What's the simplest way to calibrate a thermistor?How viable is it to just use 1% resistors and calibrate out the error?Best way to calibrate ADC for current sense MOSFETThermistor CalibrationCalibrate AC measuring channel using DC inputNTC Thermistor IdentificationHow to simulate a thermistor input without a thermistorCalibrating ADC for calibration-free temperature measurementVishay Thermistor Reading IssuesIdentify uncommon thermistor
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What's the simplest way to calibrate a thermistor?
How viable is it to just use 1% resistors and calibrate out the error?Best way to calibrate ADC for current sense MOSFETThermistor CalibrationCalibrate AC measuring channel using DC inputNTC Thermistor IdentificationHow to simulate a thermistor input without a thermistorCalibrating ADC for calibration-free temperature measurementVishay Thermistor Reading IssuesIdentify uncommon thermistor
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$begingroup$
As a hobbyist who don't have access to lab equipment, it really seems impossible to me to be able to calibrate the thermistor that i have.
Of course there are calibrated temperature sensors like DS18B20, but thermistors specially on slow MCUs like Aruino UNO (compared to new MCUs) are snappier.
What options do we have for calibrating a thermistor without using lab equipment?
thermistor calibration
asked 8 hours ago
newbienewbie
791 silver badge10 bronze badges
$endgroup$
|
show 6 more comments
$begingroup$
As a hobbyist who don't have access to lab equipment, it really seems impossible to me to be able to calibrate the thermistor that i have.
Of course there are calibrated temperature sensors like DS18B20, but thermistors specially on slow MCUs like Aruino UNO (compared to new MCUs) are snappier.
What options do we have for calibrating a thermistor without using lab equipment?
thermistor calibration
asked 8 hours ago
newbienewbie
791 silver badge10 bronze badges
$endgroup$
1
$begingroup$
Use a calibrated sensor as the DS18B20 to take a characteristic of the thermistor.
$endgroup$
– Janka
8 hours ago
$begingroup$
What do you mean by "snappier"? That doesn't sound like a good justification if you need to do software correction on the thermistor but you don't with a DS18B20.
$endgroup$
– Elliot Alderson
8 hours ago
$begingroup$
If the one second delay of the DS18B20 on full resolution is your concern, use one of the battery monitor onewire sensors, e.g. the DS2438. It has a fast temperature sensor on chip.
$endgroup$
– Janka
8 hours ago
$begingroup$
@Janka yeah the 750ms delay is really slowing down the processing. but using ds18b20 to calibrate the thermistor is an interesting idea. i need a TO92/small/2-3pin package for temperature sensor.
$endgroup$
– newbie
8 hours ago
$begingroup$
@ElliotAlderson as Janka mentioned the delay on ds18b20 is the problem.
$endgroup$
– newbie
8 hours ago
|
show 6 more comments
$begingroup$
As a hobbyist who don't have access to lab equipment, it really seems impossible to me to be able to calibrate the thermistor that i have.
Of course there are calibrated temperature sensors like DS18B20, but thermistors specially on slow MCUs like Aruino UNO (compared to new MCUs) are snappier.
What options do we have for calibrating a thermistor without using lab equipment?
thermistor calibration
asked 8 hours ago
newbienewbie
791 silver badge10 bronze badges
$endgroup$
As a hobbyist who don't have access to lab equipment, it really seems impossible to me to be able to calibrate the thermistor that i have.
Of course there are calibrated temperature sensors like DS18B20, but thermistors specially on slow MCUs like Aruino UNO (compared to new MCUs) are snappier.
What options do we have for calibrating a thermistor without using lab equipment?
thermistor calibration
thermistor calibration
asked 8 hours ago
newbienewbie
791 silver badge10 bronze badges
asked 8 hours ago
newbienewbie
791 silver badge10 bronze badges
asked 8 hours ago
newbienewbie
791 silver badge10 bronze badges
asked 8 hours ago
newbienewbie
791 silver badge10 bronze badges
asked 8 hours ago
newbienewbie
791 silver badge10 bronze badges
791 silver badge10 bronze badges
1
$begingroup$
Use a calibrated sensor as the DS18B20 to take a characteristic of the thermistor.
