mA.  __ 

Single Supply Type K Thermocouple Signal Conditioning Amplifier with Cold Junction Compensation -  The LTC2050 is a zero-drift precision chopper stabilized operational amplifier available in the 5- or 6-lead SOT-23 and SO-8 packages.  it minimizes board area while providing uncompromising DC performance, including 3mV (max) DC offset and 30nV/°C (max) DC offset drift.  it operates from a 2.7V supply while still supporting __ Linear Technology/Analog Devices App Notes, Apr 9th 2010

Thermal considerations matter for Class D Amplifiers -  04/27/06  EDN Design Ideas:  A few basic calculations can help you estimate the IC 's die temperature __ Circuit Design by John Guy, Maxim Integrated Products, San Jose, CA

Thermal Shutdown/ Protection -  The thermal protection of amplifiers is always a concern, since overheating is a sure way to reduce the life of semiconductors and other components.    Where you don't want to use a fan (such as in Project 42 - Thermo-Fan for Amplifier Cooling) , then a complete shutdown can be performed.   __ Designed by Rod Elliott  ESP

Thermal Techniques in Measurement and Control Circuitry -  Linear Technology AN5 __ Designed by Jim Williams - Dec 1st, 1984

Thermocouple Interfaces to Serial Port -  11/09/95 EDN Design Ideas:  The circuit in Figure 1 acquires temperature data via an iBM PC serial port using a thermocouple-based sensor.  The sensor is a type-K (chromel-alumel]thermocouple.  When in contact, the dissimilar metals produce a potential difference that is a function of temperature.  Additional thermocouple junctions __ Circuit Design by Daniel Segarra, Sipex Corp  Billerica, MA

Thermocouple Measurement -  Linear Technology AN28 __ Designed by Jim Williams - Feb 1st, 1988

Thermocouple Measurement -  AN28 Considerations for thermocouple-based temperature measurement are discussed.  A tutorial on temperature sensors summarizes performance of various types, establishing a perspective on thermocouples.  Thermocouples are then focused on.  included are sections covering cold-junction compensation, amplifier selection, d__ Linear Technology/Analog Devices

Thermocouple Temperature Activates Relay -  Voltage from a high temperature thermocouple activates a relay when the sensor detects a temperature above 1000 degrees F. . . Circuit by Dave Johnson P.E.-July, 2006

Thermocouple Temperature Measurement System with Amplifier-Based Cold Junction Compensation  -  The EVAL-CN0271-SDPZ contains the circuit to be evaluated, as described in this note, and the SDP-B controller board is used with the CN-0271 evaluation software to capture the data from the EVAL-CN0271-SDPZ circuit board.  Equipment Needed The following equipment is needed:, Bullet text, Getting Started Load the evaluation software by placing the CN-0271 evaluation software CD in the CD drive of the PC.  Using My Computer, locate the drive that contains the evaluation software.  , Functional Block Diagram See Figure 1 of this circuit note for the circuit block diagram and the EVAL-CN0271-SDPZ-SCH-RevA.  pdf file for t__ Analog Devices from the Lab

Thermocouple Temperature Measurement System with Less Than 500 μA Current Drain  -  For this reason, a linearization procedure is implemented in the CN0206-SDP-0 LabViEW software.  The evaluation software then searches the modified look-up table for the thermocouple input voltage, as sampled by the AD7793 System Calibration in addition to linearizing the thermocouple temperature, the evaluation software performs a two-point calibration.  __ Analog Devices from the Lab

Thermocouple Thermometer with Cold Junction Compensation -  The LTC2997 is a high-accuracy analog output temperature sensor. __ Linear Technology/Analog Devices App Note, Jul 7th 2011

Thermocoupler -  Uses a 16F84 to read a thermocouple via a Maxim's Max6674__ 

Thermoelectric Cooler Temperature Controller for Fiber Optic Lasers -  AN89 Linear Technology This App Note presents circuitry for maintaining 0.01°C temperature control of fiber optic lasers over wide ambient range variations.  The circuitry also features high efficiency power delivery, compact size and low noise.  Detailed descriptions of circuitry and results are given with special emphasis on rmal loop optimization.  An appended__ Linear Technology/Analog Devices

Thermoelectric cooler unipolar drive achieves stable temperatures -  3-Dec-07 EDN Design Ideas:  Depending on the direction of current flow, Peltier devices can both heat and cool __ Circuit Design by W Stephen Woodward, Chapel Hill, NC

Thermoelectric Generator to 2.4V Super Capacitor Charger -  The LTC3105 is a high efficiency step-up DC/DC converter that can operate from input voltages as low as 200mV.  A 250mV start-up capability and integrated maximum power point controller (MPPC) enable operation directly from low voltage, high impedance alternative power sources such as photovoltaic cells, TEGs (thermoelectric__ Linear Technology/Analog Devices App Note, Oct 26th 2010

Type K Thermocouple Signal Conditioner with ±350V Protection from Accidental Contact & Cold Junction Compensation -  A high input impedance amplifier permits the use of large valued input resistors and retains signal accuracy.  This is very useful for protecting both the amplifier and cold junction compensator in thermocouple applications as the sense element can often be inadvertently connected to destructive voltage potentials.  The 1MΩ __ Linear Technology/Analog Devices App Notes, Mar 16th 2010

Ultraprecise Instrumentation Amplifier Makes Robust Thermocouple Interface -  DN302 Design Notes__ Linear Technology/Analog Devices

USB-Based Thermocouple Temperature Measurement System using ARM7  -  in the source code, an ADC sampling rate of 4 Hz is chosen.  When the ADC input PGA is configured for a gain of 32, the noise free code resolution of the ADuC7060/ADuC7061 is greater than 18 bits.  , Circuit Function and Benefits, The following features of the ADuC7060/ADuC7061 are used in this application:, Primary 24-bit Σ-Δ ADC with programmable gain amplifier (PGA) : The PGA is set for a gain of 32 in the software for this application.  ARM7TDMi® core: The powerful 16-/32-bit ARM7 core with integrated 32 kB flash and SRAM memory runs the user code that configures and controls the ADC, processes the ADC conversions from the RTD, and controls the communications over the UART/USB interface__ Analog Devices from the Lab

USB-Based, Thermocouple Temperature Measurement System using ARM Cortex-M3  -  in the source code, an ADC sampling rate of 4 Hz is chosen.  When the ADC input programmable gain amplifier (PGA) is configured for a gain of 32, the noise-free code resolution of the ADuCM360/ ADuCM361 is greater than 18 bits.  , Circuit Function and Benefits, The following features of the ADuCM360/ADuCM361 are used in this application: , A 24-bit Σ-Δ ADC with a PGA set for a gain of 32 in the software for the thermocouple and RTD__ Analog Devices from the Lab

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Thermocouplers:  #'s - N      M - Z


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