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Sensors / Detectors: Temperature Sensors

Temperature Sensors:      #'s - A      B - G      H - L      M - Q      R - S      T - Z


Sensors / Detectors -- Main Page


Last Updated: October 18, 2017 05:04 AM

Circuits Designed by Dave Johnson, P.E. :

12v Cooling Fan Thermostat -  This circuit will turn on a 12v DC powered cooling fan when the air temperature reaches a certain high temperature and will keep the fan turned on until the temperature drops below a second lower level.  Both the high and low temperatures are both adjustable. . . Circuit by Dave Johnson P.E.-February, 2011

4 to 20ma Current Loop Senses Temperature -  I designed a circuit similar to this one years ago to accurately measure the air temperature inside a building 1000s of feet from a control room.  The circuit uses a very robust current loop method.  it uses a highly accurate semiconductor temperature sensor . . . Hobby Circuit designed by David Johnson P.E.-July, 2000

Alarm Sounds At Freezing Temperatures -  This electronic hobby circuit below is designed to activate a beeper alarm, whenever the outside air temperature is below 0 degrees C (32F).  A 9v battery powers the hobby circuit.  The average 9ua current is so low that the battery should last for many years . . . Hobby Circuit designed by David A. Johnson P.E.-July, 2006

Capacitance Proximity Switch
Draws very low power - Ideal for battery-powered applications
6 Models Available - Call 806-368-7747


Links to electronic circuits, electronic schematics, designs for engineers, hobbyists, students & inventors:

0-100°C Temperature Detector -  Here’s a temperature monitoring system capable of remote temperature reading without transmission losses in the conditioning circuit.  The IC AD590 (IC 4) is used as a temperature transducer.  This semiconductor transducer provides ...__ Electronics Projects for You

10°C to 40°C Thermistor Thermometer -  The LT1789 is a micropower, precision instrumentation amplifiers that are optimized for single supply operation from 2.2V to 36V.  The quiescent current is 95μA max, the inputs common mode to ground and the output swings within 110mV of ground.  The gain is set with a single external resistor for a gain range of 1 to 1000 for__ Linear Technology/Analog Devices App Note, Mar 30th 2010

12 Volt Differential Temperature Controller -  for hot water and hot air system control __ Designed by G. Forrest Cook

12-Bit, 4-20mA Loop-Powered Thermocouple Measurement System using ARM Cortex-M3  -  Required software for the J-Link OB is included in the software installation.  The source code used to test the circuit can be downloaded as a zip file from the ADuCM360 product page.  The source code uses the function libraries provided with the example code.  __ Analog Devices from the Lab

12v Cooling Fan Thermostat -  This circuit will turn on a 12v DC powered cooling fan when the air temperature reaches a certain high temperature and will keep the fan turned on until the temperature drops below a second lower level.  Both the high and low temperatures are both adjustable. . . Circuit by Dave Johnson P.E.-February, 2011

14-Bit, 4-20 mA, Loop Powered, Ther Mocouple Temperature Measurement System using ARM Cortex-M3  -  The duty cycle of the PWM is configured in software to control the voltage across the 47.5 Ω R LOOP resistor, which in turn sets the loop current.  This ADC measurement can be used as feedback for the PWM control software to adjust the 4 mA-to-20 mA current setting__ Analog Devices from the Lab

2-Terminal Temperature-to-Current Thermometer Suitable for Use at the End of Long Wire Runs -  By adding the LT3092 to a thermistor kit along with three 0.1% accuracy resistors and one final trim, a very accurate 2-terminal temperature-to-current converter can be built.  This circuit measures 700μA operating current at 0°C, dropping by 2μA every degree until 100°C, at which point the current measures 500μA.  The obvious __ Linear Technology/Analog Devices App Note, Mar 16th 2011

2-Wire Thermistor 0°C to 100°C Temperature Transducer with 4mA to 20mA Output -  The LTC1040 is a monolithic CMOS dual comparator manufactured using Linear Technology’s enhanced LTCMOS TM silicon gate process.  Extremely low operating power levels are achieved by internally switching the comparator ON for short periods of time.  The CMOS output logic holds the output information continuously while not consuming __ Linear Technology/Analog Devices App Note, Mar 30th 2010

3-Channel Thermocouple Temperature Measurement System with 0.25 ° C Accuracy  -  if oil bath measurements are not required, the EVAL-CN0172-SDPZ can be used to measure the three thermocouple temperatures by using the USB interface with a PC and the software provided on the CD.  information and details regarding test setup and calibration, and how to use the evaluation software for data capture can be found in the CN0172 User Guide found at: www.  analog.  com/CN0172- UserGuide__ Analog Devices from the Lab

