Testing thermistor and calibration - sensors

In summary, calibration is the process of determining how the readings of an instrument correspond to actual values of the quantity being measured. It is important for accurate measurements and can be done by comparing the instrument to known values or using known temperatures like ice water and boiling water.
  • #1
meawinner
11
0
Hi please help I have to do a piece of coursework on sensors. I am testing a thermistor and my teacher mentioned something about calibration but I don't know what it is can someone help please. I have taken results for the resistances for every ten degrees from 0 to 150
 
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  • #2
Please do not post the same question in different fora.

To "calibrate" an instrument simply means to determine how the reading of the instrument correspond to actual values of the quantity being measured. For example, if you made your own thermometer by, for example, putting mercury in a thin tube, you would have to determine what height of mercury corresponded to what temperature before you could start. Even instrument that appear to be reporting the value directly need to be calibrated: I got on a scale the other day and, to my amazement it read exactly what I consider to be my ideal weight. Unfortunately, I found out that it wasn't "calibrated" properly and was reading about 10 pounds low!

You calibrate an instrument by using it to measure something that you already know. A thermometer in a factory might be calibrated by comparing it to another thermometer that has been previously calibrated.

A person in the physics forum where you also posted this (and so my first sentence above) suggested that you put your sensor in ice-water which must have temperature 0 degrees C. I would recommend that you also put it in boiling water which must have temperature 100 degrees C. Those two values should allow you to determine the reading for other temperatures.
 
  • #3


Sure, I'd be happy to help! Calibration is the process of adjusting or setting a device to a known standard or reference, in order to ensure its accuracy and reliability. In the case of sensors, calibration involves comparing the sensor's output to a known standard or reference and adjusting it if necessary. This is important because sensors can sometimes become less accurate over time or due to environmental factors.

In your case, you are testing a thermistor, which is a type of temperature sensor that works by changing its resistance as the temperature changes. To calibrate a thermistor, you would need to compare its resistance readings at different temperatures to a known standard, such as a calibrated thermometer. This will allow you to determine if the thermistor is accurately measuring temperature and make any necessary adjustments.

It's great that you have taken results for the resistances at different temperatures. This will allow you to plot a graph and compare it to a known standard to see if the thermistor is accurately measuring temperature. If there are any discrepancies, you may need to calibrate the thermistor by adjusting its resistance values. Your teacher should be able to provide guidance on how to do this.

Overall, calibration is an important step in ensuring the accuracy and reliability of sensors. It may seem like a small detail, but it can make a big difference in the results and data collected by the sensor. I hope this helps and good luck with your coursework!
 

1. What is a thermistor and how does it work?

A thermistor is a type of temperature sensor that uses the change in resistance of a material with temperature to measure temperature. It works by having a resistance that decreases as temperature increases, and vice versa.

2. Why is calibration important for thermistors?

Calibration is important for thermistors because it ensures accurate and precise temperature measurements. Over time, thermistors may drift in their readings due to environmental factors, so calibration helps correct any errors and maintain the accuracy of the sensor.

3. How can I test the accuracy of a thermistor?

To test the accuracy of a thermistor, you can use a reference thermometer to measure the temperature and compare it to the reading of the thermistor. This can be done at various temperatures to see if there are any discrepancies.

4. Can thermistors be recalibrated if they are found to be inaccurate?

Yes, thermistors can be recalibrated if they are found to be inaccurate. This usually involves adjusting the resistance-temperature curve of the thermistor to match a reference thermometer. However, if the thermistor is significantly damaged or malfunctioning, it may need to be replaced.

5. Are there any common sources of error when testing thermistors?

Yes, there are some common sources of error when testing thermistors. These can include external factors such as ambient temperature, humidity, and electromagnetic interference, as well as internal factors like aging of the thermistor or improper installation. Regular maintenance and calibration can help minimize these errors.

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