SAFETY CIRCUIT FOR COMBUSTION APPARATUS

PROBLEM TO BE SOLVED: To prevent a microcomputer from being unnecessarily reset when any abnormality at the microcomputer is detected at combustion apparatus to control a burning state through the microcomputer, further, to permanently reset the microcomputer as needed and to avoid the runaway of the microcomputer. SOLUTION: This circuit is provided with an abnormality detecting part 19 for detecting abnormality at a microcomputer 18 corresponding to a signal from the microcomputer 18, abnormality level detecting part 20 for detecting this abnormality and outputting an abnormality level signal expressing the level of the abnormality, and reset signal generating part 21. for controlling the reset operation of the microcomputer 18 corresponding to this level of the abnormality. When the state of judging the microcomputer 18 abnormal is not continued for first prescribed time, the microcomputer 1.8 is not reset but when such a state is continued for the first prescribed time, the microcomputer 18 is reset and further when the abnormality is continued for second prescribed time longer than the first prescribed time, the microcomputer 18 is permanently reset.