4 mA-to-20 mA Loop-Powered Temperature Monitor using the ADuC7060/ADuC7061 Precision Analog Microcontroller  -  This ADC measurement can be used as feedback for the PWM control software to adjust the 4 mA-to-20 mA current setting.  , The primary ADC of the ADuC7060/ADuC7061 measures the voltage across the RTD__ Analog Devices from the Lab

4 to 20ma Current Loop Senses Temperature -  I designed a circuit similar to this one years ago to accurately measure the air temperature inside a building 1000s of feet from a control room.  The circuit uses a very robust current loop method.  it uses a highly accurate semiconductor temperature sensor . . . Hobby Circuit designed by David Johnson P.E.-July, 2000

50MHz Thermistor RMS to DC Converter using 5V Supply -  The LT1014 is the first precision quad operational amplifier which directly upgrades designs in the industry standard 14-pin DiP LM324/LM348/OP-11/4156 pin configuration.  it is no longer necessary to compromise specifications, while saving board space and cost, as compared to single operational amplifiers.  __ Linear Technology/Analog Devices App Note, Mar 30th 2010

5V Powered Thermistor Heating/Cooling Automatic Thermostat -  The LTC1040 is a monolithic CMOS dual comparator manufactured using Linear Technology’s enhanced LTCMOS TM silicon gate process.  Extremely low operating power levels are achieved by internally switching the comparator ON for short periods of time.  The CMOS output logic holds the output information continuously while not consuming __ Linear Technology/Analog Devices App Note, Mar 30th 2010

A Crystal Heater construction project -  OK, here is the circuit I used - See image below.   The original National Semiconductor circuit had a 30 K resistor in series with a 400 µF cap., both in parallel with the 100 K resistor on the input of the 1st LM324 section.   I found that combo to actually destabilize the operation of the controller for this particular application, so I removed them & changed the 2 µF cap in series with the 10 megohm resistor to 5 µF.__ Bobengler   NO6B

A Digital Thermometer/Thermostat -  it covers the range from -55 °C to 1200°C and has an over or under temperature alarm and switched outputs for thermostatic control.__ SiliconChip

A Galvanically Isolated Thermistor Digitizer -  The LTC1799 is a precision oscillator that is easy to use and occupies very little PC board space.  The oscillator frequency is programmed by a single external resistor (RSET).  The LTC1799 has been designed for high accuracy operation (≤1.5% frequency error) without the need for external trim components__ Linear Technology/Analog Devices App Note, ,Mar 30th 2010

A 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.  __ 

A PID Temperature Controller -  What's a PiD controller? PiD stands for "proportional integral differential" and relates to a process which seeks to continuously correct the error between a measured variable and a desired setting by calculating an appropriate correction process.  in practice, it can largely avoid the large overshoots and undershoots that occur in simple temerature control systems.__ SiliconChip

A 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.  __ 

A Simple Circuit Thermistor Interface to an ADC -  App Note/ 1753 / Oct-03__ Maxim Integrated

A 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.  __ 

A Temperature Sensor Control -  A basic circuit using Diodes to detect temperature differences __ Designed by G.L. Chemelec

A Thermoelectric Cooler Temperature Controller for Fiber Optic Lasers: Climatic Pampering for Temperamental Lasers -  Linear Technology AN89 __ Designed by Jim Williams - Apr 1st, 2001

A Thermostat Control for Electric Heaters -  One Advantage of these two units is the Sensor can be placed Away from the heater, therefore sensing the Actual Room temperature, not the direct heat from the heater.  These can also be used in a confined space with a Heat Lamp, to create a Drying Oven  __ Designed by G.L. Chemelec

A Very Accurate Thermometer/Thermostat -  Based on the very accurate Dallas DS18B20 digital temperature sensor, this thermometer/thermostat provides accurate readings to one decimal point.  The LCD shows current, minimum and maximum temperature readings.  An internal buzzer will sound when temperature limits are exceeded.  it is intended for controlling air conditioners, heaters, cool rooms, wine cellars, etc.  The software is user-customisable.__ SiliconChip

Accelerometer output gives temperature info -  11/19/98 EDN Design Ideas:  NOTE:  File contain several designs.  Scroll to find this one.  The ADXL202 dual-axis micromachined accelerometer from Analog Devices (Norwood, MA) is appropriate for high-resolution applications.  in these applications, you sometimes need to know the ambient temperature for control purposes or for circuit-drift compensation.  The scheme in Figure 1 offers a novel way to convey temperature information to the system µC without the need for an A/D converter or any additional i/O pins. __ Circuit Design by Harvey Weinberg, Analog Devices Inc, Cambridge, MA

Accurate USB 2.0 temperature sensor needs only a handful of parts -  05/24/07  EDN Design Ideas:  A USB-to-serial converter forms the heart of an accurate USB temperature sensor __ Circuit Design by Silvio Lauckner, Ismaning, Germany