$endgroup$
– Janka
8 hours ago
$begingroup$
What do you mean by "snappier"? That doesn't sound like a good justification if you need to do software correction on the thermistor but you don't with a DS18B20.
$endgroup$
– Elliot Alderson
8 hours ago
$begingroup$
If the one second delay of the DS18B20 on full resolution is your concern, use one of the battery monitor onewire sensors, e.g. the DS2438. It has a fast temperature sensor on chip.
$endgroup$
– Janka
8 hours ago
$begingroup$
@Janka yeah the 750ms delay is really slowing down the processing. but using ds18b20 to calibrate the thermistor is an interesting idea. i need a TO92/small/2-3pin package for temperature sensor.
$endgroup$
– newbie
8 hours ago
$begingroup$
@ElliotAlderson as Janka mentioned the delay on ds18b20 is the problem.
$endgroup$
– newbie
8 hours ago
|
show 6 more comments
1
$begingroup$
Use a calibrated sensor as the DS18B20 to take a characteristic of the thermistor.
$endgroup$
– Janka
8 hours ago
$begingroup$
What do you mean by "snappier"? That doesn't sound like a good justification if you need to do software correction on the thermistor but you don't with a DS18B20.
$endgroup$
– Elliot Alderson
8 hours ago
$begingroup$
If the one second delay of the DS18B20 on full resolution is your concern, use one of the battery monitor onewire sensors, e.g. the DS2438. It has a fast temperature sensor on chip.
$endgroup$
– Janka
8 hours ago
$begingroup$
@Janka yeah the 750ms delay is really slowing down the processing. but using ds18b20 to calibrate the thermistor is an interesting idea. i need a TO92/small/2-3pin package for temperature sensor.
$endgroup$
– newbie
8 hours ago
$begingroup$
@ElliotAlderson as Janka mentioned the delay on ds18b20 is the problem.
$endgroup$
– newbie
8 hours ago
1
1
$begingroup$
Use a calibrated sensor as the DS18B20 to take a characteristic of the thermistor.
$endgroup$
– Janka
8 hours ago
$begingroup$
Use a calibrated sensor as the DS18B20 to take a characteristic of the thermistor.
$endgroup$
– Janka
8 hours ago
$begingroup$
What do you mean by "snappier"? That doesn't sound like a good justification if you need to do software correction on the thermistor but you don't with a DS18B20.
$endgroup$
– Elliot Alderson
8 hours ago
$begingroup$
What do you mean by "snappier"? That doesn't sound like a good justification if you need to do software correction on the thermistor but you don't with a DS18B20.
$endgroup$
– Elliot Alderson
8 hours ago
$begingroup$
If the one second delay of the DS18B20 on full resolution is your concern, use one of the battery monitor onewire sensors, e.g. the DS2438. It has a fast temperature sensor on chip.
$endgroup$
– Janka
8 hours ago
$begingroup$
If the one second delay of the DS18B20 on full resolution is your concern, use one of the battery monitor onewire sensors, e.g. the DS2438. It has a fast temperature sensor on chip.
$endgroup$
– Janka
8 hours ago
$begingroup$
@Janka yeah the 750ms delay is really slowing down the processing. but using ds18b20 to calibrate the thermistor is an interesting idea. i need a TO92/small/2-3pin package for temperature sensor.
$endgroup$
– newbie
8 hours ago
$begingroup$
@Janka yeah the 750ms delay is really slowing down the processing. but using ds18b20 to calibrate the thermistor is an interesting idea. i need a TO92/small/2-3pin package for temperature sensor.
$endgroup$
– newbie
8 hours ago
$begingroup$
@ElliotAlderson as Janka mentioned the delay on ds18b20 is the problem.
$endgroup$
– newbie
8 hours ago
$begingroup$
@ElliotAlderson as Janka mentioned the delay on ds18b20 is the problem.
