Are you also scared that starting or revving your car in an enclosed garage might fill it with carbon monoxide and make it dangerous? Do you want to make sure that the quality of air in your house/ office is free from toxic gas? So, continue reading as we will be discussing a portable gas detector using an electrochemical sensor, the reference design is for a battery-powered carbon monoxide sensor.
Image of Carbon Monoxide gas detector module based on reference design(Source: ADI)
CN0234 from Analog devices is a reference design for a Carbon Monoxide detector. The ultra-low power design runs on a single supply, and uses an Alphasense CO-AX Carbon Monoxide sensor to detect the toxic gas. Electrochemical sensors are gas specific and have usable resolutions under one part per million (ppm) of gas concentration. The circuit uses a programmable rheostat which allows it to work with different gas sensors without changing the components. The reference design can work for several months with a couple of AAA cells, moreover, it can be upgraded to work with dual power source, therefore, extending its runtime.
The circuit uses a programmable rheostat AD5271, which enables it to work with various gas sensors, moreover, the rheostat offers better resistance temperature coefficient making the design more accurate. The reference design uses dual op amps to achieve lower noise and better accuracy. When connected to an ADC and a microcontroller, or a microcontroller with a built-in ADC, battery life of this reference design can be from over six months to over one year.
Circuit diagram of the gas detector
This reference design has been tested by Analog Devices. The company has also provided additional resources such as schematics, Gerber files, etc. You can find additional data about the reference design on the company’s website. To read more about this reference design click here.