Friday, February 23, 2024

PIN Diode Based Fire Sensor

D. Mohan Kumar was associate professor at Government College for Women, Thiruvananthapuram, Kerala

Construction and testing

A single side PCB for the PIN diode based fire sensor is shown in Fig. 4 and its component layout in Fig. 5. Enclose the PCB in a small box in such a way that you can connect PIN diode BPW34 easily at the rear side of the box. Install the PIN diode in a suitable place and cover it such that normal light/sunlight does not fall on it.

Fig. 4: PCB layout of the PIN diode fire alarm
Fig. 4: PCB layout of the PIN diode fire alarm
Fig. 5: Component layout of the PCB
Fig. 5: Component layout of the PCB

Testing the circuit is simple. Normally, when there is no fire flame near the PIN diode, the piezo buzzer does not sound. When a fire flame is sensed by the PIN diode, piezo buzzer sounds an alarm. Its detection range is around two metres. It can also detect sparks in the mains wiring due to short-circuit.

Download PCB and component layout PDFs: click here

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The article was originally published in June 2016 and has been recently updated.


    • the sensor is a photo diode,so it senses light.i.e: it does not senses the flame ,it senses the light from the flame ,so it easily gets activated when it is exposed to light.So the above model is used in lockers such that if any one tries to open it or when it catches fire the sensor gets activated.

  1. Could we use a series combination of cylindrical capacitor , valued 0.4763 microfarad each in place of ceramic disc capacitor , valued 0.22 microfarad . For the above mentioned fire alarm project based on PIN photo diode.

  2. I am a professor of electrical engineering. I would like to get complete knowledge about fire detector for
    our university. I would like to get it installed as project.
    Kindly supply all information regarding that on my mail.

  3. The project is designed to give alarm for 15 seconds if there is fire. Timing is decided by the resistors R5, R6 and capacitor C1. you can change these values inorder to change the output timing. Please refer the article for detail.


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