My Experiences With Sensors - Part 2
1) Ds18b20
This sensor is powered with voltages ranging from 3 to 5.5 volts. It has an accuracy of 0.5 degrees Celsius and serves to measure temperatures ranging from -55 to 125 degrees Celsius. It is a programmable digital sensor from 9 to 2 bits.
My experience has shown me that this sensor is more reliable for measuring body temperatures unlike the LM35. The communication protocol of this device is known as "One Wire".
2) Lm35dz
The LM35 temperature sensor gives us a linear scale of 10 mV per degree Celsius. It has an accuracy of 0.5 degrees Celsius and serves to measure temperatures from -55 to 150 degrees Celsius.
This sensor is very popular, and I have used it in prototypes with both Arduino boards and Microchip micro controllers. It is very practical and connects to analog ports of our microphones, to later have the process of analog-to-digital signal conversion, which are: sampling, quantification and coding.
3) Thermistor
This temperature sensor is used to measure values ranging from -40 to 125 degrees Celsius. This sensor is non-linear and has an accuracy of 0.5 degrees Celsius.
Their applications of use are rather of industrial type since they support more load of work that the two sensors LM35 and DS18B20. I have carried out projects with 10 kilo-ohm thermistors. To use it, the Steinhart-Hart formula is used, which shows a relationship between resistance of the thermistor and its temperature.
1/T = A + B ln R+ C (ln R)³
Where A, B and C are coefficients determined by calibration.
4) DHT11 Humidity Sensor
This humidity sensor is fed with voltages ranging from 3 to 5.5 volts and can measure Relative Humidity values ranging from 20 to 90% with an accuracy of 4%. It also helps us to measure temperatures ranging from zero to 50 degrees Celsius with an accuracy of 2%.
This sensor is made of a polymer resistor and has eight digital bits. The communication protocol is 12C and I have used it in projects of Meteorological Stations and Smart Homes. Currently there are sensors that measure a higher humidity and temperature range such as the DHT22, but this is an economic, reliable sensor that can help us to know and practice with them without any problem.
