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 with Thermistor and NE555 circuit

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.

 

 


Circuit diagram of 'Simple Fire Alarm with Thermistor and NE555' was posted under category: Alarm, Sensor. Tags: 555,  alarm circuit,  circuit diagram of fire alarm,  fire alarm,  fire alarm circuit,  fire alarm circuit diagram,  fire alarm circuit using ic 555,  fire alarm project,  ne555,  simple fire alarm,  simple fire alarm circuit,  You can follow any responses to this Simple Fire Alarm with Thermistor and NE555 circuit diagram through the RSS 2.0 feed.

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4 Responses to “Simple Fire Alarm with Thermistor and NE555”

  1. ASAMS PERE writes:
    No. 1 — June 25th, 2011 at 5:34 pm

    I tried it and it worked

  2. nihaar writes:
    No. 2 — September 23rd, 2011 at 1:25 am

    can we replace SL100B with CL100S

  3. Alaiyelumo david gbenga writes:
    No. 3 — November 7th, 2011 at 1:39 am

    Gdday,my is not comment but question.I need to wire about 5 fire alarm with smoke detector.I need wiring diagram

  4. kevin writes:
    No. 4 — March 16th, 2012 at 4:27 pm

    what is the temperature range of the thermisitor?


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