| 摘要 |
PURPOSE:To detect clogging of filter and resultant reduction of airflow rate, by feeding a value calculated on the basis of the radiation constant of a thermistor to a comparator, and turning an indicator lamp ON in response to the output of said comparator. CONSTITUTION:The values of resistances are so selected that electric power consumed by a thermistor can be reduced as small as possible, and the values of resistances R5, R6 are selected such that the rate of temperature change of Ve is substantially equal to that of Vb. In a comparator 14, voltage levels of Ve and Vb are compared. When Vb is equal to or higher than Ve, the output of the comparator 14 is inverted and turns an indicator lamp 3 ON. |