$endgroup$
– newbie
8 hours ago
|
show 6 more comments
3 Answers
3
active
oldest
votes
$begingroup$
Fill a cup with ice cubes and pour in water to fill up to the brim. Give it the occasional stir. When the ice is starting to melt you'll be at 0°C. Stick the sensor into the water and take a reading.
If your sensor can tolerate it, drop it into a kettle of boiling water. At sea-level that will give you a 100°C reference reading.
If you need to heatshrink your sensor for waterproofing you will have to allow some time for the reading to stabilise.
simulate this circuit – Schematic created using CircuitLab
Figure 1. Simple linear calibration curve.
- y1 is the resistance, voltage or ADC reading at 0°C.
- y2 is the resistance, voltage or ADC reading at 100°C.
$$ T = 100 fracy - y1y2-y1 $$
where y = reading at temperature T.
As pointed out in the comments, if you are using a thermistor you will need to check the datasheet for linearity. If this simple approach isn't good enough you will have to use a polynomial calculation or a look-up table in a micro-controller.
answered 8 hours ago
TransistorTransistor
99k8 gold badges98 silver badges218 bronze badges
$endgroup$
$begingroup$
can you please add the calculation or a source to read about calculating the temperature using this method?
$endgroup$
– newbie
8 hours ago
1
$begingroup$
This will give you two points, which you can use to calculate beta for those two temps. The response in that range will be nowhere near linear (assuming the OP means it when s/he calls it a "thermistor"),
$endgroup$
– Scott Seidman
8 hours ago
1
$begingroup$
@newbie: See the update.
$endgroup$
– Transistor
8 hours ago
$begingroup$
@newbie As Transistor writes at the end, this approach may not be good enough. I can't imagine it would ever be good enough, frankly. The only thing this approach will get you is repeatability (supposed 40°C will always be the same supposed 40°C, but it may really be 20°C or 60°C).
$endgroup$
– piojo
1 hour ago
add a comment |
$begingroup$
Reading Thermistor is a little tricky.
The above method of calibration, wield no yield to an error detection, It would create two points of a logarithmic curve (the thermistor response curve.
This means, for every 0.1°C of changue of temperature, the correspondent changue on resistance will vary, depending on the range of the temperature. 
At first, you might look an error about 2 to 5°C off the real temperature, yet no error, only a bad reading.
You dont post any details on how are you reading this thermistor, Arduino May be?
I must say, some libraries dont work at all, so you must create a especial function to do so.
Post on detailed explanation on how to characterize and read an thermistor.
The post is in spanish, but in the code tags, all explanation in in plain English.
Once you have obtain you ABC coeficients, your error will be about 0.1°C from another measurement, even in a 6m long run of LAN wire.
This test read at the same time the 4 thermistors, You can see a small difference in temperature from 2 of them I was holding briefly in my fingers.
answered 2 hours ago
Alejandro SantiagoAlejandro Santiago
286 bronze badges
$endgroup$
$begingroup$
@newbie This is the right approach. If you can't follow the instructions, reply to me in a day or so and I'll look up my arduino code and look up the references it contains and write an answer here.
$endgroup$
– piojo
1 hour ago
add a comment |
$begingroup$
Linearized thermometers have a gain & offset error.
- Bipolar supplies will likely have offset nulled at 0V.
- single supply bridges will have some Vref or R ratio of Vref or Vcc where offset is nulled at that deign temperature. Usually this is symmetrical, so that would correspond to the midpoint of your design range.
thermistors are calibrated at 25’C with a specific sensitivity curve with 2 variables.
to calibrate it you only need 2 measurements
- Null adjust where error voltage =null = 0 , Vt=Vref
- gain adjust at T max
- for a typical 4 R bridge, that is usually midpoint temp.
