Electronics Projects, Gas Detector Circuit ATtiny45 article
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Gas sensors are employed in a wide range of applications in the fields of safety, health, instrumentation etc… Common examples are domestic/commercial alarms for explosive or toxic gases or in automotive application, as gas leakage detectors for LPG powered cars and exhausts detectors inside any fuel-powered truck/car. Such sensors, nowadays, are found also in applications involving air quality control systems and pollution monitoring.
Today’s sensors, while featuring an high sensitivity to a wide gases variety, are very compact in size and have significantly reduced their power consumption to better adapt to portable solutions.
Building a system with a gas sensor is not as easy as it could appear. Despite the sensor could be treated basically as a variable resistor (which value depends on gas concentration in air) the practical implementation in a project should be done considering some design rules, especially if the final circuit is a device to be used in a field where reliability is strongly required (e.g. safety). As an example the internal elements of a sensor (heater and gas sensitive resistors) have to be constantly kept under control to avoid failures leading to a wrong alarm indication; furthermore, if the application needs to achieve a good measurement accuracy, factors like environment temperature, sensor life etc… have to be taken into account.
All those features and controls require to introduce in the project a certain amount of external circuitry (including components like comparators, temperature sensor, spare logic etc…) to carry out functions such us temperature compensation, sensor heating control, sensor warm-up time, sensor life time check and so on…
This project aims to show how the AVR ATtiny45, by means of its peripherals such us ADC, timers and internal temperature sensor, fits perfectly this application and it can be employed to replace a lot of external components while adding extra functionalities at a cost comparable to a simple integrated
Gas Detector Circuit ATtiny45 project files: gas-detector-circuit-attiny45.rar alternative link2 alternative link3