Acoustic Thermometry Measures Temperature to 0.1 Degree -  Start Clock Launches Acoustic Pulse into Measurement Path, Sets Width Decode Flip-Flop High.  Acoustic Paths Return Pulse, Amplified by Receiver, Trips Trigger, Resetting Flip-Flop.  Resultant Q Width Output, Representing Path’s Temperature Dependent Transit Time, is Converted to Temperature Reading by Microprocessor.  __ Linear Technology/Analog Devices App Note, Apr 29th 2011

ADC's Reference Improves RTD Measurements -  10/27/94 EDN Design Ideas:  Temperature measurements using RTDs (resistance-temperature detectors]generally employ bridge circuits with stable power supplies for signal conditioning.  Unfortunately, this scheme generally produces nonlinear outputs.  A linear b __ Circuit Design by Bharat Heavy Electricals Ltd, Tiruchirapalli, India

Alarm Sounds At Freezing Temperatures -  This electronic hobby circuit below is designed to activate a beeper alarm, whenever the outside air temperature is below 0 degrees C (32F).  A 9v battery powers the hobby circuit.  The average 9ua current is so low that the battery should last for many years . . . Hobby Circuit designed by David A. Johnson P.E.-July, 2006

Amplifier Thermal 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

An introduction to acoustic thermometry -  04/21/11  EDN Technical Article: Use an ultrasonic transducer to measure air temperature in an olive jar.   __ Circuit Design by Jim Williams, EDN's most revered contributor, passed away in June 2011 after a stroke.  He was 63.

AN131 - An Introduction to Acoustic Thermometry -  Linear Technology AN131 __ Designed by Jim Williams - Apr 26th, 2011

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

AN290 Practical Temperature Measurement -  Application Note__ Aligent

AN75 - Circuitry for Signal Conditioning and Power Conversion -  Linear Technology AN75 __ Designed by Jim Williams - Mar 1st, 1999

AN89 - A Thermoelectric Cooler Temperature Controller for Fiber Optic Lasers: Climatic Pampering for Temperamental Lasers -  Linear Technology AN89 __ Designed by Jim Williams - Apr 1st, 2001

AN98 - Signal Sources, Conditioners and Power Circuitry Circuits of the Fall, 2004 -  Linear Technology AN98 __ Designed by Jim Williams - Nov 19th, 2004

Anticipator Improves On Earlier Idea -  EDN Design Ideas:  05/24/2012   A self-biasing thermistor circuit had an overall dominant thermal/electrical time constant as small as 25 msec but had a significantly rounded response following a square (thermal) input pulse of 100 msec; the source was a pulsed blue LED.  A single-op-amp-based “anticipator-like” circuit generated a more faithful picture of the actual input excitation, and improved on the circuit described in a previous Design ideas (Reference 1).  The lowpass filter in Figure 1, with an RC time constant of approximately 25 msec, models the circuit. __ Circuit Design by Nicholas Lockerbie, Scottish Universities Physics Alliance, Glasgow, Scotland

Anticipator Speeds Signal Settling to a Final Value -  03/17/11  EDN Design Ideas:  Use a differentiator circuit to predict the final value of an exponential signal.  The circuit in this Design idea anticipates, or jumps instantly to, the final voltage of an input-signal change.  it relies on the fact that the intended input signal changes exponentially with a known time constant.  This circuit was adapted from a 1970s-era instant-reading electronic thermometer, which displayed a patient’s body temperature within seconds after a thermometer probe was placed under the patient’s tongue.  it exploits the fact that the temperature probe’s exponential thermal response-time characteristic is known.   __ Circuit Design by Tim Regan, Linear Technology App Note, San Jose, CA

AT89C2051 Digital Thermometer & Clock -  Build your own a laboratory instrument for measuring time and temperature.  The DigiThermo demonstrates the use of 'C' language, a dual-slope converter, LCD interfacing, and digital filtering as well.   __ Designed by Wichit Sirichote

Automatic Heat Detector -  This circuit uses a complementary pair comprising npn metallic transistor T1 (BC109) and pnp germanium transistor T2 (AC188) to detect heat (due to outbreak of fire, etc) in the vicinity and...__ Electronics Projects for You

Automotive Thermometer -  Keep tabs on in-car temperatures__ SiliconChip

AVR Thermometer -  Build a simple digital thermometer using 20-pin uC, AVR 90S2313 and DS1820.  The thermometer is capable of measuring temperature from -55C to +125C!  with 1 degreeC resolution.   __ Designed by Wichit Sirichote

AVR thermometer / thermostat based on an Atmel ATtiny2313 -  This is a simple thermostat that I designed to use with my central heating system.  When is not in use acts like a thermometer.  The prototype uses the AT90S2313 but it’s obsolete now, so I changed it with the pin to pin compatible ATtiny2313 (the photo shows my first prototype).  __ AVR Projects Dim


Temperature Sensors:      #'s - A      B - G      H - L      M - Q      R - S      T - Z

 


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