- use any better thermometer for calibration or
- use ice water and boiling water for 0, 100’C
answered 1 hour ago
Sunnyskyguy EE75Sunnyskyguy EE75
80.3k2 gold badges30 silver badges116 bronze badges
$endgroup$
add a comment |
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3 Answers
3
active
oldest
votes
3 Answers
3
active
oldest
votes
active
oldest
votes
active
oldest
votes
$begingroup$
Fill a cup with ice cubes and pour in water to fill up to the brim. Give it the occasional stir. When the ice is starting to melt you'll be at 0°C. Stick the sensor into the water and take a reading.
If your sensor can tolerate it, drop it into a kettle of boiling water. At sea-level that will give you a 100°C reference reading.
If you need to heatshrink your sensor for waterproofing you will have to allow some time for the reading to stabilise.
simulate this circuit – Schematic created using CircuitLab
Figure 1. Simple linear calibration curve.
- y1 is the resistance, voltage or ADC reading at 0°C.
- y2 is the resistance, voltage or ADC reading at 100°C.
$$ T = 100 fracy - y1y2-y1 $$
where y = reading at temperature T.
As pointed out in the comments, if you are using a thermistor you will need to check the datasheet for linearity. If this simple approach isn't good enough you will have to use a polynomial calculation or a look-up table in a micro-controller.
answered 8 hours ago
TransistorTransistor
99k8 gold badges98 silver badges218 bronze badges
$endgroup$
$begingroup$
can you please add the calculation or a source to read about calculating the temperature using this method?
$endgroup$
– newbie
8 hours ago
1
$begingroup$
This will give you two points, which you can use to calculate beta for those two temps. The response in that range will be nowhere near linear (assuming the OP means it when s/he calls it a "thermistor"),
$endgroup$
– Scott Seidman
8 hours ago
1
$begingroup$
@newbie: See the update.
$endgroup$
– Transistor
8 hours ago
$begingroup$
@newbie As Transistor writes at the end, this approach may not be good enough. I can't imagine it would ever be good enough, frankly. The only thing this approach will get you is repeatability (supposed 40°C will always be the same supposed 40°C, but it may really be 20°C or 60°C).
$endgroup$
– piojo
1 hour ago
add a comment |
$begingroup$
Fill a cup with ice cubes and pour in water to fill up to the brim. Give it the occasional stir. When the ice is starting to melt you'll be at 0°C. Stick the sensor into the water and take a reading.
If your sensor can tolerate it, drop it into a kettle of boiling water. At sea-level that will give you a 100°C reference reading.
If you need to heatshrink your sensor for waterproofing you will have to allow some time for the reading to stabilise.
simulate this circuit – Schematic created using CircuitLab
Figure 1. Simple linear calibration curve.
- y1 is the resistance, voltage or ADC reading at 0°C.
- y2 is the resistance, voltage or ADC reading at 100°C.
$$ T = 100 fracy - y1y2-y1 $$
where y = reading at temperature T.
As pointed out in the comments, if you are using a thermistor you will need to check the datasheet for linearity. If this simple approach isn't good enough you will have to use a polynomial calculation or a look-up table in a micro-controller.
answered 8 hours ago
TransistorTransistor
99k8 gold badges98 silver badges218 bronze badges
$endgroup$
$begingroup$
can you please add the calculation or a source to read about calculating the temperature using this method?
$endgroup$
– newbie
8 hours ago
1
$begingroup$
This will give you two points, which you can use to calculate beta for those two temps. The response in that range will be nowhere near linear (assuming the OP means it when s/he calls it a "thermistor"),
$endgroup$
– Scott Seidman
8 hours ago
1
$begingroup$
@newbie: See the update.
$endgroup$
– Transistor
8 hours ago
$begingroup$
@newbie As Transistor writes at the end, this approach may not be good enough. I can't imagine it would ever be good enough, frankly. The only thing this approach will get you is repeatability (supposed 40°C will always be the same supposed 40°C, but it may really be 20°C or 60°C).
$endgroup$
– piojo
1 hour ago
add a comment |
$begingroup$
Fill a cup with ice cubes and pour in water to fill up to the brim. Give it the occasional stir. When the ice is starting to melt you'll be at 0°C. Stick the sensor into the water and take a reading.
