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Distance Detector View Instructable »
you bring some kind of heat source near the thermistor...(eg-cigarette lighter)...as it is a NTC thermistor, on increase in temperature , the resistance will decrease and hence current will flow from the op-amp ic through the thermistor to the bezzer and hence the buzzer will sound the alarm..
we need a heat source(eg-a cigarette lighter)...bring the heat source near the thermistor...as it is a negative temperature coefficient thermistor.....resistance decreases with increase in temperator..and hence current flows from the operational amplifier through the thermistor to the buzzer which will sound the alarm......
Fire Alarm Circuit Using Op...View Instructable »