NTC Themistor Module LM393 (Temperature up to 80 Degree Celsius)

This NTC thermistor module has an NTC temperature sensor which gives an only digital output that allows you to easily add over-temperature and under-temperature condition sensing capabilities to your new project. The temperature detection threshold is adjustable via a potentiometer. It uses the LM393 based voltage comparator chip which features a clean and stable digital output signal and a driving ability of 15mA.

The DO output can be directly connected to the microcontroller, and it outputs a high or low-level voltage depending on the temperature changes from the environment.

The DO output can be used directly drive a relay module or as a thermostat switch for controlling external equipment, such as a cooling fan.

Features :

• NTC Thermistor sensor
• LM393 voltage comparator
• Mounting hole for easy installation
• Adjustable threshold via potentiometer

Specification :

• Operating Voltage: 3.3V DC to 5V DC
• Output Current: 15mA
• Output Type: Digital (HIGH OR LOW)
• PCB Size: 32 x 14mm
• Temperature Range: 20°C - 80°C

Package Include:

• 1x LM393 Thermal Sensor Module

Connect with your Arduino Tutorial

Connection: 

• Connet the VCC pin to 3.3V or 5V pin of Arduino. 
• Connect GND of the module to GND and connect DO pin of the module to D2 pin of Arduino.
• Connect an LED to pin 13 or leave it because there is already a LED on your Arduino connected to pin 13. 

The Sketch

Enter the following sketch in Arduino IDE then upload it. If you open your Arduino serial monitor you will be able to see the progress.

const int sensorDOPin = 2;     // connect DO pin to pin 2 of Arduino
const int ledPin =  13;      // the number of the LED pin

// variables will change:
int SensorState = 0;         // variable for the state of the sensor

void setup() {
  // initialize the LED pin as an output:
  pinMode(ledPin, OUTPUT);
  // initialize the sensor pin DO as input
  pinMode(sensorDOPin, INPUT);
}

void loop() {
  // read the state of the sensor value:
  SensorState = digitalRead(sensorDOPin);
// by default, the sensor sends a HIGH all the time
  //if the sensor sends a LOW
    if (SensorState == LOW) {
    // turn LED on:
    digitalWrite(ledPin, HIGH);
  }
  else {
    // turn LED off:
    digitalWrite(ledPin, LOW);
  }
}

Output: When the temperature around the sensor increases, the sensor module output a LOW signal and Arduino turns on the LED. In place of LED, you can connect a 5V relay module to turn on a fan or something operating at 110-220V AC. Make sure that you do that only using a 5V relay module.

NOTE: The default output of thermistor module is HIGH, so, you need to program your Arduino to respond to a LOW because that's what happens when you increase the temperature around the sensor. 

How to Adjust the sensitivity ?

You can adjust the sensitivity of the NTC thermistor based temperature sensor module by moving the potentiometer (a variable resistor present on the module) using a screwdriver. Keep on rotating/moving the potentiometer's knob in clock-wise direction and stop immediately after the GREEN LED on the sensor board turns off. In that way, you can increase or decrease the sensitivity. If you keep on moving the knob even after the GREEN LED has turned off, you will need more heat around the thermistor to turn it on. So, make sure that you have moved the knob according to your requirement.

NOTE: When you see that the module has turned ON the GREEN LED, the output on pin DO is LOW, otherwise, it is always HIGH.

Video:

In the video, they have burnt a match stick to make temperature change around the sensor, but that is actually NOT necessary. You can blow hot air from your mouth and increase the temperature, the effect will be same as you see on the video.