MHZ19B Carbon Dioxide (CO2) Infrared (NDIR) Sensor — Compact, Accurate CO2 Detection for Monitors and DIY Projects Why you need it Reliable CO2 measurement helps maintain healthy indoor air quality, improve ventilation, and optimize HVAC or air purifier control. The MHZ19B provides stable, selective CO2 readings using nondispersive infrared (NDIR) detection, giving you a dependable signal for monitors, controllers, and embedded projects. Compact, easy to integrate, and compatible with common microcontrollers, it solves the challenge of adding precise CO2 sensing without complex calibration or bulky equipment. Key benefits selectivity and longterm stability from NDIR sensing minimizes crosssensitivity to other gases. Multiple output options (UART serial and PWM) make integration straightforward for Arduino, Raspberry Pi, ESP32 and other controllers. Builtin temperature compensation and optional automatic baseline correction (ABC) improve realworld accuracy and reduce maintenance. Compact form factor and low power needs allow mounting in portable monitors, wall units, or retrofitted ventilation systems. Main features and attributes Model: MHZ19B (carbon dioxide infrared CO2 sensor) Sensing principle: Nondispersive infrared (NDIR) Measurement range: up to 5000 ppm CO2 (typical for this model) Resolution: 1 ppm (typical) Interfaces: TTL UART (serial) and PWM output for easy integration Supply voltage: 5 V DC (typical) Builtin temperature compensation to improve measurement accuracy across normal indoor ranges Optional automatic baseline correction (ABC) that can be disabled if fixed calibration is required Compact, lightweight housing suitable for embedded installations and small enclosures Low power consumption and stable longterm performance appropriate for continuous monitoring Compatibility and integration Directly compatible with Arduino, Raspberry Pi, ESP32, STM32, and other microcontrollers using UART serial or PWM inputs. Simple commands and responses over UART make reading values and configuring parameters straightforward. Wellsuited for custom CO2 monitors, DIY air quality projects, smart home devices, and building control systems. Use cases Indoor air quality monitoring: Install the MHZ19B in offices, classrooms, meeting rooms, or homes to track CO2 levels and trigger ventilation or reminders when concentrations rise. HVAC and ventilation control: Feed realtime CO2 data to building systems to adjust fresh air intake or fan speed, improving energy efficiency while maintaining healthy air. Greenhouses and cultivation environments: Monitor CO2 concentrations to support plant growth regimes and maintain target CO2 levels for better yields. What makes it practical The MHZ19B balances accuracy, stability, and compact design for both hobbyists and professional applications. Clear digital and PWM outputs reduce the engineering effort required to add CO2 sensing to existing systems. Temperature compensation and optional ABC simplify daytoday operation and reduce recalibration frequency. What to expect in use Fast, continuous CO2 readings suitable for realtime monitoring and control. Easy wiring to 5 Vpowered systems, with a minimal footprint for retrofits or devices. A widely adopted sensor form factor and interface set, so community resources and code examples are commonly available for rapid development. Note For critical applications, follow recommended calibration procedures and installation guidelines regarding airflow and sensor placement to ensure representative readings.