If your sensor can tolerate it, drop it into a kettle of boiling water. At sea-level that will give you a 100°C reference reading.
If you need to heatshrink your sensor for waterproofing you will have to allow some time for the reading to stabilise.
simulate this circuit – Schematic created using CircuitLab
Figure 1. Simple linear calibration curve.
- y1 is the resistance, voltage or ADC reading at 0°C.
- y2 is the resistance, voltage or ADC reading at 100°C.
$$ T = 100 fracy - y1y2-y1 $$
where y = reading at temperature T.
As pointed out in the comments, if you are using a thermistor you will need to check the datasheet for linearity. If this simple approach isn't good enough you will have to use a polynomial calculation or a look-up table in a micro-controller.
answered 8 hours ago
TransistorTransistor
99k8 gold badges98 silver badges218 bronze badges
$endgroup$
Fill a cup with ice cubes and pour in water to fill up to the brim. Give it the occasional stir. When the ice is starting to melt you'll be at 0°C. Stick the sensor into the water and take a reading.
If your sensor can tolerate it, drop it into a kettle of boiling water. At sea-level that will give you a 100°C reference reading.
If you need to heatshrink your sensor for waterproofing you will have to allow some time for the reading to stabilise.
simulate this circuit – Schematic created using CircuitLab
Figure 1. Simple linear calibration curve.
- y1 is the resistance, voltage or ADC reading at 0°C.
- y2 is the resistance, voltage or ADC reading at 100°C.
$$ T = 100 fracy - y1y2-y1 $$
where y = reading at temperature T.
As pointed out in the comments, if you are using a thermistor you will need to check the datasheet for linearity. If this simple approach isn't good enough you will have to use a polynomial calculation or a look-up table in a micro-controller.
answered 8 hours ago
TransistorTransistor
99k8 gold badges98 silver badges218 bronze badges
edited 8 hours ago
answered 8 hours ago
TransistorTransistor
99k8 gold badges98 silver badges218 bronze badges
answered 8 hours ago
TransistorTransistor
99k8 gold badges98 silver badges218 bronze badges
answered 8 hours ago
TransistorTransistor
99k8 gold badges98 silver badges218 bronze badges
99k8 gold badges98 silver badges218 bronze badges
$begingroup$
can you please add the calculation or a source to read about calculating the temperature using this method?
$endgroup$
– newbie
8 hours ago
1
$begingroup$
This will give you two points, which you can use to calculate beta for those two temps. The response in that range will be nowhere near linear (assuming the OP means it when s/he calls it a "thermistor"),
$endgroup$
– Scott Seidman
8 hours ago
1
$begingroup$
@newbie: See the update.
$endgroup$
– Transistor
8 hours ago
$begingroup$
@newbie As Transistor writes at the end, this approach may not be good enough. I can't imagine it would ever be good enough, frankly. The only thing this approach will get you is repeatability (supposed 40°C will always be the same supposed 40°C, but it may really be 20°C or 60°C).
$endgroup$
– piojo
1 hour ago
add a comment |
$begingroup$
can you please add the calculation or a source to read about calculating the temperature using this method?
$endgroup$
– newbie
8 hours ago
1
$begingroup$
This will give you two points, which you can use to calculate beta for those two temps. The response in that range will be nowhere near linear (assuming the OP means it when s/he calls it a "thermistor"),
$endgroup$
– Scott Seidman
8 hours ago
1
$begingroup$
@newbie: See the update.
$endgroup$
– Transistor
8 hours ago
$begingroup$
@newbie As Transistor writes at the end, this approach may not be good enough. I can't imagine it would ever be good enough, frankly. The only thing this approach will get you is repeatability (supposed 40°C will always be the same supposed 40°C, but it may really be 20°C or 60°C).
$endgroup$
– piojo
1 hour ago
$begingroup$
can you please add the calculation or a source to read about calculating the temperature using this method?
