I'm trying to build an anemometer having two NTC , one self-heated at constant temperature, 50 ° C above the air temperature, which is measured by the other . I plan heating it using PWM and a thyristor, but also need to measure the resistance of the same NTC at short intervals to know its temperature, and thus control the PWM I can not find a wiring diagram to facilitate me to perform these two functions in the NTC. I appreciate your help.
To measure the resistance you would use the thermistor as part of a voltage divider. To heat the thermistor you have to connect it between Power and Ground. I would connect one side of the thermistor to +5V and the other side to an analog input pin, a resistor to Ground and an NPN transistor to Ground. A digital pin controls the transistor.
As frequently as you feel the need:
digitalWrite(digitalPin, LOW); // or analogWrite(digitalPin, 0); so shut off the heating tempCount = analogRead(analogPin); // To measure the temperature // calculate temperature from tempCount // Run the temperature through PID to get Output representing PWM value analogWrite(digitalPin, Output);
I do not know if I understood well, so I put the diagram as understood
It is right?