| 摘要 |
The invention relates to a method and an apparatus for determining the concentration of combustible gases in air using a heated semiconductor sensor. The method is characterised in that the sensor is periodically heated cyclically at intervals and the resistance of the sensor is measured during a measuring phase at the end of each heating phase. The apparatus according to the invention accordingly has a timer circuit (1) which defines, periodically and in an alternating manner, heating phases during which the sensor (2) is heated, and rest phases during which the sensor (2) is not heated, and also a measuring phase at the end of every heating phase during which the resistance of the sensor (2) and, consequently, the gas concentration are measured. The apparatus according to the invention is suitable, in particular, for battery-operated or portable gas warning devices since its current consumption is extremely low. <IMAGE>
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