$endgroup$
– newbie
8 hours ago
$begingroup$
can you please add the calculation or a source to read about calculating the temperature using this method?
$endgroup$
– newbie
8 hours ago
1
1
$begingroup$
This will give you two points, which you can use to calculate beta for those two temps. The response in that range will be nowhere near linear (assuming the OP means it when s/he calls it a "thermistor"),
$endgroup$
– Scott Seidman
8 hours ago
$begingroup$
This will give you two points, which you can use to calculate beta for those two temps. The response in that range will be nowhere near linear (assuming the OP means it when s/he calls it a "thermistor"),
$endgroup$
– Scott Seidman
8 hours ago
1
1
$begingroup$
@newbie: See the update.
$endgroup$
– Transistor
8 hours ago
$begingroup$
@newbie: See the update.
$endgroup$
– Transistor
8 hours ago
$begingroup$
@newbie As Transistor writes at the end, this approach may not be good enough. I can't imagine it would ever be good enough, frankly. The only thing this approach will get you is repeatability (supposed 40°C will always be the same supposed 40°C, but it may really be 20°C or 60°C).
$endgroup$
– piojo
1 hour ago
$begingroup$
@newbie As Transistor writes at the end, this approach may not be good enough. I can't imagine it would ever be good enough, frankly. The only thing this approach will get you is repeatability (supposed 40°C will always be the same supposed 40°C, but it may really be 20°C or 60°C).
$endgroup$
– piojo
1 hour ago
add a comment |
$begingroup$
Reading Thermistor is a little tricky.
The above method of calibration, wield no yield to an error detection, It would create two points of a logarithmic curve (the thermistor response curve.
This means, for every 0.1°C of changue of temperature, the correspondent changue on resistance will vary, depending on the range of the temperature.
At first, you might look an error about 2 to 5°C off the real temperature, yet no error, only a bad reading.
You dont post any details on how are you reading this thermistor, Arduino May be?
I must say, some libraries dont work at all, so you must create a especial function to do so.
Post on detailed explanation on how to characterize and read an thermistor.
The post is in spanish, but in the code tags, all explanation in in plain English.
Once you have obtain you ABC coeficients, your error will be about 0.1°C from another measurement, even in a 6m long run of LAN wire.
This test read at the same time the 4 thermistors, You can see a small difference in temperature from 2 of them I was holding briefly in my fingers.
answered 2 hours ago
Alejandro SantiagoAlejandro Santiago
286 bronze badges
$endgroup$
$begingroup$
@newbie This is the right approach. If you can't follow the instructions, reply to me in a day or so and I'll look up my arduino code and look up the references it contains and write an answer here.
$endgroup$
– piojo
1 hour ago
add a comment |
$begingroup$
Reading Thermistor is a little tricky.
The above method of calibration, wield no yield to an error detection, It would create two points of a logarithmic curve (the thermistor response curve.
This means, for every 0.1°C of changue of temperature, the correspondent changue on resistance will vary, depending on the range of the temperature.
At first, you might look an error about 2 to 5°C off the real temperature, yet no error, only a bad reading.
You dont post any details on how are you reading this thermistor, Arduino May be?
I must say, some libraries dont work at all, so you must create a especial function to do so.
Post on detailed explanation on how to characterize and read an thermistor.
The post is in spanish, but in the code tags, all explanation in in plain English.
Once you have obtain you ABC coeficients, your error will be about 0.1°C from another measurement, even in a 6m long run of LAN wire.
This test read at the same time the 4 thermistors, You can see a small difference in temperature from 2 of them I was holding briefly in my fingers.
answered 2 hours ago
Alejandro SantiagoAlejandro Santiago
286 bronze badges
$endgroup$
$begingroup$
@newbie This is the right approach. If you can't follow the instructions, reply to me in a day or so and I'll look up my arduino code and look up the references it contains and write an answer here.
$endgroup$
– piojo
1 hour ago
add a comment |
$begingroup$
Reading Thermistor is a little tricky.
