NTC Thermistor Module with LM393 Digital Temperature Threshold Output The Thermistor Module uses an NTC thermistor and an LM393-style comparator circuit to detect temperature threshold changes. It is useful for over-temperature alarms, fan triggers, thermal experiments, and basic heat detection projects. The onboard potentiometer adjusts the trigger threshold, and the comparator provides a clean digital switching output. For comparator details, see the TI LM393 product page; for easy wiring, pair the module with an OpenELAB Sensor Shield V5. Use this module when a simple hot/cold digital trigger is enough. For precise temperature values, choose an analog thermistor circuit or a calibrated digital temperature sensor. Technical Specifications Parameter Value Sensor type NTC thermistor temperature threshold module Comparator LM393 wide-voltage comparator class circuit Output type Digital switching output 0/1 Operating voltage 3.3 V to 5 V Output drive Comparator output, over 15 mA class driving ability noted Sensitivity adjustment Onboard potentiometer sets temperature threshold PCB size Approx. 3.2 x 1.4 cm Mounting Bolt holes for fixed installation Recommended use Temperature alarm, fan trigger, heat detection Precision note Threshold module, not calibrated thermometer Development support Arduino, ESP32, STM32, Raspberry Pi Pico GPIO Board Layout & Label Guide NTC thermistor: Senses temperature change near the module. LM393 comparator: Converts thermistor divider voltage into a digital output. Potentiometer: Sets the trigger threshold. VCC/GND: 3.3 V to 5 V power input and ground. Digital output: Connect to a controller GPIO pin. Mounting hole: Fixes the module near the heat source or airflow path. Thermal placement: Avoid heat from the controller unless that is the target to detect. Application Scenarios 1. Digital Threshold Readout Read the digital output from Thermistor Module and print its trigger state for threshold adjustment. const int SENSOR_PIN = 2; void setup() { pinMode(SENSOR_PIN, INPUT); Serial.begin(115200); } void loop() { int state = digitalRead(SENSOR_PIN); Serial.println(state == LOW ? "triggered" : "normal"); delay(100); } 2. LED or Alarm Output Mirror the sensor trigger to an LED, buzzer driver, or relay input. const int SENSOR_PIN = 2; const int ALARM_PIN = 8; void setup() { pinMode(SENSOR_PIN, INPUT); pinMode(ALARM_PIN, OUTPUT); } void loop() { bool triggered = digitalRead(SENSOR_PIN) == LOW; digitalWrite(ALARM_PIN, triggered ? HIGH : LOW); } 3. Event Counter Count stable trigger events with a debounce delay for tilt, temperature, or comparator modules. const int SENSOR_PIN = 2; unsigned long events = 0; unsigned long lastEvent = 0; void setup() { pinMode(SENSOR_PIN, INPUT); Serial.begin(115200); } void loop() { if (digitalRead(SENSOR_PIN) == LOW && millis() - lastEvent > 300) { events++; lastEvent = millis(); Serial.println(events); } } Packing List 1 x Thermistor Module FAQ Q: Does this output temperature in degrees?A: No. It provides a digital threshold output. Q: Can I adjust the trigger point?A: Yes. Use the onboard potentiometer. Q: Can it work at 3.3 V?A: Yes, it supports 3.3 V to 5 V operation. Q: What is the LM393 used for?A: It compares the thermistor signal with the adjustable threshold and switches the output. Q: Why does it trigger in reverse?A: NTC resistance decreases as temperature rises, and module logic may be active-low; test your board state. Q: Can it control a fan?A: Yes through a controller or transistor/relay driver rated for the fan. Q: Is it accurate enough for thermostats?A: Use calibration and hysteresis if you need a stable control point. Q: Can it be mounted against a surface?A: Yes, but ensure the thermistor has good thermal contact and the PCB is protected.
