Design Contest Flash Innovation 2003

Gas Alarm

Motorola Flash Innovation 2003 – Design Contest
First Prize

Radek Vaclavik
Czech Republic


The Gas Alarm is ideal for use in the kitchen or garage, near a gas boiler, or while camping. The 68HC908QT2 microcontroller-based combustible gas detector is small, cost-effective, and flexible. The electronic circuit evaluates change in the internal sensor resistance. A few comparators are used to watch the reference voltage, sensor resistance, and sensor proper operation. An oscillator isn’t needed because the detector uses the Nitron microcontroller’s oscillator. There are built-in delays for after power-up and after gas is first detected in order to avoid false alarms. By changing the sensor type, the detector can be used for various gases. You can also add an additional comparator to detect two different gas concentrations.

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Contest Ended: June 30, 2003

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Gas Alarm

by Circuit Cellar Staff time to read: 1 min