The above method of calibration, wield no yield to an error detection, It would create two points of a logarithmic curve (the thermistor response curve.
This means, for every 0.1°C of changue of temperature, the correspondent changue on resistance will vary, depending on the range of the temperature.
At first, you might look an error about 2 to 5°C off the real temperature, yet no error, only a bad reading.
You dont post any details on how are you reading this thermistor, Arduino May be?
I must say, some libraries dont work at all, so you must create a especial function to do so.
Post on detailed explanation on how to characterize and read an thermistor.
The post is in spanish, but in the code tags, all explanation in in plain English.
Once you have obtain you ABC coeficients, your error will be about 0.1°C from another measurement, even in a 6m long run of LAN wire.
This test read at the same time the 4 thermistors, You can see a small difference in temperature from 2 of them I was holding briefly in my fingers.
answered 2 hours ago
Alejandro SantiagoAlejandro Santiago
286 bronze badges
$endgroup$
Reading Thermistor is a little tricky.
The above method of calibration, wield no yield to an error detection, It would create two points of a logarithmic curve (the thermistor response curve.
This means, for every 0.1°C of changue of temperature, the correspondent changue on resistance will vary, depending on the range of the temperature.
At first, you might look an error about 2 to 5°C off the real temperature, yet no error, only a bad reading.
You dont post any details on how are you reading this thermistor, Arduino May be?
I must say, some libraries dont work at all, so you must create a especial function to do so.
Post on detailed explanation on how to characterize and read an thermistor.
The post is in spanish, but in the code tags, all explanation in in plain English.
Once you have obtain you ABC coeficients, your error will be about 0.1°C from another measurement, even in a 6m long run of LAN wire.
This test read at the same time the 4 thermistors, You can see a small difference in temperature from 2 of them I was holding briefly in my fingers.
answered 2 hours ago
Alejandro SantiagoAlejandro Santiago
286 bronze badges
answered 2 hours ago
Alejandro SantiagoAlejandro Santiago
286 bronze badges
answered 2 hours ago
Alejandro SantiagoAlejandro Santiago
286 bronze badges
answered 2 hours ago
Alejandro SantiagoAlejandro Santiago
286 bronze badges
286 bronze badges
$begingroup$
@newbie This is the right approach. If you can't follow the instructions, reply to me in a day or so and I'll look up my arduino code and look up the references it contains and write an answer here.
$endgroup$
– piojo
1 hour ago
add a comment |
$begingroup$
@newbie This is the right approach. If you can't follow the instructions, reply to me in a day or so and I'll look up my arduino code and look up the references it contains and write an answer here.
$endgroup$
– piojo
1 hour ago
$begingroup$
@newbie This is the right approach. If you can't follow the instructions, reply to me in a day or so and I'll look up my arduino code and look up the references it contains and write an answer here.
$endgroup$
– piojo
1 hour ago
$begingroup$
@newbie This is the right approach. If you can't follow the instructions, reply to me in a day or so and I'll look up my arduino code and look up the references it contains and write an answer here.
$endgroup$
– piojo
1 hour ago
add a comment |
$begingroup$
Linearized thermometers have a gain & offset error.
- Bipolar supplies will likely have offset nulled at 0V.
- single supply bridges will have some Vref or R ratio of Vref or Vcc where offset is nulled at that deign temperature. Usually this is symmetrical, so that would correspond to the midpoint of your design range.
thermistors are calibrated at 25’C with a specific sensitivity curve with 2 variables.
to calibrate it you only need 2 measurements
- Null adjust where error voltage =null = 0 , Vt=Vref
- gain adjust at T max
- for a typical 4 R bridge, that is usually midpoint temp.
- use any better thermometer for calibration or
- use ice water and boiling water for 0, 100’C
answered 1 hour ago
Sunnyskyguy EE75Sunnyskyguy EE75
80.3k2 gold badges30 silver badges116 bronze badges
$endgroup$
add a comment |
$begingroup$
Linearized thermometers have a gain & offset error.
