The principle of temperature and humidity sensor and how to choose?
In addition to electrical signals, the signals that people use every day are optical, but in fact, temperature and humidity can also send signals. The equipment that receives temperature and humidity signals are temperature and humidity sensors.
People use temperature sensors to make many products, the most common one is thermometers and hygrometers. , It is the simplest kind of sensor. There are two types of temperature and humidity sensors. One type is called a contact type sensor that needs to be in contact with the substance, and the other type is non-contact because it contains sensitive components. Here's how to choose a temperature and humidity sensor.
What is a temperature and humidity sensor?
The temperature and humidity sensor refers to a sensor that can sense temperature and humidity and convert it into a usable output signal. The temperature sensor is the core part of the temperature measuring instrument, and there are many varieties. According to the measurement method, it can be divided into two categories: contact type and non-contact type. According to the characteristics of sensor materials and electronic components, it can be divided into two types: thermal resistance and thermocouple.
How to choose a temperature and humidity sensor?
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1. Thermocouple
Thermocouples are the most commonly used temperature sensors in temperature measurement. Its main advantages are the wide temperature range and adaptation to various atmospheric environments, and it is strong, low in price, does not require a power supply, and is the cheapest. A thermocouple is composed of two different metal wires (metal A and metal B) connected at one end. When one end of the thermocouple is heated, there is a potential difference in the thermocouple circuit. The measured potential difference can be used to calculate the temperature.
However, the relationship between voltage and temperature is non-linear. Because the relationship between voltage and temperature is non-linear, it is necessary to make a second measurement for the reference temperature (Tref) and use the test equipment software or hardware to process the voltage-temperature conversion inside the instrument. Finally, the thermocouple temperature (Tx) is obtained. The Agilent 34970A and 34980A data collectors have built-in measurement capabilities.
In short, thermocouples are the simplest and most versatile temperature sensors, but thermocouples are not suitable for high-precision measurements and applications.
2.Thermistor
Thermistors are made of semiconductor materials, and most of them have negative temperature coefficients, that is, the resistance decreases with increasing temperature. Temperature changes will cause large resistance changes, so it is the most sensitive temperature sensor. But the linearity of the thermistor is extremely poor, and it has a lot to do with the production process. The manufacturer cannot give a standardized thermistor curve.
The thermistor is very small in size and responds quickly to temperature changes. But the thermistor needs to use a current source, and its small size also makes it extremely sensitive to self-heating errors.
The thermistor measures the absolute temperature on the two lines with better accuracy, but it is more expensive than a thermocouple, and its measurable temperature range is also smaller than that of a thermocouple. A commonly used thermistor has a resistance value of 5kΩ at 25°C, and a temperature change of 1°C causes a resistance change of 200Ω. Note that the lead resistance of 10Ω only causes a negligible error of 0.05°C. It is very suitable for current control applications that require fast and sensitive temperature measurement. Small size is advantageous for applications with space requirements, but care must be taken to prevent self-heating errors.
The method of the temperature and humidity sensor is introduced here. I believe everyone has a certain understanding of it. The most important thing is not the selection of the temperature and humidity sensor, but everyone should understand the principle of the device and the correct use method. Let it serve people better. Moreover, people have to choose which temperature humidity sensor to use according to their own needs. Technology is still developing. I believe that the application of sensors will gradually increase, and more related materials will be invented to work for people.
The principle of temperature and humidity sensor and how to choose?
In addition to electrical signals, the signals that people use every day are optical, but in fact, temperature and humidity can also send signals. The equipment that receives temperature and humidity signals are temperature and humidity sensors.
People use temperature sensors to make many products, the most common one is thermometers and hygrometers. , It is the simplest kind of sensor. There are two types of temperature and humidity sensors. One type is called a contact type sensor that needs to be in contact with the substance, and the other type is non-contact because it contains sensitive components. Here's how to choose a temperature and humidity sensor.
What is a temperature and humidity sensor?
The temperature and humidity sensor refers to a sensor that can sense temperature and humidity and convert it into a usable output signal. The temperature sensor is the core part of the temperature measuring instrument, and there are many varieties. According to the measurement method, it can be divided into two categories: contact type and non-contact type. According to the characteristics of sensor materials and electronic components, it can be divided into two types: thermal resistance and thermocouple.
How to choose a temperature and humidity sensor?
[https://www.renkeer.com/product/industrial-temperature-and-humidity-sensor-wall-mount/]
1. Thermocouple
Thermocouples are the most commonly used temperature sensors in temperature measurement. Its main advantages are the wide temperature range and adaptation to various atmospheric environments, and it is strong, low in price, does not require a power supply, and is the cheapest. A thermocouple is composed of two different metal wires (metal A and metal B) connected at one end. When one end of the thermocouple is heated, there is a potential difference in the thermocouple circuit. The measured potential difference can be used to calculate the temperature.
However, the relationship between voltage and temperature is non-linear. Because the relationship between voltage and temperature is non-linear, it is necessary to make a second measurement for the reference temperature (Tref) and use the test equipment software or hardware to process the voltage-temperature conversion inside the instrument. Finally, the thermocouple temperature (Tx) is obtained. The Agilent 34970A and 34980A data collectors have built-in measurement capabilities.
In short, thermocouples are the simplest and most versatile temperature sensors, but thermocouples are not suitable for high-precision measurements and applications.
2.Thermistor
Thermistors are made of semiconductor materials, and most of them have negative temperature coefficients, that is, the resistance decreases with increasing temperature. Temperature changes will cause large resistance changes, so it is the most sensitive temperature sensor. But the linearity of the thermistor is extremely poor, and it has a lot to do with the production process. The manufacturer cannot give a standardized thermistor curve.
The thermistor is very small in size and responds quickly to temperature changes. But the thermistor needs to use a current source, and its small size also makes it extremely sensitive to self-heating errors.
The thermistor measures the absolute temperature on the two lines with better accuracy, but it is more expensive than a thermocouple, and its measurable temperature range is also smaller than that of a thermocouple. A commonly used thermistor has a resistance value of 5kΩ at 25°C, and a temperature change of 1°C causes a resistance change of 200Ω. Note that the lead resistance of 10Ω only causes a negligible error of 0.05°C. It is very suitable for current control applications that require fast and sensitive temperature measurement. Small size is advantageous for applications with space requirements, but care must be taken to prevent self-heating errors.
The method of the temperature and humidity sensor is introduced here. I believe everyone has a certain understanding of it. The most important thing is not the selection of the temperature and humidity sensor, but everyone should understand the principle of the device and the correct use method. Let it serve people better. Moreover, people have to choose which temperature humidity sensor to use according to their own needs. Technology is still developing. I believe that the application of sensors will gradually increase, and more related materials will be invented to work for people.
