Arduino Based Temperature Controlling of the Electronic Toothbrush
Solution 1: The required signal conditioning circuit showcases the signal coming from the selected thermistor and fed to an Arduino UNO board. As Arduino board works for a Power Supply of 0-5 Volts, we will use the same source of power to provide power to the thermistor circuit.
The output from the thermistor will be an analog signal, so it will have to be calibrated as per the Arduino UNO’s analog requirement.
The step voltage V = .0048 V ( fig 1)
Now, if Arduino needs to have an analog value =
Then, input Voltage for Arduino (or the output voltage for the temperature sensor) =
Arduino – Thermistor Interfacing- details
Figure 1
Thus, the following figure shows the layout of the circuit to be used for the same:
Figure 2
As per the circuit shown above
Fixed Resistance- The value of the fixed resistance should be roughly equal to the resistance of your thermistor. Here, in this case we have taken it as 10K Ω
Variable Resistance- To find out the relation between Temperature and variable resistance, we shall use with the following formula:
Where, T is the temperature in Kelvin.
Figure 3
Since, (Fig 3)
Thus, if Ω (as per the selected NTC Thermistor of Vishay Electronics)
Then, depending upon the value of which in turn will vary with the temperature, we will get the required voltage as
This voltage will be fed to the Arduino UNO board.
Now as the Adriano’s analog channel is just 10 bit, we will get values from 0-1023.
Here, we have selected the NTC thermistor which falls in 10K category so, we have selected the fixed resistance to be 10 K Ω.
References
http://www.circuitbasics.com/arduino-thermistor-temperature-sensor-tutorial/ (online reference for understanding the temperature- resistance variation)
https://www.vishay.com/thermistors/ntc/ ( online reference for Thermistor data)