- Bipolar supplies will likely have offset nulled at 0V.
- single supply bridges will have some Vref or R ratio of Vref or Vcc where offset is nulled at that deign temperature. Usually this is symmetrical, so that would correspond to the midpoint of your design range.
thermistors are calibrated at 25’C with a specific sensitivity curve with 2 variables.
to calibrate it you only need 2 measurements
- Null adjust where error voltage =null = 0 , Vt=Vref
- gain adjust at T max
- for a typical 4 R bridge, that is usually midpoint temp.
- use any better thermometer for calibration or
- use ice water and boiling water for 0, 100’C
answered 1 hour ago
Sunnyskyguy EE75Sunnyskyguy EE75
80.3k2 gold badges30 silver badges116 bronze badges
$endgroup$
add a comment |
$begingroup$
Linearized thermometers have a gain & offset error.
- Bipolar supplies will likely have offset nulled at 0V.
- single supply bridges will have some Vref or R ratio of Vref or Vcc where offset is nulled at that deign temperature. Usually this is symmetrical, so that would correspond to the midpoint of your design range.
thermistors are calibrated at 25’C with a specific sensitivity curve with 2 variables.
to calibrate it you only need 2 measurements
- Null adjust where error voltage =null = 0 , Vt=Vref
- gain adjust at T max
- for a typical 4 R bridge, that is usually midpoint temp.
- use any better thermometer for calibration or
- use ice water and boiling water for 0, 100’C
answered 1 hour ago
Sunnyskyguy EE75Sunnyskyguy EE75
80.3k2 gold badges30 silver badges116 bronze badges
$endgroup$
Linearized thermometers have a gain & offset error.
- Bipolar supplies will likely have offset nulled at 0V.
- single supply bridges will have some Vref or R ratio of Vref or Vcc where offset is nulled at that deign temperature. Usually this is symmetrical, so that would correspond to the midpoint of your design range.
thermistors are calibrated at 25’C with a specific sensitivity curve with 2 variables.
to calibrate it you only need 2 measurements
- Null adjust where error voltage =null = 0 , Vt=Vref
- gain adjust at T max
- for a typical 4 R bridge, that is usually midpoint temp.
- use any better thermometer for calibration or
- use ice water and boiling water for 0, 100’C
answered 1 hour ago
Sunnyskyguy EE75Sunnyskyguy EE75
80.3k2 gold badges30 silver badges116 bronze badges
answered 1 hour ago
Sunnyskyguy EE75Sunnyskyguy EE75
80.3k2 gold badges30 silver badges116 bronze badges
answered 1 hour ago
Sunnyskyguy EE75Sunnyskyguy EE75
80.3k2 gold badges30 silver badges116 bronze badges
answered 1 hour ago
Sunnyskyguy EE75Sunnyskyguy EE75
80.3k2 gold badges30 silver badges116 bronze badges
80.3k2 gold badges30 silver badges116 bronze badges
add a comment |
add a comment |
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$begingroup$
Use a calibrated sensor as the DS18B20 to take a characteristic of the thermistor.
$endgroup$
– Janka
8 hours ago
$begingroup$
What do you mean by "snappier"? That doesn't sound like a good justification if you need to do software correction on the thermistor but you don't with a DS18B20.
$endgroup$
– Elliot Alderson
8 hours ago
$begingroup$
If the one second delay of the DS18B20 on full resolution is your concern, use one of the battery monitor onewire sensors, e.g. the DS2438. It has a fast temperature sensor on chip.
$endgroup$
– Janka
8 hours ago
$begingroup$
@Janka yeah the 750ms delay is really slowing down the processing. but using ds18b20 to calibrate the thermistor is an interesting idea. i need a TO92/small/2-3pin package for temperature sensor.
$endgroup$
– newbie
8 hours ago
$begingroup$
@ElliotAlderson as Janka mentioned the delay on ds18b20 is the problem.
$endgroup$
– newbie
8 hours ago