@▷ Simple Fire Alarm with Thermistor and NE555 circuit diagram | Diagram for Schematic

Simple Fire Alarm with Thermistor and NE555 circuit diagram



The following circuit is a simple fire alarm circuit based NE555 timer and use thermistor as a temperature detector. This sensor will activate the transistor when the temperature is in high value.

simple fire alarm based NE555

The thermistor will have a low resistance at high temperature, while at low temperature, the transistor resistance is high. This characteristic of thermitor is used to build the fire alarm.

The difference value of thermistor will decide the transistor 1 and transistor 2 to switching on or off, while TI and T2 has function to drive the NE555 to generate audio frequency. We can say that the thermistor’s condition (its sensing) will determine the alarm to be on or off.

 

 

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